Molecular and field analyses of the fortuitous establishment of Lipolexis oregmae (Hymenoptera: Aphidiidae) in Jamaica as a natural enemy of the brown citrus aphid.

摘要

The brown citrus aphid, Toxoptera citricida (Kirkaldy), is a serious pest of citrus because it efficiently transmits citrus tristeza closterovirus (CTV). The invasion of Jamaica's citrus by T. citricida resulted in serious economic losses and the importation and consideration was given to the establishment of Lipolexis oregmae Gahan (Hymenoptera: Aphidiidae) in a classical biological control program. Prior to introducing L. oregmae, we conducted a survey to determine the abundance of Lysiphlebus testaceipes Cresson (Hymenoptera: Aphidiidae) in T. citricida. A high-fidelity PCR analysis was conducted using Lysiphlebus- and Lipolexis-specific ITS2 rRNA primers on alcohol-preserved brown citrus aphids and the results were positive for both parasitoids. The fortuitous establishment of L. oregmae in Jamaica was surprising, and was confirmed by rearing adults from parasitized aphids and obtaining taxonomic confirmation based on morphology. In addition, its identity was confirmed molecularly by cloning and sequencing 16S, 12S, and COI sequences from the Florida colony of L. oregmae and from Jamaican specimens. The three DNA sequences were 100% identical for specimens from both sources. The phylogenetic analysis using 16S sequences indicated a close relationship of the Florida and Jamaica populations of L. oregmae with L. gracilis. During 2005, an island-wide survey of citrus in six parishes confirmed that both L. testaceipes and L. oregmae commonly parasitize T. citricida, but that L. oregmae was the more widely distributed and abundant parasitoid. The pathway by which L. oregmae might have entered Jamaica is discussed.