Biological control of leafhopper Jacobiasca lybica (Bergevin & Zanon, 1922) (Hemiptera: Cicadellidae) by lacewing Chrysoperla carnea under laboratory conditions

The cotton leafhoppers Jacobiasca lybica (Bergevin & Zanon, 1922), is a polyphagous species considered to be a major pest of grapevines in Europe, causing significant economic damage and considered in Morocco as a secondary pest of several crops including citrus fruits. Its control mainly based on chemical treatments, which remains necessary to explore more other techniques such as biological control. In this study, we evaluated the voracious appetite of different larva instars of the green lacewing Chrysoperla carnea (Stephens, 1836) (Neuroptera: Chrysopidae) on J. lybica under laboratory conditions. The study was conducted in laboratory of INRA-Morocco (Qualipole of Berkane). The larvae and adults of leafhopper and lacewing were collected from a vineyard located in Berkane Province (Morocco) during autumn of 2021. Each lacewing instar (L1, L2 and L3) was put in a petri dish containing a humid filter paper and a freshly detached grapevine leaf, with 15 adults and 5 larvae of leafhoppers that was replicated nine times to assess the predatory potential, by counting the number of leafhopper consumed after 24 hours. Our results indicated that the predation rate for L3 instar was 47,78 % which differs significantly from L2 instar 31,11%. No significant difference was revealed between L2 and L1 instars that had a predation rate of 21,66 %. The predation rates should be interpreted with caution as C. carnea was fed on J. lybica in our laboratory conditions and that do not reflect the real conditions in fields. Further studies should be done in fields as this predator was the most abundant natural enemies during the autumn period in Moroccan.