Efficacy of inundative release ofTrichogramma chilonis in the management of the sugarcane internode borer,Chilo sacchariphagus indicus (K.)

Abstract

This paper analyses the factors governing the efficacy ofTrichogramma chilonis and the basis for its popularity as a management tool for sugarcane internode borer. Published evidences were taken as the basis for the analysis. The factors taken in to consideration in the analysis are, the capabilities of egg parasitoids as prime tool to manage pests, attributes in the biology and innate abilitiesof T.chilonis as a candidate for inundative release and, the influence of sugarcane plant characters, the aspects in commercial production and the field release procedures in influencing its efficiency. Taking all the favourable attributes ofT.chilonis and reinforcing it with assumptions favouring at various stages of its parasitisation, the impact of inundative release on the suppression of internode borer damage was extrapolated based on the literature information on the biology, life table studies and damage potential of internode borer. The theoretical prevention of intensity of internode borer damage through the current recommended dose of inundative release ranged from 3.2 tol .93 per cent between the first and 6th release. The fortnightly release procedure, the limitation ofT.chilonis to parasitise eggs for the first day of release only, its selective preference within the egg stage rendering 17 per cent of the eggs that would be in black head stage in a given time unsuitable for it coupled with the daily egg laying of internode borer due to intra and inter brood overlappings rendered this prevention insignificant and transitory. The principle of inundative release and the term ‘natural enemy’ assumed for bioagents is also discussed to reveal it as being unscientific.