Attraction ofEpilachna dodecastigma(Coleoptera: Coccinellidae) toMomordica charantia(Cucurbitaceae) leaf volatiles

Abstract

Epilachna dodecastigma (Wiedemann) (Coleoptera: Coccinellidae) is an important herbivorous pest of bitter gourd, Momordica charantia Linnaeus (Cucurbitaceae) plant in India and Bangladesh. Volatiles were collected from undamaged bitter gourd plants, and from plants 24 and 120 hours following the initiation of continuous adult female feeding damage, and subsequently identified and quantified by gas chromatography mass spectrometry and gas chromatography flame ionisation detector analyses. Of the 24 volatiles identified in the study, 22 were present in all three treatments (undamaged plants, 24 hours after feeding, and 120 hours after feeding), and all plants significantly increased emissions of these compounds following insect attack. In all plants, the compound 1-tridecanol was the most abundant, followed by phytol. Only two compounds were unique to insect damaged plants: methyl palmitate was characteristic of insect damaged plants, while nerolidol was only detected from plants 120 hours following insect attack, however neither of these insect-damage specific volatiles, when tested individually, elicited attraction in Y-shaped glass tube olfactometer bioassays. Epilachna dodecastigma showed significant preference for the whole volatile blends from insect damaged plants compared with whole volatile blends from undamaged plants. Further, the insect elicited attraction to three individual synthetic compounds: geraniol, 1-tridecanol, and phytol, which had significantly higher emissions from insect damaged leaves compared with those from undamaged plants.

Floral volatiles with colour cues from two cucurbitaceous plants causing attraction of Aulacophora foveicollis

“…Geranyl linalool was detected in the headspace of M. cochinchinensis leaves (Mukherjee et al., ) and S. amplexicaulis flowers, but not in the headspace of M. cochinchinensis flowers. Hence, this study confirms that variation in volatile compounds occurs between plant species, as well as between parts within a plant (Fernando & Grün, ; Tasin et al., , ; Sarkar et al., ).…”

“…Volatile blends are known to differ among plant species, qualitatively as well as quantitatively (e.g., Fernando & Grün, ; Bruce et al., ; Schoonhoven et al., ; Tasin et al., , ; Wang et al., ). 1‐Tridecanol was predominant followed by phytol in the volatiles of Momordica charantia L. (bitter gourd) plants, and geraniol, 1‐tridecanol, and phytol attracted Epilachna dodecastigma Wiedemann beetles (Sarkar et al., ). The major VOCs emitted by fruit and vines of bitter gourd have been found to contain myrtenol, ( Z )‐3‐hexenol, benzyl alcohol, 1‐penten‐3‐ol, ( Z )‐2‐pentenol, ( E )‐2‐hexenal, and cis ‐sabinol, and these volatiles elicited attraction of the fly Dacus cucurbitae (Coquillett) (Binder et al., ).…”

Long-chain alkanes and fatty acids fromLudwigia octovalvisweed leaf surface waxes as short-range attractant and ovipositional stimulant toAltica cyanea(Weber) (Coleoptera: Chrysomelidae)

“…A female was considered to have made a choice in case of reaching the end of one arm, the insect was removed from the Y-tube and the choice of the insect was recorded as a positive or negative response, respectively. In contrast, a female was discarded not having made a choice within 2 min (non-responding) and was replaced by a new one (Mukherjee et al ., 2015 a ; Sarkar et al ., 2015). Each experiment with one test sample was conducted until a total of 90 naïve female insects had responded; and after testing five insects the olfactometer set-up was cleaned with petroleum ether followed by acetone, and the position of the two arms was systematically changed in order to avoid positional bias.…”

Is Allelopathic Activity of Ipomoea murucoides Induced by Xylophage Damage?

“…We did not find evidence that extracts obtained from intentionally damaged branches provoked a greater allelopathic effect in T . recurvata seed germination, but according to the PCA chemical content analysis, those extracts with intentional damage contain more trans -9-hexadecen-1-ol, cis -9-eicosen-1-ol and 1-hexadecanol; of these it has been shown that 1-hexadecanol may increase their concentration due to plant injury [ 41 ]. When herbivores feed they liberate specific enzymes that activate the host defense mechanisms [ 1 , 2 , 42 , 43 , 44 ].…”