Oral to xicity of Various Insecticides, 1990-1991

Abstract

Five insecticides (abamectin, chlorpyrifos, dechlorane, permethrin, and sulfluramid) were evaluated as potential bait toxicants for black carpenter ants. All testing was done after sunset, between 2100 and 0100 h, with foragers from colonies nesting in trees. Technical abamectin, dechlorane, and sulfluramid were solubilized in acetone (20 ml) to 25 mg/u,l; 50mg of Tween80 was added to enhance even mixing in the sugar-milk bait. Formulated chlorpyrifos (4 E) and permethrin (2 E) were used, since the above procedure had not been adopted when they were tested. An appropriate volume of concentrate was diluted in given weight of sugar-milk bait (10 g raw sugar in 50 ml whole milk). Fresh sugarmilk dilutions were prepared each evening and transported on ice. Ants were attracted to a feeding station at the terminus of 3-cm diam wooden poles, supported at 50 cm above the ground, originating from a tree where the colony nested. Once ants were traveling along the poles, a bait dish on the feeding station was filled with 1 ml of toxic bait. After ants fed to repletion, and were returning to the nest, they were transferred to plastic boxes (10 per box) with a ventilated lid. This was continued until approximately 30 ants (range: 28 to 31) were dosed. Returned to the laboratory (25 ° 5°C, ambient RH), the ants were provided a moistened dental wick, and observed for cumulative mortality at 6 and 12 h after treatment and then at 12 h intervals for 21 d; dental wicks were wetted daily. At varying DAT, LC^s were estimated by regression of probit mortality vs. log10 of concentration (ppm). LT30S for 500 ppm abamectin, dechlorane, and sulfluramid and 20 ppm chlorpyrifos and permethrin were estimated by regression of cumulative probit mortality vs. logio of time (d); for LTJQS, ants fed untreated bait served as controls monitoring natural mortality.

Full text

376 INSECTICIDE & ACARICIDE TESTS, VOL. 17 J: URBAN, INDUSTRIAL, AND STRUCTURAL
FIELD TESTING:
Black carpenter ant; Camponotus pennsylvanicus (DeGeer)
B.
L. Reid and J. H. Klotz
Center for Urban & Industrial Pest Management
Department of Entomology
Purdue University
West Lafayette, IN 47907-1158
(6J)
ORAL TOXICITY OF VARIOUS INSECTICIDES, 1990-1991: Five insecticides (abamectin, chlorpyrifos, dechlorane, permethrin, and sulfluramid)
were evaluated as potential bait toxicants for black carpenter ants. All testing was done after sunset, between 2100 and 0100 h, with foragers from colonies
nesting in trees. Technical abamectin, dechlorane, and sulfluramid were solubilized in acetone (20 ml) to 25 mg/u,l; 50mg of Tween80 was added to enhance
even mixing in the sugar-milk bait. Formulated chlorpyrifos (4 E) and permethrin (2 E) were used, since the above procedure had not been adopted when
they were tested. An appropriate volume of concentrate was diluted in given weight of sugar-milk bait (10 g raw sugar in 50 ml whole milk). Fresh sugar-
milk dilutions were prepared each evening and transported on ice. Ants were attracted to a feeding station at the terminus of 3-cm diam wooden poles,
supported at 50 cm above the ground, originating from a tree where the colony nested. Once ants were traveling along the poles, a bait dish on the feeding
station was filled with 1 ml of toxic bait. After ants fed to repletion, and were returning to the nest, they were transferred to plastic boxes (10 per box) with
a ventilated lid. This was continued until approximately 30 ants (range: 28 to 31) were dosed. Returned to the laboratory (25 ± 5°C, ambient RH), the ants
were provided a moistened dental wick, and observed for cumulative mortality at 6 and 12 h after treatment and then at 12 h intervals for 21 d; dental wicks
were wetted daily. At varying DAT, LC^s were estimated by regression of probit mortality vs. log10 of concentration (ppm). LT30S for 500 ppm abamectin,
dechlorane, and sulfluramid and 20 ppm chlorpyrifos and permethrin were estimated by regression of cumulative probit mortality vs. logio of time (d); for
LTJQS,
ants fed untreated bait served as controls monitoring natural mortality.
Toxicities of chlorpyrifos and permethrin 2 DAT were greater than dechlorane. Owing to delays before mortality, it was not possible to estimate an
LCs) until 4 and 8 DAT for abamectin and sulfluramid, respectively; neither material was as toxic as permethrin or chlorpyrifos. While highly toxic, permethrin
and chlorpyrifos were too fast acting to use in carpenter ant baits, as LTgo values at 20 ppm were <1 d. This is a concern since many commercial and consumer
ant baits containing chlorpyrifos at 5000 ppm would kill foraging workers too rapidly to transfer significant quantities of toxicant to the colony. Abamectin at
500 ppm was also fast acting, as workers only lived for 1 or 2 d. This might be too fast acting to allow significant bait distribution to the colonies. The speed
of action for sulfluramid and dechlorane was considerably slower, and would allow sufficient time for bait distribution. Given the success of sulfluramid in
baits for other ant species, this toxicant, or others with a similar delayed-action toxicity, would be ideal insecticides for a carpenter ant bait.
Insecticide
Chlorpyrifos
Permethrin
Dechlorane
Abamectin
Sulfluramid
DAT
2
2
2
4
8
N1
120
90
120
121
122
Slope+
SE
3.10 ± 0.32
3.93 ± 0.25
4.22 ± 0.24
3.96 ± 0.25
4.40 ± 0.23
LCM (95%FL)2
9.6
(5.7-12.4)
18.1(15.3-28.5)
580.4 (488.2-694.7)
67.6
(56.5-81.8)
231.1(191.3-275.1)
LQB
(95%FL)2
32.7(24.9-57.9)
47.4
(29.5-367.2)
1423
(1093-2252)
176.2
(133.0-285.6)
547.0
(431.3-810.2)
Insecticide Cone (ppm) N1 Slope+
SE
LTs,
(95%FL)3
LTK,
(95%FL)3
Permethrin
Chlorpyrifos
Abamectin
Dechlorane
Sulfluramid
Control
20
20
500
500
500
90 3.85 ± 0.74 0.29 (0.21-0.35) 0.77 (0.59-1.45)
90 2.18 ± 0.46 0.71(0.43-0.95) 4.04(2.30-22.98)
217 3.46 ± 0.29 1.06(0.88-1.23) 3.17(2.61-4.25)
240 14.66 + 0.07 5.82(5.62-6.00) 7.53(7.17-8.09)
403 12.49 ± 0.08 6.20 (5.76-6.65) 8.39 (7.64-9.05)
420 21.23 ± 0.05 16.83(16.55-17.09) 20.11(19.56-20.86)
'Number of insects (LC) or observations (LT) included in the probit regressions.
Concentration [ppm] of toxicant in sugar-milk bait.
3Time (d) to moribundity in a sample of carpenter ant workers.
SINGLE-FAMILY DWELLINGS:
German cockroach; Blattella germanica (L.) C. G. Wright and H. E. Dupree Jr.
Department of Entomology
North Carolina State University
Raleigh, NC 29695-7613
W)
EVALUATION OF INSECTICIDES FOR CONTROLLING GERMAN COCKROACHES, 1990: Pin-stream sprays from self-pressurized, aerosol-
type containers, were directed into cracks and crevices of dwellings. Single-family dwellings, located in Sampson or Duplin counties, NC, served as test
sites.
Kitchens with a minimum of 100 living German cockroaches sighted in a preliminary survey were used, with 5 replications. Preapplication visual tallies
of living cockroaches in the kitchens compared to tallies at specified intervals after treatment indicated efficacy. The chlorpyrifos formulations were continued
through 24 wk in order to compare the efficiencies of chlorpyrifos with and without fenoxycarb. The amount of insecticide applied and the size, temperature
and relative humidity of the kitchens, were recorded. Insecticide reapplications were made in kitchens where living cockroaches were observed during post
application tallies. Non-test rooms in the dwellings were treated as needed at each visit to minimize migration of German cockroaches. Analysis were calculated
on percent reduction of cockroaches (pre- versus post-tallies for a kitchen). The active ingredient applied in the initial applications for all formulations ranged
from 0.12 to 5.3 g and 0.0 to 1.6 g during reapplications, respectively, for 50 m2 of kitchen floor and wall surfaces.
There was no correlation between size, temperature, or relative humidity of the kitchens and cockroach mortality. All treatments gave significant
control at 2, 4, 8, and 12 wk, with differences between various treatments at each tally time. Some individuals in the kitchens treated with fenoxycarb +
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