Effect of Four Host Plants of the Two Spotted Spider Mite Tetranychus urticae on the Consumption Rates and Reproductive Biology of the Predator Blaptostethus pallescens Poppius (Hemiptera: Anthocoridae)

Blaptostethus pallescens Poppius (Hemiptera: Anthocoridae) is a potential predator on mites and other
insects in Maize, Mango and grain warehouses in Egypt. The indirect effect of four vegetable crops; bean (Phaseolus
vulgaris), pepper (Capsicum annuum), eggplant (Solanum melongena) and cucumber (Cucumis sativus) as host-plants
of the two spotted spider mite (TSSM) Tetranychus urticae Koch on the consumption rate and reproductive biology
were studied at 30 ±1˚C and 60 ± 10% R.H. The obtained results revealed that the type of plant had a significant effect
on the daily and overall prey consumption of all the nymphal instars and total developmental nymphal periods. The
total predation rates of all nymphal instars of B. pallescens were higher with bean leaf plant (552.4 mites) than that of
pepper, eggplant and cucumber leaf plants (520.5, 451.8 and 349.2 mites, respectively). The major portion of mortality
during the nymphal stage occurred during the first instar in all tested host plants and the higher mortality was recorded
when TSSM fed on mites fed cucumber plant, and the lower one was for mites fed on bean plant. The total number of
consumed T. urticae nymphs by B. pallescens adult females was significantly different among the four host plants;
being higher in bean plant leaves (301.9 mites) and lower on cucumber plant leaves (152.4 mites). Also, the total
number of consumed T. urticae nymphs by B. pallescens adult males was significantly different among the four host
plants; being higher in bean plant leaves (158.8 mites) and lower on cucumber plant leaves (105.3 mites). Significant
differences in adult longevity among the different host plants were observed, the shortest lifetime for females was 17.7
days on cucumber, while the longest lifetime (22.3 days) was recorded with bean. The oviposition period was shortest
on cucumber (10.5 days) and longest on bean (17.7days). Meanwhile, the greatest total lifetime fecundity (70.0 eggs/
female) was observed with bean plant, which was significantly higher than on cucumber plant (22.9 eggs/female). The
success of B. pallescens as a biological control agent of TSSM seems to be strongly affected by the host plants on
which the TSSM were fed on.