Rongjiang Wang

Contrasting movement patterns in two species of chequerspot butterflies, Euphydryas aurinia and Melitaea phoebe, in the same patch network

Abstract.  1. Mark–release–recapture studies were conducted on two species of chequerspot butterfly, Euphydryas aurinia and Melitaea phoebe, in the same habitat patch network in Yanjiaping, a small basin in the Taihang Mountains, north‐west of Beijing, China, in 2000.

Dispersal in the Glanville fritillary butterfly in fragmented versus continuous landscapes: comparison between three methods

1. Habitat fragmentation may lead to natural selection on dispersal rate and other life‐history traits. Both theoretical analyses and empirical studies suggest that habitat fragmentation may select either for increased or decreased dispersal depending on the traits of the species and the characteristics of the landscape.

Volatiles induced by the larvae of the Asian corn borer (Ostrinia furnacalis) in maize plants affect behavior of conspecific larvae and female adults

Abstract  Effects of maize (Zea mays L.) volatiles induced by larvae of the Asian corn borer, Ostrinia furnacalis (Guenée), on the orientation behaviors of Asian corn borer larvae and oviposition of the females were investigated. Nineteen volatile chemicals, with terpenes being the major components, were identified from maize plants attacked by third instar Asian corn borer larvae. Coupled gas chromatographic‐electroantennographic detection (GC‐EAD) analyses revealed some electroantennographic differences between female and male Asian corn borer antennae in response to larvae‐induced maize volatiles; female responded to (E)‐2‐hexenal, nonanal, (Z)‐3‐hexen‐1‐ol and three unknown compounds while the male only responded to (E)‐2‐hexenal, nonanal and one unknown compound. In laboratory orientation bioassays, Asian corn borer neonate larvae were attracted to extracts collected from Asian corn borer‐damaged plants as well as to synthetic farnesene, but were repelled by (Z)‐3‐hexen‐1‐ol. In laboratory oviposition bioassays, gravid females laid fewer eggs on plants damaged by larvae than on mechanically damaged plants or undamaged plants. Adult Asian corn borer females deposited fewer eggs on wax paper treated with (E)‐2‐hexenal or (Z)‐3‐hexen‐1‐ol than on wax paper treated with hexane (control). The results suggest that Asian corn borer can affect the behaviors of conspecific larvae and adults by changing host plant volatiles.

Phenotypic plasticity in thermal tolerance in the Glanville fritillary butterfly.

Ambient temperature is an ubiquitous environmental factor affecting all organisms. Global climate change increases temperature variation and the frequency of extreme temperatures, which may pose challenges to ectotherms. Here, we examine phenotypic plasticity to temperature and genotypic effects on thermal tolerance in the Glanville fritillary butterfly (Melitaea cinxia). We found no significant difference in heat or cold tolerance in populations originating from a continental climate in China and from Finland with moderate temperature variation. Acclimation to large-amplitude temperature variation increased heat tolerance in both populations, but decreased cold tolerance and increased hsp70-2 expression in the Chinese population only. The latter result indicates a genotypic effect in the response to temperature variation. In the Finnish population, a non-synonymous SNP in the phosphoglucose isomerase (Pgi) gene was associated with heat knock-down time.

Stylet penetration behaviors of the cotton aphid Aphis gossypii on transgenic Bt cotton.

Stylet penetration behaviors of cotton aphids Aphis gossypii Glover on a transgenic cotton line “GK‐12” expressing Bt toxic protein of Cry1A (Bt cotton) and a non‐Bt conventional cotton line “Simian‐3” (CK cotton) were recorded with the direct current electrical penetration graph (DC‐EPG) technique. Cotton aphids reared on Bt cotton (abbreviated as Bt‐aphids) and its parental non‐Bt control line (CK‐aphids) for more than 20 generations each, were used for recordings on two cotton lines. Among 47 selected parameters reflecting the activities of aphid stylets within plant tissues, there were eight parameters of CK‐aphids showing significant differences between the performances of CK‐aphids on Bt cotton and CK cotton, while for Bt‐aphids, all the parameters were statistically equal between the performances on the two cotton lines. All parameters with significant differences indicated that CK‐aphids could penetrate into Bt cotton more easily, but the phloem saps of Bt cotton were not as good as those of regular cotton for CK‐aphids. Based on the present results, we concluded that there were some factors in Bt cotton affecting penetration behaviors of CK‐aphids, but it just took several generations for CK‐aphids to completely adapt Bt cotton, and Bt‐aphids could feed on two cotton lines without difficulty.

Genetic differentiation Within metapopulations of Euphydryas aurinia and Melitaea phoebe in China

We analyzed genetic differentiation within metapopulations of two species of checkerspot butterfly, Euphydryas aurinia and Melitaea phoebe, in China. To generate genetic information, we used a new molecular technique, DALP – direct amplified length polymorphism. AMOVA results showed that most of the variation occurred among individuals within local populations of both E. aurinia and M. phoebe. However, while there was differentiation among local population in E. aurinia (P < 0.001), there was no subdivision in metapopulation of M. phoebe (P = 0.210). This is consistent with the behavior of M. phoebe adults being more dispersive than E. aurinia. Within the M. phoebe metapopulation, three neighboring patches were always occupied during the observation period (1998–2000). In addition, the number of individuals in these three populations accounted for the majority of M. phoebe larvae, and hence we conclude that the M. phoebe metapopulation might exist as a source-sink metapopulation. On the other hand, the E. aurinia metapopulation is an example of a classical metapopulation. Therefore, the conservation management of these two species should reflect these differences.

Proteomic analysis of Arabidopsis thaliana leaves infested by tobacco whitefly Bemisia tabaci (Gennadius) B biotype

Bemisia tabaci (Gennadius) B biotype, a destructive pest causing heavy damage to crop production, has become an important economic pest of agriculture worldwide. Here, the proteome change of Arabidopsis thaliana leaves infested by B. tabaci was studied with two-dimensional electrophoresis and mass spectrometry. Twenty proteins showed a significant change in expression after B. tabaci infestation, including ten up-regulated and ten down-regulated. Using the Gene Ontology annotation, all except one were classified into one of four major groups based on their molecular function and biological process. Six of the proteins were involved in protein folding and regulation (HSP90.7, HSP90.3, HSP90.2, ERD1, FKB70, and ROC1), five in redox regulation (PRX2B, GPX6, MDAR3, MDARP, and Y4967), five in primary metabolism (TBA6, SPP2, PDX11, RR5, and RuBisCO activase (RCA)), and three in secondary metabolism (PR5, MYRO, and NMT2). All proteins belonging to the same group shared the same direction of change; the only exception was RCA. The proteins involved in protein folding and regulation were down-regulated indicating the inhibition of a plant defense response. Those involved in redox regulation were up-regulated, which may lead to an increase in tolerance as a result of a reduction in oxidation. Proteins involved in primary metabolism (except RCA) were inhibited while those involved in secondary metabolism were induced suggesting reallocation of resources with the host plant. These proteins will form the basis for future studies aimed at further understanding the mechanism underlying the host-adaptation capacity of B. tabaci.

Impacts of transgenic Bt cotton on the stylet penetration behaviors of Bemisia tabaci biotype B: Evidence from laboratory experiments

Abstract  Stylet penetration behaviors of Bemisia tabaci biotype B on two transgenic cotton lines “GK12” and “GK19” expressing Bt toxic protein Cry1A (Bt cotton) and a non‐Bt conventional cotton line “Simian‐3” (CK cotton) were recorded with the direct current electrical penetration graph (DC‐EPG) technique. Our results suggested that EPG waveform patterns, types and characteristics [non‐probe (NP), pathway (C), potential drops (pd) and phloem phase (E(pd))] of Bemisia tabaci biotype B were very similar on the three cotton lines. There were no obvious differences of pathway variables among whiteflies on the three cotton lines. Some phloem variables related to E(pd)1 differed. Duration of 1st E(pd)1 and mean duration of E(pd)1 on both GK12 and GK19 were significantly shorter than that on CK cotton (P < 0.05). Fewer whiteflies on GK have long E(pd)1. Other phloem variables including total duration of E(pd) summed, mean E(pd) duration and percentage of whiteflies reaching the phloem phase were similar among the three cotton lines.

Distribution and variations of three 1,4-benzoxazin-3-ones in maize induced by the Asian corn borer, Ostrinia furnacalis (Guenée).

Contents of three 1,4-benzoxazin-3-ones in tissue samples from different parts (young leaf, second leaf, old leaf, stem and root) of young maize plants of 4-leaves stage, fed by the third instar larvae of the Asian corn borer, Ostrinia furnacalis (Guenée), were analyzed by highperformance liquid chromatography-mass spectroscopy (HPLC-MS). Samples were taken immediately (set A) or 48 h (set B) after larvae had fed on the second leaf for 48 h. The three 1,4-benzoxazin-3-ones investigated in our experiments were 2,4-dihydroxy-7-methoxy- 1,4(2H)-benzoxazin-3-one (DIMBOA), 2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIBOA) and 2-hydroxy-7-methoxy-1,4(2H)-benzoxazin-3-one (HMBOA). In samples of set A, the levels of DIMBOA and HMBOA were significantly lifted in the old leaf (L3) and young leaf (L1), respectively, while amounts of these two chemicals in other plant parts were not significantly different between larvae-fed plants and intact plants. Concentrations of DIBOA in each plant part remained unchanged. In samples of set B, no concentration differences for any of these three 1,4-benzoxazin-3-ones between larvae-fed plants and controls were observed in any plant part. The feeding of the Asian corn borer seems to have limited effects on induction of these three 1,4-benzoxazin-3-ones in young maize plants of the variety investigated.