CAPTURE RATES AND COMPOSITION OF INSECT PREY OF THE PITCHER PLANT SARRACENIA-PURPUREA

The insect prey of 214 pitchers of Sarracenia purpurea were monitored for 55 days. A total of 504 individual prey with a dry weight of 569.5 mg were recovered. The catch comprised individuals from 49 families and 13 orders, with most individuals from the Diptera. The distribution of the prey among pitchers was highly uneven; over 50% of pitchers caught nothing and about 8% of the pitchers caught 66% of the prey biomass. Experimental manipulations failed to produce an effect of pitcher density on prey capture rates. Indeed, no significant spatial variation in prey capture rates was found. Spiders that spun webs inside pitcher apertures prevented pitcher function on about 10% of trap days and may have imposed an important reduction on pitcher success.