Exploring Sustainable Control Of Takahashia japonica With Natural Predators In Urban Green Spaces

In this study the efficacy of the biological control of Takahashia japonica with the two natural predators (Coleoptera, Coccinellidae) Exochomus quadripustulatus and Cryptolaemus montrouzieri was evaluated in comparison to the chemical control and against the untreated. 42 trees of the two species, sited in 3 municipalities of the province of Milan, in the North of Italy, were tested. Biological control was performed on n. 4 Liquidambar styraciflua L. and n. 10 Morus alba L. with the release of 40 E. quadripustulatus and 50 C. montrouzieri at adult stage. One cardboard bucket, containing the insects and a sugar supply, was hung on one branch of each infested tree. Chemical treatments consisting in the application of cypermethrin (appl. rate 0,2%) on the canopy of a set of 14 host plants. Predators' release and chemical treatment were repeated in 3 applications (5 weeks apart) and followed by 6 monitoring assessments. The effect of the treatments on T. japonica individuals was evaluated by the observation of the vegetative vigor recovery of the trees,   ranked in 4 levels (0, 1, 2, 3). Per each assessment date and treatment group the mean value of vigor recovery was calculated and data were analysed using one-way ANOVA (P<0.05) and Tukey HSD test. The treatment of T. japonica infestation with natural predators resulted in a vigor recovery extent significatively different from that observed in the untreated trees for both the species tested.