Control potential of Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae) against Lasioderma serricorne (Fabricius) (Coleoptera: Ptinidae)

Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae) usually is used as a biological control agent which is a key component of integrated pest management (IPM). The control potential of T. elegans against Lasioderma serricorne (Fabricius) (Coleoptera: Ptinidae) was evaluated in laboratory. The penetration ability of T. elegans against common packaging materials (kraft paper, cartoon, plastic woven bag, sack and plastic bag), the invasion ratios of T. elegans and L. serricorne to different sizes (0.3, 0.5, 0.6, 0.7, 0.9, 1.0 and 1.5 mm) of meshes were studied. Effectiveness of T. elegans against L. serricorne larvae at different parasitoid-to-host ratios (1:5, 1:10, 1:15, 1:20 and 1:25) and different parasitism times (24, 48, and 72 h) were investigated, and effectiveness of T. elegans against L. serricorne larvae at different space sizes (25, 50, 100, 250, 500, 1000, and 2000 ml) of plastic bottles were further investigated when the parasitoid-to-host ratio was at 1:15. The mature larvae of L. serricorne in plastic woven bags and sacks were parasitized by T. elegans, indicating T. elegans had a potent penetration capability. The meshes with a side length of 0.3 mm or smaller were not invaded through by T. elegans. Parasitism time and parasitoid-to-host ratio and their interaction significantly affected the parasitism rate of T. elegans to L. serricorne, which reached the maximum value of 62.00% when the parasitoid-to-host ratio was 1:5 for 72 h treatment. There were no significant differences in the number of parasitized hosts, parasitism ratios and the control ratios of T. elegans in the spaces of 25, 50, 100, 250, 500 and 1000 ml after 48 h treatment. These results showed that T. elegans had strong potential to control L. serricorne, which provide scientific information for the large-scale release of T. elegans.