Xylem ingestion by winged aphids

Abstract

When aphids and their host plant are incorporated in a DC electrical circuit, phloem and xylem ingestion register as separate waveforms of the electrical penetration graph (EPG) signal. Aphids are primarily phloem feeders; xylem ingestion is seldom reported but can be induced experimentally by fasting the insects in desiccating conditions. In experiments with the black bean aphid, Aphis fabae Scop., young winged (alate) and unwinged (apterous) virginoparous adults were collected from their natal host plants (broad bean, Vicia faba L.) and allowed 3-h continuous EPG-recorded access to V. faba seedlings. Several aphids (47% of both morphs) showed ingestion from phloem sieve elements. Alate aphids also showed frequent xylem ingestion (60% of individuals), but no apterous aphids exhibited this activity. The EPG technique involves attachment of a fine gold wire electrode to each insect, a process that may affect normal behaviour at the plant surface. However, when the technique was modified to monitor the stylet activities of freely-settled aphids, high levels of xylem ingestion by alates were also recorded. The results suggest that the developmental physiology of winged aphids somehow predisposes them to xylem ingestion, possibly as a result of dehydration during the teneral period. Alate aphids may reduce their weight by fasting before take-off, giving aerodynamic benefits, but making rehydration, via xylem uptake, a priority following plant contact.

Overexpression of IRM1 Enhances Resistance to Aphids in Arabidopsis thaliana

“…Contrarily, aphids on the IRM1 knock out mutant could penetrate the plant tissue easier and had faster access to the phloem than aphids on the wild type. Furthermore, the aphids spent significantly less time in the xylem on the IRM1 knock out mutant than on the wild type, which indicates sufficient uptake of phloem sap [36], [37] and also suggests that they encounter less resistance to access the phloem.…”

Location of the Mechanism of Resistance to <I>Amphorophora agathonica</I> (Hemiptera: Aphididae) in Red Raspberry

“…A possible explanation for the dilute honeydew measured by Kennedy and Schaefers (1975) is that their aphids may have engaged in xylem ingestion because the aphids were caged on the resistant plant for four days before the honeydew was analyzed. Xylem sap is a very dilute source of nutrition, yet xylem ingestion is common in aphids that are starved and may serve as an easy-toaccess water source (Powell and Hardie 2002). Although the aphids in our study rarely engaged in xylem ingestion (1Ð2% of the 12-h study time), they might have engaged in this behavior more if they had been EPG monitored for longer.…”

Impacts of elevated CO2 on the population abundance and reproductive activity of aphid Sitobion avenae Fabricius feeding on spring wheat

“…Compared with apterous Lipaphis erysimi, alate morphs developed slower and produced significantly fewer nymphs (Liu and Yue, 2001). Likewise, alate aphids (Aphis fabae) may reduce their weight by fasting before take-off, giving aerodynamic benefits (Powell and Hardie, 2002). Moreover, viruliferous alate forms can migrate among host plants over a large region; resulting in more damage from disease than direct damage resulting from aphids removing large quantities of phloem sap (Risebrow and Dixon, 1987;Luo and Li, 1991).…”