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United States Department of Agriculture

Agricultural Research Service

Title: Sex Ratio Variation As a Function of Host Size in Pseudacteon (Diptera: Phoridae) Parasitoid Flies

item Morrison, Lloyd - UNIV OF TEXAS
item Porter, Sanford
item Gilbert, Lawrence - UNIV OF TEXAS

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: August 14, 1998
Publication Date: N/A

Interpretive Summary: Scientists at the University of Texas at Austin and the USDA's Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida discovered that the sex of Pseudacteon phorid flies that attack and parasitize fire ant workers appears to be determined by the size of their host. This discovery is important because it appears to be the first example of environmental sex determination in insects. Information provided by this study has been important in allowing USDA scientists to rear increased numbers of female flies for release as fire ant biocontrol agents in North Florida.

Technical Abstract: Some Pseudacteon (Diptera: Phoridae) flies are parasitoids of Solenopsis (Hymenoptera: Formicidae) ant workers in North and South America. Laboratory studies of sex allocation revealed a pattern of sex ratio variation as a function of host ant worker size, with more females arising from larger hosts. Environmental sex determination is a likely mechanism for the observed pattern, and examination of Pseudacteon are compared with theoretical predictions and empirical data from better-studied hymenopteran parasitoids, which have haplodiploid sex determination. The pattern of sex ratio variation observed has important implications for biocontrol efforts of imported Solenopsis fire ants by the introduction of Pseudacteon parasitoids.

Last Modified: 4/22/2015
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