Evaluation of prey stage preference of the predatory mite Neoseiulus longispinosus (Evans) on the spider mite pest Tetranychus neocaledonicus (André) (Acari: Phytoseiidae, Tetranychidae)

Tetranychus neocaledonicus, the commonly called vegetable spider mite is a highly polyphagous pest, infesting over 500 species of economic plants. The species has been categorized as a major pest, inducing considerable feeding damage on vegetables, fruit crops, medicinal plants, ornamentals, plantation crops etc. The present study was concentrated to assess the predatory potential of a phytoseiid predator, Neoseiulus longispinosus on the different life stages (egg, larva, nymphs and adults) of T. neocaledonicus under laboratory conditions. Separate experimental set ups were prepared with leaf arena of mulberry plants and known numbers of different life stages of the pest mite were maintained on individual leaf arena. For evaluating the predatory potential, adult females of N. longispinosus were introduced on to the individual leaf discs in the arenas and observations were made under a stereomicroscope to record the response of the predator to the individual life stage of the pest mite. The number of prey stages consumed by the predator on individual leaf arena was recorded for a time interval of 24 hrs and the rate of consumption on individual prey instar was calculated. Except at the time of oviposition, the adult predator was found to make active prey searching movement randomly, in and around the prey patches. By sensing the prey through successive contacts with the first pair of legs and pedipalps, the predator initiated feeding actively, and sucked out the entire fluid content with its mouth parts. The adult predator showed a specific preference to feed on the egg stage of the prey mite while the predator nymph exhibited preference to the nymphal stages of the prey. A decreasing sequence in the order egg > larva > nymphs> adult was recorded in the feeding preference of the adult predator towards life stages of the prey mite and the per cent consumption on egg, larva, nymphs and adult female stages was 48.4, 29.9, 26.6 and 9.3 %, respectively. However, the feeding preference of the nymphal stage of the predator showed a slight deviation in the order nymph > larva > adult > egg and the mean rates of consumption were 31.3, 22, 11.2 and 10.3 %, respectively. Data gathered on consumption rates of the predator upon statistical analysis revealed a significant variation towards different stages of T. neocaledonicus, thereby establishing a specific preference to prey eggs by the predator.

Predatory Behavior and Prey Selectivity of the Pelagic Water Mite Piona constricta

Predation by the pelagic water mite Piona constricta on the various components of the zooplankton community of Heney Lake, Quebec, Canada, was investigated through both direct observation and several series of feeding experiments. On encountering a prey item, the mite seized the organism with its four pairs of legs and pair of palps and tore a hole in the body wall with its chelicerae. The soft body tissues of the prey were predigested and the liquid nutriment was then drawn into the mouth. Pionid adults ate an average of 10–15 prey∙mite−1∙d−1 and selected prey items as follows: Bosmina > Daphnia, Ceriodaphnia > Chydorus >> Diaphanosoma, Diaptomus > Mesocyclops. The nymphs ate only 2–3 prey∙mite−1∙d−1 with Bosmina and Chydorus as the preferred items. The other cladocerans and the copepods were only rarely eaten. The pattern of prey selection for the adults and nymphs appeared to depend primarily on the escape response of the prey (their ability to detect an approaching mite and flee the area before being grabbed). Prey size and carapace thickness were of secondary importance.Key words: water mites, Piona constricta; zooplankton, predator–prey interactions