Impacts of Water Deficiency on Life History ofSitobion avenaeClones From Semi-arid and Moist Areas

Abstract

The climate warming trend appears to be evident with an increasing frequency of drought events in Shaanxi Province of China, which may have contributed to an increase in outbreaks of the English grain aphid, Sitobion avenae (Fabricius). To explore the potential effects of water-deficit stress on aphid outbreak risks, clones of S. avenae were collected from semi-arid and moist areas of Shaanxi. The life histories of collected clones were then compared on wheat under well-watered and moderately water-stressed conditions in the laboratory. Our results demonstrated that semi-arid area clones of S. avenae had longer developmental times, shorter reproductive times, lower fecundities, and lower net reproductive rates compared with moist area clones. Age-specific reproductive rates of moist area clones tended to be higher than those of semi-arid area clones. Significant differences between semi-arid and moist area clones were found for the survival functions when tested under water-stressed conditions, and semi-arid area clones tended to have a lower survival rate than moist area clones throughout their lives. "Population origin" (i.e., semi-arid and moist area clones) and "clone" together explained 62.74-96.56% of the total variance of tested life-history traits, suggesting the genetic basis for differentiation of clones from both areas. Significant differences in correlations, and selection differentials and gradients of life-history traits were also found between clones from both areas, providing further evidence of genetic basis for the life-history differentiation between them. Divergence between clones from both areas and its implications for S. avenae outbreaks are discussed.

Impact of water-deficit stress on tritrophic interactions in a wheat-aphid-parasitoid system

“…Following previous studies [ 26 – 27 ], the areas with a mean annual precipitation up to 200 mm or less, 200–400 mm, and 800 mm or more were considered to be arid, semiarid, and moist, respectively. Sitobion avenae sample collections were made at two locations in each area from April to June 2015 ( Fig 1 ).…”

“…gifuensis larvae were sampled from local wheat fields in Yangling, Shaanxi Province ( Fig 1 ) in June 2015. This location belongs to semiarid areas according to previous studies [ 26 – 27 ]. No particular permits have been required for insect collecting activities at all the sites mentioned above, and our target insects are not endangered or protected.…”

“…We established three treatments: well-watered, intermediately water-stressed, and severely water-stressed. These water treatments were conducted as detailed previously in [ 26 ]. Specifically, we applied 10, 7, and 5 ml of water every 3 d for wheat seedlings ( T .…”

“…In northwestern China, the warming trend is particularly evident [ 2 ], and this provides an excellent scenario for addressing the abovementioned issues. The wheat aphid, Sitobion avenae (Fabricius), has been shown to cause increasing damage to wheat production in this part of China [ 26 ]. This aphid has the ability to adapt rapidly to various unfavorable environments including water-deficit stress [ 27 – 32 ].…”

Comparison of fitness traits and their plasticity on multiple plants for Sitobion avenae infected and cured of a secondary endosymbiont

“…Effects of ‘treatment’ (i.e., elimination of R. insecticola using antibiotics), ‘test plant’ (i.e., wheat, oat and rye), ‘clone’ nested in ‘treatment’, and the interactions between the first two factors were analyzed following Dai et al . 48 . Treatment means were separated using Tukey tests at α = 0.05 following significant ANOVA.…”