Green peach aphid, Myzus persicae (Hemiptera: Aphididae), reproduction during exposure to sublethal concentrations of imidacloprid and azadirachtin.
BACKGROUND
Resurgence of insect pests following insecticide applications is often attributed to natural enemy disturbance, but hormesis could be an alternative or additional mechanism. Green peach aphid, Myzus persicae (Sulzer), is an important insect pest of many crops worldwide that may be exposed to sublethal insecticide concentrations over time. Here, the hypothesis that exposure to low concentrations of imidacloprid and azadirachtin can induce hormetic responses in M. persicae is tested in the laboratory.


RESULTS
When insects were exposed to potato leaf discs dipped in sublethal concentrations of insecticide, almost all measured endpoints-adult longevity, F1 production, F1 survival and F2 production-were affected, and a statistically significant (P < 0.05) stimulatory response was recorded for F2 production following exposure to imidacloprid. No other measures for hormesis were statistically significant, but other trends of hormetic response were consistently observed.


CONCLUSIONS
Given that variable distribution and degradation of insecticides in the field would result in a wide range of concentrations over time and space, these laboratory experiments suggest that exposure to sublethal concentrations of imidacloprid and azadirachtin could stimulate reproduction in M. persicae.
Christopher Cutler
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G
Faculty of Land and Food Systems, University of British Columbia, Vancouver V6T 1Z4, BC, Canada. ccutler@nsac.ca
Ramanaidu
Krilen
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Astatkie
T
T
Isman
Murray B
MB
D000818:Animals; D001042:Aphids / Q000187:drug effects / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology*; D007306:Insecticides / Q000494:pharmacology*; D036701:Limonins / Q000494:pharmacology*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000494:pharmacology*; D010935:Plant Diseases / Q000469:parasitology*; D012098:Reproduction / Q000187:drug effects; D011198:Solanum tuberosum / Q000469:parasitology
D007093:Imidazoles; D007306:Insecticides; D036701:Limonins; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid; C010329:azadirachtin