Is attract-and-kill technology potent against insecticide-resistant Lepidoptera?

Attract-and-kill techniques, associating an attractant and a contact insect icide in a sticky formulation, are a new way of controlling Lepidopteran pe sts. Insecticide resistance may, however, limit the effectiveness and even the attractiveness of such formulations where resistance pleiotropic effect s influence pheromone perception. We have tested this hypothesis on resista nt codling moths Cydia pomonella (L) using a commercial formulation contain ing (EE)-8,10-dodecadien-1-ol (codlemone), the major component of the sex p heromone, as an attractant and permethrin as toxicant. We first compared th e attractiveness of codlemone in a wind tunnel and the contact toxicity of pyrethroids on males of one susceptible and of three strains selected for r esistance to diflubenzuron, deltamethrin and azinphos-methyl. The dose-resp onse relationships of males of susceptible and resistant strains to codlemo ne did not differ significantly. The deltamethrin-selected strain was the m ost resistant to pyrethroids, exhibiting 138-, 25- and 18-fold resistance r atios to deltamethrin, cypermethrin and permethrin, respectively. The effic iency of the attracticide formulation, applied successively on filter paper support, glass support and wood support, was estimated by recording the mo rtality delay of males after natural contact with the formulation in the wi nd tunnel. The deltamethrin-and diflubenzuron-resistant strains were signif icantly less affected than the susceptible strain by contact with the attra cticide on the wooden support, exhibiting 58- and 2.3-fold greater LT50 rat ios, respectively. Mortality of deltamethrin-resistant moths did not exceed 40% after 48 h. The LT50 value was significantly greater on filter paper s upport than on the two other supports. Surprisingly, the LT50 ratio of the deltamethrin-resistant strain was markedly higher on filter paper support ( 1021-fold), which was more absorbent, than on the glass support (31-fold). No sublethal effects in terms of pheromone response, mating or fecundity oc curred in moths surviving contact with the attracticide. Choice of insectic ides in attracticide formulations will be influenced by the resistance back ground of the target pests. Principles of insecticide resistance management may also be applied to attract-and-kill technology by alternating with oth er insecticides or control methods. (C) 2001 Society of Chemical Industry.