Predation efficiency of brown lacewing Micromus angulatus against rhododendron aphid

Belgium, especially the Ghent region, serves as a prominent center for pot azalea and rhododendron cultivation, encompassing both open-air fields and greenhouses. Azalea and rhododendron production in Belgium faces notable challenges due to the presence of the troublesome rhododendron aphid, Illinoia lambersi. The brown lacewing Micromus angulatus has emerged as a promising candidate for biological pest control, owing to its advantageous characteristics, including its effectiveness at cooler temperatures, predatory behavior, robust adult stage, high reproductive capacity, and low cannibalism rates. Despite the availability of the commercial product of Micromus angulatus since 2022, a scarcity of information regarding the utilization of this brown lacewing for aphid control remains. This thesis primarily investigates how the predation efficiency of M. angulatus adults varies with factors like sex and temperature conditions, aiming to enhance biocontrol strategies for rhododendron aphids, particularly in open-air cultivation settings. The results indicate a sex-based difference in predation efficiency, with female adults inflicting significantly higher aphid mortality than male adults at 25℃. Moreover, the results revealed a temperature-dependent effect. Female adults of M. angulatus displayed the highest aphid consumption at 25℃, among the three tested temperatures of 25℃, 20℃, and 15℃. There were no statistically significant differences observed between the groups, except for the comparison between 15℃ and 25°℃. Predatory activity was still observed at lower temperatures, such as 15℃, albeit with a smaller number of aphid consumptions. Notably, there was no significant difference in aphid mortality between 15℃ and 20℃. These findings support the practicality of utilizing adult lacewings in biocontrol strategies at lower temperatures (15-20℃). However, to maximize effectiveness, it may be necessary to increase both the rate and frequency of releases and the ratio of females to males.