BIOLOGICAL ASPECTS OF THE TORTOISE BEETLE, CASSIDA VITTATA VILL., ( COLEOPTERA: CHRYSOMELIDAE) AS AFFECTED BY FEEDING ON DIFFERENT SUGAR BEET VARIETIES

Effect of feeding the tortoise beetle, C. vittata Vill., females emerged from diapause (FED) and larvae on different sugar beet varieties on its reproductive capacity, oviposition period, incubation period & hatchability of eggs and the duration periods of larval and pupal stages were studied from February to August 2006. Results showed that the highest reproductive capacity ( 263 ± 68 eggs per female), the longest oviposition period ( 62 ± 15.8 days) and the highest feeding pores (10.6 ± 1 feeding pores /day ) were recorded on Dema poly variety under laboratory conditions of 22.7 ± 4.1 Co and 42.7 ± 6.8 % R. H. There are significant differences when compared to Toro, Monte blanco and both varieties, respectively. Dema poly was the most preferred variety for oviposition and feeding. Feeding females or larvae on different sugar beet varieties had no significant effect on the incubation period and hatchability rate of eggs as well as the duration periods of larva and pupa. C. vittata has a single generation in a year. The ovipositional activities by (FED) and active females started in mid February and April and prolonged until late March and June, respectively. Its reproductive capacities were 213.3 ± 10 eggs per (FED) and 141.7 ± 25.3 eggs per active female fed on Monte blanco variety and the difference was significant, but 106.3 ± 60.6 eggs per female collected from the field was recorded when fed on the same variety during the period of active females. Active adults entered diapause by July which ceased for laying eggs and feeding , but not continued to over the winter which died under hot and dry conditions during August. Females lived longer than males where the averages of life span and life cycle were 110.9 ± 12.1 & 92.7 ± 8.6 and 147.4 ± 17.2 & 129.2 ± 15.5 days, respectively .