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Pages 122-141
Received 01 Sep 2017
Accepted 09 Jan 2018
Published online: 30 Jan 2018
 
Translator disclaimer

Vine mealybug, Planococcus ficus, is a major pest of grapevine, which is present in at least 39 countries. According to American Vineyard Foundation, P. ficus is in the top ranks among major insect-pests of grapevine. It is the ‘top priority concerns’ by grape growers and a ‘threat to the sustainability of wine industry’ demanding a ‘high priority research’. In Douro vineyards, it is considered as an occasional insect-pest; however, its importance is increasing in some localities. The present study investigates the occurrences of P. ficus-associated fungi. Vine mealybugs were observed in two of the four surveyed farms. Out of the 183 collected mealybugs, 58 were dead of which 25 had symptoms of mycosis and 13 were parasitised. Subculturing cadavers and subsequent pathogenicity test yielded 22 entomopathogenic fungi (EPF) including yeasts. The yeast Meyerozyma (=Pichia) guilliermondii, and the EPF Sarocladium kiliense and Purpureocillium lilacinum were the most abundant, i.e. representing 18.18% (N = 4), 13.64% (N = 3) and 13.64% (N = 3) of the isolates, respectively. Considering biological affinities, fungal families Nectriaceae and Microascaceae had the most similar count-data profiles. To our knowledge, this work reports the first isolations of EPF from vine mealybug worldwide; and Pseudocosmospora rogersonii in Europe and as EPF worldwide. The mortality rate originated by mycoses on P. ficus was significantly higher than by its parasitoids, suggesting that fungi as P. ficus biocontrol agents are relatively more important than considered before. Overall, this report provides new insights into the development of mycoinsecticides and conservation biocontrol strategies for P. ficus pest management.

Additional information

Funding

Research was funded by the EcoVitis project –“Maximizing ecosystem services in Douro Demarcated Region vineyards”(co-financed by European Agriculture Fund for Rural Development through Rural Development Programme). Research was also funded by European Investment Funds by FEDER/COMPETE/POCI – Operacional Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT – Portuguese Foundation for Science and Technology, under the projects UID/AGR/04033/2013 and UID/MULTI/04621/2013.

Acknowledgements

This manuscript is a part of L. Sharma’s PhD. dissertation. The authors are grateful for the insightful comments on the manuscript by the two anonymous reviewers. The comments on the English language by Dr. Maxwell Owusu-Twum, UTAD, were also helpful in revising the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.