3/ June 1956 



ARS-33-24 



United States Department of Agriculture 

 Agricultural Research Service 



USE OF IMMATURE APPLES FOR REARING 

 THE ORIENTAL FRUIT MOTH 



By H. W. Allen, Entomology Research Branch^ 



1/ 



A satisfactory supply of food is a primary requirement for any 

 laboratory work for which an insect is reared. At the Moorestown, N. J., 

 laboratory, small green apples picked late in June by growers thinning 

 their fruit have been used for many years in rearing the oriental fruit 

 moth ( Grapholitha molesta (Busck)). These apples are sorted and packed 

 with a copious amount of oiled shredded paper in 32 -quart bean hampers 

 (fig. 1), and placed immediately in commercial cold storage at apple 

 storage temperatures (32-35° F.). The apples decompose more slowly 

 in this pack than when they are stored in bushel baskets without shredded 

 paper. In New Jersey Golden Delicious is one of the varieties most likely 

 to be thinned, and immature apples of this variety can be kept in storage 

 longer than those of other common varieties. Storage in chambers cooled 

 by expansion coils in which short periods of frosting and defr.osting 

 alternate is not satisfactory for long storage, as it desiccates the apples 

 and causes them to wither. 



Apples packed and stored late in June are generally satisfactory for 

 use until the following June. However, when rot begins to show up after 

 several months of storage, it has been found feasible to sort out and 

 discard the paper and all decaying fruit, and to wash all sound apples in 

 wettable surfur (1 ounce to 1 gallon of water) and repack them, in fresh 

 shredded paper while still wet. 



As long as lead arsenate was the principal insecticide in apple spray 

 programs, residues were readily removed by washing in a bath of 1- 

 percent hydrochloric acid. The present widespread use of DDT or 

 parathion on apple results in residues that cannot be removed without 

 injury to the fruit. This has greatly increased the difficulty of obtaining 

 supplies of apples suitable for use in rearing the oriental fruit moth and 

 its parasites. Unsprayed apples are usually diseased and heavily 

 infested with insects and do not store well. Spraying trees with lead 

 arsenate may be a bothersome and expensive means of obtaining the 

 needed supplies. 



\J Assisted by E. L. Flasket. 



