EFFECTS OF DISTANCE FROM INVASIVE LYTHRUM SALICARIA ON POLLINATOR VISITATION RATE AND REPRODUCTIVE SUCCESS IN NATIVE LYTHRUM ALATUM

by Kinyo, Anthony Steven

Invasive plant species have been studied for some time now but little attention has been given to their reproductive competitive abilities. I hypothesized that visitation rate to native Lythrum alatum would be increased in the presence of invasive Lythrum salicaria and that this facilitative effect would diminish with distance. I also hypothesized that seed set in L. alatum would be decreased in the presence of L. salicaria. To test these hypotheses I set up plots of L. salicaria and placed L. alatum mixed, 5m, 20m, and 50 m away from the L. salicaria. Pollinator visitation data, seed set per plant, and germination proportion per plant were recorded and analyzed. I found that visitation rate to L. alatum by large bees (Bombus and Apis) decreased significantly as a function of distance from L. salicaria and visitation rate by small bees (Ceratina, Lasioglossum, etc.) showed a trend of increasing as function of distance. Seed set showed no significant difference as a function of distance and proportion of seeds germinated in L. alatum showed a trend of increasing as a function of distance.