Semiochemicals from Trichosanthes anguina (Cucurbitaceae) plants influence behavior in Diaphania indica

First to third instars of Diaphania indica (Saunders) (Lepidoptera: Crambidae) feed on the lower surface of leaves, while fourth and fifth instars gregariously consume leaves of Trichosanthes anguina L. After defoliating, the caterpillar also attacks flowers and fruits of the plant and finally, results in loss of crop yield. Therefore, behavioral responses of D. indica adults were investigated to volatiles from undamaged (UD), insect-damaged (ID, plants after feeding by D. indica larvae) and jasmonic acid (JA) treated T. anguina plants.

Females showed attraction to volatiles of UD and ID plants of three T. anguina cultivars [MNSR-1 (MNS), Baruipur Long (BAR) and Polo No. 1 (POLO)] in Y-tube olfactometer bioassays. Females did not show significant negative responses from volatiles of JA treated plants. Females were more attracted to volatiles of ID plants than UD plants. Females showed attraction to volatiles of UD or ID plants compared to JA treated plants. Females were attracted to certain synthetic blends resembling volatiles of insect-damaged MNS, BAR and POLO plants in olfactometer bioassays. Females could not distinguish among these three certain synthetic blends in olfactometer bioassays. A synthetic blend of 3Z-hexen-1-ol, α-pinene, hexyl acetate, benzyl alcohol and 6Z-nonenal at mole ratios of 1.47:1.20:1:1.82:1.21 was prepared at 20 mg/mL dichloromethane and 100 μL when used as lure in funnel traps resulted in the capture of the highest number of D. indica adults in field trails.

The earlier five-component chemical lure could be used in traps in an integrated pest management program of the insect pest, D. indica. © 2023 Society of Chemical Industry.