D3405: Evaluation of phenological synchrony between a biological control agent, Neodryinus typhlocybae (Hymenoptera: Dryinidae), and its host, Metcalfa pruinosa (Hemiptera: Flatidae)

The invasive species M. pruinosa has caused serious economic damage in European and Asian countries. The parasitoid wasp N. typhlocybae has been introduced and successfully established in European countries to manage this pest. However, a predictive model for the adult emergence of N. typhlocybae has not yet been developed. Thus, this study was conducted to develop a degree-day model for the adult emergence from overwintered cocoons and evaluate phenological synchrony between N. typhlocybae adults and the nymphal stages of M. pruinosa in Korea. Cocoons were introduced from Italy to develop an adult emergence model of N. typhlocybae, and adult emergence was observed under a combination of field conditions and six constant temperatures (13.92, 17.71, 18.53, 20.53, 22.78, and 24.03 °C). The lower developmental temperature was estimated using the values of the coefficient of variation for the cumulative degree days of emerged individual adults. The estimated lower developmental temperature was 12.3 °C. With this developmental threshold, a degree-day model was developed, and this model well-predicted emergence in field conditions. By simulating this developed model with the actual occurrence of the nymphal stages of its host, M. pruinosa, adult wasp emergence was estimated to be 1.5 weeks later than the first instar nymph of the host but faster than other nymphal stages of M. pruinosa. Thus, the findings in this study would be helpful in determining the possibility of establishing N. typhlocybae and improving the management efficiency of M. pruinosa.