Abundance of pest, predator and pollinator in cotton field and their impact on yield and seed quality

Abstract

This study was undertaken with three cotton varieties viz. CB9, CB10 and SRO5 to explore the abundance of pest, predator and pollinators in the field and their impact on yield and seed quality. Results showed that 16 species of insect and one species of mite were abundant in threshold based insecticide sprayed field. The incidence of sucking pests such as jassid, aphid, white fly and thrips on different varieties were statistically different in insecticide free condition, however in threshold sprayed condition only the white fly showed significant difference. The chewing pests (american bollworm, spotted bollworm, pink bollworm) incidence were statistically similar on different cotton varieties both in threshold sprayed and no-sprayed condition. But armyworm incidence was found significantly different in no-sprayed condition. Data of the predator visitors associated with cotton plants indicated that 29 species of insects in 9 orders and 19 families were abundant during the season. One predatory mite species and one spider species were also abundant. The incidence of predators such as lady beetle, syrphids, lace wing and spider on different varieties were statistically different in insecticide free condition and in threshold sprayed condition only the lady beetle showed statistically similar incidence. The pollinator visitors on different cotton varieties constituted of 12 species of which 5 species in two families of Hymenoptera, 5 species in two families of Lepidoptera and 2 species in two families of Diptera. The major pollinator honeybee and bumblebee incidence were statistically similar on the studied cotton varieties both in threshold sprayed and non-sprayed condition. The findings of the present study demonstrated that abundance of pest, predator and pollinators significantly influenced on the production of boll / plant, yield / ha, number of seeds / boll and seed index. Boll production of different varieties under enclosed, threshold sprayed and non-sprayed condition varied from 39.4 + 11.3 to 44.2 + 8.3, 32.2 + 7.6 to 40.1 +8.8 and 8.2 + 3.5 to 12.6 +3.1 / plant, respectively. The production of yield (seed cotton) under these conditions ranged from 2350.0 + 17.3 to 2751.7 + 23.6, 2173.3 + 15.3 to 2498.3 + 18.9 and 618.3 + 12.6 to 792.3 + 8.7 kg / ha, respectively. Among the cotton varieties CB9 produced the highest number (36.2 + 6.9) of seeds / boll and the variety CB10 produced the lowest (30.2 + 5.1) number in non-sprayed condition. The variety CB9 and CB10 resulted the highest (83.5 g) and lowest (75.0 g) seed index when these varieties were cultivated under enclosed and threshold sprayed condition, respectively. The study showed that the abundance of pest, predator and pollinators did not affect significantly the ginning out tern (GOT%) and germination rates of cotton seeds.