Scanning electron microscopy and comparative morphometrics of eggs from six bot fly species (Diptera: Oestridae)

Scanning electron microscope comparisons were made of the eggs of Cuterebra austeni Sabrosky, C. fontinella Coquillet, C. jellisoni Curran, C. lepusculi Townsend, C. ruficrus (Austen) and Alouattamyia baeri (Shannon & Greene). Larvae of these flies parasitize rodents, lagomorphs, and monkeys. Image analysis of the egg length (maximum projection) and width (minimum projection), egg area (in dorsal view), operculum area (in dorsal view), and operculum area as a percentage of egg area revealed differences among species. The chorion of these eggs is sculptured with a distinct pattern of "cells" covering the dorsal, lateral, and opercular surfaces. The chorion of A. baeri eggs was distinct with deeply sculpted, large, highly polymorphic "cells." C. jellisoni eggs also had large, highly polymorphic cells, but the sculpturing was not deep. The chorion of the 4 remaining species was quite similar. Image analysis of the chorionic sculpturing patterns revealed significant differences in the area, perimeter, maximum projection, minimum projection and aspect ratio of chorionic "cells" among the species examined. The chorionic "cell" parameters of A. baeri and C. jellisoni were different from 1 another and from the other species in all parameters. The "cell" parameters of C. lepusculi and C. ruficrus were similar. A combination of overall egg features in combination with cell features allow the eggs to be differentiated from one another. There was no strong association among structural features of the eggs and the habitat in which they were found. However, the deep sculpturing of the A. baeri eggs might help to prevent drowning in tropical rain forests.