Guohui Yuan

Gene Cloning and Expression Analysis of G Protein αq Subunit from Helicoverpa assulta （ Guenée）

Abstract The cDNA encoding the G protein αq subunit was isolated from the antennae of Helicoverpa assulta (Guenee) by reverse transcription polymerase chain reaction (RT-PCR) and named as HassGαq. Sequencing analysis showed that the full-length of HassGαq open reading frame (ORF) is 1062 bp, 353 amino acid residues are encoded. The predicted molecular weights (MW) and isoelectric point (PI) are 41.5 kD and 5.15, respectively. HassGαq gene was then constructed into expression vector pGEX-4T-2 for over expression in prokaryotic cells. The SDS-PAGE and Western blot analysis showed that induced by Isopropyl-β-D-Thiogalactoside (IPTG), the GST-HassGαq fusion protein is expressed in Escherichia coli BL21, and its MW was found to be about 66 kD nearly equal to the predicted. In addition, RT-PCR analysis showed that the expressions of HassGαq are not tissue specific.

Prescription screening and field evaluation of broad spectrum attractants of scarab beetles from Ricinus communis

To screen plant-derived attractants for ecological management of three scarab beetles(Holotrichia oblita,H.parallela and Anomala corpulenta),10 binary blends(labeled as 1,2,…,10,see below) with 5 main volatiles from the leaves of Ricinus communis were selected.Then the electrophysiological activity and attractiveness of the selected R.communis volatiles blends were evaluated by electroantennogram(EAG) and field trapping experiments.The EAG bioassay showed that blends containing green leaf volatile of cis-3-hexen-1-ol usually exhibited strong EAG activities.Blend 1(cis-3-hexen-1-ol plus dibutyl phthalate) and blend 6(cis-3-hexen-1-ol plus benzyl alcohol) showed stronger EAG response to both sexes of the three scarab beetle species.Blend 7(cis-3-hexen-1-ol plus 2-phenylethanol) exhibited a fairly strong EAG activity toward H.oblita sexes.Also blend 8(cinnamaldehyde plus benzyl alcohol) effectively stimulated response to male A.corpulenta antennae.The preliminary trapping experiment indicated that among the ten candidate binary blends,blends 6,8 and 1 performed the best regarding the target species at occurrence peak with respectively 110.30,101.73 and 74.97 catches per trap in 30 days.Most interestingly,the blends also attracted a certain number of A.exoleta.Further mass-trapping experiments conducted in Luoyang and Kaifeng regions were used to compare the attractiveness of the mentioned 3 blends.The results showed that blends 6 and 1 caught significantly more scarab beetles than blend 8.A significantly great number of H.parallela and a few A.corpulenta and Popillia quadriguttata were among the species caught in the trapping experiment conducted in Luoyang.In the Kaifeng trapping experiment,Maladera orientalis was the most abundant species caught,followed by H.parallela and P.quadriguttata.The different natural distributions of the scarab species in different regions possibly explained the differences in trapped species.Altogether,blends 6 and 1 were possibly the two promising ecological control attractants that were generically targeted to several scarab beetle species in the region.

Cloning and Expression Analysis of cDNA Encoding Or83b-Like Receptor from Helicoverpa assulta

Abstract An Or83b-like receptor gene was cloned from antennae of Helicoverpa assulta (Guenee) by using reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). Sequence analysis revealed that the transcript of the Or83b-like receptor gene from H . assulta consists of 1 946 nucleotides and the open reading frame (ORF) encodes a peptide of 473 amino acids with 7 putative transmembrane domains. Alignment analysis suggested that amino acid sequence of Or83b-like receptor from H . assulta shares high identity with other Or83b family receptors and this gene was hence named as HassOr83b . Tissues expression analysis showed that the HassOr83b transcript is clearly observed in the antennae, labial palps and proboscises, but not in bodies, wings and legs. The further development expression analysis suggested HassOr83b is also expressed in several preadult stages, including early-stage larvae, late-stage larvae and pupae, but not in embryos. Locked nucleic acid (LNA)-based in situ hybridization of antennal section indicated that HassOr83b is expressed in a very large number of antennal cells, which suggests that HassOr83b may play a special role in olfaction in H . assulta .

Active compounds in Populus nigra L. wilted leaves responsible for attracting Helicoverpa armigera (Hübner) (Lep., Noctuidae) and new agaropectin formulation

Abstract:  The leaf extracts of Populus nigra were collected and identified by steam distillation, air entrainment and gas chromatographic–mass spectrometric analysis. Electroantennograms were recorded from Helicoverpa armigera adults in response to the chemicals identified. Both aromatic compounds and green‐leaf volatiles elicited strong responses. Field experiments revealed that the active compounds responsible for attracting H. armigera moths are mainly short‐side‐chain aromatic alcohols and aldehydes. We, for the first time, used agaropectin as the controlled‐release matrix of insect attractants. A five‐component lure containing all the aromatics without phenolics, mixed in the proportions as found in the steam distillate of the leaves collected in August, produced the best trap catch. The results showed that the volatiles of wilted leaves of P. nigra can attract H. armigera adults by feeding attraction.

Comparative host selection responses of specialist (Helicoverpa assulta) and generalist (Helicoverpa armigera) moths in complex plant environments

We tested the behavioral responses of ovipositing females and natal larvae of two sibling species, a generalist Helicoverpa armigera (Hübner) and a specialist Helicoverpa assulta (Guenée), to odor sources emitted from different combinations of six plant species (tobacco, Nicotiana tabacum; hot pepper, Capsicum annuum; tomato, Solanum esculentum; cotton, Gossypium hirsutum; peanut, Arachis hypogaea; maize, Zea mays). Under the conditions of plant materials versus corresponding controls, both stages of both species could find their corresponding host plants. However, H. assulta females and larvae exhibited a supersensitive and an insensitive response, respectively. Under the conditions of tobacco paired with each plant species, H. assulta females exhibited more specialized ovipositional response to tobacco than its sibling. When each plant species were combined with tobacco and tested against tobacco reference, peanut played an opposite role in the two species in their ovipositional responses to tobacco, and cotton can enhance the approaching response of H. armigera larvae when combined with tobacco. It seems that two attractive host plants also can act antagonistically with respect to host selection of the generalist via volatile exchange. Tomato should better be excluded from host list of H. assulta.

Experience-based mediation of feeding and oviposition behaviors in the cotton bollworm: Helicoverpa armigera (Lepidoptera: Noctuidae)

Experience is well known to affect sensory-guided behaviors in many herbivorous insects. Here, we investigated the effects of natural feeding experiences of Helicoverpa armigera larvae on subsequent preferences of larval approaching and feeding, as well as the effect of host-contacting experiences of mated females on subsequent ovipositional preference. The results show that the extent of experience-induced preference, expressed by statistical analysis, depended on the plant species paired with the experienced host plant. Larval feeding preference was much easier to be induced by natural feeding experience than larval approaching preference. Naïve larvae, reared on artificial diet, exhibited clear host-ranking order as follows: tobacco ≥ cotton > tomato > hot pepper. Feeding experiences on hot pepper and tobacco could always induce positive feeding preference, while those on cotton often induced negative effect, suggesting that the direction of host plant experience-induced preference is not related to innate feeding preference. Inexperienced female adults ranked tobacco as the most preferred ovipositional host plant, and this innate preference could be masked or weakened but could not be reversed by host-contacting experience after emergence.

Repellence of Common Tobacco Flavorants on Lasioderma serricorne (Coleoptera: Anobiidae)

Abstract The cigarette beetle, Lasioderma serricorne (F.) (Coleoptera: Anobiidae) is a destructive pest species of tobacco. Olfactory repellents derived from permitted tobacco flavorants have the advantage of not adversely effecting tobacco flavor. Among 12 test compounds, neral exhibited the strongest repellent effect. Among six binary blends prepared, three blends (neral + ethyl cinnamate, neral + cinnamaldehyde, and neral + methyl cinnamate) evoked the strongest repellent response.The interactions between neral and any one of the cinnamic acid derivatives were additive, and the interactions between neral and the cinnamic acid derivatives were antagonistic. In a 32-d tobacco barn bioassay, neral + cinnamaldehyde (embedded in 0.5% agaropectin) showed the strongest repellent effect with a persistence of at least 30 d. The binary blend of two tobacco additives (neral and cinnamaldehyde) appears promising as a repellent for controlling cigarette beetles in tobacco barns.