Influence of aphid community composition and host plant preference on Cucumber mosaic virus infection rates in tomatoes

Background/Question/Methods

Plant pathogens are ubiquitous and can strongly influence plant quality, plant fitness, population dynamics, plant-herbivore interactions, community structure, invasion dynamics, and ecosystem function.  Since the mid-1990’s Cucumber mosaic virus (CMV) outbreaks have impacted fresh-marker tomato growers in northern Alabama, with some fields reaching infection rates of 100%.  Over 80 aphid species can vector CMV.    Aphid density, aphid species identity, aphid host plant range, and the composition of the herbaceous plant community surrounding the tomato fields all interact to drive CMV outbreaks.  For 3 years, aphid community composition, fire ant density, and plant community composition was surveyed around fresh-market tomato fields in northern Alabama.

Results/Conclusions

In 2006, over 4000 aphids comprised of 40 different species were collected from tomato plants.  The two most abundant aphid species on tomatoes were Tetraneura nigriabdominalis (38%) and Aphis gossypii (30%).  A. gossypii individuals were found feeding on multiple herbaceous plant species around fields including Ambrosia artemissiifolia, Ipomoea spp., Lonicera japonica, Rubus spp., Rumex crispus, Trifolium repens, and Sida spinosa, all of which can be infected with CMV and therefore are possible infection sources.  Conversely, T. nigriabdominalis was not abundant around tomato fields and was only found feeding on L. japonica.  Given the high density and highly polyphagous nature of A. gossypii, this aphid species likely contributes to CMV outbreaks in northern Alabama.