Parasitism Rates of Tiphia vernalis in Connecticut  

During the 1920’s and early 1930’s USDA entomologists imported Tiphia vernalis Rohwer (Hymenoptera Tiphiidae) from Korea for the biological control of the Japanese beetle. Numerous wasp releases were made throughout the Northeast. Releases of  T. vernalis were made between 1936 and 1949 in six of Connecticut’s eight counties. This wasp, also known as the spring Tiphia, attacks the last instar of the Japanese beetle. The spring Tiphia has also been reported to attack Oriental beetle grubs. In June of 2007 and 2008, surveys were done at various locations in Connecticut to determine the parasitism rate of this beneficial wasp on the Japanese and Oriental beetle grubs. The data collected on Tiphia vernalis are the first collected in Connecticut since1950. Table 1 presents results from the 2008 survey.  

Table 1. Percent parasitism of Tiphia vernalis on Oriental and Japanese beetle larvae. 

Town Oriental Beetle Larvae/sq.ft. Percent Parasitism Japanese Beetle Larvae/sq.ft. Percent Parasitism
         
Vernon 0   0.2 100
Manchester (1) 0.3 33 0.3 0
Manchester (2) 0   0.3 0
Farmington 0.4 0 0  
Meriden 1.9 0 0.5 67
Mansfield 0.3 33 0  
Thompson (1) 0   0  
Thompson (2) 0.3 33 0  
Pomfret 1.7 23 0.1 100
Coventry 3.1 7 0  
Tolland 0.2 0 0  
         
Average 0.7 16% 0.1 53%
         
UConn,Storrs     0.8 61%
         

Prepared by Ana Legrand

August 2010

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