Spatio-temporal distribution of sugarcane shoot borer, Chilo infuscatellus (Lepidoptera: Crambidae) and its associated natural enemy Sturmiopsis inferens (Diptera:Tachinidae) in India

Abstract

Early shoot borer or shoot borer Chilo infuscatellus Snellen (Lepidoptera: Crambidae), is a major pest of sugarcane in many countries, targets the plant in early stage leading to the death of shoots and consequently yield reduction. The present study aimed at characterizing the seasonal variation and predicting the distribution of C. infuscatellus and its parasitoid Sturmiopsis inferens Townsend (Diptera: Tachinidae) in Salem, Tamil Nadu State, India. Field surveys were conducted at monthly interval in nine sugarcane farms for two consecutive years (2015 & 2016) to assess seasonal variation of C. infuscatellus. Light traps were used to assess the abundance of S. inferens. The relationship between climatic variables and population density of C. infuscatellus and S. inferens was determined. The GIS maps using Inverse Distance Weighted interpolation technique. While C. infuscatellus was active in sugarcane farms throughout the growing period with peak population between May and June, S. inferens was higher during February. GIS maps showed the highest populations of C. infuscatellus (≈ 500 insects/acre/year) in western and southern parts of Salem district and the high parasitoid population was seen in Mettur, Idappadi, Sankagiri, Salem and Omalur taluks, with a density of ≈ 400 parasitoids/acre/year in both the years. Our results will help to understand the distribution/abundance of C. infuscatellus and S. inferens, and contribute to develop management strategies.