INSECT PESTS AND THEIR DAMAGE PATTERNS IN PADDY (Oryza sativa L.) IN SAPTARI DISTRICT, NEPAL
Date
2023-08-17
Authors
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Publisher
Amrit Campus
Abstract
This study focused on to identify insect pests and their damage patterns studies were
conducted in two varieties of paddy plots in Gadhiya Village of Rajbiraj Municipality during
rice growing season of 2019. Sampling field visits consist of three stages, starting from the
vegetative growth stage, flowering stage and maturity (ripening) stages of the paddy growth
stage during different time periods of a day. Two sampling methods were used, i.e. swinging
a sweep net and ocular observation for insect pests collecting purposes. The sampling was
done three periods of a day i.e. morning, afternoon and evening. This study composition
recorded 14 insect pest species were founded that belongs to 12 families of eight orders found
in paddy field. Hieroglyphus banian was the dominant species among all stages, followed by
Nilaparvata lugens, Leptocorisa acuta, Dicladispa armigera, Cnaphalocrosis medinalis,
Stenchaetothrips bioformis, Spodoptera mauritia pests were found in both varieties of paddy
plant. Rice pest abundance shown in the field, a high relative abundance of Orthoptera
(32.8%) pests was found, followed by Homoptera (19.1%), Hemiptera (15%), Heteroptera
(12.9%), Lepidoptera (10.1%), Coleoptera (7.1%), Thysanoptera (1.9%) and Diptera (1.1%).
For the total sampling period, the biological indices calculated consist of the Shannon-Wiener
diversity index (H’) is 2.43, Pileou’s evenness index (J’) is 0.92 in a SM variety whereas the
value of H’=1.29 and J’=0.72 in JM variety. The study identified six damage patterns on the
crop (leaf cutter or miner, stem borer, immature grains milk sucker, leaf roller, sapsucker,
panicle cutter). Most of them (11) species were responsible for leaf-cutting or mining of the
leaf blade and less (two) species were leaf rollers. Results indicated that diversity of insect
pests was found more in paddy field cultivated ensured a good balance between the
populations of pests and damage patterns for better paddy development. However, the
periodic abundance was seen more in the afternoon than evening and morning. Diversified of
insects can be potentially effective to conserve, use and promote biodiversity which helps for
sustainable food security by yielding more productivity from the agricultural ecosystem in
Saptari.