Density and efficacious stages of some predator against two spotted spider mite, tetranychus urticae Koch

Abstract

The two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a one of the most important mite pests of vegetable and ornamentals crops in greenhouses as well as several other agricultural outdoor/indoor crops. It is well adapted to various environmental conditions, causing qualitative and quantitative losses in yield or death of plants by sucking the contents of cells sap. A number of natural enemies were reported to predate on the spider mites. Among these predator coccinellid genus; Stethorus, Staphylinid, Oligota sp. and phytoseiid mite, Amblyseius longispinosus (Evans) contributing the chief predatory fauna on spider mites. Hence, present investigations were carried out to study the influence of different predator prey densities on the efficacy of predators viz., the predatory coccinellid, Stethorus pauperculus Weise, staphylinid, Oligota sp. and phytoseiid mite, Amblyseius longispinosus (Evans) against T. urticae on brinjal. The results of the study revealed that the predator prey ratio of suitable for both Stethorus pauperculus and Oligota sp. Among the predators, S. pauperculus recorded the highest consumption of 17.97 ± 4.13, 39.57 ± 6.27, 118.03 ± 10.23, 124.73 ± 11.00 and 147.87 ± 10.98 number of T. urticae adults per day against first, second, third, fourth instar grubs and adults, respectively at a predator prey ratio of 5:150. The predatory staphylinid, Oligota sp. grubs fed significantly more T. urticae (133.93 ± 11.76 per day) than adults (49.42 ± 7.12 per day). Similarly, maximum consumption was recorded in 5:50 ratio of A. longispinosus and T. urticae where nymph fed were 13.93 ± 3.99 per day and adult fed were 16.32 ± 4.12 per day.