The Role of Green Gram Plant Volatile Blends in the Behavior of Arctiid Moth, Spilosoma obliqua

Abstract

Larvae of Spilosoma obliqua Walker (Lepidoptera: Arctiidae) feed on the leaves and owers of green gram [Vigna radiata (L.) Wilczek] and reduce seed yield. Therefore, it is interesting to observe whether undamaged (UD) and insect-damaged (ID, plants after feeding by S. obliqua larvae) plants cause attraction of conspeci c adult moths. Females showed attraction towards volatile blends of UD, ID and mechanically-damaged (MD) plants of three green gram cultivars [PDM 54 (PDM), Pusa Baisakhi (PUSA) and Samrat (SAM)] in Y-tube olfactometer bioassays. Females were more attracted towards volatile blends of ID plants of a particular cultivar than UD plants of the same cultivar. Total amount of volatiles was higher in ID plants than UD plants. Some herbivore-induced plant volatiles − 3Z-hexenal, 1-hexanol, 3Z-hexenyl acetate, 2-octanol and ocimene were attractive to the insect. Females were attracted towards three synthetic blends (µg in 25 µl CH 2 Cl 2 ) comprised − 2.

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

“…The results of the present study on the olfactory responses of D. indica adults revealed that virgin females and gravid females had similar behavioral response to volatiles of undamaged T. anguina plants, which indicates that the response to host plant volatiles is not associated with the physiological state (mating status) of the female. 30,35,39 Therefore, we used virgin D. indica females throughout the olfactory bioassays. However, olfactory responses of virgin and gravid females could be different when volatiles from undamaged plants were tested against volatiles from conspecific-damaged plants.…”

“…56 Our findings implicate that HIPVs not only aid predators to locate the herbivorous insect pest but also help conspecific adults to further attract the attacked host plant. 39,[65][66][67][68][69] A number of studies revealed that larvaeinduced plant volatiles attracted conspecific-adults such as larval feeding of the light brown apple moth [Epiphyas postvittana (Walker)] on apple seedlings attracted adult moths on the insect-damaged apple seedlings in comparison to undamaged plants, 68 and feeding by the cabbage moth [Mamestra brassicae (Linnaeus)] larvae on cabbage plants attracted more conspecific adult moths in comparison to undamaged plants. 66 Thus, feeding by D. indica larvae on T. anguina plants in crop fields could cause the conspecific females to lay more eggs on T. anguina plants, which could lead to further damage by the larvae on T. anguina plants.…”

“…S1). 39 Volatiles were collected for 4 h between 9 a.m. and 1 p.m. ( N = 5 experimental plants of each treatment), and a fraction of volatiles was used to identify and quantify the VOCs while remaining fractions were used for olfactory bioassays. For olfactory bioassays, volatiles were collected from 33 UD plants of each T. anguina cultivar, 79 plants of ID MNS and ID BAR, 72 plants in case of ID POLO, and 33 JA treated plants of each T. anguina cultivar over 4 h between 9 a.m. and 1 p.m. Charcoal‐filtered air was pumped in at 4 L min −1 into the top of the closed glass dome and drawn out at 2 L min −1 through four volatile collector traps (150 mm long × 5 mm outer diameter).…”

“…Damage by an insect on its host plants results in the changes of total amounts of VOCs compared to undamaged plants, and some novel herbivore-induced plant volatiles (HIPVs) that are emitted by insect-damaged plants. [35][36][37][38][39] Therefore, it is necessary to observe the role of HIPVs from T. anguina plants in the behavior of adult D. indica. In addition, the composition of VOCs varies between undamaged plants and jasmonic acid (JA) treated plants as application of JA plays an important role in plant defense by emitting VOCs, which repel an insect herbivore to feed on its host plant.…”

“…Therefore, it is necessary to find out the composition of VOCs emitted by T. anguina plants attracting adult D. indica . Damage by an insect on its host plants results in the changes of total amounts of VOCs compared to undamaged plants, and some novel herbivore‐induced plant volatiles (HIPVs) that are emitted by insect‐damaged plants 35–39 . Therefore, it is necessary to observe the role of HIPVs from T. anguina plants in the behavior of adult D. indica .…”