Sap-Sucking Pests; They Do Matter

There has been a long-standing hypothesis that specialist and generalist insects interact with plants in distinct ways. Although many tests exist, they typically compare only one species of each, they sometimes confound specialization and feeding guild, and often do not link chemical or transcriptional measures of the plant to actual resistance. In this review, we synthesize current data on whether specialists and generalists actually differ, with special attention to comparisons of their differential elicitation of plant responses. Although we find few consistencies in plant induction by specialists versus generalists, feeding guilds are predictive of differential plant responses. We outline a novel set of predictions based on current coevolutionary hypotheses and make methodological suggestions for improved comparisons of specialists and generalists. Copyright © 2012 Elsevier Ltd. All rights reserved.

Virus diseases that have emerged in the past two decades limit the production of important vegetable crops in tropical, subtropical, and temperate regions worldwide, and many of the causal viruses are transmitted by whiteflies (order Hemiptera, family Aleyrodidae). Most of these whitefly-transmitted viruses are begomoviruses (family Geminiviridae), although whiteflies are also vectors of criniviruses, ipomoviruses, torradoviruses, and some carlaviruses. Factors driving the emergence and establishment of whitefly-transmitted diseases include genetic changes in the virus through mutation and recombination, changes in the vector populations coupled with polyphagy of the main vector, Bemisia tabaci, and long distance traffic of plant material or vector insects due to trade of vegetables and ornamental plants. The role of humans in increasing the emergence of virus diseases is obvious, and the effect that climate change may have in the future is unclear. Copyright © 2011 by Annual Reviews. All rights reserved.

SUMMARY Aphids are the most common vector of plant viruses. Mechanisms of transmission are best understood by considering the routes of virus movement in the aphid (circulative versus non-circulative) and the sites of retention or target tissues (e.g. stylets, salivary glands). Capsid proteins are a primary, but not necessarily sole, viral determinant of transmission. A summary is presented of the taxonomic affiliations of the aphid transmitted viruses, including 8 families, 18 genera, and taxonomically unassigned viruses.