Fitness costs of infection with Serratia symbiotica are associated with greater susceptibility to insecticides in the pea aphid Acyrthosiphon pisum

Background: Aphids are agricultural pests that damage crops by direct feeding and by vectoring important plant viruses. Bacterial symbionts can influence aphid biology, e.g. by providing essential nutrients or facilitating adaptations to biotic and abiotic stress. Results: We investigated the pea aphid (Acyrthosiphon pisum Harris) and its commonly associated secondary bacterial symbiont Serratia symbiotica to study the effect of this symbiont on host fitness and susceptibility to the insecticides imidacloprid, chlorpyrifos methyl, methomyl, cyantraniliprole and spirotetramat. There is emerging evidence that members of the genus Serratia can degrade and/or detoxify diverse insecticides. Therefore, we hypothesized that S. symbiotica may promote resistance to these artificial stress agents in aphids. Our results showed that Serratia‐infected aphids were more susceptible to most of the tested insecticides than non‐infected aphids. This probably reflects the severe fitness costs associated with S. symbiotica, which negatively affects development, reproduction and body weight. Conclusion: Our study demonstrates that S. symbiotica plays an important role in the ability of aphid hosts to tolerate insecticides. These results provide insight into the potential changes in tolerance to insecticides in the field because there is a continuous and dynamic process of symbiont acquisition and loss that may directly affect host biology

Orally delivered scorpion antimicrobial peptides exhibit activity against Pea Aphid (Acyrthosiphon pisum) and its bacterial symbionts

Aphids are severe agricultural pests that damage crops by feeding on phloem sap and vectoring plant pathogens. Chemical insecticides provide an important aphid control strategy, but alternative and sustainable control measures are required to avoid rapidly emerging resistance, environmental contamination, and the risk to humans and beneficial organisms. Aphids are dependent on bacterial symbionts, which enable them to survive on phloem sap lacking essential nutrients, as well as conferring environmental stress tolerance and resistance to parasites. The evolution of aphids has been accompanied by the loss of many immunity-related genes, such as those encoding antibacterial peptides, which are prevalent in other insects, probably because any harm to the bacterial symbionts would inevitably affect the aphids themselves. This suggests that antimicrobial peptides (AMPs) could replace or at least complement conventional insecticides for aphid control. We fed the pea aphids (Acyrthosiphon pisum) with AMPs from the venom glands of scorpions. The AMPs reduced aphid survival, delayed their reproduction, displayed in vitro activity against aphid bacterial symbionts, and reduced the number of symbionts in vivo. Remarkably, we found that some of the scorpion AMPs compromised the aphid bacteriome, a specialized organ that harbours bacterial symbionts. Our data suggest that scorpion AMPs holds the potential to be developed as bio-insecticides, and are promising candidates for the engineering of aphid-resistant crops

Semi-Rigid connections between I-beams and high strength steel tubular columns: Technical Report No.3., Period Jul 1-Dec 31, 1991

Civil Engineering and GeosciencesStructural Engineerin

Semi-rigid connections between I-beams and tubular columns: Technical report no. 4 . , Period Jan 1 - Jun 30, 1992

Civil Engineering and GeosciencesStructural Engineerin

Semi-rigid connections between I-beams and tubular columns: Technical interim report No.5., Period Jan 1-Dec 31, 1992

Civil Engineering and GeosciencesStructural Engineerin

Kompatibilitaetsuntersuchung zur DIN 18808 -Bemessung von Hohlprofilen- anhand der CIDECT-Bemessungsvorschlaege fuer den Eurocode 3. T. 1 Abschlussbericht

TIB Hannover: RN 5905(2140) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman