Population Dynamics of Predatory Mites on Chilies and their Efficacy Against Whitefly (Aleyrodidae) Under Laboratory Conditions

Abstract

Almost 160 plant species are being infested by whiteflies (Aleyrodidae) throughout South Asian countries including Pakistan. Whiteflies are tiny, sap-sucking insects that may become an abundant pest in vegetable and ornamental plantings, especially during warm weather. Whitefly was initially controlled by using different synthetic chemicals, but now resistance is developed in sucking pests against different groups of chemicals, so the trend has now lifted towards the use of biological control agents. Predatory mites are voracious predators that can feed on all instars of whiteflies including adults. The objective of this trial was to check the population fluctuation of predatory mites on chilies in relation to metrological factors and to know the feeding rates of predatory mites against whiteflies instars under laboratory conditions. According to the results, the maximum population (3.49) of a predatory mite on chilies leaves was observed in the last week of March, while the minimum population (1.34) was observed during 3rd week of February and March which was mainly due to heavy rainfall (34mm in February and 46mm in March). Overall, there was also a small increase in the population with the temperature rise. To evaluate the predatory potential, four treatments (T1, T2, T3, T4), were considered by using different instars of mites in each cell as prey with a predator and T4 as control. Fifteen individuals of each stage of whitefly from eggs to 4th instar were provided in different cells of each predatory mite. The results showed that predatory behavior tends to decrease while feeding against the egg stage to the 4th instar. As in the case of Treatment # 3 (T3), the feeding was gradually reduced against prey from 7.33 to 5.00 while feeding on the 1st to 4th instar. The predatory potential of T1 was less than T3 due to fewer mites in T1 (2/cell). Thus, it is concluded that predatory mites can be used as potential biocontrol agents against all stages of Bemisia species.