Comparative abundance of insects’ diversity in cotton crop at two dissimilar growing seasons of selected village in Thoothukudi, Tamil Nadu, India.

Abstract

Cotton (Gossypium hirsutum L.) one of the utmost agriculturally important fiber crops and play a significant role in economics of India, they are healthy grown in the tropical and sub-tropical regions of the world wide. More than 1000 insect fauna accompanied with cotton is rich and diverse including insect pests, pollinators and natural enemies. Insects possess a positive impact on ecosystems through prey-predator contact, soil enhancement, and bio-indicative behaviours therefore, maintaining biodiversity on agricultural land is vital from both a conservational and marketable point of view this study designed with objectives, to recorded and identified insect fauna in cotton field at two different environment periods in selected village (8°36‘09.4"N 77°54‘09.0"E) at Thothukudi district. In irrigated seasons totally 25 insect’s species were spotted gone to the 7 orders and 22 families and rainfed 18 insect’s species were noticeable belonging to the 7 orders and 16 families. The maximum number 36 % and 33. 33% were observed on Hemiptera order insects at both irrigated and rainfed seasons respectively. Orthoptera Hemiptera, Lepidoptera and Mantodea order insects dominantly available in irrigated seasons whereas Hymenoptera, Coleoptera and Neuroptera order insects dominantly observed in rainfed season. Irrigate season has documented 18 family’s’ insect’s species and significantly (p = 0.003) more number (12%) of Coccinellidae family insects are recorded. Rainfed seasons 16 family’s insect’s species were noted but Coccinellidae and Hymenopodidae (11.11%) family’s insects dominantly available. Totally, 25 insect species have been noted, but nearly 48% and 28% insect species belong to the cotton pest at irrigated and rainfed seasons condition respectively. Cotton plant mostly affected Hemipteran insect order in both seasons at 36 and 33.33% at irrigated and rainfed seasons respectively. The didn’t affect any pollinator species but different seasons alter the distribution of natural enemies. Irrigated and rainfed condition, eleven and seven natural enemies were recorded and significantly a greater number of C. congregata (p = 0.003) and C. transversalis (p = 0.005) are respectively observed. Findings help to understand a diverse group of insects’ biodiversity existing in two dissimilar seasons of cotton crop field.