Bacterial Symbionts Confer Thermal Tolerance to Cereal Aphids Rhopalosiphum padi and Sitobion avenae

Abstract

High-temperature events are evidenced to exert significant influence on the population performance and thermal biology of insects, such as aphids. However, it is not yet clear whether the bacterial symbionts of insects mediate the thermal tolerance traits of their hosts. This study is intended to assess the putative association among the chronic and acute thermal tolerance of two cereal aphid species, Rhopalosiphum padi (L.) and Sitobion avenae (F.), and the abundance of their bacterial symbionts. The clones of aphids were collected randomly from different fields of wheat crops and were maintained under laboratory conditions. Basal and acclimated CTmax and chronic thermal tolerance indices were measured for 5-day-old apterous aphid individuals and the abundance (gene copy numbers) of aphid-specific and total (16S rRNA) bacterial symbionts were determined using real-time RT-qPCR. The results reveal that R. padi individuals were more temperature tolerant under chronic exposure to 31 °C and also exhibited about 1.0 °C higher acclimated and basal CTmax values than those of S. avenae. Moreover, a significantly higher bacterial symbionts’ gene abundance was recorded in temperature-tolerant aphid individuals than the susceptible ones for both aphid species. Although total bacterial (16S rRNA) abundance per aphid was higher in S. avenae than R. padi, the gene abundance of aphid-specific bacterial symbionts was nearly alike for both of the aphid species. Nevertheless, basal and acclimated CTmax values were positively and significantly associated with the gene abundance of total symbiont density, Buchnera aphidicola, Serratia symbiotica, Hamilton defensa, Regiella insecticola and Spiroplasma spp. for R. padi, and with the total symbiont density, total bacteria (16S rRNA) and with all aphid-specific bacterial symbionts (except Spiroplasma spp.) for S. avenae. The overall study results corroborate the potential role of the bacterial symbionts of aphids in conferring thermal tolerance to their hosts.

Aphid adaptation in a changing environment through their bacterial endosymbionts: an overview, including a new major cereal pest (Rhopalosiphum maidis (Fitch) scenario

“…Bacterial symbionts also contribute to the heat stress tolerance shown by aphids. The primary symbiont of aphids, Buchnera aphidicola, has been found to assist in the production of heat shock proteins (Majeed et al 2022). These symbiotic bacteria play a crucial role in supplying essential nutrients, particularly essential amino acids, which are limited in the aphids' plant sap diet (Douglas 2015;Zhu et al 2021).…”

Barley Yellow Dwarf Virus Influences Its Vector’s Endosymbionts but Not Its Thermotolerance

“…Plasticity may also contribute to the differences between our findings and those of Porras et al [ 16 ]. Rhopalosiphum padi has repeatedly been shown to increase their thermotolerance via acclimation [ 55 , 56 ]. Still, the increase in thermotolerance due to BYDV noted by Porras et al [ 16 ] was extremely large and unlikely to be explained by acclimation alone.…”

Special Issue: Selected Papers from the 1st International Electronic Conference on Entomology

“…The studies in this SI deal with various interesting aspects of research, i.e., identification of termite species in West Africa [ 1 ], characterization of the microbial symbionts of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) populations [ 2 ], the contribution of bacterial symbionts to the thermal tolerance of two aphid species Rhopalosiphum padi (L.) and Sitobion avenae (F.) (Hemiptera: Aphididae) [ 3 ], recording the nematode fauna in Greek forests [ 4 ], investigation of genetic variability in Apis mellifera L. (Hymenoptera: Apidae) from Serbia through microsatellite loci [ 5 ], comparison of damage caused to tomato plants by the biocontrol agents Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) and Dicyphus cerastii Wagner (Hemiptera: Miridae) [ 6 ], evaluation of numerous essential oil-based microemulsions as grain protectants for management of two major stored-product insects, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Trogoderma granarium Everts (Coleoptera: Dermestidae) [ 7 ], investigation of several aspects of the life history of the biological control agent Neoleucopis kartliana (Tanasijtshuk) (Diptera: Chamaemyiidae) in Greece [ 8 ], validation of theoretical models explaining the persistence of mtDNA variation within populations of Drosophila obscura Fallén (Diptera: Drosophilidae) [ 9 ], description of how thermal conditions, sex, and population origin may affect stress resistance in Drosophila subobscura Collin (Diptera: Drosophilidae) [ 10 ], the genetic structure of Corythucha ciliata (Say) (Hemiptera: Tingidae) based on mitochondrial DNA analysis [ 11 ], utilization of ecological/geographical models to evaluate changes in the distribution of Oedaleus decorus (Germar) (Orthoptera: Acrididae) [ 12 ], investigation of exposure to heavy metals and population origin on the diversity of microbiota and fitness in Drosophila melanogaster Meigen (Diptera: Drosophilidae) and D. subobscura [ 13 ], a database and checklist of alien insects in Greece [ 14 ], evaluation of direct and delayed mortality caused by the anthranilic diamide chlorantraniliprole to adults and larvae of T. castaneum , adults of Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), adults of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and adults and nymphs of Acarus siro L. (Sarcoptiformes: Acaridae) [ 15 ], identification of Pseudococcus jackbeardsleyi Gimpel and Miller (Hemiptera: Pseudococcidae) and Maconellicoccus hirsutus Green (Hemiptera: Pseudococcidae) as potential vectors of cacao mild mosaic virus (CaMMV) [ 16 ], defining relationships between coccinellids and aphids on alfalfa in Spain [ 17 ], exploration of the diversity and phylogeny of Tingidae species occurring on olive trees in South Africa using morphology and mitogeno...…”