Functional response of Neochrysocharis formosa to Tuta absoluta

Abstract

ABSTRACT Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive invasive pests of tomato worldwide. To improve biological control of T. absoluta, we studied the functional response of Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae) to T. absoluta. Under laboratory conditions, N. formosa parasitised and host-fed on the first three larval instars, while the fourth instar was not selected for oviposition or feeding. The logistic regression analyses yielded significantly negative linear coefficients, confirming a type II functional response of the parasitoid to each host stage. Irrespective of the mode of host-killing, the attack rate was the highest and the handling time the lowest on the second instar host larvae. The theoretical maximum numbers of host larvae that a single mated female N. formosa could parasitise, host-feed or host-kill over a 24 h foraging period are 2.82, 2.87 and 5.66 (first instar); 3.50, 5.99 and 9.05 (second instar); and 2.28 1.71 and 3.38 (third instar), respectively. In conclusion, the parasitoid may enhance the augmentative and/or conservation biological control of T. absoluta under Indian conditions.