Sustainable management of the vine mealybug in organic vineyards

Abstract

The vine mealybug (VMB), Planococcus ficus, is a major grapevine pest worldwide, whose chemical control is often unsatisfactory due to its cryptic behavior, insecticide resistance and high fecundity rate. Recently, increasing restrictions have been applied to insecticides used for managing VMB. This review discusses sustainable VMB management strategies in organic viticulture. Pheromone-mediated mating disruption has been proved to be effective in both organic wine and table-grape vineyards. Biocontrol projects carried out through the release of parasitoids and/or predators have often provided inconclusive results, ranging from effective reduction of mealybug infestation to a marginal impact of parasitoids on VMB density. The latter outcome is likely due to constraints affecting the parasitoid activity, such as the disrupting activity of mealybug-tending ants and broad-spectrum insecticides, or untimely release of parasitoids. Ant suppression should be associated with the release of beneficial organisms, as mealybug-tending ants can severely affect the parasitoid activity. Cultural and physical control and the employment of entomopathogens and natural products mitigate the buildup of VMB populations, but they are not widely applied. VMB control in organic viticulture requires the integration of different strategies, as application of single control tools as a stand-alone treatment may not be effective, especially for high pest infestation. Future research to determine the density action threshold below which sustainable methods are effective and calibrate efforts in relation with pest infestation is needed. A multi-disciplinary approach is required to define the most appropriate sustainable control protocols in different environmental conditions and promote a further spread of organic viticulture.

Multiple Effects of Nitrogen Fertilization on Grape Vegetative Growth, Berry Quality and Pest Development in Mediterranean Vineyards

“…Overall, the lower survival and fecundity of mealybugs developed on unfertilized grapevines may be due to nutritional limitations and/or lower nutritional value of phloem sap [57,58]. Soil management with cover crop species that participate in the N fixation process in the soil, e.g., legumes, can replace N fertilization and promote development and survival of the VMB [34]. Moreover, floor vegetation promotes the establishment of ants, which protect mealybugs from natural enemies, thereby favoring the pest infestation [59].…”

“…For instance, removal of bunch-zone leaves prevented economic damage by the European grapevine moth and grey mold [31], whereas water provision promoted the development of grapevine leafhoppers [32]. The wide literature on this subject highlights that cultural practices, including fertilization, should be included as sustainable control techniques within a multi-disciplinary approach to grape pest control [33,34]. Although such practices may not be effective as stand-alone control tactics, they can be suitably included in integrated pest control programs.…”

Old Parasitoids for New Mealybugs: Host Location Behavior and Parasitization Efficacy of Anagyrus vladimiri on Pseudococcus comstocki

“…Overall, the displays composing the host-seeking and parasitization behavior of A. vladimiri on P. comstocki were walking and drumming activity, arrestment close to the host, antennal tapping, probing, oviposition, and host dragging. In addition, a peculiar host defensive behavior was noted, i.e., a fast abdominal rocking movement against the parasitoid (kicking), coupled or not with the production of a viscous secretion against the parasitoid to impair its wings [23,24]. Host feeding behavior was not observed.…”

Use of Sugar Dispensers to Disrupt Ant Attendance and Improve Biological Control of Mealybugs in Vineyard

“…Nevertheless, the mealybug habit of staying in concealed plant parts and the waxy cover of these insects make chemical control in some conditions poorly effective [4]. New tactics, alternative to chemicals, show a potential to reduce and suppress mealybug infestations, including biological control [5]. Previous studies showed the potential of natural enemies, such as Anagyrus vladimiri Triapitsyn [3] and Cryptolaemus montrouzieri Mulsant, in controlling these detrimental pests [6,7].…”