Sublethal effects of imidacloprid on the gray-black spiny ant, Polyrhachis dives
Date Issued
2016
Date
2016
Author(s)
Dai, Yun-Wen
Abstract
The purpose of applying insecticide is to control pest, but it may affect other non-target individual, like pollinators or predators. Neonicotinoids, such as imidacloprid, is a systematic insecticide widely used around the world. It acts on nicotinic acetycholine receptor (nAChR) inducing hyperpolarization and death. Previous studies indicated sublethal effect of imidacloprid could affect behavior of insects. Only few concerned about ant, as one of the important social insects. Ant may contact the residue of insecticide or intake prey killed by insecticide to aggregate insecticide inside the body and pass to the larva through trophallaxis, thus inducing colony collapse eventually. We built oral toxicity data of imidacloprid and tested whether imidacloprid contamination could affect foraging, behavioral reactions and interactions between a native ant Polyrhachis dives and an invasive ant Solenopsis invicta with sublethal (LC1) and lethal concentrations (LC15 and LC50). The results showed that imidacloprid contamination reduces the reactions of P. dives to food signal and affects foraging patterns. The food discovery time was not affected, but dynamic in the lethal concentrations, suggesting that imidacloprid might affect cognitive system in brain and consequently hampers the reactions to stimulus. During interspecific competition at individual level, exposed individuals displayed reduced aggression at lethal concentrations, but not at sublethal concentrations. The mortality of interspecific competition was not affected. During interspecific competition at small colony fragment level, survivorship of fire ants increase in lethal concentrations, but was no significantly affected at sublethal ones. These results suggest that that the exposure of neonicotinoid could affect behaviors of ants and the interspecific interaction outcomes among different species.
Subjects
foraging behavior
interspecific competition
neonicotinoid
Polyrhachis dives
Solenopsis invicta
sublethal effect
Type
thesis
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