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.

Linking aboveground and belowground communities: the indirect influence of aphid species identity and diversity on a three trophic level soil food web

Abstract: There has been a growing recent interest in how foliar herbivory may indirectly affect the belowground sub-system, but little is known about the belowground consequences of the identity, species composition or diversity of foliar herbivores. We performed an experiment, utilising model grassland communities containing three plant species, in which treatments consisted of addition of each of eight aphid species in single and in two- four- and eight-species combinations, as well as an aphid-free treatment. While aphid species treatments did not affect total plant biomass or productivity, aphid species identity had important effects on the relative abundance of the three plant species. This in turn affected the abundances of each of three groups of secondary consumers in the soil food web (bacterial- and fungal-feeding nematodes, and enchytraeids) but not primary consumers (microbes, herbivorous nematodes) or tertiary consumers (predatory nematodes). The fact that some trophic levels responded to treatments while others did not is consistent with trophic dynamic theory. Aphid species treatments also affected the community composition within each of the herbivorous, microbe-feeding and top predatory nematode groups, as well as diversity within the first two of these groups. However, aphid species diversity per se had few effects. There were specific instances in which specific aboveground and belowground response variables in two aphid species combinations differed significantly from those in both of the corresponding single aphid species treatments (apparently as a consequence of resource use complementarity between coexisting aphid species), but no instance in which increasing aphid diversity beyond two species had any effect. Our results provide evidence that the identity of aboveground consumers can have effects that propagate through multiple trophic levels in soil food webs in terms of consumer abundance, and composition and diversity within trophic levels.

Interspecific herbivore interactions in a high CO2 environment - root and shoot aphids feeding on Cardamine.

Abstract: This study investigated the effects of elevated CO2 on populations of root and/or shoot aphids and their effects on partitioning in Cardamine pratensis. Total plant biomass in elevated ( 600 ppm) CO2 of uninfested Cardamine plants was 52% higher than in ambient ( 350 ppm) concentrations but CO2 effects were not statistically significant. In elevated CO2, feeding by shoot aphids (Aphis fabae fabae) alone and in combination with root aphids (Pemphigus populitransversus), and root aphids alone had no significant effect on plant biomass. No significant effects of elevated CO2 were detected on population size of the shoot or root-feeding species. Interspecific effects were detected between the root and shoot species. Root aphid populations were significantly smaller in the presence of shoot aphids on the same plants. In this system plant growth was unaffected by an elevated CO2 environment. Plant species which are more sensitive to elevated CO2 may show a modified response to herbivore pressure in a future atmospheric environment.

Numerical response of coccinellids to aphids in corn in southern Ontario.

Abstract: Populations of two abundant coccinellid species, Coleomegilla maculata lengi Timberlake and Hippodamia tredecimpunctata tibialis Say, responded rapidly to corn leaf aphid populations [ Rhopalosiphum maidis (Fitch)] once the aphids became exposed to predation when the plants tasselled. Coleomegilla m . lengi oviposited at lower densities of aphids than did H . t . tibialis but H . t . tibialis was shown to have a greater numerical response than C . m . lengi at high densities of aphids due to its greater fecundity. The numerical response of the coccinellids by oviposition was linear with a lag of 1/2 week behind the aphid population.

Symbionts protect aphids from parasitic wasps by attenuating herbivore-induced plant volatiles.

Abstract: Plants respond to insect attack by releasing blends of volatile chemicals that attract their herbivores' specific natural enemies, while insect herbivores may carry endosymbiotic microorganisms that directly improve herbivore survival after natural enemy attack. Here we demonstrate that the two phenomena can be linked. Plants fed upon by pea aphids release volatiles that attract parasitic wasps, and the pea aphid can carry facultative endosymbiotic bacteria that prevent the development of the parasitic wasp larva and thus markedly improve aphid survival after wasp attack. We show that these endosymbionts also attenuate the systemic release of volatiles by plants after aphid attack, reducing parasitic wasp recruitment and increasing aphid fitness. Our results reveal a novel mechanism through which symbionts can benefit their hosts and emphasise the importance of considering the microbiome in understanding insect ecological interactions.

Herbivore-mediated effects of glucosinolates on different natural enemies of a specialist aphid.

Abstract: The cabbage aphid Brevicoryne brassicae is a specialist herbivore that sequesters glucosinolates from its host plant as a defense against its predators. It is unknown to what extent parasitoids are affected by this sequestration. We investigated herbivore-mediated effects of glucosinolates on the parasitoid wasp Diaeretiella rapae and the predator Episyrphus balteatus. We reared B. brassicae on three ecotypes of Arabidopsis thaliana that differ in glucosinolate content and on one genetically transformed line with modified concentrations of aliphatic glucosinolates. We tested aphid performance and the performance and behavior of both natural enemies. We correlated this with phloem and aphid glucosinolate concentrations and emission of volatiles. Brevicoryne brassicae performance correlated positively with concentrations of both aliphatic and indole glucosinolates in the phloem. Aphids selectively sequestered glucosinolates. Glucosinolate concentration in B. brassicae correlated negatively with performance of the predator, but positively with performance of the parasitoid, possibly because the aphids with the highest glucosinolate concentrations had a higher body weight. Both natural enemies showed a positive performance-preference correlation. The predator preferred the ecotype with the lowest emission of volatile glucosinolate breakdown products in each test combination, whereas the parasitoid wasp preferred the A. thaliana ecotype with the highest emission of these volatiles. The study shows that there are differential herbivore-mediated effects of glucosinolates on a predator and a parasitoid of a specialist aphid that selectively sequesters glucosinolates from its host plant.