Australian Journal of Entomology (2004) 43, 23-27

Nathan Pike (2004)
Natural incidence of fruit flies with character states intermediate to those of the sibling species Bactrocera tryoni (Froggatt) and B. neohumeralis (Hardy) (Diptera: Tephritidae)
Australian Journal of Entomology 43 (1), 23-27
Abstract: Naturally occurring flies of intermediate form between Bactrocera tryoni and B. neohumeralis have been known since the 1950s, and their resemblance to laboratory hybrids has been repeatedly noted. It has been demonstrated that although intermediates may be hybrids, these may equally be the consequence of intraspecific variation within either parent species. This paper aims to provide insight into the true nature of field-collected intermediate flies by assessing their appearance, their mating behaviour and their incidence relative to the abundance of the parent species. Flies were reared from a variety of infested fruit that was collected over an 8 day period from coastal regions of south-eastern and central Queensland. The vast majority (93%) of the >4000 flies collected were B. tryoni. B. neohumeralis and intermediates, respectively, comprised only 5% and 2% of the population. The callus colour and patterning of intermediates did not change as flies matured. The majority of intermediates tended to have brownish calli and exhibited courtship behaviour during the day. Intercrossing of these intermediates led to a large number of flies that were morphologically identical to B. neohumeralis, although intermediate types did persist throughout the two subsequent generations studied. These data provide circumstantial evidence for the occurrence of interspecific gene flow, particularly in the direction of B. neohumeralis, but do not discount the possibility of a non-hybrid origin of intermediate flies.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Nathan Pike

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Bactrocera tryoni		Australia (NT+QLD)
	Bactrocera neohumeralis		Australia (NT+QLD)