Title: Comparative behavior, acoustical signals, and ecology of New World Passalidae (Coleoptera)
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Title: Comparative behavior, acoustical signals, and ecology of New World Passalidae (Coleoptera)
Physical Description: xi, 127 leaves : ill. ; 28 cm.
Language: English
Creator: Schuster, Jack Clayton, 1944-
Copyright Date: 1975
 Subjects
Subject: Passalidae   ( lcsh )
Entomology and Nematology thesis Ph. D
Dissertations, Academic -- Entomology and Nematology -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Jack Clayton Schuster.
Thesis: Thesis (Ph. D.)--University of Florida, 1975.
Bibliography: Bibliography: leaves 122-125.
General Note: Typescript.
General Note: Vita.
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Bibliographic ID: UF00099152
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: alephbibnum - 000569127
notis - ACZ5886
oclc - 02276448

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COMPARATIVE BEHAVIOR, ACOUSTICAL SIGNALS, AND ECOLOGY OF
NEW WORLD PASSALIDAE (COLEOPTERA)













BY

JACK CLAYTON SCHUSTER


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY




UNIVERSITY OF FLORIDA


1975


































To Laura















ACKNOWLEDGMENTS


I am deeply appreciative of T. J. Walker for his aid

in various aspects of field work, perceptive criticisms,

advice, patience, and dedication to teaching, both in and

out of the classroom. I am indebted to W. G. Eden, Chairman

of the Department of Entomology and Nematology, and to

J. E. Lloyd, F. C. Johnson, R. I. Sailer, D. W. Hall,

and D. L. Mays for criticisms of the manuscript. P. Eeyes-

Castillo and R. Ing were instrumental in insect identifi-

cation. Many people extended their kind hospitality during

field work in various countries of whom I would mention the

generosity of P. Reyes-Castillo, M. and B. Robinson, W. and

M. J. Eberhard, M. Moreno, B. MacLeod, P. Aguilar, Alcoa

Exploration Co., and the University of Mexico Biological

Station. R. and G. Wilkerson, L. Liceras, C. Arevalo,

C. Cartagena, H. Terleira, P. Drummond, and R. Walker pro-

vided welcome aid in collecting passalids. I am grateful

to J. C. Webb and J. Benner for their time and facilities at

the U.S.D.A. I.A.B.B. laboratory in Gainesville, Florida,

as well as the Universidad Nacional Agraria de la Selva,

Tingo Maria, Peru, the University of Florida, U.S. Peace

Corps Peru, and the Organization for Tropical Studies for

their support and the research opportunities they provided.










I am particularly appreciative of R. Mays and D. Mays for

help with the myriad last minute details. Most of all, I

greatly value the continuous aid of L. B. Schuster in all

phases of the work.
















TABLE OF CONTENTS


Page

ACKNOWLEDGMENTS . . . . . . . . . iii

LIST OF TABLES . . . . . . . . . vii

LIST OF FIGURES . . . . . . . . .. viii

ABSTRACT . . . . . . . . ... . x

INTRODUCTION . . . . . . . . ... .. 1

BIOGEOGRAPIHY, ECOLOGY, AND LIFE CYCLE . . . . 3

Range . . . . . . . . . .. 3
Macrohabitat . . . . . . . . . 4
Microhabitats. . . . . . . . .. 6
Stages . . . . . . . . .. . . 10
Eggs . . . .. . . . ... . . 11
Larvae . . . . . . . . . . .12
Pupae . . . . . . . . ... .. . 13
Teneral Adults . . . . . . . .. 17
Mature Adults . . . . . . . .. 17
Periodicity . . . . . . . . .. 25

ACOUSTICAL SIGNALS AND BEHAVIOR . . . . .. 34

Mechanisms of Sound Production . . . . .. 35
Frequency Analysis ............... 37
Sound Pressure Level Analysis .......... 39
Sound Structures, Behavioral Contexts, and Species
Repertoire . . . . . . . . .. 39
Materials and Methods . . . . . .. 39
Results . . . . . . . . ... . 44
Sound structure . . . . . . .. 44
Behavioral contexts and species comparison 65
Mating sequence . . . . . . .. 65
Courtship initiation . . . . .. 65
Courtship . . . . . . ... 69
Post-copulation . . . . . .. 74
Aggression . . . . . . . .. 76
Disturbance . . . . . . . .. 93










Page

Other solo . . . . . . ... .104
Larval interactions . . . . ... 107
Field Experiments . . . . . . .. 108

DISCUSSION AND CONCLUSIONS . . . . . .. 115

LITERATURE CITED . . . . . . . ... 122

BIOGRAPHICAL SKETCH . . . . . . . .. 126















LIST OF TABLES


Table Page

1. The months in which were found the differ-
ent life stages of 6 species of Passalidae
in the region of Tingo Maria, Peru . . .. 26

2. Comparison of sound pressure levels (S.P.L)
and body length of 4 individuals of 3 species
of Passalidae . . . . . . . .. 41

3. Types of disturbance signals recorded or
heard from individuals of 42 species of New
World Passalidae from 11 countries . . .. 45

4. Types of sounds observed in 10 behavioral
contexts other than disturbance from 24
species of Passalidae . . . . . .. 48

5. Sounds produced by aggressor during inter-
specific mixing experiments in which a single
beetle was introduced into a container or 1
or more individuals of a sympatric species 85

6. Information possibly conveyed by acoustical
signals during intense aggression and
possible response of aggressee to siga s . 110

7. Sounds produced by passalids during field log
introduction experiments in Florida and the
Dominican Republic . . . . . ... 112















LIST OF FIGURES


Fig. Page

1. Passalus punctiger--pupal cases in laboratory
rea :ig trays . . . . . . . ... 14

2. Passalus puncti.er--pupal case containing pre-
pupa . . . . . . . . . .. . 15

3. Passalus punctiaer--pupal case containing pupa 16

4. Odontotaenius disjunctus. Time of year of life
stages and colonization . . . . . 31

5. Representative frequency analyses of disturbance
signals of Passalidae . .. . .... . 40

6. Audiospectrograms of Type A sounds . . .. 52

7. Audiospectrograms of Type B sounds . . .. 54

8. Audiospectrograms of Type C. sounds . . .. 56

9. Audiospectrogram of Type D sounds . . .. 58

10. Audiospectrogram of E sounds; signal produced
while alone by Passalus spinifer, 26.50C . 60

11. Audiospectrogram of Type F sound produced dur-
ing post-aggression pushups by Passalus
convexus, 25.50C . . . . . . .. 61

12. Audiospectrograms of Type G sounds produced
while feeding by Passalus punctiger, 280C . 62

13. Oscillograms of bars of Type C phonatomes of 3
species of Passalidae . . . . . ... 64

14. Odontotaenius disjunctuis--audio. spectrogram of
larval sounds when contacting adult, 29.50C . 66

15. Odontotaenius disjunctus--positions of beetles
and sound types during the mating sequence 67

16. Odontotaenius disjunctus--courtship, d and ?
260C . . . . . . . . . . 72


viii


1










Fig. Page

17. Passalus punctatostriatus--sounds produced
during courtship initiation, Type C by e
Type A by P 260C . . . . . . .. 73

18. Odontotaenius striatopunctatus during strong
mutual aggression . . . . . . .. 78

19. Odontotaenius disjunctus--sound types and
position of beetles during aggression by one
beetle . . . . . . . .... . 80

20. Odontotaenius zodi.acus--audiospectrogram of
aggressive signal, 24oC . . . .... . 81

21. Petrojoides sp.n.--audiospcctrogram of Type C
( C) aggressive signal, -^C . . ... 82

22. Passalus affinis--audiospectrogram of aggres-
sive sLgnal, 22C . . . . . ... 83

23. Passalus affinis--audiospectrograms of Type E
aggressive signals of 2 ss . . . ... 88

24. Passalus punctatostriatus--audiospectrogran
of sequence of Type A to Type B disturbance
signals of one beetle, 22.50C . . ... 96

25. Passalus interstitialis--audiospectrogram of
sequence of Type to Type A disturbance sig-
nals of one beetle, 29.50C . . . . . 97

26. Passalus inops--audiospectrogram of distur-
bance signal, 23.5C . . . . . ... 99

27. Oileus nonstriatus--audiospectrogram of dis-
turbance signal, 25.5C . . . . ... 100

28. Passalus punctatostriatus--immobile position
assumed when disturbed by observer . . .. 101

29. Audiospectrogram of disturbance signal of o
mutillid wasp . . . . . . ... 105

30. Melanolestes picipes (Reduviidae)--audiospec-
trogram of disturbance signal 22.50C ... . 106










Abstract of Dissertetion Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

COMPARATIVE BEIIAVIOR, ACOUSTICAL SIGNALS, AND ECOLOGY OF
NEW WORLD PASSALIDAE (COLEOPTERA)

By
Jack Clayton Schuster

June 1975

Chairman: Thomas J. Walker
Major Department: Entomology and Nematology


Behavioral and life history studies, including

laboratory and field experiments, were made of the subsocial

family Passalidae. Rotting logs are colonized by either a

single male or female black adult that is subsequently

joined by a member of the opposite sex. Both members of

an established pair aggress against another individual of

either sex when it is introduced into their tunnel system.

The evolutionary advantage of a beetle attacking a member

of the opposite sex may result from high juvenile mortality

in the presence of non-related adults. Adult passalids

sometimes live more than 2 years and produce -:.;re than 1

brood. Cooperative care of juveniles by parents and the

continued residence of adult offspring in the tunnel system

with their parents characterize the Passalidae at a stage

between primitive subsocial and truly social behavior. Up

to 10 species may occupy the same rotting log, apparently

without connections between their respective tunnel systems.










Many species occur in wet tropical forests; few occur in

desert and temperate regions or at altitudes above 2800 m.

Seasonally synchronized life cycles are associated with

seasonal cold or dryness. Acoustical signals recorded from

adults of 42 species belong to 7 structural sound types.

The signals occur during the mating sequence, aggression,

disturbance, and other situations. Larvae stridulate in

at least 3 behavioral contexts. In 1 species, Odoitotaenius

disjunctus, adults produced 5 of the 7 sound types in 11

behavioral contexts for a total of 14 acoustical si'-nals,

i.e., sound type-context combinations, more than is known

for any other arthropod spe~ is. P. aalid signals differ

little among species, much less for exm-ple, than the

signals of Orthoptera. Passalids are n-table in that

females as well as males make a variety of signals.















INTRODUCTION


Passalids are subsocial* beetles that have an elabo-

rate system of sound communicat -t:. For example, I have

discovered more kinds of acourcical signals for one species

of passalid than are known for any other arthropod species.

This paper compares acoust cai signals and behavior within

the family, and presents life-history informatio-n in an-

ticipation that this will. providee a basis for studies of

the evolution of social I.khav or a r.. con.iun cation.

Little has been reported previously coc-erning the be-

havior of passalids, despite their ubiquitous occ rence

in rotting wood over much of the world. .-yes-Castillo

(1970) summarized the literature on the behavior and

ecology, as well as other features, of Passalidae. He also

included habitat data, where known, for each New World

genus. Gray's paper (19l6) on Odonto'-r.enius disjunctus is

the most comprehensive work on the biology of a single

passalid species.


*Subsocial insects are those that care for their own nymphs
or larvae but lack one or more of the following charac-
teristics: cooperative brood care, reproductive castes,
and overlap between generations. The latter characteris-
tics when found together delineate the truly social, or
eusocial, insects (e.g., bees, ants, termites) (Wilson,
1971).










The small size of the family, about 500 spp. compared

to, for example, 30,000 spp. in the Scarabaeidae (Woodruff,

1973), is conducive to a comparative study of behavior.

The family contains 2 subfamilies, according to the most

recent taxonomic revision (Reyes-Castillo, 1970). Only

Passalinae occurs in the New World where it is represented

by 2 tribes, the Passalini which is pan-tropical and the

Proculini which is Neotropical except for Odontotaonis

disjunctus (Illiger). This specie-, formerly known as

Pascalus cornutus Fabricius and Popil -s disjunctus Illiger,

occurs in the eastern United States. The relatively large

size and slow movements of passalids facilitate observation,

as does the fact that they can be easily maintained in the

laboratory. Since most species are tropical and live in

rotting wood, the widespread cutting of the world's forests,

particularly in the tropics, may result in a temporary in-

crease in size of some passalid populations. Subsequently,

however, the final elimination of the wood may result in

extinction for many species. These facts suggest that now

is the opportune time for investigation of Passalidae.
















BIOGEOGRAPHY, ECOLOGY, AND LIFE CYCLE

Range


Passalid ;e are primarily pan-tropical. The northern-

most record I have found for any passalid is for Odonto-

taenius disjunctus in Saginaw Co., Michigan. In the

southern hemisphere, one species, Pharochilus pcli us

(Burm.), occurs in Tasmania (Dibb, 1928) and a number of

species are found in northern Argentina. I examined tem-

pernte forests in Chile and found no evidence of Passalidae.

The record of Passalus convexus DlIman from Chile (Lueder-

waldt, 1931) is probably erroneous. The forests of

southern Chile, as well as those of the Pacific Northwest

of the United States, lack passalids and are separated from

the nearest passalid populations by extensive dry regions.

Passalids may never have inhabited Chile; however, the only

fossil known for the family is from the Oligocene of

Oregon (Chaney, 1927). The New World passalid fauna ex-

tends into the Pacific with Popilius lenzi Kuwert on Costa

Rica's Isla del Coco (Van Doesburg, 1953) and Passalus

interruptus (L.) in the Galapagos Islands. Only the

Passalini are represented in the West Indies (Reyes-

Castillo, 1970).


I










The greatest diversity of species within the tribe

Proculini occurs in the mountains of Mesoamerica and

northern South America, whereas the greatest diversity of

New World Passalini is found in South America.

Although Blackwelder (1944) lists the familiar Odonto-

taenius disjurctus as occurring as far south as Brazil,

its range is actually Ontario, Carnda, and the eastern

United State:: (Reyen-Castillo, 1970, 1973). In the United

States, it occurs north to Massachusetts and Michigan,

south to central Florida and west to Kansas. Reyes-

Castillo and I have examined many of the world's majo-

collections and have collected in rost of the countries for

which it has been cited and have yet to encounter a speci-

men from outside this range.


Macrohabitat

Passalids occur most commonly in moist forests. Both

species and individuals are abundant in tropical rain

forests (near Tingo Maria, Peru, 1 of every 3 or 4 logs

contained passalids) and quite common in montane forests

such as the cloud forests, pine forests, and pine-oak for-

ests of Mesoanerica. They are less abundant in the drier,

tropical deciduous forests (near Canas, Costa Rica),only 6

of 150 to 200 logs contained passalids. A few species

occur in savanna (Reyes-Castillo, 1970). Odontotaenius

disjunctus inhabits northern temperate deciduous forests,

including the relatively dry turkey-oak sandhills or north









central Florida. One species, Ptichopus angulatus

(Percheron), is symbiotic with leaf-cutter ants in desert

and forest regions.

Passalids are not found in regions of prolonged cool

temperatures such as occur at latitudes greater than 450 or

on tropical mountains above 3500 m. The diversity of

species decreases as these extremes are approached. Onlv

2 species are found in north temperate regions where

freezing temperatures and snow occur: Cylindrocaulus

patalis Fairm. of Japan and Odontotaenius disjunctus of the

eastern United States and Canada.

In the neotropical mountains, the few species of

Passalidae that occur above 2800 m belong to the tribe

Proculini and, as compiled from Reyes-Castillo (1970), are

the following:

Chondrocephalus granulifrons to 3300 m in pine forest
of Guatemala

Vindex agnoscendus at 2800 m in Mexico

Petrejoides recticornis at 2860 m in Mexico

Petrejoides jalapensis at 2800 m in Mexico

Undulifer inciscus at 2800 m in Mexico

Pseudacanthus spp. to 3000 m in southern Mexico

Odontotaenius striatulus at 2900 m in Ecuador
(synonymous with 0. striatopunctatus?)

Publius crassus to 3000 m

The only representatives of the New World Passalini known

from above 2200 m are a species of Passalus that I collected










at 2250 m on the Sierra Talamanca in Costa Rica and an

undescribed species of Passalus that I found in a log with

larvae and eggs at 2750 m in Ecuador.

In Peru (Tingo Maria region), I did not encounter

passalids above about 2500 m even though areas examined

contained many ap-arently suitable logs. In Costa Rica on

the Ce-ro de la Muerte of the Siec-ra Talamanca, I examined

25 to 30 logs in an oak forest above 3000 m without finding

passalids. All pasrsalids collecc.ed on this mountain were

collected below 2700 m. At 3000 m, the mear annual tem-

perature (1962) was ]0.8CC, t'e lowest temperature of the

year (1963) was 00.0C, and tie highest was 24.5C (Scott,

1966).


Microhabi tats

Passalids are found in moist, decomposing plant

material. Though I have found adults in dry rotting logs,

I have encountered juvenile stages only in moist condi-

tions. Cray (1946) showed in the laboratory that pupae of

Odontotaenius disjunctus would int reach adulthood at rela-

tive humidities below 92% and that eggs would develop only

in direct contact with water. Passalids are not generally

found where flooding is frequent, such as along some river

courses.

The commonest microhabitat of passalids is a rotting

log. They occupy standing trunks as well as fallen ones.

I found a species of Spasalus (near S. crenatus Macleay)










at a height of 7 m in a standing trunk near Iquitos, Peru.

D. Minnick has informed me that he collected a group of

0. disjunctjts more than 6 m above the ground in a standing

trunk in Marion Co., Florida.

Tunnels may occur in one area of a log and not in an-

other. I observed tunnels of the Spasalus sp. mentioned

above not to cross certain fungu.s lines in the wood (prob-

ably an ascomycete). They occurred primarily in areas

through which the fungus had apparently already penetrated.

Most species occur in dicotyledenous wood, though many

occur in conifers (e.g. Pinus, Arauraria) and a few are

found in palms (Reyes-CastJllo, 1970). Some species are

more restricted than others. For example, 0. disjunctus

is found in dicotylci.cno:s wood but seldom in pine (Savely,

1939), whereas 0. striatopunctatus (Percheron) is commonly

found in both. Up to 10 species have been encountered in

a single log (Luederwaldt, 1931). Flatter species tend to

be found under bark (e.g., Passalus interstitialis Esch.),

more convex species deeper in the log (e.g. P. convexus

Dalman).

A few species of Passalidae are found in other micro-

habitats. Passalus punctiger Lepeletier et Serville have

been found under cow manure in Brazil, and larvae, pupae,

and adults of P. dubitans (Kuwert) have been collected

under epiphytic bromeliads in Brazil (Luederwaldt, 1931).

J. G. Edwards and R. Mains (pers. comm., 1972) collected










Passalidae under stones in the Yucatan Peninsula. J.

Hendrichs and P. Reyes-Castillo (1963) discovered that

Ptichopus angulatus is commonly found in the detritus

associated with nests of the leaf-cutter ant Atta r:-xicana,

both in the wet forest regions and in the drier desert re-

gions of Mexico. In excavating these ant nests in a desert

of Hidalgo, Mexico, Reyes-Castillo and I found passalid

larvae and adults together 30 cm deep in the detritus of

the ant nest. Despite the general dryness, this section of

the nest had visibly greater moisture a.d the detritus was

well packed so that passalid runnels were easily visible

as we excavated.

In Peru, during 1970 and 1971, I found evidence of

passalids in a particularly unusual habitat: limestone

caves. Near the town of Tingo Maria is a large cave, known

locally as the "Cueva de las Lechuzas." Its mouth is about

18 m in diameter and the first chamber is about 30 m wide.

Within it lives a large colony of oilbirds, Steatornis

caripensis Humboldt. These birds feed on fruits, espe-

cially of palm (Bactris gasipaes H.B.K.) which they bring

into the cave (Dourojeanni & Tovar, 1972). The seeds are

dropped on the floor. This, as well as excrement from the

birds and from bats, provides nutrients for a large

arthropod fauna within the cave. The most abundant arthro-

pods to the unaided eye are a large black species of tene-

brionid beetle, a small species of lygaeid bug, and large










cockroaches of the cenus Blaberus. Amid the remains of in-

sects which litter the floor of the cave, I observed many

pieces of passalid exoskeletons, especially elytra. They

appeared to be most common about 45 m from the cave mouth,

but were found as far back as 200 m from the entrance. In

a 360 cm area 20 m from the entrance, I counted remain.s

of 19 individual passalid beetles. Though I saw no living

passalids in the cave, Dourojeanni (pers. corn:., 1973)

noted live passalids, adults and larvae, there in 1961, and

he suggested that they lived on the decomposing seeds

brought in by the birds (Dourojeanni and Tovar, 197?).

I noted passalid remains in 3 other caves in which

oilbirds live or formerly lived in that region of Peru.

However, I found similar remains under an overhanging cliff

(margin of cliff extended about 3 m beyond the base and

formed a grotto about 9 m wide), and in a small cave (en-

trance diameter 3 m ). In neither were there oilbirds or

evidence, such as palm seeds on the floors, that oilbirds

had ever occupied them. Both sites are located in southern

San Martin province near the village of Aspusana. In no

case did I find an entire passalid or a living beetle, only

pieces. Most of the insect remains in the cave were con-

centrated under a small ledge about 50 cm above the cave

floor. Seventy-five percent (57 individuals) of the

arthropods represented were passalids. There were remains

of 32 individuals of Passalus interruptus (L.) as well as










remains of 2 other species of Passalus and a species of

Voturius, probably V. platvrhinus (Westwood). The only

other insects represented by remains of more than one in-

dividual were 7 ponerine ants and 4 Rhinostormus barbirostris

(Fabriciui.), a large curcuionid. P. interrupts and V.

platyrhiis are among the commonest passalids collected in

this region of Peru. Since there was very little, if any,

decomposing plant matter in this cave, I am forced to con-

clude that the beetles were brought into it, perhaps by

bats or rodents, and then collected, possibly by the latter,

under thCi ledge. The high proportion of passalid poras,

predominantly elytra, might be explained by the fact that

they are quite glossy and may be more attractive to acquisi-

tive rodents than pieces- of other insects they eat or find.

Perhaps such collecting contributed to the passalid re-

mains in the oilbird caves as well.


Stages

The life cycle from egg to adult requires about 2 1/2

to 3 months, based on Gray's study (1946) of Odontotaenius

disjunctus and my observations of Passalus affinis and P.

punct.igr. Passalid adults remain with their offspring

throughout development so that it is possible to find 2

generations of adults in the same tunnel system. This

overlap between generations is one characteristic in the

development of social behavior, according to Michener

(1969). Other characteristics listed were cooperative brood










care and reproductive castes. Passalid parents cooperate

in raising the juveniles by providing frass, which serves

as food for the larvae, and by assisting the larvae in the

construction of the pupal cases. Whether the adult progeny

aid in rearing their siblings is unknown, though Miller

(1932) claimed that the parents keep the general adults

away from the pupal cases in 0. disjurctus. Reproductive

castes have not been shown to exist in Passalidae. Ac-

cording to Wilson's (1971) adaptat]i- of Micherer' classi-

fication, passalids have intermediate subsocial behavior.


Eggs

Passalids take a number of days to lay a clutch of

eggs in a restricted portion of the tunnel system, the

"nest." Gray (1946) stated that Odontotaenius disjunctus

generally lays only 2 to 4 eggs in a 24-hour period. My

observations of various tropical passalids, both in the

field and in the laboratory, also indicate a prolonged

egg-laying period. Eggs possibly are carried to the nest

after being laid. Gray observed individuals of 0. dis-

junctus carrying eggs in their mandibles. When I placed

eggs and adults in a petri dish, similar behavior was dis-

played by 0. zodiacus (Truqui) and Passalus punctiger. In

the nest, the eggs are in the midst of fine frass. The

nest dimensions range from 75 x 50 mm to 13 x 13 num. Gray

notes that there are usually 20 to 35 eggs, with a maximum

of 60, in a nest of 0. disjunctus. The maximum number of










eggs laid in a special laboratory rearing charrfisr by a P.

punctiger was 20. Of 11 natural nests of tropical passalids

I examined, the greatest number of eggs found was 12 in a

nest of P. convexus. Gray noted that the eggs of 0. dis-

junctus change color as they develop, from bright red

through brown to dark green. This appears to be the case

for other passalids as well. I observed both red and green

eggs in nests of Verres hageni Kaup in Costa Rica and P.

ca-latus Erichson in Peru. Eggs of 0. disjunct-s hatch in

about 16 days at 270C (Gray, 1946).


Larvae

Passalids have 3 larval instars, easily distinguished

by differences in head width. First instar larvae of many

species have more long setae, especially on the notum and

dorsal abdomen, than later instars. Early first instar

larvae in rearing trays with their parents usually remain

within 4 cm of the egg nest, as evidenced by the distribu-

tion of their characteristic disc-shaped fecal pellets.

Larvae are generally gregarious and are often found with an

adult, occasionally several in a line with their heads

under its body.

The principal larval foods are frass and fecal pellets.

First instar larvae feed on the fine frass around the eggs.

Third instar larvae also tear pieces from large wood

chunks. Ohaus (1900) indicated that wood must be prepared

by the adult. Pearse et al. (1936) studied the food










requirement of 0. disjunctus. This work was aptly criti-

cized by G_- (1946) for lack of controls and for not con-

sidering the effect of diet on larval ecdysis. Gray con-

cluded that larvae are best reared on wood triturated by

the adult-s.

The durations of each larval stadium, about 12 days,

for Passalus punctiger and P. affinis appear similar to

those -iven by Gray (1946) for 0. disjunctus.


Pupae

The third instar larva pupates in a case constructed

with the aid of adults. About 5 days prior to pupation,

the larva ceases feeding, beconres whiter, and enters a pre-

pupal stage. In the absence of adults, the prepupa will

roll over and over, forming a depression in the frass in

which it pupates. If adults are present, they will aid the

larva in the construction of a pupal case of fine textured,

compact frass, and excrement (Figs. 1-3) as described by

Miller (1932) for Odontotaenius disjunctus. Only one adult

need be present for pupal case construction, as was ob-

served in a petri dish containing only the larva and an

adult female of Passalus affinis. The duration of the

pupal stage of 0. disjunctus is 10 to 12 days Gray (1946).

Casual observation of 7 pupae belonging to 4 tropical

species, P. affinis, P. punctiger, Spasalus crenatus, and

Popilius near refugicornis Burnheim, indicated little dif-

ference in pupal duration from that of 0. disjunctus. All












































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pupal durations were less than 20 days, with 4 less than 16

days.


Teneral Adults

At ecdysis, the new adult is very soft and has white

elytra, with the remaining body orange. After about 3

hours, the elytra have a noticeable orange tinge. About

1 1/2 days later, the bright orange adult emerges from the

pupal case. Adults blacken--the dorsum first, the venter

last--at varying rates. Some may Le completely black after

only a few weeks, while others take many months. In the

case of 4 individuals of OContotienius striato-. ;itus

collected as red adults and maintained in the laboratory,

the elytra turned black but the venter was still a dark

maroon after 2 years.

Young adults are not sexually mature. Virkki (1965)

reported that they have spermatogonia but lack spermatozoa.

He did not state when the adults became sexually mature. I

observed courtship behavior 3 months after pupal ecdysis of

the male and female in Passalus punctiger and 4 months

after ecdysis of both sexes in 0. disjunctus, which may in-

dicate maturation by this time.


Mature Adults

Black adults migrate from one log to another by walking

or flying. Most individuals found outside logs are fully

black, or nearly so, with black elytra and blackish-maroon










venters. In a study of Odontotaernius disjunctus, 61 of 62

individuals found in recently colonized log; were com-

pletely black; the single exception possessed a blackish-

maroon venter and black elytra.

Adults are occasionally encountered outside logs. An

individual of 0. disjunctus discovered in the mi '.-. of a

dirt road at 11:04 a.m. on 26 January 1974, near Gaines-

ville, Florida, walked for 35 iin, traversing approximately

20 m, before finally entering an old passalid tunnel in a

log. During the entire period, the beetle traveled in

approximately a straight line, walking into the wind. The

antennae were extended nearly straight forward and raised

about 100 from the horizontal. While on the road, it

traversed 120 cm in 1 min; when crossing leaves on the

forest floor, it traveled 60 cm/min. Another 0. di :jinctus,

observed walking from 4:45 to 6:50 p.m. on 27 Septeib)r

1963, near Ann Arbor, Michigan, also tended to travel in

straight lines. This beetle ascended and descended the

trunks of 2 trees to heights of 55 cm and 95 cm respectively.

Occasionally while on the tree trunks it would release its

grip on the bark with its Iront legs and stand with its

prothorax and head extended away from the trunk. Its rate

of walking across the forest floor was 38 cm/min. An indi-

vidual of Passalus interruptus was observed at 9:50 a.m. on

2 October 1970, in Tingo Maria, Peru to walk in a straight

line for 3 m at a rate of 16 cm/min.










Passalids have been observed flying, though uncommonly,

and have been caught at sites to which they must have

flown. Some species have reduced wings and are incapable

of flight (e. g. Proculus spp.). Most flights appar-ently

occur at night. I observed an individual of Passalus

punctiger under a street lamp at 7:37 p.m. on 5 May 1970,

in Tingo Maria. While on the ground it raised its separated

elytra, then flew upward about 1/2 m before crashing to the

ground approximately 1 m from where it took off. In Costa

Rica during March 1967, passalids were caught in : st nets

1 to 2 m above the ground. An individual of Passa l

jansoni was caught between 9:00 and 10:30 p.m., and 3 indi-

viduals of P. punctiger were caught, 1 between 9:00 and

10:00 p.m., 1 between 10:00 p.m. and 12:00 a.m., and 1

between 3:00 and 5:00 a.m. Gray (1946) doubted that

Odontotaenius disjunctus could fly and went so far as to

drop adults with elytra unhooked and wings spread from tall

buildings to test th- ir flightl::sness. Nevertheless,

J. E. Lloyd caught one at dusk while it was flying (pers.

comnm., 1974), and D. Mays saw one fly to a black light

(pers. comi-n., 1975). Five other beetles, all female, were

either seen flying, or found in situations to which they

had probably flown, by T. J. Walker and R. Walker (pers.

comm., 1973, 1974).

In order to study colonization, unoccupied logs were

examined periodically. Ten water oak (Quercus nigra) logs










of roughly the same size (8 to 19 cm diameter, 43 to 86 cm

length) were placed 6 m apart. They were examined on the

average every 17 days beginning 22 October 1972 for 2 years.

All newly colonizing beetles were removed when found. Logs

were replaced when damaaged by excessive colonization or

forest animals. I neither collected passalids nor dis-

turbed other occupied logs within about 500 m of the ex-

perimental site. The logs were located in a mcsic hammock

near Gainesville, Florida, an area with a larce population

of 0. disjunctus. The oak logs employed had been de.d and

cut for 17 months and had never been occupied by passalids

at the time the experiment began, though other logs of the

same age had already been colonized. This indicates that

colonization occurs sooner in Florida tha:. in North

Carolina, where, according to Savely (1939), logs are at

least 2 years old before passalids enter them. Sixty-two

beetles came to the logs. Twelve were found alone in new

tunnel systems, indicating that beetles arrive singly at a

new log and begin a tunnel system. Of these, 8 were females

and 4 males, demonstrating that the first arrival may be of

either sex. The remaining 50 beetles were found as male-

female pairs. The second beetle, therefore, probably

arrives within a few days after the first. The evidence

does not eliminate the possibility that some colonies could

have been initiated by a male and a female together but

renders it unlikely.










In order to determine what occurs when a second beetle

enters an occupied tunnel system, introduction experiments

were performed with individuals of Odontotaentius disiunctus

which had not yet migrated and with individuals that had

recently migrated. Adults which had not yet migrated were

obtained by using offspring rear,-- to adulthood by pairs of

beetles in field cages. These emerged from pupation approx-

imately 1 1/2 months prior and were blac}- or nearly black

at the time of the experiment. They had never contacted

passalids other than their siblings or parents. Offspring

from 2 such families weje employed. First, 8 offspring, 2

males and 2 females from each family, were isolated in the

laboratory. Individuals of one family were placed in

terraria, those of the other in petri dishes. After 3 days,

a small log less than 30 cm long was added to each terrarium.

Three days later, a beetle from a petri dish was introduced

into a terrarium, in each possible combination, i.e. a male

to a female, a female to a male, a male to a male, and a

female to a female. In the 2 cases where a beetle was in-

troduced to another of the same sex, the intruder was

attacked by the occupant, which produced an aggressive

sound characteristic of its sex. The 2 male-female combi-

nations did not result in aggression or sound production,

though courtship was observed in one case in December, 4

months later. Lack of courtship behavior earlier might have

resulted from sexual immaturity.










Beetles which had recently migrated were obtained from

the logs examined periodically for colonization. Indi-

viduals which were found as the sole beetle in a tunnel

system were used in 2 introduction experiments. The first

was an attempt to introduce a female into a log occupied by

another female. The female being introduced could not be

forced to enter the tunnel. Since the tunnel was only 10

cm long, she probably had contacted the rear of the occupant

b-ctle and in some way determined the tunnel was already

occupied by another female.

In the second experiment, a male and a female, each

collected as the only beetle in a new colony on 6 October

1973, were kept isolated until 8 Noverioer, when the female

was placed into the male's petri dish. Contact was fol-

lowed by antennal vibration and the brief (6 sec) produc-

tion of male and female aggressive sounds. Courtship

sounds began 83 sec after the first contact. Copulation

occurred 80 min later.

Imagos reproduce during their first year of adulthood.

This was ascertained by placing a pair of red adults in a

field cage which was covered with bronze screening. The

cage was rectangular, 61 cm tall and 1655 cm2 in cross-

section, and framed by 2.5 cm x 5 cm lumber treated with

copper arsenate. A board frame was attached to the open

bottom to extend 15.2 cm into the soil. The male had been

collected as a larva in June and the female as a red adult










in July, 1973. On 5 August 1973, they were placed in the

cage and provided with moist, rotting oak wood. On 5 May

1974, first instar larvae were found with the pair, which

still had not completed their first year of adulthood.

Adults produce more than one clutch of eggs. In the

laboratory, a pair of Passalus affinis produced 2 clutches

3 months apart, and a pair of P. punctiger produce' 3

clutches, each separated by 3 months. Larvae were reared

from all but the second clutch of P. punctiger eggs, which

I had disturbed. Reproduction by a single pair appears to

be almost continuous in the field in certain climates.

Eggs and pupae were found 3 cm apart in a tunnel system

occupied by a black adult male and female of Verres hageni

in Costa Rica.

Adults may live mcre than 2 years in the field. Pres-

ently, I have field cages that have contained the same

adults of Odontotaenius disjunctus for 1 1/2 years. I have

had adults of various species live longer than 2 years in

the laboratory. Of these, individuals of Passalus punctiger

were still reproducing after 2 years.

The number of adults found in a single tunnel system

varies. Occasionally, one may find a single beetle in a

short tunnel, obviously recently arrived. Frequently, a

system contains just 2 adults. In logs that have been

colonized for a long period, there may be interconnections

between different colonies. Generally, when more than 2










beetles are found in the same system or same area of a

large system, they are probably the original colonizing pair

and/or their immediate offspring. This is indicated by the

general reddishness often present in many individuals of

larger groups.

I have never observed the tunnel systems of different

species to interconnect. What happens hen tunnel systems

of 2 species meet may be similar to the reactions in cer-

tain mixing experiments: An individual of Passalus inter-

ruptus was introduced into a container of 3 Veturius

platyrhinus. It aggressed agait:lt all 3 Veturius. The

first P. interruptus was removed and another introduced.

Upon contacting the Veturius, the new Passalus rapidly broke

contacL. Two of the Veturius aggressed against it. The

behavior of these 2 Veturius was unlike any previously

noted. When one contacted P. interrupLus, it would back

up, lower its head, bulldoze forward, then lift the head.

This resulted in piling of frass and pieces of wood against

the P. interrupts. At least 8 separate sequences of this

behavior were observed. Perhaps in this manner accidental

linkages between tunnel systems are blocked. This bull-

dozing behavior seems similar to that described by Miller

(1932) for Odontotaenius disjunctus adults during pupal case

construction.










Periodicity

Passalid life cycles were examined in warm, moist

areas having relatively little fluctuation in either tem-

perature or moisture throughout the year (Tingo Maria, Peru;

Osa Peninsula and Arenal, Costa Rica), in an area with a

pronounced dry season (Canas, Costa Rica), and in areas

with a pronounced cold season northernn Florida, Sierra

Madre Oriental near Monterrey, Meyico). The Tingo Maria

region (approximately 90 S. latitude), is a zone of Sub-

tropical Wet Forest (Tosi, 1960). The precipitation is

3300 nm/year, August being the driest month, with 100 mm of

rain. The mean annual temperature is approximately 24C

(Tosi, 1960). Adults collected at any time of the year

were active. Life-cycle information concerning 6 of the

commoner species of this region is presented in Table 1.

Considering all of the species together, and assuming that

development from egg to adult requires 2 1/2 to 3 months

( p. 10), one can infer the presence of juvenile stages in

all months of the year. Likewise, adults were occasionally

observed flying or walking (apart from logs) throughout the

year. Therefore, in the warm, moist environment of Tingo

Maria, with minor oscillations of temperature and rainfall

during the year, the life cycles of the various passalid

species are probably periodic and are at least not syn-

chronous.

Near Petropolis, Brazil, Ohaus (1909) observed that

some species were periodic, with eggs, larvae, pupae, and





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red and black adults present at all times of the year.

Other species were seasonal. They were found only as pairs

of adults with or without eggs, in September and October

at the comrnE-ncement of the more rainy period.

In Costa HTica, at approximately 90 N. latitude, I

collected passa'l-ds in tropical wet areas (Osa Peninsula

and Areial) and in Tropical Dry Forest (Caias) during

February and Mar.;i, i.e. in the dry season. This dry sea-

son is most pronoun-ed around Canas in Guanacaste Province,

where from Decemoi:;r throLugh March the monthly rainfl11 is

less than 20 :rm. The toLal yearly precipitation is about

1800 mmn (Scott, 1966). The mean annual temperature in 1963

was 27.8C; the lowi .'t temperature recorded for the year

was 20.0C, and the highest was 36.5C (Scott, 1966).

Records for 1964 for the Osa region (Golfito) give the

annual rainfall at 3800 mm, February having the lowest

monthly total of 58 um. That year's lowest recorded tem-

perature was 21C, the highest 350C (Anonymous, 1967).

During the pronounced dry season near Canas, adult

Passalidae were mostly inactive. Of 7 specimens of

Passalus pu:ctigor, 5 had to be forcibly probed before they

would show any movement. This inactive state was also seen

in the 1 live specimen of Verres hageni collected there.

This inactivity appears to be a response to dryness, since

adults (n=19) of both of these species, when collected on

the Osa Peninsula, were very active. In addition, adults

(n=7) of V. hageni were similarly active at Arenal.










Juveniles were sought during the dry Feason. Near

Canas, examination of 150 to 200 logs yielded 9 live adults

and 14 dead ones. No juveniles were found. Juvenile V.

hageni were present at Arenal and the Osa Peninsula. At

the Osa Peninsula, two species that were not found in the

Tropical Dry Forest, Pas'-alus jansoni and Veturius sp.,

were with eggs and/or larvae. This indicates that, in

areas with a pronounced dry season, the unfavorable period

is passed only in the adult stage.

Northern Florida, at 300 N. latitude, at the southern

edge of the temperate deciduous forest of the eastern United

States, has a pronounced cold season, often .,ith frosts

occurring from November through February. Odontoi :ni u

disjunctu. is the only passalid in this region. When en-

countered in wood on cold dayr, adults do not move and are

extremely sluggish when manually disturbed. On warm days

during the winter, however, adults are active when found.

The seasonal life history of Odontotacnius disjunctus

in northern Florida (Fig. 4 :) was determined by examining

1 to 4 occupied logs every 2 to 3 weeks from October 1972

to September 1973, and on occasion for 1 1/2 additional

years. Extrapolations beyond actual observations are based

on laboratory studies of development time at 27C by Gray

(1946). The earliest red egg (recently oviposited) dis-

covered was collected on 9 February 1974. Cooler winter

temperatures probably retard egg development enough that










the first larvae are probably not present until early March.

In 1975, green eggs (near eclosion) were found on 1 March,

indicating first larval appearance as early March. Egg-

laying may continue until September with larvae present

into November. After September, development would again

be prolonged due to dropping temperatures. Though red

adults are probably found through December, partially black

ones were found into May of the following years. As one

proceeds northward, the period during the year when juvenile

forms can be found becomes shorter. In .lorida, juveniles

are present from February through early December, whereas

in North Carolina the juveniles occur commonly from May

through Septermber (Fig. 4 A) (Gray, 1946). A female lays

eggs in pairs, 2 to 4 eggs every 24 hours during 2 or more

weeks (Gray, 1946).

Migration and colonization of 0. disjunctus in northern

Florida were studied by the method detailed on p. 19. Of the

10 beetles collected outside logs, 9 were discovered from

1 May to 31 October. The number of adults found in new

colonies is shown for each month in Fig. 4 C. The only

month in which no colonization occurred was February. Most

new colonies were found in summer and fall; colonizations

during the winter were preceded by several days of unsea-

sonably warm weather. The cold season apparently causes

periodicity in the life cycle of 0. disjunctus with regard































Fig. 4. Odontotaeniu.u disjunctus. T-._ie of year of
ljif stages and colonization. (a) North : 1:o1ia d. :..a arc
fr;. -.,-y (1946) and refer to the "most f_ -rab:i collect-
ing- Li..es." (b & c) Northern Florida. (b) Clea bars inj-
ca!,t actual field record from Octobe- 1972- .o Marh 175.
HI..C-ch'nq indicates probable occurrence of ?. ;_'ticular
s..cage bascd on field observ-aions of other st'-,es and oa-
tory studies of developnien' time:. (c) Th -: number of acdli,
colonizing is an average for each monzh based on 2 years
observat-ion (October 1972-1974) of 10 logs.









SI 1


A.


North C'olor'a


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A A M 'J 'J A S N D

Time (months)


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32



to both the presence of immature stages and the activities

of migration and colonization.

In the motintains near Monterrey, Mexico, about 25 N.

latitude, 1 collected passalids in late December during the

co1d season. Winter days are mild, but nights sometimes

have; ter.f ?rtures below freezing. The summer is hot an'.

hasu most of the precipitation. This area appears to be

about the fartherst north that tropical species of passalids

occur in eastern Mexico. Here I found a species of

Heliscus and a species of Petrejo'des with first, second

and third instar larvae present, -,hen night temperatures

were below 0C; therefore, I susp-ct' that in these species

the life cycle is periodic. At the same time, however,

Odontotaeniu. striatopunct atus adults were collected there

in much greater abundance, yet I found no juvenile stages.

It would be particularly interesting to make a more detailed

study of this area to determine if it contains some species

which are periodic and other species which are periodic

with respect to the cold season.

Lack of periodicity, or at least synchronus perio-

dicity, of passalid life cycles is associated with a warm,

moist climate and little seasonal fluctuation in tempera-

ture or rainfall in regions of Peru and Costa Rica. Life-

cycle periodicity is associated with a marked dry season

in southwest Costa Rica, and with a marked cold season in

the United States. Both periodic and periodic species






33



were found by Oh.aus (1909) near Petropolis, Brazil, where

the periodism was related to precipitat.ocn. Periodic and

periodic specie? may inhabit the Sierra Madre Oriental

near Monterrey, Mexico, an urea with a definite cold season

but at the northern ext-eme of the range of tropical

passalids. In most cases, the imaco was t.he only stage

present during tiLm s of seasonal environi1:Ental stress.















ACOUSTICAL SIGNALS AND BEHAVIOR


Apparently all species of Passalidae produce sounds.

Until the work of Schuster and Schuster (1971), the only

modern analyses of their sounds wer'e tose of Baker (1971)

for 3 African species, and Alexander, i'oore, and Woodruff

(1963) for 0Odotota'nius disjiinr--us. In t,-e latter 2 papers,

a total of 3 structurally different sound types produced by

adults in 2 contexts v-ere de.c ribd. Baker descrih-d 2

kinds of disturbance signals and Alex.ander et al. described

an aggressive signal. Mullen and Hurtecr (1973) described

aggressive behavior in 0. disjunctus. Schuster and Schuster

(1971) worked with 9 species of New World passalids and

described 4 new acoustical signals. This study is a con-

tinuation of their work. The extent of signals now known

is illustrated by the fact that in just one species,

0. disjunctus, I describe 14 different signals associated

with a minimum of 11 behavioral contexts, to my knowledge

the most known for any arthropod species. This figure

does not include sounds that the larvae produce. Larvae

produce at least 1 sound type in a minimum of 3 behavioral

contexts.


*Sound type in this paper will refer to the structure of
the sound; signal will refer to a particular sound type
produced in a particular behavioral context.










The insect sounds familiar to most people are calling

signals. Passalids lack an acoustical calling signal such

as those produced by cicadas and many Orthoptera. The adult

acoustical signals may be arranged into 4 general cate-

gories: (1) mating sequence, (2) aggros-ion, (3) disturbance,

and (4) other solo, i.e., signals produced in other con-

texts when not contacting other individuals. The larvae

produce sounds (1) when disturbed, (2) when contacting adults

or other larvae, and (3) when mouthing wood or frass.


Mechanisms of Sound Production

The adult's method of sound production is the subject

of a controversy recently summarized by Baker (1967). One

method, that of brushing cone-bearing, abdominal, epipleural

plates against bristles under the elytra, was suggested by

Ohaus (1900) for South American passalids and by Baker

(1967) for the African genus PertaLobus. Another method,

that of rubbing 2 spinose ovate areas on the fifth (actually

the sixth according -o Reyes-Castillo, 1970) abdominal

tergite against the wings, was indicated in experiments

with Odontotaenius disjunctus (Babb, 1901)

I removed the right elytron and wing of an 0. disjunc-

tus individual. Under a stereomicroscope, I was able to

observe the left ovate area of the sixth tergite rise,

move forward, and rub against the wing as the abdomen was

lifted. Sound was produced with each lift of the abdomen.

The return movements were silent. With a pair of fine










forceps, I moved the wing slightly to one side so that the

ovate area rubbed on a different part of the wing but

elytral-plcoral contact remained unchanged. No sound was

produced, thus confirming Dabb's hypothesis. In further

confirmation of this, I placed a piece of paper between the

wings and the termites of individuals of 0. disjunctus and

PasalIs: aff'inis. This prevented Babb's mechanism from

functionjn;. but left elytr,--pleural contact. Only faint

noises were heard, sounding like the. tergite rubbing against

the paper. Thi revel se experiment, with paper blocking the

elytral-pl]ural junction and the tergal-wing contact free,

resulted in loud sourd product-i.on. In another experiment,

Reyes-Casti:1c and I removed the posterior-lateral portions

of the elytra from an, individual of Pren ciljIs brevis.

Sound was subsequently produced. These experiments lead

me to conclude that, at least in New World Passalidae,

sound is produced only by the tergal-wing mechanism. The

importance of the wings in stridulatio. is emphasized by

the fact that in some species, the wings are so reduced

that they are incapable of flight, yet they retain the

stridulatory mechanism as an enlarged distal area at the

end of a long, thin strap (Arrow, 1904).

Baker (1967) repeated one of Babb's experiments using

Pentalobus. He removed the wings above the wing fold,

but found that the beetles were still able to stridulate.

He states that the spiny ovate areas on the sixth abdominal










tergite and ridges on the wing fold are not as well

developed in Pentalobus as in 0. dinjunctus and attributes

stridulation to the clytral-pleural mechanism. When I

removed the wings of 0. disjunctus no sounds were si bse-

quently produced, but when the .ings were removed from

P. brevis faint sounds were heard, seemingly the ovate

areas rubbing against the elytra. Perhaps this sound is

what Baker heard as well.

The larvae also stridulo]te. The mechanism appe-s to

be the same for all species. Riley (1872) and Sharp (1901)

described the stridulatory apparatus. The mi-tathoracc c

legs are reduced, forming specialized structures that rub

against striated areas on the mesothoracic coxae.

Ritcher (1966) mentions that the dorsal surface of the

stipes of passalid larvae have conical stridulatory teeth.

I have never heard sounds that I could attribute to maxil-

lary stridulation, nor does he mention any.


Frequency Analysis

Since the U.S.D.A. Agricultural Research Service's

Insect Attractants, Behavior and Basic Biology Laboratory

(IABB Laboratory) in Gainesville, Florida, was kind enough

to offer me an opportunity to use their well equipped

sound laboratory, I was able to do frequency analyses, as

well as a few other tests on some representative passalids.

In some insects which have broad spectrum, buzz-like sounds











similar to Passalidae, such as Te-rigoniidae, much of the

sound energy is actually in the ultrasonic frequencies.

Frequency analyses were made of the disturbance sig-

nals of 2 beetles each of Passalus affinis, P. pun'c.to-

striatus, and Odontotaenius disjunctus. The beetles were

placed less than 2 cm from a microphone (either a Bruel

and Kjaer condenser 1/2-inch type no. 4133, or a Bruel and

Kjaei condenser 1/2-inch type no. 4135) in a specially

constructed anechoic c umber at the U.S.D.A., IAnB Labora-

tory. Sounds were elicited by squeezing or blowing upon

the beetles. The sound was fed into a Honeywell 5600

Magnetic Tape Recorder (frequency response 3 dh:at 15

inches per second, 100-75,000 Hz; at 30 i.p.s., 150-150,000

Hz) using 1/2-inch Li:pex Instrumentation Tape. The signal

was then passed via a Mclntosh Power Amplifier Model MC75

to a Signal Analysis Industries Corp. SAT-52 Real Time

Spectrum Analyzer-Digital Integrator. The resulting

analysis was printed up to 80,000 Hz by a Honeywell 540

XYY' Graph Recorder. Control analyses were run on the

anechoic chamber without the beetes as well as the tape

by itself without the microphone.


Results

The controls as well as the test analyses showed high

peaks below 2,000 Hz (highest peaks below 500 Hz), appar-

ently due to circuit "noise" and tape "hiss." The sounds of

the 3 species were all quite similar with most energy










peaking in the range from 4,000 to 10,000 Hz (Fig. 5).

Individuals of all 3 species produced do; -ctable sounds up

to 16,000 Hz. These tests su'jge.t that passalid signals

contain no significant cncrgy at ultra. onic frequencies.


Sound Pressure Lc:v\cl A', lysis

Materials and Metholds

Sound pre.s:ure levels we,'. cor:-.arce am(nong the sami

3 species at the U.S.D.A. IABB LaboraLory. The ssamie micro-

phones and procedurLs were used as in the frequency analy-

ses. The subsequent sound produce :.d was fed directly into

a 2608 Bruel and Kjaer Measurirn3 Armplifier for pressure

level determination.


Results

Sound pressure levels for 4 individuals are given ;n

Table 2. The levels for beetles of the smaller species

were lower than those of the larogr species. This confirms

my casual observations that larger beetles generally made

louder disturbance signals.


Sound Structures, Behavioral Contexts,
and Species Rcpercoire

Materials and Methods

Logs were carefully dissected in the field to deter-

mine which passalids were found in the same tunnel system.

Each such group was caged separately in a terrarium or in

































4 B 12 16 20
4 8 12 16 20


C ^**--


24 28 32 36 40


F r I T I
8 16 24 32 40 48 56 64 72 80
kHz


Fig. 5. Representative frequency n analyses of disturbance
signals of Passalidae. (a) Frequency analyses of 9 and 5
Passalus affinis. (b) Frequency analyse. of Odontotaenius
disjunctus and control without beetle--due to scale differences
(a) is not directly comparable to (b) on either axis.


i I


-YC`.'L----Wss-~~_..,~__~~~/ i\~..- r.------I------^ r~--L.---dC















Table 2. Comparison of sound pressure levels (S.P.L,)
and body length of 4 individuals of 3 species of Passalidae.
S.P.L. were measured using 1/2 inch! and 1/4 inch condenser
microphones at 76C'.

Body S.P.L. (diB)
Species length (rm) 1/2" mic 1/4" mic

Passalus 43 -- 67.4
affinis

Odontotaenius 38 66 65,4
disjunctus

Passalus 23 49
punctatostriatus

Passalus 24 46
punctatostriatus


*re: 2 x 10-5 N/m2










a large (15 cm x 2 cm) petri dish. These were kept in my

home in places which would maximize observation time (e.g.,

kitchen table). One method effective in stimulating sound

production was introducing other passalids that had been

isolated for a week or more.

Sounds of beetles from Peru, Ecuador, Colombia, Panama,

Puerto Rico, Belize, and central Mexico (i.e., stat-s of

Hidalgo, Puebla, and Veracruz) were recorded at 3 3/4 i.p.s.

on a Craig 212 1,attery-operated portal;ie tape recorder with

a Craig microphone. To check for variation in tape speed,

time markers (i.e., a single sharp sound every 5 sec for

over a minute) were record-.1 on several tapes when i ;:-,

batteries were inserted into the recorder. The recojd:,r's

speed was checked using the time-marked tapes before

recording and before making audiospectrographs. Variation

in tape speed was less than 5%. By using a note from a

banjo, it was possible to check for wow and flutter.

Beetles from Costa Rica and Jamaica were recorded on a

Roberts 720 stereo tape recorder at 7 1/2 i.p.s. with a

Roberts Model 3815 microphone. Those from the United

States, the Dominican Republic, and northern Mexico (i.e.,

states of Tamaulipas and Nuevo Le6n) were recorded at

7 1/2 or 15 i.p.s. on a Kudelski Nagra III tape recorder

with an American D33A microphone. Temperatures were mea-

sured in all cases with the same calibrated thermometer.

The first 2 tape recorders and an Ampex Model 351 were used










for playback analysis. Audiospectrograms were made with a

Kay Electric Co. Sonagraph audiospectrograph. Sounds were

played into the Sonagraph at original tape speed. The

Sor 'g:.ph voltage unit meter was kept at a level of -5 or

bel ow.

Field monitoring of occupied logs in the United States

was with So:.itrol Corp. Sonitrol Detector and with the

Nagra III tape recorder with the American D33A microphone

placed against the wood. The tape recorder detected L sounds

as well as, if not better than, the Sonitrol. In the

Dominican Republic, a Kudc-lski Nagra IV tape recorder with

an American D33A microphone was used. Logs chosen for

field studies were small (7 1/2 cm to 20 cm dia. x 50 cm

to 120 cm long) to facilitate log monitoring and tracing

tunnel systems subsequent to monitoring. Once selected,

the undisturbed log was monitored for spontaneous sounds;

then a single beetle was introduced into the entrance of

a p.ssalid tunnel present in the log. The introduced beetle

had obeen previously marked by engraving an identification

nur.ber on the pronotaum with an insect pin. All 9 of the

introduced beetles had been collected within 2 weeks of

introduction, 5 on the same day they were introduced. All

were handled only with gloves and forceps. After monitor-

ing, tunnel systems were completely traced, all passalids

collected, and the adults sexed. Field temperatures were

measured in the air next to the upper surface of the log










in the shade because it was impossible to locate a measur-

ing device closer to an undisturbed passalid. Temperatures

inside different parts of a shaded log will vary from the

air temperature by as much as 60C, depending on the time of

day. This was; determined in separate observations by use of

a bailey Instrument Co. BAT-4 Thermocouple indicator and

3 thernocouple probes.


Results

Aconstical signals were recorded from 42 species of

Passalidae (Tabloes 3 and 4). They are produced in a variety

of beh-vjoral situations, as outli'.;d at the top of the

tables. These signals may be classified on the basis of the

structure of the sound into 7 types, A-G. Which of these

types are produced by any given species in particular situa-

tions is indicated in the body of the table.


Sound structure

Passalid sounds may be described in terms of "pulses,"

"bars," and "phonatonims." The first 2 terms depend only

on sound structure, whereas the latter requires knowledge

of how the sound is produced. A pulse is "wave train

isolated or nearly isolated in time (discrete) when viewed

with an oscilloscope" (Morris and Pipher, 1972). A bar

consists of a pulse or pulse train isolated from other

sound by silences greater than 0.005 sec at 26'C.* A series


*The term pulse in Schuster and Schuster (1971) is here
replaced by the term bar.

















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equal duration forms a .iJmple bar train; at a varying

rate and/or with bars of unequal duration, a complex bar

train. A phonatome, in the sense of Walker and Dew (1972)

and Leroy (1966), is the sound produced by a complete cycle

of movement of the stridulatory apparatus (the abdcnen, in

the case of adult Passalidae).

The 7 types of sounds produced by adult pas.alids are

described in the following key.


Key to 7dult Pcssslid Sounds (260C)

Bars longer than 0.06 sec; phonatome consists of
1 bar (Fig. 6) . . . . . . . . . TYPE A

Bars shorter than 0.06 sec; phonatome consists of
1 or more bars.

Complete sequence of sounds consists of 1 bar,
or a series of bars produced in an irregular
pattern (Fig. 9) . . . . . . .. TYPE D

Complete sequence of sounds consists of a series
of bars produced in a regular pattern (Figs. 7,
8, 10, 11, 12)

Sequence composed of paired units, each unit
(a bar or bar train) less than 0.05 sec
long and interpair silences greater than 0.8
sec (Fig. 11) . . . . . . ... TYPE F

Sequence composed principally of unpaired
units, occasional paired units not as
above.

Phonatome consists of 1 bar; sequence
a simple bar train ( Fig 7) . . .. TYPE B

Phonatome consists of more than 1 bar;
sequence a complex bar train.











Eighty percent of more of bars longer
than 0.01 sec (Fig 8) . . . .. .TYPE C

Eighty percent or more of bars shorter
than 0.01 sec.

End of phonatone with 2 or more
bars longer uhan 0.01 sec (Fig.
12) . . . . . . ... TYPE G

End of phonatome with at most
1 bar longer than 0.01 sec
(Fig. 10) . . . . ... TYPE E

Whereas a bar of most sound types has a more or less

"rasping" texture, those of Type F sound more 3ii;e "clicks"

or "snaps." The behavior of the beetle is quite peculiar

during the production of this sound. The pair of clicks is

produced as the beetle partially straightens the hind legs

so that the posterior portion of the body is briefly raised,

as if it were doing a pushupp" with the hind legs.

The fine structure of representative soui.is was ana-

lyzed on an oscillograph (Honeywell 2160 Visicorder). It

was discovered that sound units which were superficially

similar (the bars defined above) could consist of either a

pulse or a train of closely spaced pulses. For example,

even in a single sequence by 1 individual the bar comprising

a Type A phonatome sometimes consists of a pulse, some-

times of a pulse train. Also, i of the bars of a Type C

phonatome may consist of a single pulse (Fig. 13 A) or a

pulse train (Fig. 13 C).

Larval sounds are fundamentally different from those

of the adult in that a sound may be produced on both the

























































































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of 3 species of Fassalidae. (a) Odontotaenius disjunctus,
(b) Passalus affinis, (c) Passalus sp. XV.


__~-










upstroke and the downstroke of the stridulatory apparatus

(Fig. 14). By manually rubbing a metathoracic leg against

the coxal striae, I produced the loudest sound on the down-

stroke with larvae of Odontoaenius disjunctus and Ph'aro-

chilus politus. Sounds are most similar structurally to

the Type A or Type 7, sound,- produced by the adults.


Behavioral contexts and species comp-triso:1

The types of sounds described aovc are prc. 'd in a

nurbl"r of different behavioral situations. For example, the

sounds produced in a disturbance situal on, the- "disturbance

signals," are coitmonly of Type' A, somectir.ms of Type B, C,

or other types. The various behavioral situations are de-

scribed below, along with a comparison of the signals of

different species.


Mating sequence. The re productive sequence coisjists

of 4 stages: (1) courtship initiation, (2) courtship,

(3) copulation, and (4) post-copulation. Positions of

beetles and sounds frequently produced in each stage are sum-

marized for Odontoaenius disjunctus in Fig. 15. Sounds are

not usually produced during copulation and therefore this

will not be treated here. Copulation was described in

Schuster (1975).


Courtship initiation. Upon contacting the female with his

antennae, the male produced a Type C sound, the same type as

produced by a male during aggression, though usually of less




















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7ig. 15. Odontotaenius di junctus -positions of beetl.:s and
sound tiocs during the mating sequence. (a) courtship initiation,
(b) courtship, (c) copulation and (r) post cooul action. he
clouds contain diagrams o' audionnectrociraan s and indicate the
beetle producing the sound.










intensity. Cou'rtshiip initiation is ailb similar to aggres-

sion, though usually of less intensity. Courtship initia-

tion is also similar to aggression in that the male's head

is to the cther animal's side or rear (Fig. 15 a), but

dissimilar Jn that Lho male roots the female little or not

at all anl sIhe does no' tilt Cdotnward the side of her body

facing hLii. Each beetle vibrates its ant-innae againi:t- the

body of the other but Ic.. vigCn-ov sy than during aggression.

The affinity botve-:cn courtship nitiaLjon and aggression was

further illurtrated in 2 cases, 1 with Passales interruptus

and the other with P_. elfi wedre, in whi ch behavior indis-

tinguislable from aggr-icssjon init--ited the s'-quence and was

followed by courtshiLp.

The Type C courtship initiation signal is k ow.n from

13 species; in 9 of these, Type C sounds have also been

observers du-ing aggression (Ta' le 4). One species,

Odontoae-iJus zodiact:-, produced a Type C courtship initia-

tion signal that is very different from those of the other

species. Its phonattome is 0.63 to 0.97 sec long and con-

sists of 30 to 53 very closely spaced bars (Fig. 8 A).

The phonatome of all other species is shorter (less than

0.56 sec), and contains considerably fI;,wer bars (13 or less--

Fig 8 B). The number of bars/phonatome varies with the

species, e.g., 2 to 4 in Passalus punctiger from Peru,

and 7 to 13 in P. affinis.










The courtship initiation signal may aid in communicat-

ing the beetle's identity as a male to the female, since

Type C sounds are usually produced only by males (Table 4)

The courtship signal would not serve this function because

the male and female signals are similar. The courtship

initiation signal may help the male to inform the female of

his readiness to mate, and act as a release of female court-

ing behavior.


Courtship. Cour.tship initiatio-! gives way to courtship is

the male switches from the Type C sound to a Type A sound.

This occurs while hi, head is still to the female's side.

Subsequently, he turns so that he is parallel to her,

usually facing in the same direction-, and they walk in a

circle with the female on the inside (Fig. 15 b). Repeat-

edly, the male shifts from the parallel position to the

head-to-side position and back again. In the head--to-side

position, he may switch from the Type A sound to the Type C

sound and vice versa; in other words, behavior similar to

courtship initiation is recurrently intercalated into the

courtship sequence. This "dance" comprised of courtship

and courtship initiation behavior may continue for up to

12 hours, the male stridulating constantly. If separation

occurs, recontact is followed by courtship initiation

behavior.

The female also produces a Type A courtship signal,

but less constantly than the male. When she stridulates,










she usui.ly does so in approximate one-to-one relationship

with the male's phonatomes, sometimes overlapping, sometimes

a]-i-c eating with his (Fig. 16). In Odontotaenius dis-unctus,

the femal courtLhip signal occurs only with the mEle court-

ship signal (ig. 16), hut in Passalus punctatostriltus, the

male s spend: monr, time thi.n do males of other species in the

heed-to-sid p o.eition producing the courtship initiation

sij ;.n an; the female priH-uces her courtship signal with it

(Fig. 17). In On: ;iae.nus zo 'cus, there is apparently

no rl;.].c courtship sign] and the female courtship sign is

produced alcnc, during courtship as wel1 as in company with

the male's Type C signal during court:.hip initiation.

The mal.e courtship signal, known from 12 species (Table

4) ranges froii 0.06 to 0.31 ';ec in phonatome duration. It

resembles the disturbance signal in that both are Type A

soun-ds, but generally differs from the latter in pitch and

length. The pitch remains, re v Lively constant throughout

a courts..ip phonatormc, but varies during a disturbance

phonatome. In some species, the courtship si final is shorter

than the disturbance signal (e.g., in Petrejoides sp. n.,

courtship = 0.09 to 0.12 sec, disturbance = 0.16 to 0.35 sec

at 230C). In other species, the courtship signal is longer

than the disturbance signal (e.g., in Passalus spinifer,

courtship = 0.13 to .17 sec, disturbance = 0.06 to 0.10 sec

at 24 1/20C), and in some they are of similar duration. The

commonest situation among species appears to be courtship










sig:aals shorter than disturbance signals. In most cases,

the variation in length at a given temperature is less for

courtship phonatomes than fur disturbance ph. atomes of the

same individual (e.g., in a Passclu convexuis male at 260C,

courtship: K = .23 sec, coefficient of variation, CV =

.18; disiurbance: x = .42 sec, CV = .30; n = 5 and 5). The

female court hiJp signal, k,1own from 5 species (Table 4), is

similar in length to thai: of the male.

The court hi1i sigra;]s my ai in ke:7p the pair to-

gether, increase the other ind vi ual 's readinetns to copulate,

and inCorn.i ith other individua] of the signaler's readiness

to copulate. Recurren ce of the courtship initiation signal

may reinform the fe:irle of the mi-l's sex.

In 2 species, certain signal : were app gentlyy lacking.

Males of Odontotaer.i.us zoi.acuf did niot produce a courtshiip

signal though they did produce a courtship initiation signal

and the female produced c-ourtship signals. In O. St.riato-

punctatus fromi northi,:rn Mexico) female and male courtship

signals as well as the courtship initiation signals were

lacking. The sigle pair studied performed a silent "dance"

on at least 2 occasions, culminating in copulation once. In

contrast, the male produced Type C sounds in aggression,

and both he and the female produced Type A sounds when dis-

turbed.

At times during the dance, the malE or female may place

a hind leg upon the posterior portion of the elytra of the

other beetle. At other times, 1 of the pair (usually the
















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male) turns onto its back and the doiseon-up individual may

move the posterior portion of its body onto the ventral sur-

face of the i avertedd one. Sounds usually cease at this

time, and copulation ensues (Fig. 14 c) as described by

Schuster (1975)


Pos .-copulation:.l Immediately after the a-c sguV s pull. free

of the female, the male usually is very active, talking

rapidly, or pivoting on the front legCj while. rotating the

posterior portions of his body left and ri.h11. Dur.inr this

timi', he often produces a distinctlyve Type A scund up t"

0.5 sec in duration, much longer than the cour-ship s, nal,

similar to a long disturbance signal (T'ia. 6 B). i'his

sicg1l is known for Passalus puncti -er, P?. affjiris, :.ri

Odonrtotaenius disjunc'lus. SuLseyquely, other foundd types

(D, E, C, or B) are produced by thI male (Table ,1 and Fig.

15 D) many -of them of relative lo, inL:'ity. The iale

makes sounds both when contacting the fem Ie and when alone.

He sometimes roots the female, and once a female" of 0.

disjunctus produced Type A disturb.'.ico-like sounds in this

situation. In one case, with Passmlus affinis, the female

aggressed against the male and concurrently produced a

series of Type B sounds, typical of female aggression in

other contexts. On 1 occasion, copulation was observed

in a cage containing 2 males and 1 female (P. punctigc-r










from Ccsta Rica) The posL-copulatory male aggressed against

the ot or male with the production of the Type C aggressive

signi]l, despite the fact that he had not aggrensed against

tei latter t -ien contn;.-tin him during courtship.

Concerning ihe function of post-copul atory signals,

several suggest g ,s can be made: (1) they keep the pair

together, (2) they are non-comrun captive byproducts, and

(3) they rep 1: other individuals. First, Alexander (1967)

suggest'. tl-it, in crjicets, post--ccpulatory signals rm.-y keep

the female with the mali u.ntil. he is ready to copulate

again. This app'i'rs not to be the case in passalids for the

following ri'asorls: (1) th mcal e locomotes quite actively

after copulation, which, in the tunnel syste- probably

resu-ts in his leaving the in.;:.ediate vicin-ity of the female,

and (2) since the female remains in the tunnel system, she

is available for subs-'.quenL copulations. Second, the

ini tial Type A sounds produced by the male may be byproducts

of the physical movements involved in replacing 'ihe aedeagjas

in its normal position within the body. Third, the aggres-

sive state of a post-copulatory male is suggested by the

sound types he produce:, his occasional rooting of his

mate, and his reac tion to another male described in the pre-

ceding paragraph. His rapid locomotion after copulation

may lead him to traverse much of the tunnel system, and in

his aggressive state, to attack any adults that he en-

counters, probably resulting in departure of those other










than hi:- mate from; the tunnel systemm. The post-copulatory

sg~rals produced while the male is alone may help maintain

hii,, through auditory feedback, in this excited state dur-

ing his travis through tie tunnels. Those signals pro-

duced upon cont-actii with another beetle may aid in repelling

it.


Aggrarcion. Aggression in Passalidae is complex, in-

volving 6 types of sounds (C, B*, E, A, D, and F). The

particular type produced is apparc t]y d!epndetit on the

iitinsity of t!be aggrcssios the rol, of the producer as

aggressor or aggressce, the sex of the aggressor, and the

int a- or inter-specific nature of the interaction (Tables 4

and 5). Th,' Type C aggressive signal w.s first describe'-,

for Odonito-'a.enius disjunctus, by Alexa'n.r et al. (1963),

but in relation to the producers' sex, as it will be here.

AggreFsion Pt its highest intensity is characterized

by rapid vibiraion of the antennae of each beetle against

the other. T-he aggrL-esor's mandible::. are spread wide and

placed under the body of the other beetle. It then jerks

upward rctpiatedly with the head and forebody, rooting the

other beetle. Occasionally the mandibles close firmly on

an appendage. In these cases, the aggressor may lift the

other beetle entirely off the substrate. The beetle attached


*The Type B aggressive signal is identical to what Schuster
and Schuster (1971) referred to as the defensive signal.
The pulses they mention have been identified as phonatomes.










may tilt its body down on the side facing the attacker, thus

restricting access beneath its body to the attacker's

mandibles, or it may run rapidly, thDiereby breaking contacW.

The attacker may walk rapidly after a retreazting opponent,

kcepin g antenna contact. Sometimes the beetle att aciiied

turns its head to the aggressor and count -raLttacks. In this

case, the animals may meet hecn to head with mirh violenri

viLrating of antennae and .interloc] ing, of mandi l- 1. (Fig.

18). During int-.cspecific in lracti o ts, the aggre'sor piro-

duces ouuid Types C, B, or E, while the bcrtle att.- :.::2

usually does not striculatce but sometimns produce Typ' A

sounds similar to disturbance sji n-ils (Table 4 ar d Tig 10 A)

During interspecific interactions, the] a -rcssor cc.:r i.o.ly

is silent or produces sourjd often of T'yp, E (Tahbl 5) The

aggressee may produce sound Type A.

Usually after contact was broken, fc 1 1.ing intencer

aggressive encounters, aggressing indivi;rils of Pi; a]us

convexus produced signals (Tables 4 an l 5). The sound was

always associated with the pushup behavior decri.iedC pre-

viously, but the pushups sometimes occurred without the

sound. Pushups were performed in groups of 5 or more.

During mild aggression, 1 beetle, without vibrating its

antennae, places its head to the side or rear of another

and, with mandibles only slightly spread, lifts its head a

few times. The other beetle may move or the aggressor may

push on past it. Lifting may occur without sound, or a













phonatome may accombpaLny each upward nivemner, of the hed.

In the latter case, the aggressor produces sound Types D

(Fig. 19 B), E or, in P. corver-us, Type A (Table 4). The

aggressee remains silent.

A beetle of a given sex may attack individuals of the

sara or opposite sex. Male aggressors produce Type C

signals, and female aggressors Type B signals':, except in a

feo species (Table 4). In some species, sboth sexes produce

Type E signals. A type C aggre's-cJ.i' ignal w3s regLl .rly

produced by a female only in Odontoitr '_.; zc... icIs. In

this species, both male and female make an unusual Type C

sor.d (Fig. 20). In a single case, a female of 0. striato-

punctatus gave Type C signals when attacking another female.

The Type 6 sound was produced by a female in a non-aggr..'ssive

context only once, a single female of Passalus sp. XV that

produced the sound as a disturbance signal (Tables 3 and 4)

The Type B aggressive signal was produced by females

except in 3 case, described in Schuster and Schust--r (1971),

with Passalus punctiger from Costa Rica. The Type B sound

is also known from non-aggressive situations, i.e., distur-

bance, post-copulation, and other solo situations (Tables 3

and 4). In disturbance, it is commonly produced by males

as well as females. A post-copulatory male of 0. zodiacus

produced a Type B signal while separate from the female but

a Type C signal when in contact.





























l i llIIijiii llfllflllljlllffllllllill / a
















Fig. 19. Odontotaenius disjunctus--sound types and position
of beetles during aggression by one beetle. (a) Strong
aggression, (b) mild aggression.










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Types B and C aggressive signal.,, wh-'-h are character-

istically sex-specific, were not produce' in inte specific

encounters ex:..ept in 2 casos (Table 5). In 1 case, 0.

zodiacs made its peculiar Type C acc;gresive s jigal, but in

this species the Type C signal is not sc.:---w:ci-i: In the

second case, a female of Passaluvs convr :u s produced tie

Type B aggi essive signal against P. coni 1oreo, Lau a few

minute:; earlier she had bheen produciilIg tLis signal aggress-

ing against mirrmbers of licr own sp:eccs.

The role of aggressor can shift in some situations.

For exmaple, a female of P. conw..::u i rs introd:t.ic into the

petri dish of another isolatele fcoEi.ae. The occupant attacked

the introduced beetle and produced sound Ty -.s B and F.

After a few minutes, however, the introduced beetle became

aggressive and began producing the 2 sound types while the

other beetle became passive and silent.

Fourteen species are known to produce Type C sounds

during aggression (Table 4). One species, ldontotac.nius

zodiacus, produces a Type C aggressive signal th-it is very

different from those of other species- Its phlnato-ime is

0.31 to 0.41 sec long at 250C and consists of 15 to 25 very

closely spaced bars (Fig. 20). It is similar to the unusual

courtship initiation signal of this species (Fig. 8 A), but

about half the length. In the Type C aggressive signal

common to other species (Figs. 21 and 22), the bar production

rate in phonatomes of comparable duration is less than 2/3














Table 5, Sounds produced by gcjgressor during inter-
spccific imioxing experiments in which a single beeLle was
introduced into a container of 1 or more individual ls of a
sympatr c species.


Species introduced tr,

Passalus daoiniic;nus----

*P. convcxus---

P. interti tial i s- -- -

P. intersttiia s----


P. coni forus-- -- ---

P. coniferus------- -


SSoec-'- s -5-

*Pgs -lus aff' is

P, inters;tit l is

*P, nrfrcr toriforus

*P. pun cti -

'P,. sp, XV

*P, convos p


Sound types
produced by
aqqr .ar

E

F

F


P. sp, VIII --

P. interrulotu- ---s -

P. interruptus--- ------



P. interruptus-------r

V---
Veturius plat /hianus- -

fV. platyrhinus- --

Proculejus brevis-- --.




*Indicates aggressor.


*P, co( j. r

*P, sp. XVIl

Veturi... .latyrhjinu:;

*V. platyr. y inu_.:

*V. latyrhinus

*P. convexus

*P. ounctiger

*Odontotaenius oodiacus










that of 0. zodiacus. In these species, the phon tome dura-

tion is from 0.09 to 0.39 sec at 25C and there are fro:n

4 to 14 bars/phonatome. The cur ctiotni of a phonat ome con-

taining a given number of bars at a given teiper tinu-'e varies

with the species (ij.gs. 21 and 22) and the i-nternsity of

aggress.iun. The longest signal (0.39 sec -.,:ith 14 bars) was

produced in a violent head-to-hea C co-f ronta-tion by 2 males

of 0. disjun ctus. ar duration varies 'ii p.-cies fcm

0.01 to 0.04 sec.

The Type B aggressive signal is k-i.n fr(,7 8 species

(Table 4). The phonatone duration va i.ss vith the species

from 0.01 to 0.06 sec r 2?- (Fig 7). The ra: of phona-

tome production is greater with mor-e i. ten.-- aggrccsion.

The Type P phonatome of .a given species '::y ble quite similar

in length to a bar of its Type C aggr; .ive sign.i!, but the

rate of Type B phonatome production is never as gieat as

the bar rate of the Type C signal of t _. s spic ci''c..

The Type E aggressive signal is known fro'.' 8 species

(Table 4). Phonatome duration (0.14 to 0.92 s.-c at 260C)

and number of bars/phonatome ve--y widely (Fig. 23) even

for the same individual. The rate of phonatome production

increases with the intensity of aggression.

The Type D aggressive signal is known from 5 species

(Table 4). It is a highly variable signal with most bars

less than 0.02 sec long (Fig. 9 A). In Verres hageni, this

signal sometimes tends to be more regular and grade toward

a Type B signal.
































































































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Type A aggressive signals produced by the aggressor

are known only from Pass.lus convcx3s. Type A signals

produced by the aggressee are known from 3 species (Table 4)

They are all similar to disturbance signnal.'.

Type- F ajres ive signals are known only from P. conv-xus

(Fig. 11), and are always associated with pushups. Puslups

occurim.d after aggression in an under _tified specic.--

Passalu. (Pertjnii -) sp. XVII--from Peru, but no sound w.as

he rd.

Acoustical aggressive signals, in con r-It to piysicl

violence, could( cause a change in th-. behavior of the

aggrissEc w ith less risk of injury to either it or the

aggressor. The beetle attacked may be informed by the

aggressor's acoustical signals o, the latter's s:n and

mating potential, with the result being (1) the beetle

attacked leaving the tunnel system, (2) temporary separation,

or (3) a shift to mating behavior.

The aggressor usually has its h(-.d to the side or rear

of the other animal. Tn this position, through repeated

antenrnal contact, it receives chemical and tactile informa-

tion concerning the sex and other attributes of the beetle

contacted. The aggressee, however, has little antennal con-

tact with the aggressor and apparently lacks chemical and

tactile information concerning the latter. A beetle's lack

of information concerning an individual at its side or rear

is indicated by the following: if 1 beetle is aggressing




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