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.

Chemically Mediated Associative Learning in the Host Foraging Behavior of the Aphid Parasitoid Aphidius ervi (Hymenoptera: Braconidae)

Abstract: The effect of experience on the responsiveness of the braconid parasitoidAphidius ervi to host(Acyrthosiphon pisum)-associated cues was investigated on bean plants(Vicia faba) using a wind tunnel bioassay. Oviposition experience on the plant-host complex significantly increased the oriented flight and landing responses ofA. ervi females to an undamaged plant and to a plant-host(A. pisum) complex. However, oviposition experience onA. pisum aphids when isolated from the plant did not change their responses to the intact plant and the complex. Searching on an unwashed plant which had been previously damaged byA. pisum also increased their response to an undamaged plant and a host-damaged plant, whereas the experience of searching on an undamaged plant did not significantly change their responses to undamaged plants. However, when parasitoids were allowed to search on an undamaged plant which had been sprayed withA. pisum honeydew, this significantly increased their response to an undamaged plant. Oviposition experience on the plant-host complex and foraging experience on a host-damaged plant or an undamaged plant sprayed with honeydew also significantly reduced the mean time taken by the parasitoids to respond in the wind tunnel. The behavioral changes associated with such experience were acquired within 30 min and persisted for at least 3 days. The results demonstrate the capacity ofA. ervi to learn associatively olfactory cues from plants, host-damaged plants, and plant-host complexes and confirm the role of aphid honeydew as a host recognition kairomone forA. ervi.

Heterologous Expression of the Mi-1.2 Gene from Tomato Confers Resistance Against Nematodes but Not Aphids in Eggplant

Abstract: The Mi-1.2 gene in tomato (Solanum lycopersicum) is a member of the nucleotide-binding leucine-rich repeat (NBLRR) class of plant resistance genes, and confers resistance against root-knot nematodes (Meloidogyne spp.), the potato aphid (Macrosiphum euphorbiae), and the sweet potato whitefly (Bemisia tabaci). Mi-1.2 mediates a rapid local defensive response at the site of infection, although the signaling and defensive pathways required for resistance are largely unknown. In this study, eggplant (S. melongena) was transformed with Mi-1.2 to determine whether this gene can function in a genetic background other than tomato. Eggplants that carried Mi-1.2 displayed resistance to the root-knot nematode Meloidogyne javanica but were fully susceptible to the potato aphid, whereas a susceptible tomato line transformed with the same transgene was resistant to nematodes and aphids. This study shows that Mi-1.2 can confer nematode resistance in another Solanaceous species. It also indicates that the requirements for Mi-mediated aphid and nematode resistance differ. Potentially, aphid resistance requires additional genes that are not conserved between tomato and eggplant.

Effect of Neem Seed Extract on the Brown Citrus Aphid (Homoptera: Aphididae) and its Parasitoid Lysiphlebus testaceipes (Hymenoptera: Aphidiidae)

Abstract: The biological effects of a commercially available neem seed extract (Neemix. 4.5, 4.5% azadirachtin, AZ) were assessed on the brown citrus aphid, Toxoptera citricida (Kirklady), a recently introduced insect pest of citrus in the United States and its parasitoid, Lysiphlebus testaceipes. When small citrus seedlings were dipped with the neem extract at 11–180 ppm AZ, 0–8% of nymphs and 0–17.5% of adults survived 7 d after the treatment while 95% of nymphs and 42.5% of adults in the control survived for the same period. The extract drastically reduced longevity of both adults and nymphs, adult fecundity, and molting of nymphs at all tested concentrations. Spraying neem extract (11–180 ppm AZ) onto potted citrus plants in the greenhouse also significantly reduced aphids by 20–100%, while control aphid populations increased by 950% 7 d after treatment. Application of the extract had little impact on the survival of adult parasitoids and developing parasitoids within aphids because parasite emergences...

Multiple routes of pesticide exposure and the risk of pesticides to biological controls : A study of neem and the sevenspotted lady beetle (Coleoptera: Coccinellidae)

Abstract: Microcosms were used to illuminate community-level interactions among the pea aphid, Acyrthosiphon pisum Harris (Homoptera: Aphididae), and the sevenspotted lady beetle, Coccinella septempunctata L., after a spray exposure to a commercial neem pesticide. The instantaneous rate of increase (r1) of pea aphid populations was used as a response variable in a 2 × 3 factorial experiment. Microcosms were treated with 100 ppm (mg/liter) or 600 ppm azadirachtin, the active ingredient in the commercial neem insecticide, or with water in the presence or absence of adult or 4th instar lady beetles. We compared our results with those of a previous study where C. septempunctata was exposed to only 1 route of exposure, direct application. Results from the previous study indicated that 100 ppm of the neem insecticide was sublethal ( 0.05) interaction between the predator and the pesticide was detected indicating that the chemical and biological control agents are not working synergistically. Furthermore, exposure to the pesticide in micrososms significantly reduced or completely eliminated oviposition in adult C. septempunctata, and all of the larval lady beetles exposed to 100 or 600 ppm died within 10 d of treatment. Based on these results, we question the value of toxicity tests where only 1 route of pesticide exposure is considered.

Benefits to aphids from feeding on galled and virus-infected leaves.

Abstract: IT has been shown that robust green leaves which have ceased growth and not yet entered upon senescence are unsuitable, by comparison with growing or senescing leaves, for colonization by Aphis fabae Scopoli and Myzus persicae (Sulzer)1–3. Abnormally extended growth or premature senescence-like changes, or both, are characteristic of both the ‘pseudo-galls’ (curling and pocketing of leaves) and the virus diseases which plants can develop as a result of aphid attack. Experiments were therefore undertaken to see whether such pathological changes in the plants might not be beneficial to the aphids initiating them.