White grubs, Holotrichia rustica and Holotrichia mucida (Coleoptera: Scarabaeidae) as pests of teak (Tectona grandis L. f.) seedlings

Field observations were carried out between 2002 and 2005 on bio-ecology of white grubs infesting teak (Tectona grandis Linn. f.) seedlings at Ramdongari Forest Nursery, Forest Development Corporation of Maharashtra, Nagpur in central India. The study collected the data required for an integrated pest management strategy against the white grubs. The species damaging teak seedlings were Holotrichia rustica (Burmeister) and H. mucida Gyllenhal. The beetles (adults) of both these species began to emerge just after the pre-monsoon showers and when the relative humidity had risen rapidly over several days, but before the first monsoon rains. While the adults fed and mated on naturally growing bushes of Ziziphus jujuba, Z. mauritiana, Z. xylopyra, Acacia leucophloea and A. catechu immediately after the emergence from the teak beds in the nursery, the immature stages (grubs) of both species fed on roots of the teak seedling, leading to plant death. This is the first report of (i) damage caused to teak seedlings by grubs of H. rustica and H. mucida, and (ii) of Z. jujuba and Z. mauritiana being hosts for the beetles of H. mucida and H. rustica. It is also the first detailed report on the field bio-ecology of the H. rustica and H. mucida as major pests of teak. White grubs are among the toughest-to-manage pests of economic importance and information presented here on the pest incidence and damage of H. rustica and H. mucida is important to researchers and nursery field managers for the management of these pests on teak.