Effect of the cereal aphid infestation on the oxidative damages of protein in the maize (Zea mays L.)

We studied the effect of the cereal aphid (the bird cherry-oat aphid Rhopalosiphum padi L. and grain aphid Sitobion avenae F.) infestations on the oxidative damages of protein in the maize (Zea mays L., cultivar Touran) seedlings. We found that the content of protein thiols and protein bound carbonyls were dependent from study factors: time of feeding, the number of aphids and species. In relation to uninfested plants (control), prolonged insect (R. padi and S. avenae) feeding (24–96 h post infestations) was linked to depletion in levels of protein thiols in foliar tissues of maize genotype and accumulation after 96 h post infestations in maize seedlings investigated by higher number of aphids, protein bound carbonyls. Our results indicated that the biotic stress factors, including aphids evoke the oxidation of protein in the maize. The stronger protein damages occurred in the maize seedlings infested with oligophagous R .padi females.

Moderately decreasing fertilizer in fields does not reduce populations of cereal aphids but maximizes fitness of parasitoids

Examination of the tradeoff between the extent of decreasing nitrogen input and pest suppression is crucial for maintaining the balance between essential yield and an efficient, sustainable pest control strategy. In this study, an experiment with four manipulated nitrogen fertilizer levels (70, 140, 210, and 280 kg N ha−1 = conventional level) was conducted to explore the effects of decreasing nitrogen on cereal aphids (Sitobion avenae and Rhopalosiphum padi) (Hemiptera: Aphididae), Aphidiinae parasitoids (Hymenoptera: Braconidae: Aphidiinae), and body sizes of parasitoids. The results indicated that nitrogen application, in the range of 70–280 kg N ha−1, has the potential to impact the populations of cereal aphids and their parasitoids. However, both differences between densities of cereal aphids and their parasitoids in moderate (140–210 kg N ha−1) and those in high nitrogen input (280 kg N ha−1) were not significant, and the parasitism rate was also unaffected. A higher parasitism rate reduced population growth of the cereal aphid (S. avenae). Additionally, a moderate decrease of nitrogen fertilizer from 280 to 140–210 kg N ha−1 maximized the body sizes of Aphidiinae parasitoids, indicating that a moderate decrease of nitrogen fertilizer could facilitate biocontrol of cereal aphid by parasitoids in the near future. We conclude that a moderate decrease in nitrogen application, from 280 to 140–210 kg N ha−1, does not quantitatively impact the densities of cereal aphids or the parasitism rate but can qualitatively maximize the fitness of the parasitoids.

The species composition of the harmful entomofauna of soybean crops in the conditions of rice paddies

Goal. To determine the species composition of soybean phytophages under rice checks. Methods. The main field method with related phenological observations and analyzes. The study of the species composition of soybean pests was carried out in rice paddies of the Institute of Rice of the NAAS by collecting all objects with their subsequent identification. The survey was carried out once every 3—7 days: the first counts were in the third decade of May, when the plants were in the germination phase. Recorded plants were placed diagonally. On the experimental site, five plants were examined in 20 places. Results. Studies have been carried out to clarify the species composition of harmful entomofauna in soybean crops under the conditions of rice checks in the Southern Steppe of Ukraine. Found 20 species of phytophagus from 7 rows and 11 families and one species of spider mite: мeadow moth (Margaritia sticticalis L.); thistle, or vanessa thistle (Vanessa cardui L.); grass bug (Lygus rugulipennis Popp.); alfalfa bug (Carpocoris fuscispinus Boh.); alfalfa stink bug (Piezodorus lituratus F.); tobacco thrips (Thrips tabaci Lind.); scoop-gamma (Autographa gamma L.); alfalfa moth (Chloridea viriplaca Hfn.); green horse (Tettigonia viridissima L.); Italian Prussian (Calliptamus italicus L.); large cereal aphid (Sitobion avenae F.); Moroccan locust (Dociostaurus maroccanus Thunb.); six-point leafhopper (Macrosteles laevis Kib.); striped leafhopper (Psammotettix striatus L.); nosy tree (Aelia rostrata Bsh.); striped nodule weevil (Sitona lineatus L.); gray bristly weevil (Sitona crinitus Hfn.); cotton scoop (Helicoverpa armigera Hfn.); acacia moth (Etiella zinckenella Tr.), two-spotted spider mite (Tetranychus urticae Koch.). Conclusions. As a result of research in the conditions of the Southern Steppe of Ukraine, 20 species of phytophagous insects from 7 rows, 11 families and one species of tick were found in soybeans. The vast majority of pests in terms of numbers are among the Lepidoptera — 38%. These species damaged soybeans during the growing season and influenced the formation of the yield.

Grain aphids (Sitobion avenae) with knockdown resistance (kdr) to insecticide exhibit fitness trade-offs, including increased vulnerability to the natural enemy Aphidius ervi

The development of insecticide-resistance mechanisms in aphids has been associated with inhibitory, pleiotropic fitness costs. Such fitness costs have not yet been examined in the UK’s most damaging cereal aphid, Sitobion avenae (grain aphid) (Hemiptera: Aphididae). This study aimed to evaluate the fitness trade-offs of the insecticide-resistant S. avenae clone versus an insecticide-susceptible S. avenae clone. Additionally, the parasitoid, Aphidius ervi (Hymenoptera: Braconidae), was introduced to examine its potential as a biological control agent. This study found that insecticide-resistant clones had significantly lower population growth and individual relative growth rate. Furthermore, insecticide-resistant clones suffered from a significantly greater rate of parasitisation (mummification) compared to their insecticide-susceptible counterparts. The successfulness of the parasitoid as a biological control agent could prevent the spread of the insecticide-resistant genotype. However, for this to be possible, insecticide spraying regimes need to be moderated, and habitat modification and parasitoid manipulation must be considered.

Differential Defense Responses of Upland and Lowland Switchgrass Cultivars to a Cereal Aphid Pest

Yellow sugarcane aphid (YSA) (Sipha flava, Forbes) is a damaging pest on many grasses. Switchgrass (Panicum virgatum L.), a perennial C4 grass, has been selected as a bioenergy feedstock because of its perceived resilience to abiotic and biotic stresses. Aphid infestation on switchgrass has the potential to reduce the yields and biomass quantity. Here, the global defense response of switchgrass cultivars Summer and Kanlow to YSA feeding was analyzed by RNA-seq and metabolite analysis at 5, 10, and 15 days after infestation. Genes upregulated by infestation were more common in both cultivars compared to downregulated genes. In total, a higher number of differentially expressed genes (DEGs) were found in the YSA susceptible cultivar (Summer), and fewer DEGs were observed in the YSA resistant cultivar (Kanlow). Interestingly, no downregulated genes were found in common between each time point or between the two switchgrass cultivars. Gene co-expression analysis revealed upregulated genes in Kanlow were associated with functions such as flavonoid, oxidation-response to chemical, or wax composition. Downregulated genes for the cultivar Summer were found in co-expression modules with gene functions related to plant defense mechanisms or cell wall composition. Global analysis of defense networks of the two cultivars uncovered differential mechanisms associated with resistance or susceptibility of switchgrass in response to YSA infestation. Several gene co-expression modules and transcription factors correlated with these differential defense responses. Overall, the YSA-resistant Kanlow plants have an enhanced defense even under aphid uninfested conditions.

In-vitro Response of Cereal Aphid Sitobion avenae (Homoptera: Aphididae) against some Selected Botanical Extracts

Cereal aphid, Sitobion avenae (Homoptera: Aphididae), is one of the destructive pests of wheat and other crops around the globe. Irrational utilization of highly toxic synthetic chemicals against this particular pest has led to several issues of health and environment. In such case, there is a need to find out the control measures, which are less toxic and friendly to environment. The present study was aimed to evaluate the effectiveness of aqueous extracts of four indigenous plants, i.e. akk (Calotropis procera), lemon (Citrus limon), neem (Azadirachta indica) and dhatura (Datura alba), against S. avenae in laboratory conditions. Toxicity bioassays were conducted according to Completely Randomized Design using 2% aqueous extracts with three replications. Results showed a differential response of aphids to all botanical extracts. Aphid mortality increased with the exposure time with maximum values (i.e. 39.52, 31.75, 26.76 and 24.07% for A. indica, C. procera, C. limon and D. alba extracts, respectively) recorded at 72 h posttreatment. Similarly, A. indica extract exhibited minimum fecundity (2.67 offspring per adult) and adult body weight (340.09 µg) and maximum nymphal development time (9.32 days), followed by C. procera, C. limon and D. alba. Overall study results suggest that A. indica and C. procera extracts would be effective botanical options for combating aphid infestations on wheat and other cereal crops

Suitability and Profitability of a Cereal Aphid for the Parasitoid Aphidius platensis in the Context of Conservation Biological Control of Myzus persicae in Orchards

The use of cover crops can promote the abundance and early arrival of populations of natural enemies. Cereal cover crops between orchards rows could encourage the early arrival of the parasitoid Aphidius platensis, as they offer alternative winter hosts (e.g., Rhopalosiphum padi), enhancing the control of Myzus persicae in spring. However, the preference for and suitability of the alternative host must be addressed beforehand. To evaluate the potential of this strategy, we assessed host preference using behavioural choice tests, as well as no-choice tests measuring fitness traits, when developing on both host species. One source field for each aphid population from the above hosts was chosen. There was a clear choice for R. padi compared to M persicae, independently of the source, probably due to more defensive behaviours of M. persicae (i.e., kicks and escapes). Nevertheless, both aphid species were suitable for parasitoids’ development. The female progeny developed on R. padi were larger in size, irrespective of their origin. According to our results, in peach orchards with cereals sown between peach trees during the autumn, where we expect when R. padi populations will no longer be available during spring, A. platensis should be able to switch to M. persicae.