Insect biodiversity and seasonal incidence of major insect pests in wheat (Triticum aestivum L.) ecosystem in mid-hills of Meghalaya
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Date
2019
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College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University-Imphal
Abstract
Studies on “insect biodiversity and seasonal incidence of major insect pests in wheat ecosystem in mid hills of Meghalaya” was conducted in 2018-19 Rabi season at the experimental farm at College of Post Graduate Studies in Agricultural Sciences (CPGSAS), CAU(I), Umiam, Meghalaya. Wheat crop was raised in 9 different plots with three sowing dates. Field surveys, observations, collection, identification and preservation of insect species was done in the cropping season. A total of 58 insect species recorded to be associated with wheat crop. The insects belonged to 32 families of 8 orders, viz., Diptera (16 species), Coleoptera (13 species), Hemiptera (11 species), Hymenoptera (9 species), Orthoptera (4 species), Lepidoptera (3 species), Odonata (1 species) and Neuroptera (1 species). The collected insect species were categorized into pests (32 species), natural enemies (24 species), pollinators (1 species) and visitors (2 species). Insect pests were further divided into major and minor pests, having two species (Rhopalosiphum padi L. and Sitobion avenae F.) and 30
species, respectively. Minor pests comprised of 5 orders which belonged to 16 families. Natural enemies comprising of 6 orders and 12 familes were classified as predators (14 species), parasites (5 species) and parasitoids (5 species). Only one species of pollinators, viz., Plecia nearctica (Hardy) and two species of occasional visitors, viz., Pieris brassicae nepalensis (Doubleday) and Bactrocera dorsalis (Hendel) were recorded. R. padi population was found increased in the early crop growth stage, viz., seedling and tillering stages and was maximum in November second week 2018, with 13.20 aphids per plant, whereas S. avenae population was maximum during the earhead emergence until ripening stages with 35.39 aphids per earhead on 28th February 2019. The study on correlation between pest incidence and weather factors showed that minimum temperature (r= 0.50*) and evening relative humidity (r= 0.45*) had significant positive effect on R. padi and S. avenae population, respectively. Regression co-efficient (R) was also worked out. Impact of dates of sowing on major pest incidence on wheat revealed that R. padi population was maximum on the wheat crop sown first (27th October 2018) and minimum on the wheat crop sown last (17th November 2018). The infestation of S. avenae was maximum in the crop sown on 17th November 2018, whereas minimum in the crop sown on 27th October 2018 and 7th November 2018, respectively.