Feeding on Non-Host Plants by the Tobacco Hornworm (Manduca Sexta (Lepidoptera: Sphingidae)

R. W. Flowers, R. T. Yamamoto


Feeding responses of Manduca sexta larvae reared on artificial diet, a host plant (jimsonweed) and a non-host plant (cowpea) were tested with leaves of 4 selected non-host plants and compared. Larvae reared on diet and the host plant fed equally on collard, dandelion and cowpea while the diet-reared larvae found mullein more acceptable than did the jimsonweed-reared larvae. Both groups of larvae found mullein and collard significantly more acceptable than cowpea or dandelion. Larvae reared on the non-host plant readily ate all 4 test plants. Acceptance of non-host plants increased the longer the larvae fed on cowpea. Larvae were fed initially on cowpea for varying lengths of time and then transferred to either diet or jimsonweed. Acceptance of the test plants was not as great and took place more slowly in larvae transferred to jimsonweed. The possible chemosensory basis of this feeding behavior is discussed.

Full Text: