Aphytis lepidosaphes (Hymenoptera: Aphelinidae) as an Effective Parasitoid for Controlling the Lepidosaphes tapleyi (Williams)

Background and Objective: The guava long scale insect Lepidosaphes tapleyi (Williams) (Hemiptera: Diaspididae) is considered one of the main destructive pests of guava around the world. Biological control represents a sustainable alternative for saving control of L. tapleyi . The main objective of the present work was to study the seasonal activity and evaluate the impacts of climatic factors on populations of the parasitoid, Aphytis lepidosaphes , during two successive years (2017/2018 and 2018/2019) in Esna district, Luxor Governorate, Egypt. Materials and Methods: Estimation of the relationship between the population density of L. tapleyi and A. lepidosaphes activity, by using different models of correlation and regression analyses. The estimate of the effects of climatic factors (daily mean max. temp., min. temp., mean of % relative humidity and mean of dew point) on seasonal activity of the parasitoid, A. lepidosaphes , during two successive years (2017/2018 and 2018/2019). Results: The results showed that the relationship between the population density of L. tapleyi and A. lepidosaphes activity was positive during both years. Furthermore, simple regression analysis indicated that the abundance of A. lepidosaphes was more highly correlated with the L. tapleyi population density in each whole year during the two successive years. The percentages of explained variance EV (%) indicated that all tested variables, i.e. daily mean maximum temperature, minimum temperature, relative humidity and dew point were responsible for 76.26 and 65.40% of the changes in parasitoid, respectively. Furthermore, the dew point was the most effective variable for the change in the parasitoid populations by 33.61 and 18.62%. Conclusion: The results showed that A. lepidosaphes had three peaks of seasonal abundance over the entire year. As well, the activity of A. lepidosaphes was more highly correlated with the L. tapleyi population size over the two successive years.