| Material Information
||Observations of the biology and control of the tomato pinworm in Florda
||Bradenton AREC research report
||3 leaves : ; 28 cm.
||Poe, S. L ( Sidney LaMarr ), 1949-
Everett, P. H ( Paul Harrison ), 1927-
Crill, Pat, 1939-
Agricultural Research & Education Center (Bradenton, Fla.)
||Agricultural Research & Education Center, IFAS, University of Florida
||Place of Publication:
||Tomato pinworm -- Florida ( lcsh )
Tomato pinworm -- Control -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||S.L. Poe, P.H. Everett and J. Pat Crill.
||Florida Historical Agriculture and Rural Life
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Copyright 2005, Board of Trustees, University
C' AGRICULTURAL RESEARCH & EDUCATION CENTER
IFAS, UNIVERSITY OF FLORIDA
BRADENTON AREC RESEARCH REPORT GC-1974-8 MAY, 1974
OBSERVATIONS OF THE BIOLOGY AND CONTROL OF THE TOMATO PIUNORM IN FLORIDA
S. L. Poe, P. H. Everett and J. ?at Crill
The tomato pinworm, Keiferja vcooersicella (Walsh.), a small gelechiid moth,
Is native to tropical areas of the United States, i&i.o, Central America and
the Bahamas. It is of economic consequence in Florida because its preferred
host plants are tomato, potato and eggplant, all ccmniercially important crops
in central and south Florida.
The pinworm has long been a resident of Florida but was rarely cause for con-
cern until late 1972 when populations attained le-els cufficIent to cause
economic damage and crop loss to tomatoes. The sudden population increase
appears to be the result of altered cultural practices, intensified plant
production and shifts in the nature of chemical to:icants used for insect
Several observations of the biology and life history of tha pinworm and the
importance of these facts to control are discussed. The observations were
made during the period 1972-1974 in commercial fields, experimental plots and
plant production house culture.
Life Cycle in Florida Agriculture
Pinworm moths infest fields or may enter plant production houses through open
vents, doors, or sides. Eggs are laid singly, preferably on tomato but also
on eggplants. Young larvae hatch from the eggs and begin to feed, which
results in the characteristic blotch leaf T.ina. Older larvae fold or tie
together adjacent leaves and their feeding activity leaves broan, dead
foliage. The early stages of pinorm are tan to hbotin but as the larva
matures a purple to green color appears. The larvae can be observed by
separating leaf folds or ties. As the larvae mature they eolt or shed their
skin, and increase in body size. Shortly after molt the larva may abandon
the old mine or fold and see% a new- feeding site. The firstt stage of growth
is spent as a leaf miner and the second stage usually a. a leaf folder or
tier. The third and remaining growth stage larvae, however, may choose to
enter the stem, vine, a new leaf fold or the tolmato fruit. Thz .i-_ spent
between stages of growth is relatively long (5-10 days) but the larva is
extremely well protected by the leaZ or plant enclosure. Mature larvae leave
their feeding sites in fruit, stem, or leaf, drop to the soil and construct a
cocoon (about 3/8 in. long) of loose sand ga-ins rnd debric tied together with
silk. Inside the cocoon the pupa forns, which .ill give rise to a new moth
after about 10-20 days. The entire cycle front egg to adut1 may require more
than two months and is rarely completed in less than one month. Pupae inside
cocoons and old cocoons can be readily found on rtrlch or soil beneath infested
Control of Pinworm Populations
Prevention: Control properly begins by preventing the establishment and develop-
ment of populations. Where possible adult moths should be screened out of pro-
duction houses. Infested plants, abandoned fields and fruit should be destroyed.
Moths which mature on plant debris, volunteer plants or abandoned fields readily
attack young new fields nearby. Maintenance of fields for long periods of
time with no chemical treatments after commercial harvest has ceased will provide
moths in numbers sufficient to infest all nearby fields. Burial of pupae in
sand 1.5 to 2.0 cm was adequate to prevent emergence of the adult in laboratory
studies, therefore, thorough tilling of fields immediately after harvest should
limit population increase.
Eradication: Eradication of established populations begins by inducing mortality.
Natural pinworm mortality is very slight during the growth of the larvae,
however, up to 60% of prepupae have been observed to be killed by two species of
parasites. These biological agents thus slow the numerical increase of the
population but do little to prevent damage to the vine or fruit.
Mortality due to chemical toxicants is at present the only means of successful
population management. Selection of treatments varies somewhat from situation
to situation and success or failure may be dictated by situation and larval age
more than by choice of chemical. For this reason chemical control will be
discussed for seedling plant production and for field production: maintenance
of field plants free of pinworms and for control of pinworms populations on the
Chemical Control (Seedling Production): To date no way is known to prevent moths
from infesting production houses if the population source persists nearby.
There is no evidence of effective varietal resistance to the pest, therefore it
is important to destroy all discarded plants or plant parts immediately and to
maintain plant houses free of wild plant growth, which occurs under benches or
in trash piles. When infestations are local, hand picking and destruction of
infested plants might be feasible. Pinworm-free tomato plants have been produced
by weekly applications of diazinon, endosulfan (Thiodan) or methomyl (Lannate).
However, the best control was obtained with two applications each week, one of
Thiodan and the other of diazinon.
The rationale for two applications per week is to provide a toxic residue at all
times during the lengthy life cycle and continuous egg hatch to obtain mortality
of newly hatched larvae. Greater larval mortality was obtained on infested
plants with leaf mines and leaf folds present, with Systox or Phosvel, but
certain rates of these materials were phytotoxic under certain conditions. In
all cases thorough plant coverage by the spray chemical is essential.
Chemical Control (Field Production): Infested field plants can be successfully
managed to produce a crop. The most critical element is to protect fruit from
the attack of larvae. Protection of fruit is sustained by repeated applications
of one or two insecticides tank mixed and sprayed at frequent intervals. In
experimental tests, weekly applications provided sufficient toxic residue on the
foliage at all times to intercept the larva when it abandoned one feeding site in
search of another. Eradication of tir popiit-l.at n wae achieved only after eight
consecutive weekly treatments. The time required was due to the extended life
cycle and the slow development of larvae, many of which were killed only as
they changed feeding sites. Several chemical combinations which gave good
control and have eradicated established infestations are diazinon + methomyl,
endosulfan + Phosvel, Systox + Phosvel, parathion + methomyl and Guthion +
Sevin. The necessity of adequate and thorough coverage is again emphasized.
In many cases even after two or three applications of a chemical, larvae within
mines were unharmed and the tendency is to switch to another chemical compound.
This is not necessary because the pinworm was susceptible to almost all
contact chemicals tested. However, none of the chemicals gave a sufficiently
high mortality of larvae within mines protected from direct chemical contact.
Uninfested fields can be maintained pinworm free by routine weekly application
of the aforementioned tank mixed insecticides where no source of infestation is
nearby. Complications arising from use of other than conventional high volume
spray equipment has not been observed. The effect of overhead irrigation and
removal of the needed chemical residue is also an unknown factor, however,
sprays should be applied after irrigation to ensure adequate residue.
Finally, although chemicals are available which will protect fruit and control
pinworms in tomato fields, they will function optimally only where reinfestation
does not occur. Under situations of constant reinfestation from adjacent
abandoned fields, plant parts, culled fruit, etc., it is doubtful if any chemical
applied in any manner or at any time interval could withstand such population
pressure and its use assure a marketable product.
Therefore, pinworm population control at the present time is contingent upon
(1) sound sanitation practices, and (2) judicious use of conventional chemicals
to maintain a lethal residue on the plants.