Aphids enemies

Finally, density-dependent mortality from various enemies may be enhanced by host plant variation. Again, focusing feeding activities on a restricted set of suitable tissues should also focus the activities and abundance of pathogens, parasitoids, and predators. Sessile insects, such as gall-forming aphids (55,62),... 

Many species of the Ladybug family (Coccinellidae) play a beneficial role in controlling populations of harmful insects such as aphids, mealy bugs and scale insects (70MI30800). Ladybugs have few natural enemies. When disturbed they emit droplets of a fluid from their joints which serve as an efficient deterrent to would-be predators. 

ANTHOCORID BUGS (anthocoridae). These include the genera Anthocoris and Orius. Whereas bugs of the Anthocoris genus, which are larger in size, are the most important enemies of the pear leafsucker, the smaller Orius species feed on spider mites. The Anthocoris hugs also feed on aphids. 

ENEMIES. Aphids have many enemies, hut in the case of the rosy apple aphid they are not effective enough, especially in spring. The most important enemies are ... 

ENEMIES. The rosy leaf-curling aphid has the same enemies as the rosy apple aphid. In the case of the rosy leaf-curling aphid, however, the enemies are much more effective, as the rosy leaf-curling aphid does not have the same reproductive potential. 

As far as possible, control measures should not be applied immediately, in order to give beneficials (predators and parasites) the possibility of self-regulation. Because the rosy leaf-curling aphid has a large number of enemies, this is easier than in the case of the rosy apple aphid. 

DAMAGE THRESHOLD. The apple grass aphid is an important source of food for all the enemies of aphids and does not actually do any damage. 

CONTROL. Under no circumstances should the apple grass aphid be harmed, as its early occurrence attracts a very large number of benefi-cials. If large numbers of enemies of aphids appear very early, natural regulation of other aphid species is much easier. 

ENEMIES. The most important enemy is the wasp-like insect Aphelinus mali. This parasitoid has a higher temperature requirement than the woolly aphid and is therefore not as common in the spring. As temperatures rise, the development of the parasitoid proceeds faster, and para-sitization levels of up to 90% can be achieved by the autumn. Parasitized aphids do not have the typical wax covering, and the opening where the parasitoid has hatched can be seen in the dead aphids. Aphelinus mali is sensitive to high levels of sulphur, however. 

Variability in induced plant volatiles complicates the reliance of natural enemies on these cues. One way of dealing with variability is through associative learning, which may allow parasitoids to learn which cues are most likely to lead them to suitable hosts at a particular time in a particular area. Moreover, recent studies suggest that plant volatile blends alone carry specific information on the herbivores by which they are attacked. For example, predatory mites can distinguish between the blends of apple trees infested by two herbivores species (20). Du et al. (21) showed that different aphid species elicit different volatile blends in bean plants and that the aphid parasitoid, Aphidius ervi, can use these differences to distinguish plants infested by its host. Aphis pisum from those infested by a nonhost. Aphis fabae... 

To summarize the resistance situation in broad terms, no key pest such as the codling moth, apple maggot, plum curculio has developed resistance to the OP azinphosmethyl, whereas a variety of secondary pests such as mites, aphid, leafhoppers, leafminers and their natural enemies have developed resistant strains thus azinphosmethyl has become more selective. The example cited later of management of cyhexatin resistance management in the spider mite... 

Community-wide effects on endophytes may be extended beyond herbivores to their associated parasites and predators in other trophic levels. For example, Neotyphodium endophytes of Lolium multiflorum, lower plant quality, reduce the densities of aphid herbivores, and indirectly reduce the rate of parasitism on aphids by parasitoids [105]. The potential for alteration of the interactions of grasses with herbivores and their natural enemies will clearly depend on many factors, including the frequency of infected hosts within the commxmity, the types and relative levels of bioprotective alkaloids, and the spatial distribution of grasses and herbivores. 

Plant communication via volatile sesquiterpenes at the third trophic level, namral enemies of herbivores, has been shown in soil ecosystems. Root beetle damages on maize root system will induce production and emissions of ( )-p-caryophyllene, also known as an aphid alarm pheromone. This compound spreads through soil pores where it attracts entomopathogenic nematodes that, in turn, control root beetle larvae [13]. 

Klingauf, F.. In Aphids Their Biology, Natural Enemies and Control. Minks, A. K and Harrewijn, P., Eds. Host Plant Finding and Acceptance Elsevier New York, NY, 1987 Vol. 2A p 209-233. 

Mittler, T.E. 1988. Applications of artificial feeding techniques for aphids. In Aphids Their Biology, Natural Enemies and Control, Vol. 2B, eds., A.K. Minks P. Harrewijn, pp. 145-170, Elsevier, Amsterdam. 

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