Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

The Brazilian peppertree drupe feeder Megastigmus transvaalensis (Hymenoptera: Torymidae): Florida distribution and impact.

Abstract

The distribution of M. transvaalensis in Florida, USA, the dynamics of wasp emergence, and the impact of wasp on the reproductive output and seed viability of Schinus terebinthifolius were studied. In addition, the importance of photoperiod as a factor influencing emergence from diapause, and the host range of this wasp from native Florida members of Anacardiaceae were also studied. A total of 18 sites were sampled during 1997-99. M. transvaalensis was widely distributed throughout the range of S. terebinthifolius in Florida and was recovered from all sites visited. Natural populations of the wasp caused significant damage to the reproductive potential of S. terebinthifolius. Overall, drupe mortality from wasp damage averaged 22.3-38.5% during the primary fruit production period (November-January) whereas during the second fruit production period (June-July) a much higher drupe mortality (74-76.3%) was observed. Wasps emerged rapidly from fresh drupes, often within a few days of collection. The wasp may have a significant impact on the reproduction and possibly the spread of the weed. Increased levels of damage were observed only during 1998-99 at the inland sites compared with the 2 coastal regions. The wasp was also present in at least one commercial source of S. terebinthifolius imported from RĂ©union which exhibited damage consistent with M. transvaalensis and could probably account for the wasp's occurrence in North America.