Impact of pesticidal spray on seasonal availability of natural predators and parasitoids in the tea ecosystem.
The most important pest attacking tea bushes in Himachal Pradesh are purple mite, Calacarus carinatus, thrips, Scirtothrips dorsalis, leafroller, Gracillaria theivora [Caloptilia theivora], aphid, Toxoptera aurantii, mealybug, Nipaecoccus sp. and leafminer, Tropiomyts theae [?Tropicomyia theae]. The important natural enemies in the tea orchards are Syrphus sp., Coccinella septempunctata, Oxyopes sp. and the parasitoid, Diaeretiella sp. A field experiment was conducted in Himachal Pradesh, India, during 1994-97 to investigate the impact of pesticides on pests of tea and their natural enemies. Among the insecticides and biopesticides evaluated against natural enemies, deltamethrin at 0.005%, cypermethrin at 0.01% and ethion at 0.1% sprays were found highly toxic to Syrphis sp. and Coccinella septempunctata and their adult and larval populations were not seen even on 7th and 4th days of spray, respectively. Neemark [Azadirachta indica] at 0.3%, Achook at 0.3% and Bacillus thuringiensis formulation (Dipel 8L at 0.3%) were quite safe to natural enemies. Endosulfan was relatively safe to Syrphis sp. but highly toxic to Coccinella septempunctata.