Life cycle, feeding behavior and nature of damage of sweet potato leaf moth, Agrius Cingulata (Fabricius) and Agrius Convolvuli (Linnaeus) (Lepidoptera: Sphingidae)

Abstract

The sweet potato hornworm Agrius cingulata and Agrius convolvuli are
destructive pests of sweet potato. This study was conducted to observe the life
cycle and the feeding potential of larval instars of A. cingulata and A. convolvuli
under laboratory condition (28 ± 4ºC, 70 ± 4% RH and 12 L : 12 D photoperiod).
The laboratory study revealed an average incubation period of 6 ± 0.50 days for
A. cingulata and 4 ± 0.50 days for A. convolvuli, larval duration of 42 ± 1 days for
A. cingulata and 24 ± 1 days for A. convolvuli, pupation period 26±1 days for A.
cingulata and 14±1 days for A. convolvuli. The life span from egg to adult stage, on
an average, was 73 days for A. cingulata and 55 days for A. convolvuli. The larval
feeding potential was determined by both the maturity and availability of
suitable leaves although mature larvae were observed to feed on the stems and
flower of the host plant in absence of suitable leaves. The larvae of both
hornworms preferred mostly the young and mature leaves. The caterpillars of A.
cingulata and A. convolvuli were found voracious feeder. The nature of damage of
sweet potato hornworm mostly occurred on the host-plant. The yield of sweet
potato was reduced due to the infestation of the pests.