Functional response of menochilus sexmaculatus F. (Coleoptera: coccinellidae) to different densities of aphis craccivora koch (Homoptera: aphididae)
Keywords:
Biological control, predator-prey interactions, lady bird beetle, Aphis craccivora.Abstract
Investigations of the characteristics related to prey consumption and searching capacity of the predator could yield important information for the selection of efficient bio-control agents. The relationship between the consumption rate of the predator Menochilus sexmaculatus F. (Coleoptera: Coccinellidae) and its prey density of Aphis craccivora Koch (Homoptera: Aphididae) on country bean (Lablab purpureus L.) was studied under laboratory conditions. Functional responses of four larval instars as well as adult males and females of M. sexmaculatus following the type II Holling’s model. Rates of searching efficiency were estimated and found to be as high as 1.19 d-1 for adult males while low as 0.58 d-1 in first instar larvae. Handling time for adult females was found the lowest (10.8 min) while the highest for first instar larvae (90.57 min) during the observations of 24 hrs. The most effective stages of M. sexmaculatus to capture the prey were adult males, and females and fourth instar larva. As regards functional response data, the model predicts a maximum number of 142.85, 78.74, 61.43, 34.13, 16.23 and 15.89 nymphs to be consumed per day by an individual adult female, fourth instar, adult male, third, second and first instar larvae, respectively. Adult females consumed the highest number of prey, followed by fourth instar larvae and adult males. The voracity of first, second, third, fourth instar larvae, adult males and females was estimated as 11.13, 12.332, 21.182, 32.51, 27.82 and 35.87 (aphids/d) when given 50 individuals of A. craccivora, respectively.
Bangladesh J. Agril. Res. 48(4): 469-479, December 2023
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