Management of Pseudaulacaspis pentagona in French blackcurrant

Pseudaulacaspis pentagona, Targioni Tozetti (Hemiptera, Diaspididae) has become a problematic pest in France in blackcurrant (Ribes nigrum L.). With two generations per year, populations of scale weaken bushes within a few years. All professional blackcurrant producers, scientists, and marketers in France were mobilized to propose solutions to this scale insect infestation. Control with chemical products registered in France did not achieve satisfactory results. Populations were always high at the end of the year, and infestations began again the following year. Control with a beneficial insect has worked since 2013, when the ladybird species Rhyzobius lophantae Blaisdell (Coleoptera, Coccinellidae) was favored for study because it is less specific than microhymenoptera like Aphytis and Encarsia genus. A commercial source of R. lophantae was available in Holland, so releases were made in 2013 with an efficiency recognized over P. pentagona when large amounts of ladybirds were released. This first encouraging result had to be refined. A trial was established in 2014 on the same plot with larger area and different amounts of ladybirds released. The results showed a decrease in populations of P. pentagona females between the 1st and 2nd generations. In addition, 2nd generation crawlers were not observed in any treatment plot. This suggests an efficiency of R. lophantae; however, this ladybird moved a lot. The experimental design adopted therefore was not suitable because it was not possible to differentiate between treatment plots. It is recommended to conduct research on remote plots in order to avoid R. lophantae contamination between plots. This type of test is set up in 2015 at only one producer farm. In 2016, a multisite project will take place.