Biology and Life Table Parameters of Tetranychus urticae Koch (Acari: Tetranychidae) and Two Phytoseiid Predatory Mites on Two Watermelon Cultivars

Abstract

The duration of developmental stages and life table parameters of the two spotted-spider mite; Tetranychus urticae Koch and the two predatory mites; Phytoseiulis persimilis Athias-Henriot and Neoseiulis californicus McGregor were carried out at the laboratory (on two different temperatures; 25±1ºC and 30±1ºC and (R.H.) 70%) on leaves of two watermelon cultivars; Aswan and Giza-1, which had a high and low infestation, respectively with T. urticae. The two watermelon cultivars and the two temperature degrees affected the duration of all developmental stages as well as adult longevity and female fecundity of T. urticae, P. persimilis and N. californicus. Duration of female developmental stages being the shortest when rearing on leaves of Aswan cultivar at 30°C and the longest on leaves of Giza-1 cultivar at 25°C. The shortest mean generation time (T) of T. urticae was 13.68 days on Aswan cultivar at 30°C; while the longest was 19.52days on Giza-1 cultivar at 25°C.The highest net reproductive rate (Ro) and intrinsic rate of natural increase (rm) were 32.81 ♀/♀ & 0.255♀/♀/day on Aswan cultivar at 30°C, respectively and the lowest were 15.04 ♀/♀ & 0.139♀/♀/day on Giza-1 cultivar at 25°C, respectively. The shortest (T) of P. persimilis was 12.40 days on Aswan cultivar at 30°c, and the longest was 16.41days on Giza-1 cultivar at 25°c.The highest (rm) was 0.285 ♀/♀ /day on Aswan cultivar at 30°c; while the lowest was 0.217 ♀/♀ /day on Giza-1 cultivar at 25°C. N. californicus showed similar trend as that of P. persimilis but with lower values in (Ro) and (rm).