Spatio-temporal dynamics of viruses are differentially affected by parasitoids depending on the mode of transmission.

Beatriz Dáder,Elisa Viñuela,Aránzazu Moreno,Alberto Fereres

doi:10.3390/v4113069

Abstract

Relationships between agents in multitrophic systems are complex and very specific. Insect-transmitted plant viruses are completely dependent on the behaviour and distribution patterns of their vectors. The presence of natural enemies may directly affect aphid behaviour and spread of plant viruses, as the escape response of aphids might cause a potential risk for virus dispersal. The spatio-temporal dynamics of Cucumber mosaic virus (CMV) and Cucurbit aphid-borne yellows virus (CABYV), transmitted by Aphis gossypii in a non-persistent and persistent manner, respectively, were evaluated at short and long term in the presence and absence of the aphid parasitoid, Aphidius colemani. SADIE methodology was used to study the distribution patterns of both the virus and its vector, and their degree of association. Results suggested that parasitoids promoted aphid dispersion at short term, which enhanced CMV spread, though consequences of parasitism suggest potential benefits for disease control at long term. Furthermore, A. colemani significantly limited the spread and incidence of the persistent virus CABYV at long term. The impact of aphid parasitoids on the dispersal of plant viruses with different transmission modes is discussed.

Highlights

Aphids (Hemiptera: Aphididae) are considered one of the most important pests worldwide because of the direct damage they cause, and because their alimentary habits involve indirect damages
Plant viruses can be classified in two categories differing by the site in which the virus is retained by the vector and the retention period: non-circulative and circulative or persistent viruses, which frequently accumulate in the salivary glands [1,4]
The present study aimed to investigate the tritrophic interactions within a system that included the host plant Cucumis sativus L., the cotton aphid Aphis gossypii Glover, a cosmopolitan pest species that colonises more than 600 host plants [30], and the widely used parasitoid wasp Aphidius colemani

Summary

Introduction

Aphids (Hemiptera: Aphididae) are considered one of the most important pests worldwide because of the direct damage they cause, and because their alimentary habits involve indirect damages. Transmission from plant to plant mediated by vectors is the most useful strategy for virus dispersal, as they are obligated parasites [3]. Transient vectors that land and probe on a plant without colonising the crop are often the main vectors of non-persistent viruses, while colonising vectors are involved in transmission of persistent viruses [4]. Host preference first involves phototactic responses to visual cues that may be modified by the emission of plant volatiles [5,6]. The interaction between plant pathogens and vectors has been widely discussed but there is no general consensus on whether the parasite-induced changes in host phenotype favours vector’s responses such as settlement, behaviour, performance and overall fitness [6,7,8,9]

Methods

Results

Conclusion