Potential detoxification of gossypol by UDP-glycosyltransferases in the two Heliothine moth species Helicoverpa armigera and Heliothis virescens

Homologues of Heliothis virescens ascovirus 3h (HvAV-3h) orf21 are found in 9 completely sequenced members of the ascoviruses, but so far their functions are unknown. Here, orf21 (3h-21) was cloned in-frame into a pET-28a bacterial expression vector. The fusion protein produced by this construct was used for the preparation of a polyclonal antiserum. RT-PCR analysis showed a single transcript of 3h-21 of approximately 0.7kb was transcribed beginning at 24h post-infection in infected Helicoverpa armigera larvae. Western blot analysis of extracts from HvAv-3h-infected Helicoverpa armigera larvae detected a 25.6 kDa protein late in infection. This antiserum also reacted with a 25.6 kDa protein in purified virions of HvAv-3h. The protein was not extensively modified post-translation. Immunoelectron microscopy confirmed that the 3H-21 is associated with the structure of HvAV-3h virions.

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Habituation to a Deterrent Plant Alkaloid Develops Faster in the Specialist Herbivore Helicoverpa assulta Than in Its Generalist Congener Helicoverpa armigera and Coincides with Taste Neuron Desensitisation

Insects ◽

10.3390/insects13010021 ◽

2021 ◽

Vol 13 (1) ◽

pp. 21

Author(s):

Dong-Sheng Zhou ◽

Chen-Zhu Wang ◽

Joop J. A. van Loon

Keyword(s):

Host Plant ◽

Helicoverpa Armigera ◽

Artificial Diet ◽

Leaf Disk ◽

Specialist Herbivore ◽

Helicoverpa Assulta ◽

Electrophysiological Tests ◽

Helicoverpa Armígera ◽

Sensillum Styloconicum ◽

Moth Species

The two closely related moth species, Helicoverpa armigera and H. assulta differ strongly in their degree of host-plant specialism. In dual-choice leaf disk assays, caterpillars of the two species that had been reared on standard artificial diet were strongly deterred by the plant-derived alkaloid strychnine. However, caterpillars of both species reared on artificial diet containing strychnine from neonate to the 5th instar were insensitive to this compound. Fifth instar caterpillars of H. assulta and 4th or 5th instars of H. armigera not exposed to strychnine before were subjected to strychnine-containing diet for 24 h, 36 h, 48 h, or 72 h. Whereas H. assulta displayed habituation to strychnine after 48 h, it took until 72 h for H. armigera to become habituated. Electrophysiological tests revealed that a deterrent-sensitive neuron in the medial sensillum styloconicum of both species displayed significantly reduced sensitivity to strychnine that correlated with the onset of habituation. We conclude that the specialist H. assulta habituated faster to strychnine than the generalist H. armigera and hypothesis that desensitization of deterrent-sensitive neurons contributed to habituation.

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Host Plant Chemical Mediation of Heliothis Reproductive Behavior

10.32747/1992.7568753.bard ◽

1992 ◽

Author(s):

Peter Landolt ◽

Ezra Dunkelblum ◽

Robert R. Heath ◽

Moshe Kehat

Keyword(s):

Sexual Behavior ◽

Host Plant ◽

Helicoverpa Armigera ◽

Heliothis Virescens ◽

Helicoverpa Zea ◽

Host Plants ◽

Crop Plants ◽

Plant Chemicals ◽

Helicoverpa Armígera ◽

Oviposition Sites

Phytophagous insects respond to chemicals from their host plants in a number of ways, including orientation or attraction in response to volatiles produced by plants. Orientation to odors from host plants may occur in order to locate food, mates, or oviposition sites. A detailed understanding of these behaviors are the chemical stimuli evoking them may provide useful means for attracting and trapping insect pests of crop plants. Heliothine moths (Helicoverpa and Heliothis herein) include a number of major pests of cultivated crop plants throughout the world. In North America, these include Heliothis virescens and Helicoverpa zea. In much of Eurasia (including Israel) Australia, and Africa, these include Helicoverpa armigera and Helicoverpa peltigera. These 4 species of concern all are attracted to odorants from host plants (Tingle and Mitchell 2992, Mitchell et al 1991, 1992 BARD feasibility study report). Host plant chemicals also play a role in the sexual behavior of Helicoverpa species. Synthesis and possibly release of sex pheromone in H. zea and H. phloxiphaga is stimulated by kairomones from hosts plants (Raina 1988, 1992). Pheromona scent marking on host plants also occurs in H. virescens and H. zea. Studies of several other insects, including the cabbage looper Trichoplusia ni, have a variety of other behaviors may occur in association with host plants, including the use of plants as sexual rendesvous sites and of direct involvement of plant chemicals in sexual behavior. Some pest species of moths also may use host plants as adult food sources. These studies were undertaken to develop a more thorough understanding of how Heliothis/Helicoverpa moths use host plant odorants to locate and select foods, mates, and oviposition sites. We used Heliothis virescens and Helicoverpa zea in Florida, and Helicoverpa armigera and Helicoverpa peltigera in Israel as objects of study because of their pest status. It is hoped that such an understanding will provide direction for work to discover and develop novel means to control these pests through behavioral manipulation. The specific objectives of the proposal were to 1) identify host odor affects on known Heliothine sexual behavior, 2) identify novel sexual behavior that is how dependent, 3) isolate and characterize host kairomones important to pest Heliothine host and mate-location behavior, and 4) investigate female attraction to males.

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