Varietal preference, growth and development of pests necrobia Rufipes de geer and oryzaephilus surinamensis linn, in stored copra

Abstract

Copra is subjected to the attack of various insect pests during storage. Necrobia rufipes De Geer and Oryzaephilus surinamensis Linn, were found to be the most important. The varieties / cultivars tested were Chavakkad Dwarf Orange x West Coast Tall, Laccadive Micro, Gangaboridam, West Coast Tall x Chavakkad Dwarf Orange, Chavakkad Dwarf Orange, West Coast Tall, Laccadive Ordinary, West Coast Tall x Chavakkad Dwarf Green and Chavakkad Dwarf Green. Data on larval period, larval mortality, Chavakkad Dwarf Green. Data on larval period, larval mortality, pupal period, pupal mortality, percentage of adult emergence, adult longevity and the fecundity of the beetles and incubation period of the eggs were recorded daily after releasing one day old larvae of the insects in these varieties. The growth index of the insects in each treatment was calculated by dividing the percentage of adult emerged with the mean number of days for adult formation. Studies conducted revealed that the severity of infestation varied with varieties and the growth index varied with respect to larval period, larval mortality, pupal period, pupal mortality, adult emergence, adult longevity and fecundity. In overall assessment of the study, CDO x WCT, LM and LO were identified as less desirable for keeping the population build up low, while CDG and WCT x CDG were better and the remaining varieties were found to be intermediate.