Spiders That Feed on Leafhoppers 

 and Leafminer Larvae 



Joanna \^sniewska and Ronald Prokopy 



Department of Entomology, University of Massachusetts 



Recently in Fruit Notes [58(1): 20-23], we 

 showed that spiders were signiRcantly more abun- 

 dant in second-level than in first-level IPM blocks. 

 We concluded by asking whether or not increased 

 numbers of spiders in second-level blocks were great 

 enough to contribute to the control of foliar pests. 

 Here, we describe 1992 laboratory studies in which 

 some of the most abundant types of spiders collected 

 in second-level blocks were offered white apple leaf- 

 hopper nymphs and adults and apple blotch 

 leafminer larvae as potential prey. 



Each spider was placed in a waxed paper cup 

 (four inches tall by three inches in diameter) with a 

 plastic lid. Into each cup we introduced an apple leaf 

 kept turgid by placing its stem in water. The leaf 

 harbored one tissue-feeding (late instar) leafminer 

 larva and two 

 leafhopper 

 nymphs (or 

 one nymph 

 and one 



adult). The 

 test lasted for 

 24 hours. Re- 

 sults 



are 

 in 



Table 1. Laboratory tests of orchard-collected spiders feeding on 

 potential prey. 



Family 

 of spiders 



Number 

 tested 



a cat stalks a mouse before the final pounce. They 

 may even capture it in mid air and then climb back 

 to the leaf fVom which they have jumped using a 

 piece of silk previously attached to that leaf. Salticid 

 spiders are successful nine times out often. They are 

 active only during the day. 



Of the Araneid spiders, 28% fed on leafhoppers. 

 Most of these spiders were smaU immature individu- 

 als otAraniella displicatta, which are found com- 

 monly on terminals of apple tree branches. They 

 build tiny orb webs stretching across dorsal surfaces 

 of leaves. Their webs are found at night and during 

 the day. These spiders prayed mostly on the adult 

 leafhoppers which got caught in their webs. 



Only members of the Anyphaenid family fed on 

 leafminers. Predation on leafminer larvae took 



place by 90% 

 of the 



Anyphaenid 

 spiders 

 tested. In all 

 the 



Spiders that 



fed on 



leafhoppers (%) 



Spiders that fed 



on leafminer 



larvae (%) 



Philodromidae 



Araneidae 



Salticidae 



Anyphaenidae 



Thomisidae 



27 

 22 

 11 

 10 



7 



given 

 Table 1. 



Of the 

 five families 

 of spiders ex- 



a m i n e d , _^^^^^^___^^^^^^_^^^^^_ 

 members of 



three families fed on leafhoppers: Anyphaenidae 

 (hunting spiders), Salticidae (jumping spiders), and 

 Araneidae (orb web spiders). The Anaphyenid spi- 

 ders were the most voracious, as 100% of the tested 

 individuals fed on leafhopper nymphs and adults 

 (their behavior will be described later in conjunction 

 with predation on leafminers). 



Of the Salticid spiders, 36% fed on leafhoppers. 

 These visually oriented spiders are often observed 

 running around on leaves and branches moving 

 their heads from side to side as they search for prey. 

 Once they locate a prey insect, they stalk it much as 



4 



28 



36 



100 









 

 

 90 

 



cases 



mines were 

 opened from 

 the underside 

 of the leaf and 

 the larvae 

 were missing. 

 It was not 

 possible to 

 identify the 

 specific spe- 

 cies, because they all were immature. But our best 

 guess is that 9 of the 10 individuals tested were 

 Aysha gracillis. These hunting spiders are common 

 on foliage. They forage for prey mostly by sensing 

 vibrations on leaves and (possibly) branches. They 

 were often found foraging at night but they may also 

 be active during the day. 



The type of leafminer predation observed in this 

 experiment is characterized by a very specific mark 

 left on the leaves. For this reason it may be possible 

 to quantify predation by Anyphaenid spiders in the 

 field by counting the leaves which have the signs of 



Fruit Notes, Spring, 1993 



