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.

Density‐Dependent Mutualism in an Aphid‐Ant Interaction

Abstract: Our objectives were to determine if the mutualistic effect of ant tending on aphid population growth varied with aphid density, and to consider possible mechanisms explaining such a context-dependent effect. We studied the interaction between Aphis varians and Formica cinerea on fireweed (Epilobium angustifolium) in the Rocky Mountains of Colorado. In 1988 we used two experiments to examine the interaction between ant tending and aphid density on the per capita growth of aphid populations at naturally occurring low aphid densities, and naturally occurring high aphid densities. In 1989, we conducted a similar experiment, but we manipulated aphid densities to include the full range from low to high. The results of these experiments were consistent: ant tending significantly improved the growth of small aphid populations, but the benefit from ant tending decreased or disappeared at higher aphid densities. We considered possible mech- anisms for the density-dependent mutualistic effect by examining the relationships among aphid density, the number of ants tending, and predator abundance. We show that the relative number of ants tending declined as aphid density increased, and ant tending did not reduce predator abundance at any aphid densities. Therefore, the cause of the density- dependent mutualism is probably a decline in the direct effect of ants on aphids resulting from a decline in the relative number of ants tending aphids at higher aphid densities. We discuss the implications of density-dependent mutualism for the dynamics and evolution

Flonicamid, a novel insecticide with a rapid inhibitory effect on aphid feeding

Abstract: Flonicamid (IKI220; N-cyanomethyl-4-trifluoromethylnicotinamide), a pyridinecarboxamide compound, is a novel systemic insecticide with selective activity against hemipterous pests, such as aphids and whiteflies, and thysanopterous pests. The purpose of this study is to clarify the biological properties of flonicamid against aphids. Flonicamid is very active against aphids, regardless of differences in species, stages and morphs. This compound inhibited the feeding behaviour of aphids within 0.5 h of treatment without noticeable poisoning symptoms such as convulsion, and this antifeeding activity was not recoverable until death. The nymphs born from adults exposed to flonicamid for 3 h showed high mortality. The effect of flonicamid on the feeding activity of an individual aphid was studied using electronic monitoring of insect feeding behaviour (EMIF). Although the treated aphid attached the head of its proboscis to the leaf surface, salivation and sap feeding were strongly inhibited. These results suggest that the main insecticidal mechanism of flonicamid is starvation based on the inhibition of stylet penetration to plant tissues.

Genetic variation in the effect of a facultative symbiont on host-plant use by pea aphids

Abstract: Ecological specialisation on different host plants occurs frequently among phytophagous insects and is normally assumed to have a genetic basis. However, insects often carry microbial symbionts, which may play a role in the evolution of specialisation. The bacterium Regiella insecticola is a facultative symbiont of pea aphids (Acyrthosiphon pisum) where it is found most frequently in aphid clones feeding on Trifolium giving rise to the hypothesis that it may improve aphid performance on this plant. A study in which R. insecticola was eliminated from a single naturally infected aphid clone supported the hypothesis, but a second involving two aphid clones did not find the same effect. We created a series of new pea aphid–R. insecticola associations by injecting different strains of bacteria into five aphid clones uninfected by symbionts. For all aphid clones, the bacteria decreased the rate at which aphids accepted Vicia faba as a food plant and reduced performance on this plant. Their effect on aphids given Trifolium pratense was more complex: R. insecticola negatively affected acceptance by all aphid clones, had no effect on the performance of four aphid clones, but increased performance of a fifth, thus demonstrating genetic variation in the effect of R. insecticola on pea aphid host use. We discuss how these results may explain the distribution and frequency of this symbiont across different aphid populations.

Ladybird-induced life–history changes in aphids

Abstract: Predator–mediated plasticity in the morphology, life history and behaviour of prey organisms has been widely reported in freshwater ecosystems. Although clearly adaptive, similar responses have only recently been reported for terrestrial organisms. This is surprising as aphids are polyphenic and develop very rapidly compared with their predators and often produce very large colonies, which are attractive to predators. Therefore, one might expect terrestrial organisms like aphids to show a facultative change in their development in response to the presence of predators and other results have confirmed this. The results presented below indicate that the pea aphid responded to the tracks left by ladybird larvae by producing a greater proportion of winged offspring, which avoid the impending increased risk of predation by dispersing. Associated with this was a short–term increase in activity and reduction in fecundity. The black bean and vetch aphids, which are afforded some protection from ladybirds because they are ant attended and/or unpalatable, did not respond in this way to the presence of ladybird larvae.

An experimental investigation of inter-relationships between the wood-ant (formica rufa) and some tree-canopy herbivores

Abstract: SUMMARY (1) Previous work on interactions between F. rufa and some canopy herbivores is briefly reviewed. (2) In limestone woodland in N. England, populations of defoliators (illustrated by the Winter Moth, Operophtera brumata L.), a non-tended aphid species (Drepanosiphum platanoidis Schr.) and a tended aphid species (Periphyllus testudinaceus Fernie), are all affected by the presence of the ant. (3) Predation of D. platanoidis by F. rufa results in significant depression of the population compared with experimental conditions where ants were excluded from shoots. (4) Trees without ants have significantly higher populations of Lepidoptera larvae than do foraged trees. (5) On trees with ants an average of 1% of the leaf area had been removed by defoliators at the end of the season; without ants the total was nearly 8%. (6) Formica rufa tended eight aphid species and one psyllid in the woodland. The association of F. rufa with one of the aphids (P. testudinaceus) was studied. (7) Periphyllus testudinaceus populations were significantly increased in the presence of ants. When ants were excluded from colonies on shoots a significant fall in numbers occurred. There was probably also a reduction in the proportion of alatae. (8) The results are discussed in relation to previous work on aphid predation by ants and to the practice of introducing ants into woodland to protect trees from the effects of defoliators. It is concluded that this practice may be ill-founded.