2007 Volume 2007 Issue 54 Pages 133-138
Two predatory bugs, Piocoris varius (Uhler) and Geocoris proteus Distant, were evaluated for control of the two-spotted spider mite Tetranychus urticae Koch on strawberry and the cotton aphid Aphis gossypii Glover on watermelon under greenhouse conditions. Third instar nymphs of either of the two predators were released three times to each greenhouse. The release of P. varius suppressed the population densities of both mite and aphid to a lower level than the control greenhouses. P. varius persisted on the plants throughout the research periods. By contrast, the release of G. proteus suppressed the mite density in the strawberry greenhouse over a short period, but had no effect on the aphid density in the watermelon greenhouse. The instability of pest control efficacy of G. proteus may be caused by their micro-habitat selection since they were frequently observed on the ground rather than plants. These results suggest that P. varius is more suitable for the release than G. proteus.
