Egg morphology of two sibling species of the Bactrocera dorsalis complex Hendel (Diptera: Tephritidae)

Abstract

In the present study, the eggs of Bactrocera carambolae (Drew and Hancock) and Bactrocera papayae (Drew and Hancock) were described for the first time. Eggs were collected from 10 F1 females of each species emanating from infested guava fruits sampled from guava orchards in Songkhla province of southern Thailand. Eggs were examined by using Olympus microscope with inbuilt ocular micrometer for morphometric study, Olympus DP72 Universal Camera microscope to capture the image of the eggs and Scanning Electron Microscope (SEM) was used for the detailed morphological studies. At least 30 eggs of each species were used for morphometric and image capturing, and additional 30 eggs of each species were submitted for SEM analysis. None of the eggs of the two species had conspicuous respiratory appendage. The eggs were similar in gross morphology, and tapering towards the anterior and posterior ends. Presence of papillae, mycropyles and aeropyles are peculiar to both species but with some variations. The papilla and micropyle with clumsy woolly structure was common to B. carambolae, but aeropyles on the chorion of B. papayae were numerous and in variable diameters. The diagnostic characters to differentiate between these two species include the chorion ornamentation, location of aeropyles, and rim of chorion.