Population Dynamics Features of Willow-feeding Aphids

Willow-feeding aphid colonies were sampled on scattered trees (Salix alba) from April until November, in 1999. The collected individuals belonged to 9 aphid species of 3 families (Lachnidae, Chaitophoridae, Aphididae). The aphid populations showed two peaks in May and in October. The indirect negative effect of the rainfall seems to be responsible for this temporal pattern. The Shannon diversity also exhibited spring and autumn peaks during the year. The willow-feeding aphid guild seasonally rearranged, different species were dominant in each period. Four types of population dynamics of the 9 species were established based on the abundance changes. The time of appearance of different morphs in two dominant species was compared, they belonged to Pterocomma genus. In spring, there were uncoordinated schedule in the development of populations of P. pilosum konoi and P. rufipes, the different morphs of P. pilosum konoi increased earlier. In autumn both species reached their peaks simultaneously, but there were fewer individuals of P. pilosum konoi for a longer time. This species was more vulnerable to aphid parasitoids in each season

Comparative gut transcriptome analysis reveals differences between virulent and avirulent Russian wheat aphids, Diuraphis noxia

Citation: Anathakrishnan, R., Sinha, D. K., Murugan, M., Zhu, K. Y., Chen, M. S., Zhu, Y. C., & Smith, C. M. (2014). Comparative gut transcriptome analysis reveals differences between virulent and avirulent Russian wheat aphids, Diuraphis noxia. Retrieved from http://krex.ksu.eduThe Russian wheat aphid, Diuraphis noxia, is a destructive pest of cereal crops that exhibits virulence to D. noxia resistance genes in wheat. Therefore, it is important to identify D. noxia virulence factors. The insect gut, the primary site of defense to ingested toxins, is also a likely site of differential gene expression in virulent insects. Comparative analyses of gut transcriptomes from virulent and avirulent D. noxia can improve an understanding of aphid gut physiology and may reveal factors critical to compatible D. noxia-wheat interactions. A total of 4, 600 clones were sequenced from gut cDNA libraries prepared from avirulent (biotype 1) and virulent (biotype 2) D. noxia feeding on biotype 1-resistant wheat. A majority of the sequences (66% in biotype 1, 64% in biotype 2) matched those from the NR database. BLASTX analysis of sequences with the highest E-values revealed that 59% of the biotype 1 sequences matched those of the pea aphid, Acyrthosiphon pisum. However, only 17% of the biotype 2 sequences were similar to those of A. pisum. RT-qPCR expression analyses confirmed that the biotype 2 gut transcriptome differs significantly from that of biotype 1. A transcript coding the tRNA-Leu gene was significantly up-regulated in the biotype 2 transcriptome, strongly suggesting that leucine metabolism is a critical factor in biotype 2 survival. Many more transcripts encoding protease inhibitors occurred in the avirulent biotype 1 gut than in the gut of virulent biotype 2. However, more protease transcripts occurred in the biotype 2 gut than in the biotype 1 gut, suggesting that the avirulent biotype produces protease inhibitors in response to plant proteases. The virulent biotype 2 produces trypsin-like and chymotrypsin-like serine protease counter-defenses to overcome biotype 1-resistant plants