Effects of host plants and seasons on the biology of the two-spotted spider mite, Tetranychus urticae (Koch).

The developmental and reproductive biology of the two-spotted spider mite, Tetranychus urticae (Koch), a devastating polyphagous pest, were studied on five vegetables in summer (27-36 °C, RH 81-85 %) and winter (5-19 °C, RH 70-75 %) under prevailing laboratory conditions. Immature developmental time and adult longevity were inversely related to seasons. The results indicated that the development of the mite increased more rapidly on bean in summer than on the other tested hosts. The longest developmental period was 41.94 and 41.07 days for females and males, respectively, in winter when T. urticae was fed on cowpea. In contrast, it was the shortest (11.25 and 10.39 days) in summer while reared on bean. Lifetime fecundity (62.71) and daily fecundity (5.48) was the highest on bean in summer. The sex ratio (female:male) was the highest (0.76) on cowpea and the lowest (0.66) on brinjal in winter. Survivorship during immature development varied from 82.14 to 95.65 %, with the lowest rate in summer when reared on bean. Life table parameters were analysed and the generation time (T) was found the lowest (20.37) in summer when fed on bean, net reproductive rate (R0) was the highest (36.29) in summer on cowpea and both intrinsic rate of natural increase, rm (0.17), and finite rate of increase, λ (1.19), were the highest in summer when fed on bean. [ABSTRACT FROM AUTHOR]