Effects of Natural Food Sources on 

 Attraction of Apple Maggot Flies 

 to Baited Traps 



Juan Rull, Alan Reynolds, Michelle Balds, HoUy Gagne, and 



Ronald Prokopy 



Department of Entomology, University ofMiissachusetts 



The effectiveness of visually attractive red 

 sticky spheres can be increased by the addition 

 of odor lures. In recent study in commercial 

 orchards by Reynolds and Prokopy (1996), it 

 was shown that red sphere traps baited with 

 butyl hexanoate (an odor emitted by ripening 

 apples) realized a four-fold increase in captures 

 of apple maggot flies (AMF) when compared to 

 unbaited spheres. However, the addition of 

 ammonium carbonate (an odor emitted by 

 sources of food) to red sphere traps did not 

 enhance capture of flies on baited traps. The 

 above study involved trapping wild flies 

 entering commercial orchards. Their physi- 

 ological state was unknown. 



While the nature of fly attraction to butyl 

 hexanoate was clear, the cause underlying lack 

 of attractiveness of ammonium carbonate was 

 uncertain. In order to reach a better 

 understanding of AMF response to both lure 

 types, we decided to perform an experiment in 

 which flies of known physiological and 

 nutritional state (mature protein fed or 

 immature protein starved) would be released in 

 blocks where different combinations of lures 

 would be displayed. Further, all treatments 

 would be replicated in blocks where natural 

 food sources were added or suppressed. In this 

 way, we could assess which synthetic lures are 

 attractive to flies of different physiological 

 states and whether or not the presence of 

 natural food in orchards interferes with 

 attraction to lures. 



Materials & Meth(fds 



Four sets of six square blocks of 49 apple 

 trees each were selected in four commercial 



orchards, with one set of blocks per orchard. In 

 every block, red sticky spheres were positioned 

 on every perimeter tree. In two of the blocks, 

 sources of butyl hexanoate and ammonium 

 carbonate were placed 15 cm away from every 

 sphere. In two other blocks, only butyl 

 hexanoate was added to spheres. Spheres in 

 the remaining two blocks were not lured. One 

 block of each lure-type treatment was treated 

 with Provado''''^ to prevent buildup of aphid and 

 leafhopper honeydew (natural food sources). 

 The other block of each lure-type treatment 

 received a large amount of bird droppings (also 

 a natural food source) that was distributed by 

 hand (in slurry form) onto the foliage of each 

 tree. Thus, half of the blocks of each treatment 

 type had a paucity of natural fly food; whereas, 

 the remaining blocks had abundant natural fly 

 food. 



Apple maggot flies of known physiological 

 state were released into the central tree of each 

 block. The flies emerged in our laboratory and 

 were subjected either to a diet including 

 protein and sugar for 14 days (mature flies) or 

 a diet limited to sugar for four days (immature 

 flies). When ready to be released, flies were 

 marked on the back of the thorax with a small 

 dot of paint. Approximately 50 mature flies and 

 50 immature flies were released in each block. 

 Flies of each physiological state released in 

 each block bore a distinct color (12 different 

 colors used across all blocks in an orchard). 

 Flies captured by the traps in each block were 

 counted after four days. The percentage of flies 

 recaptured was used to compare response to 

 treatments. Wild flies captured in the different 

 blocks were also counted and their numbers 

 compared. 



Fruit Notes, Volume 62 (Number 3), Summer, 1997 



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