First Record of a Phytophagous Seed Chalcid from Brazilian Peppertree in Florida

Abstract

Brazilian peppertree, Schinus terebinthifolius Raddi (Anacardiaceae), a tree of Brazilian origin, has become a serious weed since its introduction as an ornamental into Florida. During a 14-month survey, Cassani (1986) recorded 115 arthropods, 46 of them phytophagous, associated with this plant in southern Florida. This list did not include any major seed feeders and for this reason, insects which seed production were to be given priority in the search for effective natural enemies in Brazil (Bennett et al. in press). A collection of drupes of S. terebinthifolius from Jupiter, Palm Beach County, FL (by DHH) on 23 February 1988, yielded several microhymenoptera which proved to be Megastigmus transvaalensis (Hussey) (Torymidae). Described as Eumegastigmus transvaalensis by Hussey (1956), this genus was placed in synonymy with Megastigmus by Boucek (1978). During March-June 1988, collections, each consisting of several hundred drupes, were made at several other localities in south and central Florida. With the exception of a few emergents from two collections, one from near Miramar, Broward County on 21 March, and one from Key Largo, Monroe County on 22 March, no other specimens of this torymid have been reared. In the United States, Megastigmus transvaalensis has been reported, only from California, from Schinus molle L. (Harper & Lockwood 1961). Our rearings represent the first record for M. transvaalensis from Florida and the first record from S. terebinthifolius in the continental United States. The species is also widespread in the seeds of S. terebinthifolius in Hawaii (E. R. Yoshioka, pers. comm. 1988 and personal observations by FDB in May 1988). M. transvaalensis was described by Hussey based on specimens from seeds of S. molle collected in Pretoria, South Africa. It is also known, from the Canary Islands, from the same host (Grissell 1979). Interestingly, the genus Schinus is limited in natural distribution to South America, although S. molle extends northward into Mexico (Barkley 1957). Therefore, it might seem questionable to find an endemic, African species of Megastigmus on plants endemic to South America. There are two reasons to believe that M. transvaalensis is an endemic, African species which has host-shifted from native vegetation to introduced Schinus. Firstly, because it is more closely related to species of Old World origin than New World, especially M. rhusi (Hussey) (which may be a synonym) and M. pistaciae (Walker). The former seed feeder attacks Rhus and the latter Pistacia, both of which are related to Schinus in the Anacardiaceae. And secondly, because no Megastigmus species have been reliably reported from South America. Megastigmus mendocinus Kieffer & Joergensen was reported by De Santis (1967) in Argentina, but this is a parasite of cecidomyiids on Solanaceae, a host relationship unknown in Megastigmus.