Functional response of Harmonia dimidiata (fab.) to melon aphid, Aphis gossypii Glover under laboratory conditions

Functional response of Harmonia dimidiata (Fab.) to melon aphid, Aphis gossypii Glover was studied in the laboratory at 25 +/- 0.5 A degrees C, 70 +/- 5% RH and 12L:12D photoperiod. All the predator stages exhibited Type II functional response to the aphid. Based on Rogers's random predator equation the predator's attack rate was lowest (0.128) in the first-instar and highest (0.21) in the adult stage. Handling times of the adult beetle and the fourth-instar (0.148 and 0.164 h, respectively) were much shorter than other stages. The maximum number of aphids that could be consumed over a period of 24 h by first, second, third and fourth instar; and adult of H. dimidiata was estimated to be 47.2, 80.2, 79.7, 146.2 and 161.7 aphids/ predator. Functional response parameters indicate that the adult beetles and the fourth-instar were the most voracious stages and could be important for the biological control of the aphid.