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.

Honeydew amino acids in relation to sugars and their role in the establishment of ant‐attendance hierarchy in eight species of aphids feeding on tansy (Tanacetum vulgare)

Abstract: . The ratio of the concentration of honeydew total amino acids to total sugars in the honeydew of eight species of aphids, all feeding on tansy, Tanacetum vulgare (L.), was determined and correlated with honeydew production and ant-attendance. The honeydew of the five ant-attended aphid species [Metopeurum fuscoviride (Stroyan), Trama troglodytes (v. Hayd), Aphis vandergooti (Borner), Brachycardus cardui (L.), Aphis fabae (Scopoli)] was rich in total amino acids, ranging from 12.9 to 20.8 nmol µL−1 compared with the unattended aphid Macrosiphoniella tanacetaria (Kalt.) with only 3 nmol µL−1. Asparagine, glutamine, glutamic acid and serine (all nonessential amino acids) were the predominant amino acids in the honeydew of all species. The total concentration of amino acids in the phloem sap of tansy was much higher (78.7 nmol µL−1) then in the honeydew samples, and the predominant amino acids were glutamate (34.3%) and threonine (17.7%). A somewhat unexpected result was the finding that those aphid species with the highest total amino acid concentration in the honeydew always had the highest concentration of sugars. The lowest amino acid–sugar combined value was 104–28.8 nmol µL−1 in the non ant-attended species M. tanacetaria, and the highest value was an average of 270–89.9 nmol µL−1 for the three most intensely attended aphid species M. fuscoviride, A. vandergooti and T. troglodytes. There is no evidence that any single amino acid or group of amino acids in the honeydew acted as an attractant for ant-attendance in these eight aphid species. The richness of the honeydew (rate of secretion × total concentration of sugars), along with the presence of the attractant sugar melezitose, comprised the critical factors determining the extent of ant-attendance of the aphids feeding on T. vulgare. The high total amino acid concentration in sugar-rich honeydews can be explained by the high flow-through of nutrients in aphids that are particularly well attended by ants.

Impact of plant nutrients on the relationship between a herbivorous insect and its symbiotic bacteria.

Abstract: The interactions between herbivorous insects and their symbiotic micro-organisms can be influenced by the plant species on which the insects are reared, but the underlying mechanisms are not understood. Here, we identify plant nutrients, specifically amino acids, as a candidate factor affecting the impact of symbiotic bacteria on the performance of the phloem-feeding aphid Aphis fabae. Aphis fabae grew more slowly on the labiate plant Lamium purpureum than on an alternative host plant Vicia faba, and the negative effect of L. purpureum on aphid growth was consistently exacerbated by the bacterial secondary symbionts Regiella insecticola and Hamiltonella defensa, which attained high densities in L. purpureum-reared aphids. The amino acid content of the phloem sap of L. purpureum was very low; and A. fabae on chemically defined diets of low amino acid content also grew slowly and had elevated secondary symbiont densities. It is suggested that the phloem nutrient profile of L. purpureum promotes deleterious traits in the secondary symbionts and disturbs insect controls over bacterial abundance.

Natural Control of Cereal Aphids (Homoptera: Aphididae) by Entomopathogenic Fungi (Zygomycetes: Entomophthorales) and Parasitoids (Hymenoptera: Braconidae and Encyrtidae) on Irrigated Spring Wheat in Southwestern Idaho

Abstract: Data on the natural control of cereal aphids, Diuraphis noxia (Mordvilko), Metopolophium dirhodum (Walker), and Sitobion avenae (F.), by entomophthoralean fungi and hymenopterous parasitoids on furrow-irrigated spring wheat in southwestern Idaho are presented. The important fungi involved were Pandora neoaphidis (Remaudire & Hennebert) Humber and Conidiobolus spp., including C. obscurus (Hall and Dunn) Remaudire, C. thromboides Drechsler, and C. coronatus (Constantin) Batko. During 1986–1989, M. dirhodum and S. avenae populations usually reached or exceeded economic levels. D. noxia did not enter the region until late June 1987. It was the first aphid found infesting the crop in 1988 and reached high densities that summer but was not found in 1989, perhaps because of mortality during an extremely cold winter. Fungal infection occurred ≍2,3, and 6 wk after colonization of the crop by M. dirhodum, S. avenae , and D. noxia, respectively. Epizootics occurred each summer but usually after the crop was damaged by large aphid populations. An exception occurred during 1987 when M. dirhodum and S. avenae populations were effectively suppressed by mycoses, apparently enhanced by unusually frequent rainfall during late May and June. M. dirhodum experienced much higher mortality from fungal infection than did S. avenae and D. noxia. P. neoaphidis was the dominant fungus infecting M. dirhodum and D. noxia, whereas Conidiobolus spp. were most important on S. avenae. Entomophthora chromaphidis Burger & Swain and two Zoophthora species sporadically infected cereal aphids. Parasitoids, mainly Aphidius ervi Haliday for S. avenae and M. dirhodum and Diaeretiella rapae (M'Intosh) for D. noxia, usually attacked cereal aphids earlier than the fungi but were less influential during the decline of host populations. Multiple regression and correlation analysis indicated that mycoses and parasitoids made significant contributions to the reduction of peak populations of each aphid species compared with the influence of crop maturation. Weak correlation between fungal infection and host density and climatic factors ( r2 ranging from 0.35 to 0.53) was found. Development of fungal infection seemed to be better correlated with host density than with climatic factors. Precipitation was more associated with fungal infection of S. avenae, which inhabits upper portions of the host crop, but had little effect on that of M. dirhodum and D. noxia, which inhabit more humid microenvironments. No other climatic factors were significantly correlated with fungal infection. A hypothesis is proposed that the site on a wheat plant typically occupied by an aphid species influences the development of mycoses.

Glucosinolate Content and Susceptibility for Insect Attack of Three Populations of Sinapis alba

Abstract: Sinapis alba is less susceptible to damage by insect pests than Brassica napus. We investigated the composition and distribution of glucosinolates in different plant parts in three populations of S. alba; two populations selected for low-seed-glucosinolate content and one commercial cultivar. We have assessed the susceptibility of low-seed-glucosinolate content populations of S. alba to four insect pests, a flea beetle, a pollen beetle, and two species of aphids. Over 90% of the total glucosinolates in the cotyledons of the three populations of S. alba consisted of sinalbin. There was no difference in feeding damage by flea beetles on different S. alba populations at the cotyledon stage, nor was there a difference in sinalbin concentration of cotyledons. Total glucosinolate levels were highest in younger plant tissues. Sinalbin declined as a proportion of total glucosinolate content in later growth stages, especially in the “low” breeding lines. Reproduction by aphids was the same on all three populations despite differences in sinalbin content of the S. alba leaves at the growth stage tested. The specialist aphid, Brevicoryne brassicae, was found mainly on young tissues, while the generalist aphid, Myzus persicae, was found predominantly on older plant parts. There was no difference in oviposition by pollen beetles between the S. alba populations, despite the fact that on one population total glucosinolate concentration and the proportion of sinalbin found in the buds were much lower than on the other two populations.