food and slightly diluted food require about the same 

 "handling time": food in dry form takes the longest to 

 ingest, but requires only a relatively brief resting pe- 

 riod for cleaning, and no time for "bubbling". Slightly 

 diluted food is ingested faster but requires more resting 

 time afterwards to process the food through "bub- 

 bling". Very diluted food requires the longest "han- 

 dling time": it is consumed the fastest, but flies must 

 interrupt feeding by increasingly longer bubbling peri- 

 ods to be able to continue ingesting liquid food. 



These findings are not only of academic interest. 

 Efforts are underway to substitute the sticky material 

 on host-odor baited red sphere interception traps with 

 a more practical alternative (Fruit Notes 54:18-19). 

 Insights gained from this study will be useful in the 

 development of such a substitute, which most likely 

 will be a slow-release feeding stimulant combined with 

 a toxicant. To be effective, the food type and quantity 



covering a red sphere should not only arrest and stimu- 

 late the feeding of flies landing on a sphere, but also the 

 form of presentation of food should maximize the food 

 "handling" time. By so doing, flies would be exposed 

 for a sufficiently long period (through contact or inges- 

 tion) to the food-toxicant mixture. As a result, they 

 would die sooner and no longer be able to continue egg- 

 laying in that orchard. 



Acknowledgements 



We thank Jung Tang Wang for his help during 

 various aspects of these studies. This work was sup- 

 ported by the Science and Education Administration of 

 the USDA under grant 8700564 from the Competitive 

 Grants Office, and by the Massachusetts Agricultural 

 Experiment Station Project 604. 



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What Kinds of Food Do Apple Maggot Flies 

 Need for Survival and Reproduction? 



Jorge Hendrichs, Sylvia Cooley, and Ronald Prokopy 



Department of Entomology, University of Massachusetts 



Carol Lauzon 



Department of Entomology, University of Vermont 



In a field study (first article in this series), we iden- 

 tified various sites where apple maggot flies were ob- 

 served feeding in nature. Since then, we have collected 

 naturally occurring potential food sources at these sites 

 and assessed their contribution to apple maggot fly sur- 

 vival and egglaying. Here, we report results of these as- 

 sessments obtained both in the laboratory and on host 

 trees in large field cages. 



Laboratory Tests 



First, we carried out laboratory tests in which we 

 compared the standard laboratory food (yeast hydroly- 

 sate and sucrose) with potential food substrates col- 

 lected in nature. These included: bird droppings, insect 

 frass, apple leaves (small branches placed in a nutritive 

 solution), fruit surfaces, and combinations of these. We 

 knew that flies need carbohydrate for survival and pro- 



tein for egg production (see the fifth article in this se- 

 ries). Therefore, to determine the nutritive nature of 

 the field collected materials, these were presented to 

 flies both with and without sucrose as carbohydrate. 

 Flies were provided with hawthorn fruit or artificial 

 fruit as egglaying sites. 



Most flies, when provided with sucrose only and 

 artificial fruit as egglaying sites, were unable to pro- 

 duce eggs (Table 1). However, when the same sucrose 

 only treatment was provided with hawthorn fruit, 

 females consistently laid eggs, although well below the 

 egglaying obtained from yeast plus sucrose. Flies pro- 

 vided with only water (no sucrose) and hawthorn fruit 

 had a high mortality rate and no egglaying. We con- 

 cluded that flies were not able to obtain much carbohy- 

 drates, but possibly some proteins, from hawthorn 

 fruit. 

 With artificial fruit as egglaying sites, only combina- 



Fruit Notes, Summer, 1990 



