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.

Demography of Soybean Aphid (Homoptera: Aphididae) at Summer Temperatures

Abstract: Soybean aphid, Aphis glycines Matsumura, is now widely established in soybean, Glycine max L., production areas of the northern United States and southern Canada and is becoming an important economic pest. Temperature effect on soybean aphid fecundity and survivorship is not well understood. We determined the optimal temperature for soybean aphid growth and reproduction on soybean under controlled conditions. We constructed life tables for soybean aphid at 20, 25, 30, and 35°C with a photoperiod of 16:8 (L:D) h. Population growth rates were greatest at 25°C. As temperature increased, net fecundity, gross fecundity, generation time, and life expectancy decreased. The prereproductive period did not differ between 20 and 30°C; however, at 30°C aphids required more degree-days (base 8.6°C) to develop. Nymphs exposed to 35°C did not complete development, and all individuals died within 11 d. Reproductive periods were significantly different at all temperatures, with aphids reproducing longer and producing more progeny at 20 and 25°C than at 30 or 35°C. Using a modification of the nonlinear Logan model, we estimated upper and optimal developmental thresholds to be 34.9 and 27.8°C, respectively. At 25°C, aphid populations doubled in 1.5 d; at 20 and 30°C, populations doubled in 1.9 d.

Biological control of cereal aphids in north america and mediating effects of host plant and habitat manipulations.

Abstract: The predator and parasitoid fauna associated with cereal aphids is described, emphasizing the fauna associated with classical biological control efforts against the greenbug and Russian wheat aphid. We focus on literature from North America and include work from Europe and elsewhere when it is desirable to draw contrasts between approaches that affect cereal aphid biological control. Effects on natural enemies of cereal aphids are described that appear associated with plant traits that are innate, bred, or induced by aphid feeding. Examples of habitat manipulations, within and bordering cereal fields and within the broader landscape in which cereal production resides, affecting predators and parasitoids of cereal aphids are presented. These mediating effects of host plant and habitat manipulations on cereal aphid biological control provide significant and underexplored avenues to optimize cereal aphid management.

Aphid and Plant Volatiles Induce Oviposition in an Aphidophagous Hoverfly

Abstract: Episyrphus balteatus DeGeer (Diptera, Syrphidae) is an abundant and efficient aphid-specific predator. We tested the electroantennographic (EAG) response of this syrphid fly to the common aphid alarm pheromone, (E)-β-farnesene (EβF), and to several plant volatiles, including terpenoids (mono- and sesquiterpenes) and green leaf volatiles (C6 and C9 alcohols and aldehydes). Monoterpenes evoked significant EAG responses, whereas sesquiterpenes were inactive, except for the aphid alarm pheromone (EβF). The most pronounced antennal responses were elicited by six and nine carbon green leaf alcohols and aldehydes [i.e., (Z)-3-hexenol, (E)-2-hexenol, (E)-2-hexenal, and hexanal]. To investigate the behavioral activity of some of these EAG-active compounds, E. balteatus females were exposed to R-(+)-limonene (monoterpene), (Z)-3-hexenol (green leaf alcohol), and EβF (sesquiterpene, common aphid alarm pheromone). A single E. balteatus gravid female was exposed for 10 min to an aphid-free Vicia faba plant that was co-located with a semiochemical dispenser. Without additional semiochemical, hoverfly females were not attracted to this plant, and no oviposition was observed. The monoterpene R-(+)-limonene did not affect the females’ foraging behavior, whereas (Z)-3-hexenol and EβF increased the time of flight and acceptance of the host plant. Moreover, these two chemicals induced oviposition on aphid-free plants, suggesting that selection of the oviposition site by predatory hoverflies relies on the perception of a volatile blend composed of prey pheromone and typical plant green leaf volatiles.

Hopkins' 'host selection principle', another nail in its coffin.

Abstract: . Adult female parasitoids (Aphidius rhopalosiphi De Stef.) (Hymenoptera: Aphidiidae) reared on the aphid Metopolophium dirhodum (Walk.) (Homoptera: Aphididae) changed their responses to odours of two wheat cultivars (‘Maris Huntsman’ and ‘Rapier’) when the parasitized aphids had been moved from the former to the latter cultivar at various times after parasitization. If the aphids were moved after less than 6 days, the female parasitoids emerging from mummies by then formed on ‘Rapier’ responded positively to that cultivar, whereas parasitoids emerging from mummies transferred as still living aphids after 8 days on ‘Maris Huntsman’, responded positively to that cultivar rather than to ‘Rapier’ on which they had emerged. This appeared to be evidence for Hopkins' ‘host selection principle’, which states that chemical experience acquired by the larva of an endopterygote insect can be transferred through the pupal stage to the adult. However, discrimination in favour of either cultivar disappeared when the parasitoids were reared in aphids on both cultivars, and the emerging females were tested following excision of the pupae from the aphid mummies. The previous discrimination shown by adult parasitoids emerging from aphid mummies must therefore be determined by the chemicals contacted by a parasitoid on the skin of the mummy or while biting its way out of the dead aphid.

Involvement of the octadecanoid pathway in bluegreen aphid resistance in Medicago truncatula

Abstract: Aphids are major insect pests of plants that feed directly from the phloem. We used the model legume Medicago truncatula Gaert. (barrel medic) to elucidate host resistance to aphids and identified a single dominant gene which confers resistance to Acyrthosiphon kondoi Shinji (bluegreen aphid). To understand how this gene conditions resistance to bluegreen aphid, transcription profiling of 23 defense-related genes representing various signaling pathways was undertaken using a pair of near-isogenic lines that are susceptible or resistant to bluegreen aphid. All salicylic acid- and ethylene-responsive genes tested were induced by blue-green aphid in resistant and susceptible plants, although there were some differences in the magnitude and kinetics of the induction. In contrast, 10 of 13 genes associated with the octadecanoid pathway were induced exclusively in the resistant plants following bluegreen aphid infestation. These results are in contrast to plant-pathogen interactions where similar sets of defens...