This report presents the experimental work and outcomes of the project that commenced in 2006 and was completed on 30 June 2010 (03DAN001). The aim of the project was to develop and commercialize two new fungal insecticides viz; BC667 (Beauveria spp) and BC 639 (Aspergillus sp.) for control of Helicoverpa spp. and sucking pests on cotton. In achieving the project’s aim various studies were conducted in the laboratory, mesh house and field. The study objectives were (1) assess BC667 and BC639 for efficacy against green mirids and aphids (2) evaluate the efficacy of lower rates (below 50g spore/ha) of BC667 and BC639 against green mirids and aphids on cotton; (3) determine the oviposition and feeding responses of green mirids and aphids to BC 667 and BC639 treated plants; (4) evaluate the efficacy of different rates of BC667 and BC639 fungal insecticides and identify the optimum rate effective against green mirids, aphids and beneficial insects and (5) identify the best method for the manufacture and formulation of large quantities of BC 667 and BC 639 spores for commercial use.

In 2005 - 2007, a commercial formulation of BC 667 and BC 639 that incorporates horticultural oil and emulsifiers was developed. Several laboratory, mesh house and field studies were undertaken to determine the efficacy of the formulated fungal products against Helicoverpa spp, sucking pests and beneficial insects on cotton plants. The results of the studies showed that both BC 667 and BC 639 were pathogenic to H. armigera eggs, larvae, and sucking pests including silverleaf whitefly but not pathogenic against predatory insects. The two fungi were also found to be pathogenic to Helicoverpa spp. first to third instar larvae within 3-4 days after treatment. In contrast, the fungus was found ineffective against medium to large Helicoverpa spp. larvae.

In 2008 - 2010, field trials concentrated on BC 639 to generate more efficacy data to support registration of the BC 639 fungus upon the advice of the commercial partner (Becker Underwood Pty Ltd). Overall, the efficacy of the fungal insecticides particularly BC639 was tested at 14 different sites on commercial cotton crops against Helicoverpa spp eggs, very small and small larvae, medium and large larvae, green mirid adults and nymphs, gereen vegetable bugs, apple dimpling bugs, cotton aphids, silverleaf whiteflies (b-type). A total of 65 experiments were conducted on commercial cotton crops in terms of individual insects assessed. In each experiment, different rates of BC 639 was assessed and compared with commercial insecticides used against these pests on commercial cotton crops.

The results showed that BC 639 applied at the following rates: 125ml/ha, 250ml/ha, 500ml/ha, 750ml/ha and 1.0L/ha were found to be efficacious against all the test insects. No significant difference in efficacy was found when the product was applied at 1.0 L/ha, 750ml/ha and 500ml/ha against all the test insects. However, application of lower rates of BC 639 at 250ml/ha and 125ml/ha were efficacious at low pest pressure situations but at high pest pressure it will require paired application of the product especially sucking pests such as green mirids, green vegetable bug, aphids and whiteflies.

The optimum rate of application of BC 639 was identified as 500ml/ha. The 500ml/ha rate was as effective as 1.0 L/ha, 0.75L/ha BC 639 and also the recommended rates of commercial insecticides used in controlling green mirids, green vegetable bugs, silverleaf whiteflies, aphids, apple dimpling bugs and Helicoverpa spp. Application of BC 639 rates was done at the recommended thresholds for each of the targeted pests. For example, application of BC 639 against green mirids was done when the number of green mirids per metre row of cotton was equal or greater than 0.5 per metre (recommended visual counts threshold). It should be noted that when green mirid nymphs and adults reached a threshold of 0.5 per metre, there may be eggs already laid in the crop that have not hatched. Therefore, application of BC 639 will control the green mirid adults and the nymphs already on the plants not unhatched nymphs. Thus, any nymphs hatching from eggs after BC639 application may not be infected and killed due to lack of residual effect and low number of BC 639 spores after initial application. In this situation, pair applications of BC 639 irrespective of the rate will be required.

In general, the efficacy of BC 639 rates against the test insects was found to be similar and in most instances better than the commercial insecticides especially green mirids and silverleaf whiteflies. Additionally, the studies found that both BC 667 and BC 639 were more selective to beneficial insects especially predatory insects than the commercial insecticides used by the cotton industry to manage Helicoverpa and sucking pests on cotton. The product was also found not to be phyto-toxic to the cotton plant itself nor squares and bolls of the plant. The yield recorded on plots treated with conventional insecticide and BC 639 was not significantly different. Thus the application of BC 639 did not have any detrimental effect on yield relative to commercial conventional treated plots. In terms of quality, there was no difference between the BC 639 treatments and conventional insecticides for the characteristics of length, strength or micronaire.

In conclusion, application of entomopathogenic fungus to manage cotton pests will enhance conservational biological control, support IPM and reduce pest control costs on both Bollgard and conventional cotton.