Interactions of elevated carbon dioxide and temperature with aphid feeding on transgenic oilseed rape: Are Bacillus thuringiensis (Bt) plants more susceptible to nontarget herbivores in future climate?

Abstract

Interactions of elevated carbon dioxide and temperature with aphid feeding on transgenic oilseed rape: Are Bacillus thuringiensis (Bt) plants more susceptible to nontarget herbivores in future climate? Abstract Climate change factors such as elevated carbon dioxide (CO 2 ) and temperature typically affect carbon (C) and nitrogen (N) dynamics of crop plants and the performance of insect herbivores. Insect-resistant transgenic plants invest some nutrients to the production of specific toxic proteins [i.e. endotoxins from Bacillus thuringiensis (Bt)], which could alter the C-N balance of these plants, especially under changed abiotic conditions. Aphids are nonsusceptible to Lepidoptera-targeted Bt Cry1Ac toxin and they typically show response to abiotic conditions, and here we sought to discover whether they might perform differently on compositionally changed Bt oilseed rape. Bt oilseed rape had increased N content in the leaves coupled with reduced total C compared with its nontransgenic counterpart, but in general the C : N responses of both plant types to elevated CO 2 and temperature were similar. Elevated CO 2 decreased N content and increased C : N ratio of both plant types. Elevated temperature increased C and N contents, total chlorophyll and carotenoid concentrations under ambient CO 2 , but decreased these under elevated CO 2 . In addition, soluble sugars were increased and starch decreased by elevated temperature under ambient but not under elevated CO 2 , whereas photosynthesis was decreased in plants grown under elevated temperature in both CO 2 levels. Myzus persicae, a generalist aphid species, responded directly to elevated temperature with reduced developmental time and decreased adult and progeny weights, whereas the development of the Brassica specialist Brevicoryne brassicae was less affected. Feeding by M. persicae resulted in an increase in the N content of oilseed rape leaves under ambient CO 2 , indicating the potential of herbivore feeding itself to cause allocation changes. The aphids performed equally well on both plant types despite the differences between C-N ratios of Bt and non-Bt oilseed rape, revealing the absence of plant composition-related effects on these pests under elevated CO 2 , elevated temperature or combined elevated CO 2 and temperature conditions.

Changes in Life History Parameters of <I>Rhopalosiphum maidis</I> (Homoptera: Aphididae) Under Four Different Elevated Temperature and CO<SUB>2</SUB> Combinations

“…Elevated temperature and CO 2 increased the aphids (green peach aphid and potato aphid) fecundity, and in turn, forecasting its abundance might be increased under conditions of climate change (Bezemer et al 1998, Flynn et al 2006), but elevated CO 2 reduced the cumulative number of progeny for green peach aphid according to Himanen et al (2008). The Newman model (Newman 2003) was used to examine the combined effects of elevated CO 2 concentrations and temperature on aphid population sizes.…”

“…The study was conducted as a 2 (temperatures) ϫ 2 (CO 2 levels) factorial experiment with completely randomized design, with the two consecutive generations as the factor. Development time, fecundity and survivorship, proportion of alates, and life table parameters were recorded and analyzed with analysis of variance (ANOVA) for main effects of temperature and CO 2 levels, as well as generation and their interactions (SAS Institute 2006, Himanen et al 2008. Fisher protect least signiÞcant different (LSD) test was used to temperature under ambient (Amb; 350Ð400 l/liter) or elevated (Elev; 700Ð750 l/liter) CO 2 level.…”

“…A number of experiments have been conducted in recent years to examine the aphid response to elevated CO 2 (Bezemer et al 1998(Bezemer et al , 1999Hughes and Bazzaz 2001;Holopainen 2002;Newman et al 2003;Flynn et al 2006;Gao et al 2008). At the same time, interactions between elevated CO 2 and temperature affecting aphids also have been reported (Bezemer et al 1998, Newman 2003, Hoover and Newman 2004, Flynn et al 2006, Himanen et al 2008. Some results showed that, when the above-mentioned two factors are elevated, cereal aphid population dynamics will be much similar to current ambient conditions (Newman et al 2003, Hoover andNewman 2004), while green peach aphid, Myzus persicae Sulzer, and potato aphid, Macrosiphum euphorbiae Thomas, abundance were increased by both temperature and CO 2 treatments (Bezemer et al 1998, Flynn et al 2006).…”

Elevated CO2 alters the feeding behaviour of the pea aphid by modifying the physical and chemical resistance of Medicago truncatula

“…For piercing‐sucking insects such as aphids, however, recent reviews conclude that the effects are species‐specific (Hughes & Bazzaz ; Himanen et al . ). Importantly, some aphid species exhibit increased fecundity, abundance and survival under elevated CO 2 (Pritchard et al .…”

The Effects of Climate Warming on Plant-Herbivore Interactions

“…Such changes were correlated with changes in the efficacy of plant chemical extracts at higher temperatures. Earlier studies addressing the interaction between diet quality and temperature on generalist herbivore performance have largely used artificial diets or measured variation in nutritional quality within a single plant species (Himanen et al 2008). To our knowledge, this is the first study demonstrating that temperature-driven changes in herbivore feeding preferences and performance correlate with natural variation in nutritional quality and secondary chemical composition across a range of plant species.…”