Amino acid utilization in the aphid Acyrthosiphon pisum infected by the parasitoid Aphidius smithi

The green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae) is one of the potato important pests; it is the most efficient vector of potato viruses. Myzus persicae harbors the endosymbiotic bacteria Buchnera aphidicola which supplements their diet. There is increasing evidence that B. aphidicola is involved in plant-aphid interactions and we previously demonstrated that B. aphidicola disruption (aposymbiosis) affected the probing behavior of M. persicae on radish plants, delaying host plant acceptance. In this work, we evaluated the effect of aposymbiosis on the probing behavior of M. persicae on 2 Solanum species with different compatibility with M. persicae, Solanum tuberosum (susceptible) and Solanum stoloniferum (resistant) with the electrical penetration graph technique (EPG). To disrupt B. aphidicola, rifampicin was administered to aphids through artificial diets. Aposymbiotic aphids, on both plant species, showed increased pathway activities, mechanical problems with the stylets, and delayed salivation in the phloem. The extended time in derailed stylet mechanics affected the occurrence of most other probing activities; it delayed the time to the first phloem phase and prevented ingestion from the phloem. The effect of aposymbiosis was more evident in the compatible interaction of M. persicae-S. tuberosum, than in the incompatible interaction with S. stoloniferum, which generated the M. persicae-S. tuberosum interaction to become incompatible. These results confirm that B. aphidicola is involved in the plant-aphid interaction in relation to plant acceptance, presumably through a role in stylets penetration in the plant.

Probing behavior of aposymbiotic green peach aphid (Myzus persicae) on susceptible Solanum tuberosum and resistant Solanum stoloniferum plants.

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Genotypic and endosymbiont-mediated variation in parasitoid susceptibility and other fitness traits of the potato aphid, Macrosiphum euphorbiae

Order Hemiptera—Bugs

In various studies aphids have been reared on chemically defined nutrient solutions. Mittler & Dadd (1962) developed a now widely used technique by which an appropriate amount of diet is enclosed between two stretched Parafilm "M' | membranes which form a sachet. The sachet is stretched over the opening of a short section of a glass or plastic cylinder that serves as a feeding chamber. By frequently replacing the sachets with new ones (usually at intervals of 2 or 3 days) one ensures that oxidation of, and chemical interactions between, dietary components do not adversely affect aphid feeding and nutrition. While aphid performance may improve with such frequent changes, the manipulations necessary for transferring the aphids to a new sachet can result in some insects being injured (Mittler, 1972). Perhaps more important, handling can cause restlessness in some aphid species. Harrewijn (1973), for example, has shown that an increase in aphid activity may bias the results of studies on the effect(s) of nutritional factors on wing determination in Myzus persicae. In an attempt to reduce aphid handling as much as possible, we have modified Mittler & Dadd's sachet technique as follows (Fig. 1): (1) A Parafilm membrane (bm) is stretched across the upper opening of the aphid rearing chamber (c). (2) A second membrane (lm), which has been surface-sterilized with UV, is stretched over the first one. (3) A variable amount of sterile diet (d) is then placed onto the second membrane and sealed in with a third, surface-sterilized membrane (um) under aseptic conditions. (4) To renew the diet, it is only necessary to peel the sachet formed by the two uppermost membranes gently off the base membrane which covers the feeding chamber; a new sachet is then prepared as described above. The procedure allows the medium to be renewed as often as desired without disturbing the aphids at the same time. The periodic removal of honeydew from the cage walls with a moist cotton swab is the only additional maintenance required. The technique has been used for over one year in our laboratory and has given satisfactory results in the rearing (for three successive generations) of a laboratory strain of pea aphid (Acyrthosiphon pisum) on a holidic diet. The procedure was also used with potato aphid

C. Cloutier

Papers

A modified technique for rearing of the pea aphid on artificial diets.