Volatiles of Solena amplexicaulis (Lam.) Gandhi Leaves Influencing Attraction of Two Generalist Insect Herbivores

Abstract

Epilachna vigintioctopunctata Fabr. (Coleoptera: Coccinellidae) and Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) are important pests of Solena amplexicaulis (Lam.) Gandhi (Cucurbitaceae), commonly known as creeping cucumber. The profiles of volatile organic compounds from undamaged plants, plants after 48 hr continuous feeding of adult females of either E. vigintioctopunctata or A. foveicollis, by adults of both species, and after mechanical damaging were identified and quantified by GC-MS and GC-FID analyses. Thirty two compounds were detected in volatiles of all treatments. In all plants, methyl jasmonate was the major compound. In Y-shaped glass tube olfactometer bioassays under laboratory conditions, both insect species showed a significant preference for complete volatile blends from insect damaged plants, compared to those of undamaged plants. Neither E. vigintioctopunctata nor A. foveicollis showed any preference for volatiles released by heterospecifically damaged plants vs. conspecifically damaged plants or plants attacked by both species. Epilachna vigintioctopunctata and A. foveicollis showed attraction to three different synthetic compounds, linalool oxide, nonanal, and E-2-nonenal in proportions present in volatiles of insect damaged plants. Both species were attracted by a synthetic blend of 1.64 μg linalool oxide + 3.86 μg nonanal + 2.23 μg E-2-nonenal, dissolved in 20 μl methylene chloride. This combination might be used as trapping tools in pest management strategies.

Attraction of the potential biocontrol agent Altica cyanea by volatile compounds of three species of Ludwigia weeds from rice fields

“…This study corroborates that the VOC profiles from plants can vary within the genus Ludwigia (Carruthers et al, 2011;Roitman et al, 2011;Mukherjee et al, 2015;Sarkar et al, 2016). Carruthers et al (2011) reported that profiles of VOCs in subspecies of Ludwigia peploides (Kunth) PH Raven ssp.…”

“…The VOC profile of L. octovalvis after 6 h of insect feeding was similar to that of undamaged plants, whereas 2-Z-penten-1-ol, geraniol, farnesene, 1-tridecanol, and farnesyl acetone were only detected after 48 h of feeding. Several reports have shown increases in the emission of individual and total VOCs after insect feeding Malik et al, 2016;Sarkar et al, 2016;Karmakar et al, 2018).…”

“…One µl sample was injected with a split ratio of 1:5 (Sarkar et al, 2016). The oven temperature programme was initially 50°C held for 3 min, then ramped to 240°C at 3.8°C per min, and finally held for 5 min.…”

“…The MS parameters were 250°C at the interface, ionization energy 70 eV, scan speed 5 scans s À1 . One µl sample was injected with a split ratio of 1:5 (Sarkar et al, 2016). The volatile compounds were established by comparison of the diagnostic ions (NIST 2014 library) and GC retention times with those of respective authentic standards.…”

“…Herbivorous insects often use a complex blend of green leaf volatiles as olfactory cues to find their host (Bruce et al, 2005;Sarkar et al, 2015Sarkar et al, , 2016. Volatile organic compounds (VOCs) in blends may be ubiquitous in various plants, but the combination and ratios of VOCs differ between plants species (Bruce & Pickett, 2011).…”