Electrophysiological responses of the rice leaffolder, Cnaphalocrocis medinalis, to rice plant volatiles

Abstract

The rice leaffolder, Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae), is one of the most destructive pests of rice. Electrophysiological responses of this species to 38 synthetic volatiles known to be released from rice plants (Poaceae: Oryza spp.) were studied using the electroantennogram (EAG) method. Compounds that elicited the strongest EAG responses for each physiological condition were selected for EAG dose-response tests at five concentrations. These compounds included: methyl salicylate, heptanol, linalool, cyclohexanol, and 2-heptanone for one-day-old male moths; heptanol, hexanal, (Z)-2-hexen-1-ol, and nonadecane for one-day- old females; methyl salicylate, heptanol, (E)-2-hexen-1-ol, and (Z)-2-hexen-1-ol for three-day- old males; linalool, heptanol, (E)-2-hexen-1-ol, 2-heptanone, and hexanal for three-day-old females; 2-heptanone, cyclohexanol, linalool, heptanol, and methyl salicylate for five-day-old virgin females; and methyl benzoate, (Z)-2-hexen-1-ol, heptanol, linalool, and hexanal for five- day-old mated females. Female and male C. medinalis exhibited broad overlap in their EAG responses, and there was no clear difference between male and female EAG responses to different compounds. Statistical analyses revealed that both volatile compound chemical structure and C. medinalis physiological condition (age, sex, and mating condition) had an effect on EAG response.

Interactions of two odorant‐binding proteins influence insect chemoreception

“…Our results demonstrated that the binding activity of CmedOBPs was diverse depending the structure of ligands and interactions of the CmedOBPs. All of the compounds that had high binding activity to CmedOBPs have been showed could elicit high EAG responses in C. medinalis (Sun et al ., ). Furthermore, CmedOBP2 showed high binding activity to host volatiles, whereas CmedOBP3 showed relatively low activity to these volatiles.…”

“…A constant flow of 2 l/min of active charcoal air was applied over the antennae through the glass tube. 200 ml/min of air was passed over the filter papers for 0.5 s through the Pasteur pipette, creating odorant stimulation for the antenna (Sun et al ., ). The compound (Z)‐3‐hexenol was used as the reference standard.…”

“…The response of (Z)‐3‐hexenol was recorded at the beginning and end of each recording, and the difference between these points was used to correct for the loss of sensitivity of the antenna. The previous results showed that the decrease of antenna in sensitivity was linear with time (Sun et al, ). Data were then normalized to the standard as follows: where rEAG is the relative EAG response; EAG(A) is the amplitude (mV) of the EAG response to compound A; EAG(std1) is the EAG response to the standard at the beginning of the recording; EAG(std2) is the EAG response to the standard at the end of the recording; T(A) is the time elapsed before stimulation with compound A; T(std1) is the time of the first stimulation; and T(std2) denotes the time of the final stimulation (Gouinguene et al ., ).…”

“…We selected five previously reported electrophysiologically active compounds, (Z)‐3‐hexenol, 2‐heptanone, α‐cedrene, eicosane and methyl benzoate, which belong to the alcohols, carbonyls, alkenes, alkanes and aromatics, respectively, to perform EAG analyses (Sun et al ., ). EAG mean responses of dsRNA‐CmedOBP2‐injected, dsRNA‐CmedOBP3‐injected and dsRNA‐CmedOBP2&3‐injected moths were calculated from six to eight individual males and females.…”

Isolation and identification of attractants from the pupae of three lepidopteran species for the parasitoid Chouioia cunea Yang

“…It has been detected in volatiles from a variety of plants, such as Epipogium aphyllum and Acacia cyclops (Fabaccae), as well as the fecal headspace volatiles of Triatoma dimidiata and the Dufour's gland secretions of some ants . Sun et al . found that the volatile nonadecane of rice plants could induce strong EAG responses in female Cnaphalocrocis medinalis , a phytophagous insect.…”