Journal of Pest Science 78: 167-174, 2005

Influence of leaf portion and plant species on the egg-laying behaviour of the predatory ladybird Serangium parcesetosum Sicard (Col., Coccinellidae) in the presence of a natural enemy

Abstract: Serangium parcesetosum Sicard (Col., Coccinellidae) is promising biological control agent against Bemisia tabaci (Genn.) (Hom., Aleyrodidae). However, information on the its egg-laying behavior is still lacking in the literature. Therefore, this study was aimed to investigate the egg-laying behavior of S. parcesetosum and preferred leaf portion for laying eggs with B. tabaci as prey on cucumber and cotton leaves in the absence and presence of the green lacewing predator, Chrysoperla carnea (Stephens) (Neur., Chrysopidae) in the laboratory at different temperatures. The results showed that at 18°C on cucumber leaves, S. parcesetosum females preferred to lay their eggs significantly between veins with a mean of 10.1 eggs and close to the veins with 7.5 eggs/two females/7-day-period in the absence of C. carnea, while in the presence of C. carnea they preferred to lay eggs significantly close to veins and close to petiole with a mean of 6.5 and 5.6 eggs/two females/7-day-period, respectively. On cotton leaves females preferred to lay eggs significantly close to the petiole with a mean of 8.4 eggs and close to the veins with 5.6 eggs/two females/7-day-period in the absence of C. carnea, while in the presence of C. carnea they preferred to lay eggs significantly close to the veins and close to the petiole with a mean of 6.3 and 4.4 eggs/two females/7-day-period, respectively. At 30°C S. parcesetosum females laid significantly eggs close to veins with 10.9 and 10.4 eggs/two females/7-day-period in the absence and presence of C. carnea, respectively on cucumber leaves. Whereas, on cotton leaves more eggs were laid significantly close to the petiole with a mean of 7.6 eggs and close to the veins with 6.2 eggs/two females/7-day-period in the absence of C. carnea, while in the presence of it, females preferred to lay eggs significantly close to veins and close to petiole with a mean of 8.7 and 6.1 eggs/two females/7-day-period, respectively. At 18°C on cucumber leaves S. parcesetosum females preferred significantly to lay eggs singly in the absence and presence of C. carnea with 14.2 and 11.7 eggs/two females/7-day-period, respectively. While on cotton leaves, more eggs were laid significantly together in the absence and presence of C. carnea with 11.1 and 9.6 eggs/two females/7-day-period, respectively. In total, a mean of 18.1 and 16.8 eggs were laid in the absence and presence of C. carnea, respectively on cucumber, while on cotton leaves 16.9 and 14.5 eggs were laid in the absence and presence of C. carnea, respectively. Between the absence and presence of C. carnea, there were no significant differences in the way of laying eggs weather it singly or together on and cucumber and cotton leaves. But, total number of laid eggs was significantly higher on cotton in the absence of C. carnea than in the presence of it. At 30°C on cucumber leaves, they preferred to lay eggs significantly singly in both absence and presence of C. carnea with 19.7 and 14.1 eggs/two females/7-day-period, respectively. In total, a mean of 24.0 and 21.2 eggs were laid in the absence and presence of C. carnea, respectively on cucumber, while on cotton leaves 20.0 and 21.9 eggs were laid in the absence and presence of C. carnea, respectively. Within the same plant species, there were significant differences between the absence and presence of C. carnea in total between laid eggs, but there were no significant difference on cucumber leaves. On cotton leaves, there were no significant differences between eggs laid singly with 10.6 and together with 9.4 eggs/two females/7-day-period in the absence of C. carnea, while in the presence of C. carnea, females preferred significantly to lay eggs together with 17.4 eggs/two females/7-day-period.