Insecticide Transfer Efficiency and Lethal Load in Argentine Ants.
Trophallaxis between individual worker ants and the toxicant load in dead and live Argentine ants (Linepithema humile) in colonies exposed to fipronil and hydramethylnon experimental baits were examined using accelerator mass spectrometry (AMS). About 50% of the content of the crop containing trace levels of14C-sucrose,14C-hydramethylnon, and14C-fipronil was shared between single donor and recipient ants. Dead workers and queens contained significantly more hydramethylnon (122.7 and 22.4 amol/μg ant, respectively) than did live workers and queens (96.3 and 10.4 amol/μg ant, respectively). Dead workers had significantly more fipronil (420.3 amol/μg ant) than did live workers (208.5 amol/μg ant), but dead and live queens had equal fipronil levels (59.5 and 54.3 amol/μg ant, respectively). The distribution of fipronil differed within the bodies of dead and live queens; the highest amounts of fipronil were recovered in the thorax of dead queens whereas live queens had the highest levels in the head. Resurgence of polygynous ant colonies treated with hydramethylnon baits may be explained by queen survival resulting from sublethal doses due to a slowing of trophallaxis throughout the colony. Bait strategies and dose levels for controlling insect pests need to be based on the specific toxicant properties and trophic strategies for targeting the entire colony.
Department of Environmental Science, Louisiana State University, Baton Rouge, LA 70803 ; Department of Entomology, University of California, Riverside, CA 92521.
L M
LM
Hooper-Bui
Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521.
E S C
ES
Kwok
Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94551 ; Department of Environmental Toxicology, University of California, Davis, CA 95616.
B A
BA
Buchholz
Department of Entomology, University of California, Riverside, CA 92521.
M K
MK
Rust
Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521.
D A
DA
Eastmond
Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94551.
J S
JS
Vogel
AMS; Argentine ant; Linepithema humile; accelerator mass spectrometry; fipronil; hydramethylnon; resurgence; trophallaxis