Aphid

About: Aphid is a research topic. Over the lifetime, 11380 publications have been published within this topic receiving 229721 citations. The topic is also known as: Aphidoidea & plant lice.

Response of The Lacewing Chrysopa cognata to Pheromones of its Aphid Prey

Abstract: The lacewing Chrysopa cognata, one of the principal predators of aphids in Korea, was tested for responses to the aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol and the aphid alarm pheromone (E)-β-farnesene. Electroantennogram responses were obtained to the sex pheromone components but not to (E)-β-farnesene. The sex pheromone components were attractive in a Y-tube olfactometer assay and in field trials with water traps, but no attraction was observed to (E)-β-farnesene.

The nature of the effects of the aphids Sitobion avenae and Metopolophium dirhodum on the growth of wheat

Abstract: SUMMARY Field-caged, post-anthesis populations of the aphids Sitobion avenae and Metopolophium dirhodum reduced grain weight of wheat by 14 and 7% respectively and induced changes in the senescence of the flag leaf. Spikelet number and grain number were unaffected as they are normally determined by pre-anthesis factors. Percentage grain protein was significantly reduced by both aphid species. The pattern of grain weight reduction within the ear was consistent with known limitations on the distribution of flag leaf assimilates among the grains. The relative effects of the two aphid species apparently resulted from the degree of nutrient drain imposed at particular feeding sites and the reduction in the leaf area duration of the flag leaf.

Aphids in a changing world: testing the plant stress, plant vigour and pulsed stress hypotheses

Abstract: 1. The plant stress, plant vigour and pulsed stress hypotheses describe the relationships between drought stress, plant quality and herbivore performance. We used an aphid- Brassica system to test these hypotheses under different drought treatments. 2. The quantity of water added per plant/week was 75%, 50% and 25% of the control (unstressed) water regime for low, medium and high drought stress, respectively, and 50% applied fortnightly for pulsed drought stress. The performance of a ‘senescence’ (generalist) and a ‘flush’ feeder (specialist) aphid species and host plant quality were assessed. 3. Drought treatments had a similar effect on the fecundity and intrinsic rate of increase of both aphid species. Aphid perforance on unstressed and highly drought-stressed plants was significantly lower compared with medium drought stress. On average, 20% greater fecundity and 40% greater intrinsic rates of increase were recorded for both aphid species at medium drought stress compared with unstressed plants. 4. Plant biomass and relative water contents were significantly greater for unstressed plants compared with high and pulsed drought treatments. Foliar nitrogen concentration was significantly greater in the high drought stress and pulsed treatments, and the dominant glucosinolate (glucobrassicin) concentration was significantly greater in drought stress treatments. 5. The present study supports the plant stress hypothesis, although the plant vigour and pulsed stress hypotheses are not supported by our data. The implications of these findings for plant–herbivore interactions under changing environmental conditions are discussed.

Cowpea aphid (Aphis craccivora) associated with different host plants has different facultative endosymbionts

Abstract: Maternally inherited facultative endosymbiotic bacteria are common among insects, including many polyphagous insect herbivores. To investigate whether symbiont infection is structured by host plant in the polyphagous aphid Aphis craccivora Koch, pyrosequencing and diagnostic PCR were performed on 26 populations from two different host plants, alfalfa (Medicago sativa) or black locust (Robinia pseudoacacia). Results indicated that Aphis craccivora harbours distinctly different microbial communities in alfalfa versus locust. The facultative symbiont Hamiltonella was found only in aphids collected from alfalfa, and the facultative symbiont Arsenophonus was found only in aphids from locust. Hamiltonella is known to protect aphids against hymenopteran parasitoids, whereas the phenotypic effects of Arsenophonus in aphids are unknown. Correspondingly, a screen of the aphid samples for hymenopteran DNA indicated that Hamiltonella-bearing alfalfa populations of A. craccivora experienced lower parasitism than Arsenophonus-bearing locust populations. This study contributes to the growing body of evidence that correlative associations between bacterial endosymbionts and host plants may be a common phenomenon in polyphagous herbivores, and suggests that microbial symbionts have the potential to act as drivers for observed ecological differences among host-associated populations of polyphagous insects.

The diversity and fitness effects of infection with facultative endosymbionts in the grain aphid, Sitobion avenae

Abstract: Mutualisms with facultative, non-essential heritable microorganisms influence the biology of many insects, and they can have major effects on insect host fitness in certain situations. One of the best-known examples is found in aphids where the facultative endosymbiotic bacterium Hamiltonella defensa confers protection against hymenopterous parasitoids. This symbiont is widely distributed in aphids and related insects, yet its defensive properties have only been tested in two aphid species. In a wild population of the grain aphid, Sitobion avenae, we identified several distinct strains of endosymbiotic bacteria, including Hamiltonella. The symbiont had no consistent effect on grain aphid fecundity, though we did find a significant interaction between aphid genotype by symbiont status. In contrast to findings in other aphid species, Hamiltonella did not reduce aphid susceptibility to two species of parasitoids (Aphidius ervi and Ephedrus plagiator), nor did it affect the fitness of wasps that successfully completed development. Despite this, experienced females of both parasitoid species preferentially oviposited into uninfected hosts when given a choice between genetically identical individuals with or without Hamiltonella. Thus, although Hamiltonella does not always increase resistance to parasitism, it may reduce the risk of parasitism in its aphid hosts by making them less attractive to searching parasitoids.