Comparative biology, host preference behaviour and biological control of Melolontha cuprescens, Melolontha furcicauda and Melolontha indica (Coleoptera: Scarabaeidae)

Melolontha is a polyphagous pest in north-western Himalayan regions. Present study was conducted to understand the biology, host preferences, oviposition potential on different hosts and biocontrol of Melolontha sp. In the biennial life cycle of these Melolontha species, M. cuprescens had the longest larval stage (614 days), followed by M. furcicauda (581 days) and M. indica (602 days). Respective body length of fully fed first, second and third instar grubs ranged between 10.01-16.87 mm, 21.87-24.18 mm and 40.13-58.20 mm. A significantly positive relationship was observed between feeding and the number of eggs laid per female beetle. Rose was most preferred by M. furcicauda and M. indica while M. cuprescens beetles preferred apple. The LC50 values of dip treatment and oral feeding of CH I isolate of Beauveria brongniartii for first, second and third instar of M. cuprescens grubs were 5.45 x 10(5) and 5.47 x 105; 5.98 x 10(5) and 5.52 x 10(5); and 6.27 x 10(5) and 5.56 x 10(5) conidia/ml, respectively. Therefore, highly effective and economic biological control of Melolontha grubs is possible through Beauveria brongniartii.