9. 



DO CALCIUM CHLORIDE SPRAYS AFFECT APPLE MAGGOT FLY EGGLAYING? 



1 2 ^ 



Ronald J. Prokopy , Sylvia S. Cooley , Bonnie L. IVeeks^, and 



Anne L. Averill 



Department of Entomology 



In an earlier issue o£ FRUIT NOTES (Vol. 42, No. 1), we des- 

 cribed how, after laying an egg, an apple maggot female drags its 

 ovipositor on the fruit surface. In so doing, the female releases 

 a substance (called a pheromone) which deters other females from 

 attempting to lay an egg in that fruit. 



For the past three years, in cooperation with chemists from the 

 USDA Lab in Gainesville, Florida and neurophysiologists from the 

 Department of Zoology at the University of Massachusetts, we have 

 been working on the chemical identity of this pheromone and on 

 various physiological, behavioral, and ecological aspects of the 

 pheromone deterrent system in the flies. Our eventual aim is to 

 apply synthetic pheromone in sprays to prevent maggot fly egglaying. 



In the course of recent laboratory studies, we found that apple 

 maggot fly egglaying is deterred not only by the pheromone but also 

 by sodium chloride (table salt). As shown in Table 1, sodium chlor- 

 ide at concentrations of 2 and 9 pounds per 100 gallons gave about 

 the same moderately-strong levels of egglaying deterrence as 2 and 

 3 ovipositor dragging equivalents (ODE) of pheromone laid down by 

 the flies (1 ODE = amount of pheromone deposited after laying 1 egg) . 

 Apparently the flies do not like to lay eggs in fruit treated with 

 table salt any more than they like to lay eggs in fruit treated with 

 pheromone. 



Table 1. Percent arriving females attempting egglaying into hawthorn 

 fruits treated with different concentrations of pheromone, sodium 

 chloride, and calcium chloride (ODE = ovipositor dragging equivalent), 



Attempting Attempting Attempting 



egglaying Sodium egglaying Calcium egglaying 

 Pheromone [%) chloride (%) chloride (%) 



Clean check 77 Clean check 79 Clean check 86 



2 ODE 50* 2 lbs/100 gal 49* 3 lbs/100 gal 68 



3 ODE 28* 9 lbs/100 gal 35* 7 lbs/100 gal 83 



Significantly less than egglaying in clean check fruit 



Extension Entomologist 

 2 



Extension Technicians 

 3 



Graduate student. Entomology 



