Small cages with insect couples provide a simple method for a preliminary assessment of mating disruption.

Mating disruption by sex pheromones is a sustainable, effective and widely used pest management scheme. A drawback of this technique is its challenging assessment of effectiveness in the field (e.g., spatial scale, pest density). The aim of this work was to facilitate the evaluation of field-deployed pheromone dispensers. We tested the suitability of small insect field cages for a pre-evaluation of the impact of sex pheromones on mating using the grape moths Eupoecilia ambiguella and Lobesia botrana, two major pests in vineyards. Cages consisted of a cubic metal frame of 35 cm sides, which was covered with a mosquito net of 1500 µm mesh size. Cages were installed in the centre of pheromone-treated and untreated vineyards. In several trials, 1 to 20 couples of grape moths per cage were released for one to three nights. The proportion of mated females was between 15 to 70% lower in pheromone-treated compared to untreated vineyards. Overall, the exposure of eight couples for one night was adequate for comparing different control schemes. Small cages may therefore provide a fast and cheap method to compare the effectiveness of pheromone dispensers under standardised semi-field conditions and may help predict the value of setting-up large-scale field trials.

Diversity of insecticide resistance mechanisms and spectrum in European populations of the codling moth, Cydia pomonella.

Only a few of the registered insecticides against Cydia pomonella L. are still effective in areas where insecticide resistance has emerged in this pest. Resistance mechanisms are multiple, and their lone or cumulative effects in a single population are not completely understood. A detailed estimation of resistance spectrum is still required to define the suitable insecticides to use against a given population. The efficacy of ten insecticides was therefore investigated together with the resistance mechanisms expressed in four laboratory strains and 47 field populations of C. pomonella from five countries. Bioassays were performed using topical applications of diagnostic concentrations on diapausing larvae, and resistance mechanisms were analysed on adults emerging from control insects. All populations exhibited a reduced susceptibility to at least one insecticide when compared with the susceptible laboratory strain. Cross-resistances were observed between azinphos-methyl or phosalone and more recent compounds such as spinosad and thiacloprid. Resistances to azinphos-methyl, diflubenzuron, spinosad, tebufenozide and thiacloprid were significantly correlated with mixed-function oxidase activity, while increased glutathione-S-transferase and reduced non-specific esterase activities were correlated with resistance to azinphos-methyl and emamectin, respectively. Conversely, resistances to azinphos-methyl, tebufenozide and thiacloprid were negatively correlated with increased esterase activity. None of the observed mechanisms explained the loss of susceptibility of populations to chlorpyrifos-ethyl, and no significant correlation was detected between resistance to deltamethrin and the presence of the kdr mutation. The suitability of such non-target instars to monitor insecticide resistance in field populations is discussed.

Ovicidal and larvicidal effectiveness of insecticides applied by dipping apples on the small fruit tortrix Grapholita lobarzewskii.

The larvicidal and ovicidal effectiveness of twelve insecticides on Grapholita lobarzewskii Nowicki was tested by dipping apples in different concentrations of the insecticides. Emamectin was the most effective larvicidal product, with an LC(50) of 0.01 mg kg(-1), closely followed by spinosad, methoxyfenozide and chlorpyrifos-methyl, with LC(50) values between 0.2 and 0.7 mg kg(-1). Products like imidacloprid, indoxacarb, phosmet and thiacloprid gave LC(50) values between 1 and 2 mg kg(-1). Lastly, chlorpyrifos-ethyl and phosalone had LC(50) values of around 4 mg kg(-1), whereas tebufenozide and diflubenzuron had almost no larvicidal effect. Most of the products tested had low ovicidal effectiveness, and only fenoxycarb and emamectin gave LC(50) values worthy of note, close to 2 mg kg(-1).

Effectiveness of twelve insecticides applied topically to diapausing larvae of the codling moth, Cydia pomonella L.

Dose-mortality curves were established for 12 insecticides administered by topical application to diapausing larvae from a susceptible codling moth strain. Toxicity varied greatly among the insecticides tested. LC50 values ranged from 0.1 mg kg(-1) for fenoxycarb to over 2800 mg kg(-1) for diflubenzuron and indoxacarb. Discriminating dose levels were determined from dose-mortality reference curves for the detection of resistance in field-collected diapausing larvae.