Pyrethroid and carbamate resistance in Australian Helicoverpa armigera (Lepidoptera: Noctuidae) from 2008 to 2015: what has changed since the introduction of Bt cotton?

Pyrethroid and carbamate resistance was evaluated in Helicoverpa armigera from 2008 to 2015. Insects were collected as eggs primarily from cultivated hosts in the major cropping areas of New South Wales and Queensland, Australia. Larvae reared from eggs were tested for resistance to fenvalerate, bifenthrin or methomyl in the F0 generation using a topical application of a discriminating dose of insecticide. In 2008-2009, resistance to fenvalerate was 71% and no resistance to bifenthrin was recorded. In the following two seasons, resistance to pyrethroids was relatively stable with fenvalerate resistance ranging from 63% to 67% and bifenthrin resistance ranging from 5.6% and 6.4% in 2009-2010 and 2010-2011, respectively. However, in 2011-2012, pyrethroid resistance had increased to 91% and 36% for fenvalerate and bifenthrin, respectively. Resistance remained above 90% for fenvalerate and above 35% for bifenthrin in the following three seasons from 2012 to 2015. In 2008-2009, methomyl resistance was 33% and declined to 22% and 15% in 2009-2010 and 2010-2011, respectively. Methomyl resistance remained at moderate levels from 2011-12 to 2014-15, ranging from 21% to 40%. Factors that influenced selection pressure of pyrethroid and carbamate insecticides and impacted resistance frequency in H. armigera may have been associated with changes in the composition of the cropping landscape. The rapid expansion of the pulse industry and the commensurate increased use of insecticide may have played a role in reselection of high-level pyrethroid resistance, and highlights the need for an urgent and strategic response to insecticide resistance management in the Australian grains industry.

The Use of F2 Screening for Detection of Resistance to Emamectin Benzoate, Chlorantraniliprole, and Indoxacarb in Australian Populations of Helicoverpa armigera (Lepidoptera: Noctuidae).

The ability to effectively detect changes in susceptibility to insecticides is an integral component of resistance management strategies and is highly dependent upon precision of methods deployed. Between 2013 and 2016, F2 screens were performed for detection of resistance alleles in Helicoverpa armigera (Hübner) to emamectin benzoate, chlorantraniliprole, and indoxacarb in major cropping regions of eastern Australia. Resistance to emamectin benzoate was not detected. There were low but detectable levels of survival at discriminating concentrations of chlorantraniliprole and indoxacarb. Alleles conferring an advantage to chlorantraniliprole were present at a frequency of 0.0027 (95% CI 0.0012-0.0064; n = 1,817). Alleles conferring an advantage to indoxacarb were present at a frequency of 0.027 (95% CI 0.020-0.035; n = 1,863). Complementation tests for allelism in six of seven positive indoxacarb tests indicated that resistance was due to alleles present at the same locus. The majority (88%) of lines that tested positive for indoxacarb resistance deviated from a model of recessive inheritance. Pheromone-caught male moths contributed significantly greater numbers of F2 lines compared with moths derived from field-collected eggs or larvae. There was no difference in the detectability of indoxacarb resistance in F2 lines from pheromone-caught moths compared with moths derived from immature stages collected from the field and reared to adult under laboratory conditions. Therefore, we recommend the use of pheromone traps for sourcing insects for F2 screening as a more cost- and time-efficient alternative to traditional methods of sampling.

Susceptibility of Helicoverpa armigera (Lepidoptera: Noctuidae) to Cyantraniliprole Determined From Topical and Ingestion Bioassays.

The use of insect bioassay to establish baseline susceptibility and monitor changes in sensitivity to insecticides over time has been a key component of resistance management of Helicoverpa armigera Hübner in Australia for over 30 yr. Cyantraniliprole is a recently introduced insecticide, where toxicity is mediated at the ryanodine receptor. Baseline susceptibility of H. armigera to cyantraniliprole was determined in both topical and ingestion assays performed on field populations collected primarily from commercial farms across eastern Australia. Intraspecific variation in cyantraniliprole susceptibility amongst field strains was 9.3-fold in topical bioassays ( n = 23 strains) and 2.6-fold in ingestion bioassays ( n = 31 strains). The median lethal concentration in field strains was 28 mg/liter in topical bioassays and 0.065 mg/liter in ingestion bioassays, demonstrating that cyantraniliprole was >400-fold more toxic when administered orally than by contact. The narrow range of intraspecific tolerance, high slope values, goodness-of-fit to the probit binomial model, and enhanced toxicity in diet incorporation bioassays compared with topical bioassays suggest that delivery by ingestion is an effective laboratory method for measuring the dose-response of cyantraniliprole in H. armigera . A discriminating dose of 1.5 mg of cyantraniliprole per liter of diet was calculated from diet incorporation bioassays, as a first step in resistance management of cyantraniliprole in Australia.

Rapid antibody-based field test to distinguish between Helicoverpa armigera (Lepidoptera: Noctuidae) and Helicoverpa punctigera (Lepidoptera: Noctuidae).

Helicoverpa armigera (Hübner) and Helicoverpa punctigera (Wallengren) are the two most important insect pests of cotton production in Australia and require application of insecticides to control them. H. armigera has developed resistance to several insecticides but H. punctigera has not. Cost-effective management of insecticide resistance requires that growers be able to determine the proportion of H. armigera eggs or young larvae present on their crop before applying insecticides. This is impossible visually. We generated two monoclonal antibodies that reacted with the insect protein "lipophorin" and were capable of discriminating individuals of the two species at all life-stages. The antibodies were incorporated into a rapid test kit that was tested under field conditions over two growing seasons. Results obtained with the kit agreed closely with those obtained by rearing larvae through to second instar.

Computerization in the OR.

This article highlights the process of establishing a computerized scheduling and materials management system in a surgical department. The following facets of the computerization process are discussed: options staff members should consider when choosing a computer system, the importance of scheduling and inventory control, cost savings, how computer systems work when using electronic data interchange and bar coding, and case studies.