Susceptibility of Lobesia botrana (Lepidoptera: Tortricidae) to chlorantraniliprole in the Emilia Romagna Region of Northeast Italy.

The European grapevine moth, Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae), is regarded as the most important insect pest of wine grapes in Europe. If not properly controlled, it can cause significant direct and indirect yield losses due to secondary infections of grape berries by Botrytis cinerea. For these reasons, it is important to preserve the activity of insecticides used against this pest, as the number of insecticidal mode of actions available to control Lepidoptera species on wine grapes in Europe is limited. Following a report of suboptimal control of L. botrana after field applications of chlorantraniliprole-containing products, an extensive monitoring program was conducted in the Emilia Romagna Region of North East Italy to determine L. botrana susceptibility to chlorantraniliprole. This study consisted of 11 bioassays conducted with chlorantraniliprole on L. botrana populations collected in the Emilia Romagna Region in 2014-2016, 5-7 years after its introduction into the market. Bioassay results were compared to results previously obtained from the chlorantraniliprole pre-comercialization baseline susceptibility survey conducted from 2007 to 2011. The Lethal Concentration values obtained for field populations of L. botrana in this study are comparable to those reported for the pre-comercialization susceptibility baseline. We demonstrate that there is no significant change in L. botrana susceptibility to chlorantraniliprole in the Emilia Romagna Region. Emphasis should be given to implement appropriate insecticide resistance management strategies, including nonchemical agronomic practices and biological control methods, to preserve effective insecticides like chlorantraniliprole for future use in controlling the European grapevine moth.

Identification and detection of indoxacarb resistance mutations in the para sodium channel of the tomato leafminer, Tuta absoluta.

BACKGROUND: Indoxacarb is an important active ingredient extensively used for the control of Tuta absoluta, a major tomato pest, playing a particular role in insecticide resistance management schemes. RESULTS: Reduced susceptibility to indoxacarb was identified (1794-fold resistance) through toxicological bioassays in a field population from Greece and evolved rapidly to resistance after short laboratory selection. Combined bioassays with synergists and biochemical analysis suggested only a partial involvement of detoxification enzymes in the resistant phenotype. To investigate the role of target-site resistance, segment 6 of domain IV of the sodium channel in T. absoluta was cloned and the sequences compared between susceptible and indoxacarb-resistant T. absoluta insects. The presence of the F1845Y and the V1848I indoxacarb resistance mutations was detected and was strongly associated with the phenotype. These amino acid substitutions correspond to recently characterised indoxacarb resistance mutations in diamondback moth (Plutella xylostella). Robust and accurate PCR-RFLP assays were subsequently developed and successfully validated for detecting both indoxacarb resistance mutations in field T. absoluta populations. CONCLUSION: The identification of indoxacarb resistance mutations and the development of diagnostic tools will allow early detection of indoxacarb resistance, facilitating implementation of appropriate resistance management strategies, thus delaying the spread of resistance. © 2016 Society of Chemical Industry.

Determination of baseline susceptibility of European populations of Tuta absoluta (Meyrick) to indoxacarb and chlorantraniliprole using a novel dip bioassay method.

BACKGROUND: Tuta absoluta(Meyrick) is one of the most serious pests of tomato recently introduced in the Mediterranean region. A novel bioassay method designed for the accurate determination of insecticide toxicity on T. absoluta (IRAC method No. 022) was validated by three different laboratories [Greece (NAGREF), Italy (UC) and Spain (UPCT)] on European populations. RESULTS: The insecticides indoxacarb and chlorantraniliprole were used as reference products. The IRAC leaf dip method is easy to perform, producing repeatable, homogeneous responses. LC(50) values for indoxacarb ranged between 1.8 and 17.9 mg L(-1) (NAGREF), 0.93 and 10.8 mg L(-1) (UC) and 0.20 and 0.70 mg L(-1) (UPCT), resulting in a tenfold, 12-fold and fourfold difference between the least and most susceptible populations at each laboratory respectively. For chlorantraniliprole, LC(50) values ranged between 0.10 and 0.56 mg L(-1) (NAGREF), 0.23 and 1.34 mg L(-1) (UC) and 0.04 and 0.24 mg L(-1) (UPCT), resulting in a sixfold difference in all three cases. Overall, UPCT reported lower mean LC(50) to indoxacarb, while UC reported higher LC(50) to chlorantraniliprole. CONCLUSIONS: The new bioassay is reliable, providing a useful tool in the design of IRM strategies. Within each country/lab, the variability observed in the results for both indoxacarb and chlorantraniliprole can be attributed to natural variation. Future research is necessary to determine the extent to which it is possible to compare results among laboratories.

Susceptibility of standard clones and European field populations of the green peach aphid, Myzus persicae, and the cotton aphid, Aphis gossypii (Hemiptera: Aphididae), to the novel anthranilic diamide insecticide cyantraniliprole.

BACKGROUND: Parthenogenetic clones of the green peach aphid, Myzus persicae (Sulzer), and the cotton aphid, Aphis gossypii Glover, were tested with the anthranilic diamide insecticide cyantraniliprole (i.e. DuPont(™) Cyazypyr(™) ) in systemic-uptake bioassays to investigate potential for cross-resistance conferred by mechanisms of insecticide resistance to organophosphates, carbamates and pyrethroids and, in the case of M. persicae, reduced sensitivity to neonicotinoids. These data were compared with the response of field samples of M. persicae and A. gossypii collected from around Europe. RESULTS: Cyantraniliprole was not cross-resisted by any of the known insecticide resistance mechanisms present in M. persicae or A. gossypii. The compound was equally active against resistant and susceptible aphid strains. The responses of the M. persicae field samples were very consistent with a maximum response ratio of 2.9 compared with a standard laboratory clone. The responses of the A. gossypii field samples were more variable, although a majority of the responses were not statistically different. CONCLUSION: Cyantraniliprole is currently the only anthranilic diamide (IRAC MoA 28) insecticide targeting aphid species such as M. persicae and A. gossypii. There is no evidence to suggest that the performance of this compound is affected by commonly occurring mechanisms that confer resistance to other insecticide chemistries. Cyantraniliprole is therefore a valuable tool for managing insecticide resistance in these globally important pests.

Pyrethroid resistance monitoring in European populations of pollen beetle (Meligethes spp.): a coordinated approach through the Insecticide Resistance Action Committee (IRAC).

BACKGROUND: Pollen beetle (Meligethes spp.) is a major pest of European oilseed rape crops. Its resistance to pyrethroid insecticides has been recorded in samples of beetles collected in Europe since at least 1999, and problems with the control of the beetle in the field have been widely reported. In 2007, a Pollen Beetle Working Group was formed through the Insecticide Resistance Action Committee (IRAC) in order to coordinate efforts for surveying pyrethroid resistance development. RESULTS: The results of the first 3 years of the pollen beetle pyrethroid susceptibility survey using a laboratory test are presented in this paper. Resistant beetle samples were collected from 20 of the 21 countries surveyed, with a general trend of increasing frequency and spread of resistant samples in European oilseed-rape-growing regions. CONCLUSION: Pyrethroid-resistant beetles dominate in Western and Central Europe and are becoming established in the North and East, the main oilseed-rape-growing areas of Europe. The development and spread of pyrethroid-resistant pollen beetles highlights the need for effective management strategies for oilseed rape insect pests.