Abstract:

 Jujube gall midge Dasineura jujubifolia is an important pest in jujube orchards in Xinjiang. Clarifying population dynamics and spatial distributions of the jujube gall midge and its related predatory natural enemies in orchards is important for the management of the gall midge. In this study, population dynamics of jujube gall midge adults and larvae, predatory natural enemies in jujube orchards, as well as leaf damages caused by gall midge larvae were investigated in Aksu area in southern Xinjiang, in 2021 and 2022. Densities of gall midge larvae, predatory natural enemies, and degrees of leaf damage were analyzed in relation to directions of the jujube tree. Our results showed that the gall midge mainly occurred in May and June, with two population peaks. Larvae started feeding on jujube leaves one week later following the occurrence of adults, and adults of the next generation emerged after two or three weeks. Predatory natural enemy species were dominated by lady beetles and lacewings, with low population density during the whole growing season. Gall midge larvae caused serious damage in May and June, with young leaf damage rate of 6.2%—17.8% and bearing branch damage rate of 11.0%—33.8%. No direction-related biases were detected in population densities of gall midge larvae, predatory natural enemies, or the damage degree of jujube leaves. The damage degree of jujube leaves was positively correlate with the density of gall midge larvae. Results of population dynamics and distributions of the jujube gall midge and predatory natural enemies in jujube orchards in Aksu area of southern Xinjiang provide a scientific basis for the control of jujube gall midge.

Key words: jujube gall midge, natural enemy, population density, spatial distribution, occurrence regularity