Comparisons Of Life Histories, Feeding Behaviors And Activities Of Detoxification Enzymes For Sitobion Avenae On Different Host Plants

Sitobion avenae(Fabricius) is a serious pest which can reduce the yield and quality of cereal crop production. This aphid can feed on cereals and various grasses with complex life cycles and high genetic diversity. Using ecological and biochemical assay methods, we examined life-history and feeding behaviors of S. avenae on different host plants, as well as effects of host plants and genetic factors on activities of detoxifying enzymes in S. avenae.The main results are as follows:1. Life-history parameters such as the nymphal development period, lifespan and fecundity of S. avenae were significantly affected by both ‘host plant’ and ‘clone’. The lengths of nymphal development period of S. avenae on different host plants were in the order of ryegrass > barley or oat > wheat. The fecundities and lifespans of S. avenae on different host plants were in the order of wheat > barley or oats > ryegrass. These results indicat that the fitness of S. avenae on cereal crops was higher that on ryegrass, and ryegrass could be highly resistant to feeding of this aphid.2. For the first and third generation of S. avenae, the numbers of C and Np were the highest, and the duration of Np wave was the longest on ryegrass. Total duration of E1, total duration of E1 followed by sustained E2(>10 min), total duration of E1 followed by E2, and total duration of single E1 of first generation S. avenae were the longest on oat. When first generation S. avenae fed on barley, the number of waveform F was the highest among all test plants, and the percentage of F was as high as 41.2%. These results suggest that the epidermal layers of ryegrass and phloem of oat might have resistance factors for S. avenae’s feeding,and this aphid’s feeding during the penetration phase could encounter higher resistance on barley.3. It was shown that higher activities of GST and AChE were induced by barley for generation one of S. avenae, whereas higher activities of CarE were found on oat for the same generation. Compared to other test plants, barley induced higher activities in AChE of genotypes 1, 2, 3 and 8, in CarE of genotypes 2, 4, 5, 6 and 8, and in GST of genotypes 1, 2, 3and 8. In terms of comparisons between generations of S. avenae, the activities of CarE were higher on all test plants for generation one, compared to those of generation three; barley induced higher activities of GST for generation one, but its activities were higher forgeneration three on wheat, oat and ryegrass. Differential responses to various host plants were identified for different families of detoxification enzymes in S. avenae, and the plant-dependent inductive effects were also closely related to aphid genotypes, generations and interactions between the abovementioned factors.In conclusion, the factors of ‘host plant’, ‘generation’ and genetic background all showed significant impacts on the performance of S. avenae in terms of life-history, behavioral and biochemical traits. Complex interactions among these factors were also identified. Further studies are needed to explore the molecular aspects and mechanisms underlying the interactions of factors mentioned above. Such studies will be of significance in understanding the adaptation of S. avenae on different host plants and developing ecological control strategies for this pest.