from Lannate technical, died within 24 hours. 



In our third experiment, we evaluated the residual 

 effectiveness of Lannate SL and Lannate technical. 

 Mixtures contained 4% active ingredient of each. For 

 this test, Lannate EC (16% formulated material) was 

 mixed with 58% corn syrup, 13% ethanol, 13% water, 

 and 0.3% Vaporguard. Lannate technical was mixed 

 with 10% table sugar and 86% of a polymeric thickener. 

 All spheres were kept under protection from rainfall 

 and sunlight until tested at 1, 5, 12, and 21 days after 

 treatment. 



The results (Experiment 3 of Table 1) show that 

 both formulations of Lannate yielded 55 to 65% kill 

 (within 24 hours) at 21 days. Interestingly, nearly all 

 deaths occurred while AMF were still on a sphere and, 

 on average, within a minute or so of fly arrival on a 

 sphere. 



Together, the results of these 3 experiments indi- 

 cate that Lannate was more effective than Pounce, 

 Asana, or Guthion in killing AMF that alight on a 

 treated red sphere. Under protected conditions, the 

 residual effectiveness of Lannate remained high at 3 

 weeks, with half of the AMF dying within a minute or 

 so after landing on such a sphere 3 weeks after treat- 

 ment. 



Residue-extending Agents 



Several possibilities emerged in our search for 

 ways to extend the residual effectiveness of fly feeding 

 stimulants and pesticides on spheres. 



One way involved protecting the sphere with a 

 conical cover in the shape of a traditional Chinese hat. 

 We constructed cones (16 cm in rim diameter) of green 

 cardboard, yellow cardboard, or clear acetate. The 

 peak was fixed at 2 cm above a sphere, with the rim 

 extending mid-way down the sphere and 

 about 4 cm from the sphere surface. We 

 reasoned that cones of this size would pro- 

 vide excellent protection of a sphere against 

 rainfall, while allowing the entire lower half 

 of the sphere surface to remain fully exposed 

 to fruit-seeking flies. Each sphere was 

 coated with tangletrap and was baited with 

 a single polyethylene vial that contained 

 synthetic apple odor (butyl hexanoate) re- 

 leased at about 700 apple equivalents per 

 hour. All spheres were hung in a commer- 

 cial apple orchard. 



As shown in Table 2, irrespective of 

 whether the vial of odor bait was 15 cm 

 above, 15 cm to the side, or 15 cm beneath a 

 sphere, none of the 3 types of cone-covered 

 spheres captured even half as many AMF as 

 comparably baited unprotected spheres. 



Hence, although a cone protects a sphere against run- 

 off of pesticide during rainfall, it cuts down on arrivals 

 of AMF to an unacceptable level. 



Another way we envisioned of extending the resid- 

 ual life of fly feeding stimulant and pesticide on a 

 sphere was to envelop the sphere in a cotton red sock 

 (much like a Fenway Park red sock) which would be 

 more absorbent than the smooth surface of a painted 

 wooden sphere. Better yet, we hypothesized, why not 

 replace the wooden sphere inside a red sock with a 

 sphere of sawdust or the liner from a disposable baby 

 diaper formed into a sphere? These would absorb a 

 great deal of liquid pesticide mixture and possibly 

 afford continued release over a very long period. We 

 therefore constructed red spheres of these types, using 

 socks the same color as our red-painted wooden 

 spheres and having 60 strands of fiber per cm. We 

 dipped them until saturated in a mixture containing 

 16% Lannate 1.8 SL (4% active ingredient), 58% corn 

 syrup, 0.3% Vaporguard, and 26% water. Half of the 

 spheres in each treatment were continuously protected 

 from sunlight and rainfall. The remaining half were 

 hung from tree branches and thereby exposed continu- 

 ously to the weather. All spheres were tested 21 days 

 after dipping. 



As shown in Table 3, the proportion of AMF visit- 

 ing red sock-covered diaper, sawdust, or wooden 

 spheres was consistently slightly less (45-57%) then 

 the proportion visiting smooth red wooden spheres 

 (59-67%). Among spheres protected from weather 

 over the 21 day pre-test period, 55% of AMF that visited 

 smooth wooden spheres died within 24 hours com- 

 pared with only 25, 15, and 20% deaths among AMF 

 that visited red socks enveloping a diaper, sawdust, or 

 a wooden sphere, respectively. Moreover, in the case of 

 spheres exposed to the full range of weather conditions 



Table 2. Total AMF females captured on odor-baited sticky 

 red spheres protected from rainfall by green, yellow, or clear 

 plastic cones above the spheres and hung in apple trees 

 (July 2 to August 3, 1989).* 



Color of 



protective 



cone 



Position of odor vial relative to sphere 



15 cm 

 above 



15 cm 

 to side 



15 cm 

 below 



Green 

 Yellow 

 Clear 

 No Cone 



8b 



20 b 



21 b 

 75 a 



4 b 

 11 b 

 29 b 

 70 a 



6b 



7b 



14 b 



56a 



•Four replications per treatment. Values not followed by 

 the same letter are significantly different at odds of 19 to 1. 



Fruit Notes, Spring, 1990 



19 



