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Aphidius wasps are endoparasitoids of aphids. The female wasp lays eggs in an aphid. When the eggs hatch, the wasp larvae feed on the inside of the aphid. As the larvae mature, the hosts die and become slightly enlarged or mummified, often becoming tan or yellow. Complete metamorphosis occurs within the host.
The aphids may not be the original source of infection, but are instrumental in spreading the virus through the crop. [9] Various chemical treatments are available to kill the aphids and organic growers can use a solution of soft soap. [12] Wasp laying egg inside an aphid's body Aphids tended by ants
The eggs hatch as caterpillars which feed on the aphids. The ants do not defend the aphids from the caterpillars, since the caterpillars produce a pheromone which deceives the ants into treating them like ants, and carrying the caterpillars into their nest.
The aphids tend to concentrate on the growing tips of plants, young leaves, shoots, flowers and developing seed pods. They are often tended by ants which feed on the secretions they produce and deter predators. Natural enemies include parasitic wasps, ladybirds, lacewing larvae and hoverfly larvae. [3]
The aphids migrate back to primary hosts in August and overwinter as eggs on weeds. In North America they are heavily parasitized by the braconid wasp Aphidius nigripes , which lays its eggs in the aphid nymphs, and these are eventually killed by the wasp larvae developing inside them.
As with other aphids, honeydew may be found on infected leaves, excreted by the aphids after feeding on the plant's sap. American elm leaves with woolly elm aphid infestation. Curled elm leaves are characteristic of the effects of the aphids, even prior to cottony masses being apparent.
In aphids, the presence of a particular species of γ-3 Pseudomonadota makes the aphid relatively immune to their parasitoid wasps by killing many of the eggs. As the parasitoid's survival depends on its ability to evade the host's immune response, some parasitoid wasps have developed the counterstrategy of laying more eggs in aphids that have ...
Thus, aphids show very complex and rapidly changing within-year dynamics, with each clone going through several generations during the vegetative season and being made up of many individuals, which can be widely scattered in space. The survival of the eggs and/or overwintering aphids determines the numbers of aphids present the following spring ...