| Title: | Effects of predator cues and pesticide resistance on the toxicity of a (bio)pesticide mixture |
| Author(s): | Delnat V; Janssens L; Stoks R; |
| Address: | "Evolutionary Stress Ecology and Ecotoxicology, University of Leuven, Leuven, Belgium" |
| ISSN/ISBN: | 1526-4998 (Electronic) 1526-498X (Linking) |
| Abstract: | "BACKGROUND: Populations of target species are typically exposed to pesticide mixtures and natural stressors such as predator cues, and are increasingly developing resistance to single pesticides. Nevertheless, we have poor knowledge whether natural stressors and the presence of pesticide resistance shape mixture toxicity. We tested the single and combined effects of the pesticide chlorpyrifos and the biopesticide Bacillus thuringiensis israelensis (Bti) on the survival of the Southern house mosquito (Culex quinquefasciatus, Say) and whether these effects were magnified by synthetic predator cues of Notonecta water bugs and differed between a chlorpyrifos-resistant (Ace-1R) and non-resistant (S-Lab) strain. RESULTS: Single exposure to Bti caused mortality in both strains (S-Lab approximately 27%, Ace-1R approximately 41%) and single exposure to chlorpyrifos caused only mortality in the S-Lab strain ( approximately 33%), while predator cues did not induce mortality. The chlorpyrifos-resistant strain was 1.5-fold more sensitive to Bti, indicating a cost of resistance. The interaction types between chlorpyrifos and Bti (additive), between chlorpyrifos and predator cues (additive), and between Bti and predator cues (synergistic) were consistent in both strains. Despite predator cues making Bti approximately 8% more lethal, they did not change the additive interaction between Bti and chlorpyrifos in their mixture in either strain. CONCLUSION: These results indicate that the resistance against chlorpyrifos was not partly lifted when chlorpyrifos exposure was combined with Bti and predator cues. Identifying the interaction type within pesticide mixtures and how this depends on natural stressors is important to select control strategies that give a disadvantage to resistant individuals compared to non-resistant individuals. (c) 2019 Society of Chemical Industry" |
| Keywords: | Animals Bacillus thuringiensis Chlorpyrifos Cues Culex Larva Pesticides/*pharmacology integrated pest management (IPM) mixture toxicity pesticide resistance semiochemicals synergism vector control; |
| Notes: | "MedlineDelnat, Vienna Janssens, Lizanne Stoks, Robby eng G.0943.15/Fund for Scientific Research Flanders/ C16/17/002/KU Leuven/ England 2019/10/23 Pest Manag Sci. 2020 Apr; 76(4):1448-1455. doi: 10.1002/ps.5658. Epub 2019 Nov 19" |
