Table 1 shows the number of parasites released in the survey sites. A total of 264,000 P.
foveolatus were released in those sites during 2012 with 8,000 wasps released per site. All of
the sites were in areas that were highly susceptible to Mexican bean beetle outbreaks in past
years. In Figure 2 those sites are indicated on the map by the black circles. The stars in
Figure 2 indicate areas where field releases were made. In Mercer, Morris and Warren
Counties the field releases were in those areas with high Mexican bean beetle populations in
snap bean fields. In counties south of and including Mercer, the stars in Figure 2 indicate
releases in strategic areas where a Mexican bean beetle population may develop. These
additional field releases totaling 278,000 parasites (Table 2) were made to keep pressure on
the Mexican bean beetle population as in past years. Direct field releases are also made into
soybean, snap bean and lima bean fields throughout Central and Southern New Jersey
3
wherever MBB are observed. The purpose of the P. foveolatus releases is threefold: 1) to
suppress the MBB in areas where it could potentially reach damaging levels, 2) to reduce the
over wintering MBB population and 3) to utilize surplus P. foveolatus laboratory stocks.
Using P. foveolatus as a biocontrol agent has resulted in substantial savings to the growers in
reduced insecticide costs as well as reduced environmental pollution.
The drawback with the 2012 procedure is that there were no nurse plots so it was difficult to
project where and what the Mexican bean beetle populations would be. The indication from
the field surveys is that the Mexican bean beetle population is low because none were
observed in any soybean fields. Conversely, since no nurse plots were planted with snap
beans to attract in and concentrate any overwintering adults, it is difficult to determine where
there may be the beginnings of a burgeoning population.