Inheritance and Synergism of Resistance to Imidacloprid in the Colorado Potato Beetle (Coleoptera: Chrysomelidae)

Abstract

Colorado potato beetle, Leptinotarsa decemlineata (Say), adults and larvae collected from Long Island, NY, were 100.8 and 13.2 times more resistant to imidacloprid, respectively, compared with a susceptible strain. This high level of resistance appeared in only the third field season of imidacloprid use. Analysis of probit lines from F1 reciprocal crosses indicated that resistance to imidacloprid in adults was inherited autosomaly as an incompletely recessive factor. The degree of dominance of the resistance was -0.23 and -0.10, respectively, 3 and 7 d after treatment (incompletely recessive). The chi2 analysis of response ratio statistics from F1 x susceptible back crosses compared with a monogenic model suggested that more than one locus is responsible for resistance to imidacloprid. Synergism studies with piperonyl butoxide suggested that mixed-function oxidase mediated detoxification is responsible for the resistance to imidacloprid in adults. Synergism studies with S,S,S-tributyl phosphorotrithioate (DEF) indicated that esterase mediated detoxification may be an additional resistance factor. Mixed-function oxidase mediated detoxification is probably also one of the mechanisms of resistance to imidacloprid in larvae. Because the synergists used did not completely eliminate resistance in the resistant strain, there may be additional mechanisms involved. Refugia and crop rotation decrease the frequency of homozygous resistant genotypes and may be effective resistance management strategies, because of the recessive nature of the resistance.

Resistance Potential of Colorado Potato Beetle (Coleoptera: Chrysomelidae) to Novaluron

“…In the current study, the imidacloprid 96-h LC 50 for second instars of the resistant strain was 0.57 ppm (Table 1), approximately four-fold that of the susceptible strain, but considerably less than the 91-fold imidacloprid resistance for adults of this strain originally determined by GraÞus and Byrne (personal communication). However, larvae are much more sensitive to imidacloprid than adults (Zhao et al 2000;Tolman et al 2002Tolman et al , 2003. Furthermore, bioassays that expose insects through contact and feeding on treated foliage often result in lower lethal concentrations than bioassays using direct topical exposure (ffrench-Constant and Roush 1990; Tolman et al 2002Tolman et al , 2003.…”

“…Increased efÞciency or quantity of mixed function oxidases and esterases has been reported as a mechanism of Colorado potato beetle resistance to organophosphorous insecticides, carbamates, pyrethroids, abamectins (Bishop and GraÞus 1996, and references therein), and imidacloprid (Zhao et al 2000). When PBO, a mixed function oxidase inhibitor, was applied to larvae before exposure to novaluron-treated foliage, there was no signiÞcant change in the LC 50 value, as indicated by the overlap of the 95% CL in the novaluron and novaluron ϩ PBO treatments (Table 1).…”

“…Third, the mode of action of novaluron dictates its use against larval stages, which are usually more sensitive to and less capable of developing resistance to insecticides (Roush 1989). Indeed, Hilton et al (1998) found Colorado potato beetle larvae to be more susceptible than adults to eight different insecticides and Zhao et al (2000) found that potato beetle larvae are much more sensitive to imidacloprid than adults. In the current study, Colorado potato beetle larvae from adults exhibiting 91-fold resistance to imidacloprid were highly susceptible to novaluron.…”

“…However, in 2002 and2003, per-sonnel in Agriculture and Agri-Food Canada detected the onset of potential imidacloprid resistance development in several Canadian Colorado potato beetle populations and strongly recommended incorporation of a new control agent in future management programs (Tolman et al 2002(Tolman et al , 2003. Imidacloprid resistance has developed in a number of U.S. Colorado potato beetle populations (Olson et al 2000, MotaSanchez et al 2000, Zhao et al 2000.…”

The invertebrate pharmacology of insecticides acting at nicotinic acetylcholine receptors

“…3,4) In all cases, resistance can be associated with the poor implementation of rotation management practices as recommended by the Insecticide Resistance Action Committee (IRAC). 2,3,[5][6][7][8][9][10] The spinosyns (spinosad and spinoteram) are used principally to control chewing pests, for example leafminers, but also display efficacy against certain cell-feeding insects such as thrips. The nereistoxins are a niche market product used for controlling certain pests in rice, vegetables and potatoes.…”