University of Florida IFAS
Ft. Lauderdale ARC Research Report FL-77-5
Third Research Progress Report on
CHEMICAL CONTROL OF THE CITRUS BLACKFLY, ALEUROCANTHUS WOGLUMI
James A. Reinert, George E. Fitzpatrick, an 4I4j el
University of Florida, ARC, IFAS i b L
Ft. Lauderdale, Fla.
March 10, 1977 AUG 14 198
This report is an update of research completed or -p r'ni fida
last ARC Research Report FL-77-1 January 17, 1977 was completed. The
following summarizes the experiments completed or in progress for control
of the citrus blackfly, Aleurocanthus woglumi Ashby, by chemical insecticides.
1. Aldicarb was re-evaluated for control of CBF on potted citrus trees.
The plants were reinfested throughout the test to insure a continual presence
of viable insects. Table 1 lists the percentage of live CBF on treated vs.
untreated trees up to 10 weeks post treatment. This test was reported in
the last report and this represents a continuation until the aldicarb
treatments failed to provide control.
TABLE 1. An evaluation of aldicarb at 10 lb AI/Acre for control of citrus
blackflyy on container grown citrus trees (4 reps.).
% CBF Alive
Post 2 4 5 6 7 8 9 10
Larvae 12.4 3.2 1.3 17.8 22.1 54.6 49.5 77.4
Pupae 7.0 0 1.6 0 0 0 0 0
Larvae 84.5 85.0 71.4 83.4 77.3 88.2 93.0 96.3
Pupae 88.6 93.7 98.8 95.2 93.4 78.7 98.3 78.1
Research Report FL-77-5
2. A second experiment was conducted to evaluate systemic activity
of several insecticides when applied only to the upper surface of the
infested leaves. A similar test was conducted earlier and results appear
in.the last progress report. Spray tank solutions of the insecticides
(Table 2) were painted on 50 leaves per tree. An average of 2.65 micro
liters of solution (at the respective rates) was applied to each cm2 of
treated leaf area.
Samples of treated leaves taken from the test trees were covered with
hatched egg spirals, but only a small percentage of the resulting larvae
were present. Of the larvae present, most were alive. Possibly many of the
larvae had been killed by the treatments, but a large number still remained
on each leaf and were healthy. None of the treatments resulted in more than
12% control of the remaining population when evaluations were made at 4 weeks
TABLE 2. Insecticides used in upper surface leaf treatment test.
Insecticide lb AI/100 gal Insecticide lb AI/100 gal
Acephate 1 Oxydemetonmethyl 0.5
Acephate 0.5 Malathion 1.25
Acephate 0.25 Azinphos-methyl 0.5
Dimethoate 0.5 Untreated Check 0
3. A pilot study was jointly established between IFAS and DPI to
determine the feasibility of an eradication program for the CBF. Three
chemical treatments were evaluated: (1) acephate applied at 0.5 Ib AI/100
gal by hydraulic sprayer; (2) acephate applied at 2.0 Ib AI/100 gal by
back-pack mist blower; and (3) malathion applied at 1.25 lb AI/100 gal by
Research Report FL-77-5
hydraulic sprayer. Each of these 3 treatments was applied to 4 city blocks
and 4 additional city blocks were used as untreated checks. All citrus,
mango, Surinam cherry, and any other plant which can act as a host for CBF
were treated. The treatments were applied 3 times at 21-day intervals and
performance of the treatments on citrus was evaluated 5 times during the
course of the study.
Results of this study are given in Table 3, and indicate a substantial
difference between .the acephate mist blower treatment and acephate applied
with hydraulic sprayer treatments. The differences between the 2 application
techniques persisted through time, and were greatest at the conclusion of
the study, 4 weeks after the third treatment.
No significant differences were noted between the performance of mala-
thion and acephate when applied by hydraulic sprayer. Levels of control
with each compound were greater than 95% after the second treatment and
greater than 99% after the third treatment. Control levels of at least 99%
continued for 4 weeks after the third treatment.
TABLE 3. A comparison of treatments of acephate by mist blower and foliar
spray with malathion by foliar spray.
2 wk post
1st 2nd weeks post 3rd treatment
Insecticide Treatment Treatment 1 wk 2 wk 4 wk
Treatment* L** P** L P L P L P L P
Acephate MB 85.7**45.2 77.7 76.2 86.9 82.4 91.4 85.8 70.0 62.1
Acephate S 92.3 92.1 99.9 97.8 99.8 99.7 100 .100 100 99.9
Malathion S 97.4 72.1 99.6 95.5 99.8 99.8 100 99.0 99.9 99.9
*MB = mist blower; S = hydraulic foliar spray
** = % dead CBF, L = larvae, P = pupae.
4. A bioassay study was initiated and is underway at present to assess
the impact of CBF control toxicants on Amitis hererridium, a parasite of CBF
currently being evaluated as a biological control agent. Ten concentrations
Research Report FL-77-5
of acephate, malathion, and diazinon have been screened against this
beneficial arthropod. Preliminary results indicate that field rate
(0.5 Ib AI/100 gal acephate; 1.25 Ib AI/100 gal malathion; and 0.5 Ib
AI/100 gal diazinon) of these 3 compounds are highly toxic to A. hesperidium.
An approximate 24 hour LC50 for acephate was determined to be 0.005 Ib
AI/100 gal when insects were placed into contact with treated citrus leaves.
Work is continuing in this study to determine comparative toxicity of the
various chemical treatments to A. hesperidium and other beneficial arthropods.
1. In response to the lack of information about the phytotoxicity of
acephate and malathion on orchids, bromeliads and ferns, several species of
each will be evaluated at high and low rates of these insecticides.
2. Additional insecticides, combinations of insecticides, and formu-
lations will be evaluated for this pest.
3. Penetrants and other insecticide additives will be evaluated in an
effort to get better coverage and penetration of insecticides (primarily
acephate) which show promise for the eradication program.
4. Systemic insecticides will be tested for control by soil injection
in an effort to develop alternate methods of treatment for citrus blackfly.
5. Tests to determine insecticide decay curves of foliar applications
are also planned.
6. Additional evaluations of interactions of the parasite-predator
complex with insecticide treatments will be conducted.
7. A residue extraction lab is being set up to complement Dr. Nigg's
work at Lake Alfred.