Identification of Vitis Cultivars, Rootstocks, and Species Expressing Resistance to a Planococcus Mealybug.

Rachel P Naegele,Kent M Daane,Peter Cousins

doi:10.3390/insects11020086

Abstract

Mealybugs cause economic loss to vineyards through physical damage, fouling fruit and leaves with honeydew, and the transmission of viruses. Planococcus ficus is one of several mealybug species in vineyards, and one that causes economic damage over a relatively large global range. To develop novel management tools, host resistance to P. ficus, which has not previously been identified for any grape cultivars, was studied. Ten grape lines (species, cultivars, and rootstocks) were evaluated for P. ficus resistance across two separate potted plant assays. Significant differences were detected among cultivars and rootstocks in the recorded number of P. ficus juveniles, adults, and egg sacs. Cabernet Sauvignon and Chardonnay were two of the most favorable grape cultivars for mealybug population growth, whereas rootstocks IAC 572, 10-17A, and RS-3 all demonstrated some level of resistance. Southern fire ant (Solenopsis xyloni) was positively associated with mealybug populations, but did not have a negative effect on the observed presence of other arthropod species including potential predators.

Highlights

Grapes have a long history of cultivation and breeding for a wide range of soils, climates and commodities [1]
Own-rooted cuttings were collected from mature field-grown grapevines, including rootstocks and species at the San Joaquin Valley Agricultural Sciences Center (SJVASC), Parlier, CA, or the University of California’s Kearney Agricultural Research and Extension Center (KARE), Parlier, CA
Planococcus ficus is one of several mealybug species found in grape vineyards globally

Summary

Introduction

Grapes have a long history of cultivation and breeding for a wide range of soils, climates and commodities (e.g., table grapes for fresh consumption and processed grapes that are dried into raisins or pressed for grape juice or wine) [1]. Mealybugs (Hemiptera: Coccoidea: Pseudococcidae) are one of the more important arthropod pests in vineyards [1], and economic losses resulting from mealybugs have dramatically increased in the past decades, in part as a result of globalization [7], despite the fact that many countries impose regulations on the movement of vine material [8]. Vineyard mealybugs are phloem-feeding pests that can cause economic loss through feeding damage to leaves, resulting in reduced photosynthetic capability, and the excretion of carbohydrate-rich honeydew that can further foul the leaves, stems, and fruit and lead to the accumulation of sooty molds [9,10] (Figure 1). Mealybug control costs were estimated to range from $50

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