Abstract

Aphid-borne viruses are frequent yield-limiting pathogens in open field vegetable crops. In the absence of curative methods, virus control relies exclusively on measures limiting virus introduction and spread. The efficiency of control measures may greatly benefit from an accurate knowledge of epidemic drivers, in particular those linked with aphid vectors. Field experiments were conducted in southeastern France between 2010 and 2019 to investigate the relationship between the epidemics of cucurbit aphid-borne yellows virus (CABYV) and aphid vector abundance. Winged aphids visiting melon crops were sampled daily to assess the abundance of CABYV vectors (Aphis gossypii, Macrosiphum euphorbiae and Myzus persicae) and CABYV was monitored weekly by DAS-ELISA. Epidemic temporal progress curves were successfully described by logistic models. A systematic search for correlations was undertaken between virus variables including parameters µ (inflection point of the logistic curve) and γ (maximum incidence) and aphid variables computed by aggregating abundances on periods relative either to the planting date, or to the epidemic peak. The abundance of A. gossypii during the first two weeks after planting was found to be a good predictor of CABYV dynamics, suggesting that an early control of this aphid species could mitigate the onset and progress of CABYV epidemics in melon crops.

Highlights

  • In France, melon (Cucumis melo var. cantalupensis) is cultivated in three main production areas: South-East, South-West and Centre-West

  • Aphis gossypii (RIS-181), Myzus persicae (RIS-322), Macrosiphum euphorbiae (RIS-410) and total aphid abundances were monitored with suction traps between 1 and 55 days after planting

  • cucurbit aphid-borne yellows virus (CABYV) epidemics were observed in all eleven field experiments conducted between 2010 and 2019 in Avignon, confirming that among the viruses frequently infecting melon crops, namely cucumber mosaic virus (CMV, Cucumovirus, Bromoviridae), watermelon mosaic virus (WMV, Potyvirus, Potyviridae) and zucchini yellow mosaic virus (ZYMV, Potyvirus, Potyviridae), it has become one of the most prevalent

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Summary

Introduction

In France, melon (Cucumis melo var. cantalupensis) is cultivated in three main production areas: South-East, South-West and Centre-West. Since its first report in the 1980s [1], CABYV has been detected in an ever-increasing number of countries [2] and recent surveys indicate that it is becoming prevalent in many cucurbit growing areas [3,4] It induces typical symptoms of yellowing of the older leaves and impacts yield via flower abortion and reduced number of fruits per plant. A recent study showed that the Vat gene conferring resistance to the melon aphid A. gossypii and the viruses it carries [11] had a significant impact on CABYV epidemics with the mean incidence reduction exceeding 50% in some trials [7]. We looked for potential relationships between numerous variables computed from these two datasets with the overall aim of modelling CABYV epidemics using aphid abundances

Field Experiments
Plant Sampling and Virus Monitoring
Insect Sampling and Aphid Monitoring
Computation of Variables Related to Virus Epidemics
Computation of Variables Related to Aphid Abundance
Relationship between Aphid and Virus Variables
Virus Epidemics
Vector Abundances
Correlations between Virus and Aphid Variables
Prediction
Discussion
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