Antifeedant and sublethal effects of imidacloprid on Asian citrus psyllid, Diaphorina citri

BACKGROUND: Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, transmits the causal bacteria of the devastating citrus diseasehuanglongbing(HLB).Becauseofthevariationinspatialandtemporaluptakeandsystemicdistributionofimidacloprid applied to citrus trees and its degradation over time in citrus trees, ACP adults and nymphs are exposed to concentrations that may not cause immediate mortality but rather sublethal effects. The objective of this laboratory study was to determine the effects of sublethal concentrations of imidacloprid on ACP life stages. RESULTS: Feeding by ACP adults and nymphs on plants treated daily with a sublethal concentration (0.1 µ gm L −1 )o f imidacloprid significantly decreased adult longevity (8 days), fecundity (33%) and fertility (6%), as well as nymph survival (12%)anddevelopmentalratecompared withuntreatedcontrols.Themagnitudeofthesenegativeeffectswas directlyrelated to exposure duration and concentration. Furthermore, ACP adults that fed on citrus leaves treated systemically with lethal and sublethal concentrations of imidacloprid excreted significantly less honeydew (7‐94%) compared with controls in a concentration-dependent mannersuggesting antifeedantactivity of imidacloprid. CONCLUSIONS: Sublethal concentrations of imidacloprid negatively affect development, reproduction, survival and longevity ofACP,whichlikelycontributestopopulation reductionsovertime.Also,reducedfeedingbyACPadultsonplantstreatedwith sublethal concentrations of imidacloprid may potentially decrease the capacity of ACP to successfully acquire and transmitthe HLB causal pathogen. c � 2009 Society of Chemical Industry