Journal of Pest Science 78: 179-186, 2005

Prey consumption by larval and adult stages of the entomophagous ladybird Serangium parcesetosum Sicard (Col., Coccinellidae) of the cotton whitefly Bemisia tabaci (Genn.) (Hom., Aleyrodidae) at two different temperatures

Abstract: A successful predator of a pest species depends on a fact that it destroys, kills or consumes a sufficient number of the pest to keep its density at a low level. However, the predator, Serangium parcesetosum Sicard (Col., Coccinellidae) appears to be a promising biological control agent of Bemisia tabaci (Genn.) (Hom., Aleyrodidae). Such knowledge on its prey consumption with B. tabaci as prey has received little research interest. Therefore, the present study was undertaken to investigate the daily and total prey consumption by S. parcesetosum through the entire larval instars development as well as during three different periods of longevity of adult females and males by feeding on nymphs or puparia of B. tabaci as prey as well as the daily prey consumption by the adult females with a changing number of B. tabaci puparia at two different temperatures in the laboratory. The results showed that mean daily prey consumption by S. parcesetosum larval instars with nymphs or puparia of B. tabaci increased gradually with the progress of development at both temperatures. Significant differences were found in the mean total prey consumption among the different predatory larval instars. In total, S. parcesetosum consumed during its entire larval development significantly more nymphs rather than puparia, where it consumed at 18 °C a mean of 1566.1 (♀♀) and 1443.9 (♂♂) nymphs or 280.0 (♀♀) and 250.8 (♂♂) puparia, while at 30 °C, it valued a mean of 1119.1 (♀♀) and 979.9 (♂♂) nymphs or 188.2 (♀♀) and 171.6 (♂♂) puparia. Over the three studied periods of S. parcesetosum longevity, the mean daily prey consumption by the females and males fluctuated irregularly at both temperatures. At 18 °C and 30 °C, both females and males consumed significantly more nymphs than puparia. Between females and males, no significant differences were found by feeding on nymphs, but with puparia there were significant differences at 18 °C only. The mean total prey consumption over the three studied periods of longevity was 2188.4 (♀♀) and 1994 (♂♂) nymphs or 727.1 (♀♀) and 624.8 (♂♂) puparia at 18 °C, while at 30 °C it valued 3947.7 (♀♀) and 3577.3 (♂♂) nymphs or 1600.5 (♀♀) and 1448.8 (♂♂) puparia. S. parcesetosum has adapted itself smoothly to a fluctuating in prey availability, where the mean daily prey consumption became higher when 50 puparia/day were offered. In contrast, the predator consumed most of the individuals offered when the prey offer was 10 or 5 puparia/day. The prey consumption decreased during the second experimental week in the trial, before which 50 puparia/day had been offered. While in the other trials, before which 20, 10 and 5 puparia/day were offered, a considerable increase in the prey consumption was noticed.