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.

Tri-trophic interactions involving pest aphids, predatory 2-spot ladybirds and transgenic potatoes expressing snowdrop lectin for aphid resistance

Abstract: Transgenic crops genetically engineered for enhanced insect resistance should be compatible with other components of IPM for the pest resistance to be durable and effective. An experimental potato line was genetically engineered to express an anti-aphid plant protein (snowdrop lectin, GNA), and assessed for possible interactions of the insect resistance gene with a beneficial pest predator. These extended laboratory studies are the first to demonstrate adverse tri-trophic interactions involving a lectin- expressing transgenic crop, a target pest aphid and a beneficial aphidophagous predator. When adult 2-spot ladybirds (Adalia bipunctata[L.]) were fed for 12 days on peach-potato aphids (Myzus persicae Sulzer) colonising transgenic potatoes expressing GNA in leaves, ladybird fecundity, egg viability and longevity significantly decreased over the following 2–3 weeks. No acute toxicity due to the transgenic plants was observed, although female ladybird longevity was reduced by up to 51%. Adverse effects on ladybird reproduction, caused by eating peach-potato aphids from transgenic potatoes, were reversed after switching ladybirds to feeding on pea aphids from non-transgenic bean plants. These results demonstrate that expression of a lectin gene for insect resistance in a transgenic potato line can cause adverse effects to a predatory ladybird via aphids in its food chain. The significance of these potential ecological risks under field conditions need to be further evaluated.

A multispecies aphid–ant association: density dependence and species-specific effects

Abstract: In the central Rocky Mountains of Colorado 4 species of aphids feed on fireweed, and 10 species or ants have been observed tending 3 of these species of aphids. Local populations of aphids and their associated ants were counted nondestructively at weekly intervals for up to 11 weeks. The effects of ants upon the persistence of recently initiated populations and the growth of populations during 1-week intervals were assessed by multidimensional contingency table analysis. Macrosiphum valerianae, which is not tended by ants, was affected negatively by ants. Aphis varians and A. helianthi were affected by tending, but A. salicariae was not affected. The responses of both A. varians and A. helianthi to tending were density dependent; i.e., small populations that were untended were more likely to decrease than tended populations, but large populations that were tended were either more likely to decrease than untended populations or equivalent to them. Possible reasons for this density-dependent effect are disc...

Induced plant responses to multiple damagers: differential effects on an herbivore and its parasitoid.

Abstract: Herbivore-induced plants responses can affect the preference and performance of herbivores and their natural enemies. These responses may vary depending on the identity and number of herbivore species feeding on the plant so that when herbivores from different guilds feed on plants, the interactions between plants, herbivores, and natural enemies may be disrupted. Tomato plants were damaged either by the caterpillar Spodoptera exigua, or the aphid Macrosiphum euphorbiae, or damaged by both herbivores, or undamaged controls. We measured the preference and performance of S. exigua and its parasitoid Cotesia marginiventris, and activity of proteinase inhibitors (PI) as an indicator of induced resistance. Compared to undamaged plants, caterpillar damage reduced the number of eggs laid by S. exigua adults, reduced growth, consumption, and survival of larval S. exigua and C. marginiventris, and increased activity of PIs 43%; but did not increase attraction of C. marginiventris. While pupal mass of S. exigua was not affected, the pupal mass of C. marginiventris decreased on caterpillar-damaged plants compared to controls. In contrast, plants damaged by aphids were preferred for oviposition by S. exigua, and had increased larval consumption and survival, compared to controls. Aphid feeding did not affect the preference or performance of C. marginiventris, or PI activity, compared to controls. While oviposition was deterred on caterpillar-damaged plants, plants damaged by both herbivores received the same amount of oviposition as controls. The attraction of C. marginiventris to plants damaged by caterpillars and aphids was increased compared to controls. However, plants damaged by both herbivores had similar PI activity, larval growth and survival of S. exigua and C. marginiventris, as plants singly damaged by caterpillars. Overall, the preference component for both the herbivore and parasitoid was more strongly affected by damage due to multiple herbivores than the performance component.

Predators Suppress Aphis glycines Matsumura Population Growth in Soybean

Abstract: The soybean aphid, Aphis glycines Matsumura, is an invasive pest of soybean, Þrst discovered in North America in 2000. We studied the ability of the existing predator community in soybean to suppress A. glycines population growthduring JuneÐAugust 2002, in Þeld studies using predator exclusion and sham cages or no-cage controls. Cages were infested with uniform initial densities of A. glycines adults, and subsequent populations of aphids and predators were monitored. After 2 wk, exclusion and sham cages were switched, with aphid and predator density followed for additional 2 wk. The experiment was repeated a second time, allowing observation of predator community response to bothlow and h ighdensity aph id populations over several time periods and stages of soybean development. Cages had minimal effects on temperature, relative humidity, or soybean growth. In contrast, predator communities and aphid populations were strongly affected by cage treatments. In the Þrst trial, the activity of foliar-foraging predators effectively prevented A. glycines population growthmaintaining populations below 10 aph ids per plant (adult nymphs) in sham cages, while populations exceeded 200 aphids per plant in exclusion cages. After cage switch, these high A. glycines populations in the former exclusion cages were rapidly colonized and reduced by nearly an order of magnitude within 2 wk by a combination of generalist and specialist predators. The second trial produced qualitatively similar results, but at much lower aphid densities. The most abundant predators in bothtrials included: Harmonia axyridis Pallas, Orius insidiosus (Say), and Leucopis spp. These studies demonstrate that existing predator communities comprised of a mixture of indigenous and naturalized species can suppress A. glycines population density in soybean. The impact of existing predator communities should be further investigated as a component of A. glycines management in United States soybean production systems.

Predation on immature parasitoids and its impact on aphid suppression

Abstract: Many predatory arthropods eat both unparasitized herbivores and herbivores that are parasitized and contain the immature stages of endoparasitoids, a form of intraguild predation. Thus, the biological control of herbivorous arthropods can be either enhanced or disrupted by introducing a predator species to an existing host-parasitoid system. We evaluate the impact of introducing a predator, the convergent ladybird beetle, Hippodamia convergens, on the biological control of the cotton aphid, Aphis gossypii, by the parasitoid Lysiphlebus testaceipes, under field conditions. Predation on immature parasitoids by H. convergens was intense: 98–100% of aphid mummies were consumed by the end of the experiment, and H. convergens substantially reduced immature parasitoid populations. Despite the negative impact of H. convergens on aphid parasitoids, aphid population suppression was greatest in treatments containing both H. convergens and parasitoids. The parasitoid alone or in combination with H. convergens suppressed cotton aphids in a density-dependent manner and increased total plant leaf area and biomass, H. convergens did not substantially alter the percentage of aphids mummified by parasitoids and showed a partial feeding preference for unparasitized aphids over aphid mummies. We conclude that under conditions where a predator shows both a partial preference for unparasitized hosts and high levels of predation on unparasitized hosts, we may expect the predator to improve suppression of herbivores even if it produces high levels of intraguild predation. While intraguild predation is an important ecological interaction in the early-season cotton agroecosystem, it does not disrupt cotton aphid biological control.