Age specific survival/mortality and fertility life table studies of mustard sawfly Athalia proxima Klug. on crucifers

The age specific survival/mortality and fertility of the female mustard sawfly, Athalia proxima was evaluated in laboratory on five crucifers namely, Brassica rapa var. toria, Brassica rapa var. yellow sarson, Brassica juncea, Raphanus sativus and Brassica napus. The survivorship (1_x) of mustard sawfly declined gradually up to first 7 days on all five host plants due to egg mortality. Thereafter, 1_x reduced sharply from 8 to 10 days on all test plants due to mortality among the early instars. Further, a gradual fall in 1_x between 20 to 28, 21 to 29, 21 to 31, 20 to 29 and 23 to 34 days was recorded on various host plants i.e. B. rapa var. toria, B. rapa var. yellow sarson, B. juncea, R. sativus and B. napus, respectively, due to death of pupae. Later 1_x reduced sharply on 39, 33, 38, 33 and 39 days on these plants, respectively, due to death of the adults. The potential fecundity was maximum on toria while minimum on B. napus. Net reproductive rate (Ro), intrinsic rate of increase ®, finite rate of increase (ë) and annual rate of increase (ARI) were found to be higher in case of B. rapa var. toria and lowest in B. napus.