Toward Traps Alternative to Black 

 Pyramids for Capturing Plum Curoulios 



Ronald Prokopy, Bonnie Dixon, and Tracy Leskey 

 Department of Entomology, University of Massachusetts 



In the two preceding articles, we concluded 

 that unbaited black pyramid traps (and prob- 

 ably all other unbaited traps) aimed at captur- 

 ing plum curculios intent on entering host trees 

 by crawling or flying onto tree trunks are un- 

 satisfactory for monitoring curculios in a way 

 that reflects accurately the potential for curculio 

 damage to fruit. In the 1997 Winter issue of 

 Fruit Notes, we presented results of a prelimi- 

 nary test in 1996 showing that sticky-coated 

 squares of clear Plexiglas positioned just out- 

 side of apple tree canopies captured about as 

 many plum curculio adults as black pyramid 

 traps next to tree trunks. Here, we report on a 

 1997 study further comparing these two trap 

 types. We also report preliminary results on a 

 potentially useful third trap type. 



Materials and Methods 



The first study was carried out in a small 

 block of unmanaged semi-dwarf apple trees at 

 Hampshire College in South Amherst. The 

 Plexiglas traps were designed to capture plum 

 curculios fl3ring toward tree canopies from over- 

 wintering sites or from other host trees. Each 

 trap was constructed of clear Plexiglas (2 feet 

 by 2 feet) attached 

 vertically on a 

 wooden pole posi- 

 tioned 2 feet away 

 from the edge of the 

 tree canopy. The 

 outer-facing but 

 not the inner-fac- 

 ing surface of the 

 Plexiglas was 

 coated with 



Tangletrap to cap- 



ture curculios flying toward the tree canopy. 

 Two such traps were attached to each pole, one 

 opposite the lowermost foliage and the other 

 opposite the uppermost foliage. Two poles with 

 traps were placed on opposite sides of each of 

 six trees. Two unbaited black pyramid traps 

 were placed on opposite sides of and immedi- 

 ately next to the trunks of each of six other trees. 

 All traps were emplaced at the beginning of 

 apple tree bloom (May 24) and were examined 

 daily thereafter for 22 days for captured 

 curculios. Each day, 16 fruitlets on each of the 

 12 trees were examined for evidence of plum 

 curculio damage. Each day, temperature, rela- 

 tive humidity, and wind speed were recorded. 

 The second study was carried out in two 

 unmanaged apple trees, one in Amherst and one 

 in Conway. Traps were designed to capture 

 plum curculios that had already arrived in tree 

 canopies and were searching for resources of 

 fruit borne on twigs or resting sites on twigs. 

 Each trap, constructed of cardboard, was cylin- 

 drical in shape (8 inches tall and either 1 or 3 

 inches in diameter), coated with yellow or black 

 latex paint, and capped with an inverted screen 

 funnel developed originally to capture boll wee- 

 vils. The yellow cylinders were intended to 



Table 1. Numbers of plum curculios captured daily by traps in 

 unmanaged apple trees. May 24 - June 15, 1997. 



Traps 



Clear Plexiglas, low position 12 



Clear Plexiglas, high position 12 



Black pyramid traps 12_ 



Number of Mean number of curculios 

 replicates captured per trap * 



10.0 a 

 7.6 a 

 9.1a 



* Numbers followed by a different letter are significantly different at 

 odds of 19:1. 



14 



Fruit Notes, Volume 63 (Number 1), Winter, 1998 



