Performance of Aphytis lepidosaphes Compere as a Biological Control Agent of Lepidosaphes beckii (New.)

摘要

Background and Objective: The purple scale, Lepidosaphes beckii (New.) (Hemiptera: Diaspididae) is considered one of the most important pests of citrus around the world. Biological control represents a sustainable alternative for save control of L. beckii . The present work was conducted to study the factors affecting the biological control of L. beckii by Aphytis lepidosaphes compere (Hymenoptera: Aphelinidae) in Egypt Valencia orange. Materials and Methods: The parasitism rates by A. lepidosaphes were determined throughout two years on the scales of L. beckii which attacks leaves (upper and lower surfaces) and fruits of Valencia orange. The effectiveness of 5 insecticides namely, dinotefuran, imidacloprid, pyriproxyfen, azadirachtin, abamectin also were tested against L. beckii as well as A. lepidosaphes . Results: It was found that all nymphal instars and adult of L. beckii were parasitized by A. lepidosaphes . However, percentage parasitization was higher in the 4th instar males and gravid and non-gravid females compared with the 2nd and 3rd instar of males and 2nd instar of females. Parasitism percentages of L. beckii on fruits were significantly lower than its on the leaves. The differences in the parasitization percentages with regards to the seasons were determined to be statistically significant. The tested insecticides showed high effectiveness against L. beckii and A. lepidosaphes . But a better effect, reflected in high reduction percentages in L. beckii compared with low reduction percentages in the parasite was found for the soil application with dinotefuran, imidacloprid. Conclusion: The host stage preference showed that the parasitoid had a significant preference for the older host stages. The soil application of insecticides was less harmful to the parasite.