Environmental risk assessment for Neodryinus typhlocybae, biological control agent against Metcalfa pruinosa, for Austria

Abstract

The potential environmental risks of Neodryinus typhlocybae, a parasitic wasp from North America, were evaluated with regard to its safe use as an exotic biocontrol agent for the planthopper Metcalfa pruinosa in Austria. Following an earlier host range study of N. typhlocybae conducted in the laboratory, the present study assessed the potential for establishment and spread as well as negative indirect effects on non-target organisms. The potential release sites in Austria were analysed for matching of the climatic requirements for establishment of N. typhlocybae. The two proposed release locations, Vienna and Graz, have a predominantly similar climate to the parasitoid's region of origin, though the comparably cooler mean summer temperatures might result in a low emerging rate of the partial second generation. Natural spread potential of N. typhlocybae was reviewed and is considered to be sufficiently good to reach nearby sites infested with M. pruinosa. However, a perceptible spreading of N. typhocybae females only occurs a few years after release and seems to be strongly dependent on the host density. Gelis aerator, a hyperparasitoid of N. typhlocybae known to occur in Austria, might have negative effects on the population of the beneficial organism. Advantages and disadvantages of chemical and biological control methods against M. pruinosa were evaluated. It is concluded that N. typhlocybae is very well suited as a biological control agent for M. pruinosa in Austria, as no adverse effects on non-target species are expected but its release offers advantages with regard to sustainable and environmentally friendly pest management.