-7- 



The actual damage done to plantings by the larvae was of 

 interest. Growers were asked to estimate the percentage of 

 blossoms lost when larvae consumed either blossoms or blossom 

 stems. A summary of responses is given in Table 1. These esti- 

 mates should be viewed as conservative because in many instances, 

 control measures were undertaken during the initial stages of 

 larval feeding. Clearly, GM reduced potential crops in 1981 and 

 1982 and temporarily superseded the blueberry maggot as the most 

 important insect pest of blueberry. 



Table 1. Feeding damage by gypsy moth larvae in southeastern 



Mass. blueberry plantings, 1980-1982. 



Percent 



flowers Number of plantings 



consumed 1980 1981 1982 



9-25 5 3 



26-50 10 



51-75 13 



76-100 110 



Insecticide usage ranks alongside damage as a leading indi- 

 cator of pest status. A glance at Table 2 should leave no doubt 

 about the impact GM feeding had on the minds of most blueberry 

 growers from 1980 through 1982, During that period, half of the 

 growers who applied insecticide used Sevin , 5 treated with for- 

 mulations of the bacterium. Bacillus thuringiensis , and 3 treated 

 with malathion. On average, 3 applications were made prior to 

 and during bloom by each grower, with 10 being the maximum number. 

 Opinions about the results of these applications were mixed 

 (Table 2). Dissatisfied growers lamented the insecticides' lack 

 of residual activity and the ineffectiveness of Dipel^ and Thuri- 

 cide^ against older GM larvae. Only positive opinions were re- 

 corded by lone users of methoxychlor, Guthion^, and Imidan^. A 

 planting deliberately left untreated despite damaging levels of 

 GM lost an estimated 75% of its flowers. 



Insecticide applications during bloom are potentially harm- 

 ful to native and rented pollinators. New Jersey has overcome 

 the problem somewhat by obtaining a state local need registra- 

 tion for Dylox^, an insecticide reported to be less harmful to 

 pollinators than Sevin. The questionnaire alluded to this issue 

 by asking if additional insecticides are needed in Massachusetts 

 to control GM larvae during bloom . Ten growers responded posi- 

 tively, 10 were negative, and 7 had no opinion. 



