Evaluation of neem triterpenes as ovipositional and feeding deterrents to the tea mosquito bug, Helopeltis antonii Sign. on cashew

Abstract

Experiments were conducted at the Department of Entomology, College of Horticulture, Vellanikkara, to ascertain the feasibility of utilizing the commercially available neem products for the management of populations of tea mosquito bug, Helopeltis antonii Sign. On cashew, Anacardium occidentale L. The effects of three neem products in altering the ovipositional behaviour and the feeding behaviour of H. antonii through contact and translaminar effects and the number of feeding punctures as affected by the contact and translaminar effects, were tested in comparison with NKS. Radio labelling of cashew seedlings prior to application of treatments and quantification of feeding based on the quantum of radio activity in the bodies of test insects fed on the treated seedlings was developed as a new technique. The study resulted in the following findings. 1. Godrej Achook at 1.6 and 3.2 per cent doses and Rakshak at all the tested doses significantly reduced the number of egg laying sites. 2. Duration of egg laying was significantly reduced by Godrej Achook and Rakshak at 1.6 and 3.2 per cent doses. 3. Significant reduction in the total number of eggs laid was brought about by Rakshak 1.6 per cent and Godrej Achook at 1.6 and 3.2 per cent doses. 4. Rakshak at all doses and Godrej Achhok at 1.6 and 3.2 per cent doses significantly reduced the nymphal duration. The nymphs failed to reach adult hood. 5. Feeding deterrency through contact action was exhibited by the treatments. Nimbecidine and Godrej Achook at higher doses were better. 6. The number of feeding punctures was influenced by the treatments through translaminar effects. 7. Development of feeding punctures was affected by the treatments through contact action also. Higher doses of Godrej Achook and Nimbecidine were better than the other treatments. In conclusion it can be stated that the commercially available neem products showed a high degree of effectiveness in reducing the feeding and oviposition by H. antonii, eventhough the neem tree is an alternate host of the tea mosquito bug. The neem products can be included as candidates for the management of population of H. antonii on cashew.