Potential of Blaptostethus pallescens Poppius (Hemiptera: Anthocoridae) on Tetranychus truncatus Ehara (Prostigmata: Tetranychidae)

Efficiency, functional and numerical responses of anthocorid bug Blaptostethus pallescens Poppius on the spider mite, Tetranychus truncatus Ehara were examined under laboratory conditions. Nymphs of B. pallescens exhibited a Hollings type II functional response when females of spider mite were offered at densities of 10, 20, 30, 40, 50, 60 and 70 mites/bug. Individual fifth instar bugs consumed up to 45.3 adult females of T. truncatus in 24 h at prey mite densities of 60 mites/ bug. Studies on numerical response revealed that the nymphs of the anthocorid bug failed to complete development when the food was restricted to mite alone. Numerical response studies on adult bugs, when offered T. truncatus at densities of 10, 20, 30, 40 and 50 females showed no significant differences in the average fecundity of the female bug. Results indicate that the anthocorid predator, B. pallescens has a very high predatory potential though with a weak numerical response.

COMPARATIVE BIOLOGY AND PREDATORY POTENTIAL OF Cryptolaemus montrouzieri ON MEALYBUGS

Comparative biology of Cryptolaemus montrouzieri on Maconellicoccus hirsutus and Pseudococcus citri revealed that it had completed its life cycle successfully on both species. The mean total developmental period (egg to pupa) was 18.1 days, when reared on P. citri and it was 20.9 days in M. hirsutus. The adults developed on P. citri had high fecundity 284.2 eggs / female and longevity 47.0 days than those developed on M. hirsutus. Analysis on the growth indices of C. montrouzieri showed more preference on P. citri with high suitability index of 2.51 than M. hirsutus (1.78). Among two life stages, adults of C. montrouzieri was more voracious and each adult consumed an average 258.7, 352.1 and 217.3 numbers on M. hirsutus while, it was 323.8, 715.6 and 328.6 number of eggs, nymphs and adults for P. citri, respectively. The grubs required 221.1, 55.1 and 36.6 numbers of M. hirsutus and 1079.0, 341.3 and 41.0 number of eggs, nymphs and adults of P. citri, respectively to complete life stages. Out of different instars of C. montrouzieri, third and fourth instars required around 92.1, 78.5 and 85.9 per cent and 88.9, 93.5 and 79.0 per cent of total eggs, nymphs and adults of P. citri and M. hirsutus consumed, respectively.

Using a Two-Sex Life Table Tool to Calculate the Fitness of Orius strigicollis as a Predator of Pectinophora gossypiella

A two-sex life table is a useful tool for studying the fitness of predators. Previous studies of Orius strigicollis Poppius (Heteroptera: Anthocoridae) fitness have not been done on Pectinophora gossypiella (Lepidoptera: Gelechiidae) using a two-sex life table tool. This study reports the fitness of the minute predatory flower bug, O. strigicollis when feeding on the cotton pest P. gossypiella using a two-sex life table tool. Different densities (5, 10, and 15 eggs) of P. gossypiella eggs were used to calculate the feeding capacity and fitness of O. strigicollis in the laboratory at 28 °C ± 1, 75 ± 5% RH and 16:8 (L:D). The results concluded that O. strigicollis is an efficient predator of P. gossypiella. The maximum growth capacity of the predatory bug O. strigicollis was attained when it was fed on 10 and 15 P. gossypiella eggs. Furthermore, shorter generation and development time were also observed in the case of 15 eggs of P. gossypiella. These results suggest that O. strigicollis has considerable predatory potential and prefers feeding on P. gossypiella eggs than on the first instar larvae at the fourth instar or the female stage. Although the field potential of O. strigicollis is still unknown, this study will support future investigations in terms of field applications.