Influence of grain fractions on the progeny adult emergence of the lesser grain borer, rhyzopertha dominica (F.) (coleoptera: bostrychidae) in stored rice varieties and pulses

Abstract

Infestation of stored grains by the lesser grain borer Rhyzopertha Dominica causes serious quantitative and qualitative losses. Grains get fractioned during milling and the availability of brokers with the whole grains may alter the rate of insect infestation and progeny adult emergence. Traditional rice varieties are being reconsidered in addition to the new improved varieties in the diet of Sri Lankans due to the accompanying health benefits. In this study, the progeny development of R. Dominica in locally available traditional and new improved rice varieties and pulses containing different percentages of grain fractions was determined at 2-week intervals following initial infestation. More progeny adults emerged in rice than on pulses. In rice, Red Kekulu and Kuruluthuda varieties had higher adults emerged than in other varieties. Blackgram and green gram had the lowest adult emergence. Increased percentage of grain fragments in the sample decreased the progeny adult emergence. More R. Dominica adults emerged later than early stages following initial infestation. Minimization of initial infestation reduces damage caused by R. Dominica. The future studies need to test how the infestation by other insect species is affected by grain type and availability of broken grain in the medium to ensure better protection of stored grains from insect damage.