Role of TRP channels and HSPs in thermal stress response in the aphid parasitoid Aphelinus asychis(Hymenoptera:Aphelinidae)

Aphelinus asychis is an important aphid endoparasitoid.Under field and greenhouse conditions,high temperature is one of the factors limiting the application of A asychis for biological pest control.To explore the potential role of transient receptor potential(TRP)channels and heat shock proteins(HSPs)in this process,we identified 11 genes encoding TRP channels and nine genes encoding HSPs.Three proteins(AasyTRPA5,AasyPyrexia,AasyPainless)that belong to transient receptor potential ankyrin(TRPA)subfamily and nine HSPs are involved in the response to high temperature.We also investigated the survival of A asychis and the response of the identified TRP channels and HSPs to high temperature.The results showed that the maximum temperature that allowed A.asychis survival was approximately 41°C;females had higher survival rates than that of the males at 40 and 41°C.Short-term heat-shock resulted in increased expression of Amsysbsp in males,and Aasyhsp40,Aasyhsp68,Aasyhsp70-4,Aasyhsp70-5 and Aasyhsp90 were upregulated and then down regulated,whereas Aasyhsp70-3was upregulated at41°C.Moreover,Aasyhsp40and Aasyhsp90showed higherexpression levels in females,while Aasyshsp and Aasyhsp70-3 presented opposite expression patterns.At temperature above 35°C,expression of AasyPyrexia in females was significant higher than that in males,whereas AasyPainless mnd AasyTRPA5 presented higher expression in males at 40 and 41°C,respectively.Altogether,these results indicate that protect!on against thermal stress in A.asychis is coordinated by TRP channels and HSPs.These findings provide a basis for understanding the potential mechanism of A asychis in response to high temperatures.

The phylogenetic relationships of introduced Aphelinus （Hymenoptera： Aphelinidae）, biological control agents of the Russian wheat aphid （Homoptera： Aphididae）

Several species of Aphelinus have been introduced to the US from the Old World for biological control of the Russian wheat aphid, Diuraphis noxia （Modvilko）. Reproductive incompatibility has been observed among populations collected from different geographic areas. We examined whether or not the reproductive incompatibility between strains of A. asychis was caused by distant phylogenetic relationships. Ribosomal DNA sequences of internal transcribed spacers 2 （ITS2） were analyzed in several species of Aphelinus collected from multiple sites of Europe and Asia. Yhe phylogenetic analysis showed that strains within the species A. albipodus and A. asychis are not monophyletic, and two clearly divergent clades were revealed among sequenced samples. Our results suggest that the reproductive incompatibility between three exotic strains ofA. asychis was more likely caused by divergence of phylogeny than by symbiotic bacteria.

Isolation and characterization of nine microsatellite loci from Aphelinus mali （Hymenoptera： Aphelinidae）, a parasitoid of Eriosoma lanigerum （Hemiptera： Aphididae）

Nine novel microsatellite markers are presented for Aphelinus mali, a parasitoid of the woolly apple aphid Eriosoma lanigerum. Loci were characterized for 28 individuals from a single orchard in central Chile. Seven loci were polymorphic within A. mali （3-6 alleles per locus; observed heterozygosity ranging from 0.04 to 0.57） and are therefore useful for population genetic studies within this species.