A chemical basis for different oviposition rates of Helicoverpa assulta across two Nicotiana species

Abstract

The tobacco Nicotiana rustica is widely used as a trap crop in the fields of Nicotiana tabacum in China, by attracting oviposition of Helicoverpa assulta females, thus preventing damage to N. tabacum. The mechanism underlying the differential oviposition rates of H. assulta across these two tobacco species, however, is largely unknown. We investigated the mechanism of host plant acceptance of H. assulta with respect to these two tobaccos by using a two-choice behavioral bioassay and GC–MS. Our results indicate that both the leaves and inflorescences of N. rustica attracted significantly more eggs than the corresponding parts of N. tabacum. Extracts of leaves and inflorescences of N. rustica with two different solvents elicited similar oviposition patterns to the corresponding parts of the plants. Chemical analysis by GC–MS revealed that the volatiles of N. rustica contain larger amounts of nicotine than those of N. tabacum at the flowering stage. In addition, γ-terpinolene and β-elemene are found only in extracts of N. rustica. A two-choice bioassay on the individual compounds showed that γ-terpinolene, which is specific to the vegetative stage of N. rustica, and nicotine attracted oviposition by H. assulta. The volatile β-elemene, which is present only in N. rustica, was also attractive. We conclude that the larger amount of nicotine, and the species-specific γ-terpinolene and β-elemene may mediate the different oviposition rates of H. assulta females across N. rustica and N. tabacum.

Grass-like plants release general volatile cues attractive for gravid Anopheles gambiae sensu stricto mosquitoes

“…In our study, three volatile chemicals, namely 1,1-dimethyl-3-methylene-2-vinylcyclohexane, α-guaiene and β-elemene, have not been tested previously, yet were detected frequently in four out of the five test plants. It might be useful to explore their potential to manipulate odour-orientation of Anopheles mosquitoes in followup studies, since they have been implicated as semiochemicals for other insect species [75][76][77][78][79]. For example, 1,1-dimethyl-3-methylene-2-vinylcyclohexane was attractive to the beech leaf-mining weevil [76], guaiene has been suggested to play a role in the attraction of the litchi stem-end borer [80] and β-elemene has been implied to contribute to attraction of the gravid tobacco moths [77] and the white-spotted longhorn beetle [78].…”

Grass-Like Plants Release General Volatile Cues Attractive for Gravid Anopheles Gambiae S.S. Malaria Vector Mosquitoes

“…It might be useful to explore their potential to manipulate odour-orientation of Anopheles mosquitoes in follow-up studies, since they have been implicated as semiochemicals for other insect species [75][76][77][78][79].…”

“…[76], guaiene has been suggested to play a role in the attraction of the litchi stem-end borer [80] and βelemene has been implied to contribute to attraction of the gravid tobacco moths [77] and the whitespotted longhorn beetle [78].…”

An Odorant Receptor Expressed in Both Antennae and Ovipositors Regulates Benzothiazole-Induced Oviposition Behavior in Bactrocera dorsalis

“…During this process, odorant cues from external environment are critical for females to make a decision regarding where to lay eggs. For example, nicotine and the species-specific γ-terpinolene and β-elemene from Nicotiana rustica and Nicotiana tabacum mediate the different oviposition rates of Helicoverpa assulta . Geosmin from microbes attracts Aedes aegypti to lay eggs .…”

“…For example, nicotine and the species-specific γ-terpinolene and β-elemene from Nicotiana rustica and Nicotiana tabacum mediate the different oviposition rates of Helicoverpa assulta. 1 Geosmin from microbes attracts Aedes aegypti to lay eggs. 2 The oviposition behavior of butterfly Papilio polytes could be induced by trans-4hydroxy-N-methyl-L-proline isolated from the host plant Toddalia asiatica.…”