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.

The role of intra-specific mechanisms and predation in regulating the numbers of the lime aphid, Eucallipterus tiliae L.

Abstract: Analysis of changes in numbers of the lime aphid, Eucallipterus tiliae L., reveals that there is an overcompensated density dependent factor acting within years, and an inverse density dependent factor acting between years. Because of its effect on the aphid's rate of development and reproduction the variation in temperature from year to year acts as a density disturbing factor.

Influence of plant resistance at the third trophic level: interactions between parasitoids and entomopathogenic fungi of cereal aphids.

Abstract: Host-plant resistance can affect herbivorous insects and their natural enemies such as parasitoids and entomopathogenic fungi. This tritrophic effect acts on interspecific interactions between the two groups of natural enemies distantly related in phylogenetic terms. The intra- and extra-host aspects of the interaction between the cereal aphid parasitoid Aphidius rhopalosiphi and the entomopathogenic fungus Erynia neoaphidis developing on the grain aphid, Sitobion avenae, on resistant and susceptible wheat (Triticum aestivum) cultivars, were studied. The competitive outcome of the intra-host interaction depended on the timing of parasitoid oviposition and fungal infection and was affected by wheat resistance. In particular, survival of the parasitoid was lower on the resistant wheat cultivar than the susceptible wheat cultivar, when the competitive outcome of the interaction was favourable for either parasitoid or fungal development. Before and after this period the influence of plant resistance was not significant. Furthermore, the extra-host interaction was not affected by the wheat cultivar, although an increase in fungal infection of S. avenae was observed when parasitoids foraged in the experimental arena with sporulating aphid cadavers compared with foraging in the absence of sporulating cadavers. Our results showed that the host plant may affect interspecific interactions between parasitoids and fungi and that these interactions depended on the timing of parasitoid oviposition and fungal infection.

Outbreaks of Two-Spotted Spider-Mites and Cotton Aphids Following Pesticide Treatment. I. Pest Stimulation vs. Natural Enemy Destruction as the Cause of Outbreaks

Abstract: Numerous pesticides are known to provoke outbreaks of a variety of mites and aphids. Some of the conditions surrounding-these upsets are reviewed, and the capabilities of 59 different pesticides to induce increases of mites and/or aphids are examined in relation to their individual effects on some of the major natural enemies of mites and aphids. When critical examination is made of the arguments for either of the 2 suspected causes of such pesticide-induced outbreaks, i.e., (a) natural enemy destruction and (b) pest fecundity stimulation, it appears that neither by itself offers a completely adequate explanation. Since one of the methods now commonly used for evaluating natural enemy effectiveness relies on measurement of host increases in insecticidal check plots, this technique may credit the natural enemies with undeserved efficiency if the insecticide stimulates the pest’s fecundity. In this first of a series of experimental programs designed to resolve the problem of whether abnormal mite or aphid increases can be generated by pesticidal stimulation of the fecundity of mites or aphids, 59 different materials were examined for their effect on the reproductivity of the two-spotted spider mite, Tetranychus urticae Koch, and the cotton aphid, Aphis gossypii Glover. Following treatment with the different materials, population fold increases of each pest were measured weekly on the potted cotton plants held in the greenhouse and outdoors in the complete absence of natural enemies. The period of retention of toxicity of each material to mites and aphids (or the period during which any stimulation effect might be masked) is presented. Some anomalous conditions of treatment which caused abnormal increases in these tests could be explained by elimination of either pest when competing with the other. Some other abnormal increases of both mites and aphids were found which were difficult to explain other than as a pest-stimulation effect. For these cases no common denominator could be found. A few of the stimulatory responses obtained appeared in-consistent with the recorded performance of the materials in inducing upsets in the field.