Reproductive biology of Holepyris sylvanidis (Hymenoptera: Bethylidae)

Holepyris sylvanidis (Hymenoptera: Bethylidae) is reported as a cosmopolitan parasitoid of coleopteranincluding a major pest of stored products, the confused flour beetle Tribolium confusum. The reproductivebiology, and hence biocontrol potential of H. sylvanidis is relatively little known. Here we describe andevaluate aspects of egg size, immature development, adult mating behaviour, pre-oviposition time,fecundity, host attack and use, and adult longevity. Our key findings are that 72% of presented T. confusumimmatures presented to females were attacked and 39% of these were fed on destructively withthe remainder oviposited onto. First instar host larvae and host pupae were only utilized for feeding, secondand third instar larvae were commonly used for either feeding or oviposition while fourth, fifth andsixth instar hosts were almost exclusively used for oviposition. Females usually laid single egg clutchesand their average lifetime fecundity was 16.5 eggs. Females regularly provisioned with hosts oftenceased laying eggs up to several weeks before their death but continued to kill and feed on hosts duringthis period. Adult longevity was greatly enhanced by the provision of hosts (females) or by non-host foodsources (males). We conclude that the inoculative biocontrol potential of H. sylvanidis is likely to be limitedby a low realized fecundity and the combination with other control methods in an IPM-approach isneeded. Its ability to find and kill hosts may make it more suitable for inundative deployment.