Ovarian development in the Caribbean fruit fly, Anastrepha suspensa (Diptera: Tephritidae)

Authors: Kendra, Paul; Montgomery, Wayne; Epsky, Nancy; Heath, Robert

Submitted to: Fruit Flies of Economic Importance International Symposium
Publication Type: Proceedings
Publication Acceptance Date: 10/30/2006
Publication Date: 11/1/2008
Citation: Kendra, P.E., Montgomery, W.S., Epsky, N.D., Heath, R.R. 2008. Ovarian development in the Caribbean fruit fly, Anastrepha suspensa (Diptera: Tephritidae). Pp. 227-232 In R.L. Sugayama, R.A. Zucchi, S.M. Ovruski, and J. Sivinski (eds.). Fruit Flies of Economic Importance: From Basic to Applied Knowledge. Proceedings of the 7th International Symposium on Fruit Flies of Economic Importance, 10-15 Sept 2006, Salvador, Brazil.

Interpretive Summary: The Caribbean fruit fly is an important agricultural pest in Florida, impacting production and marketability of citrus, guava, and other tropical fruits. As a result, research efforts have focused on development of effective trapping systems for detection of this and related pest species. Previously, scientists at the Subtropical Horticulture Research Station have developed ammonia-based synthetic lures for monitoring fruit flies. Recent laboratory findings indicate that response of female flies to ammonia depends upon age, and different doses of ammonia may be attracting flies of different ages. Testing this hypothesis in the field requires a method for determining the maturity status of field-caught flies. To provide such as tool for the Caribbean fruit fly, this study examined several ovarian characters – ovary length, ovary width, an ovary index (length multiplied by width), and length of terminal follicle, as well as the number of mature eggs per ovary (egg load). Changes in these characters were documented over a four week period following adult emergence, and this information was than used to develop a six-stage system to classify female sexual maturity. Use of this classification system will facilitate evaluation of a fly population responding to current field lures, and lead to the development of improved fruit fly attractants.

Technical Abstract: Reliable methods are needed for assessing sexual maturity in field-caught tephritid fruit flies. To provide such a tool for female Caribbean fruit flies, Anastrepha suspensa (Loew), we documented changes in ovarian development over a four-week period following adult eclosion. The ovarian maturation process was classified into six developmental stages. Stages 1-4 described sequential steps in the development of immature ovaries, stage 5 indicated presence of mature oocytes, and stage 6 was the ovipositional phase. For each stage, four morphometric characters were examined – ovary length, ovary width, an ovarian index (ovary length multiplied by ovary width), and length of terminal follicle. Ovarian characters were compared by stage and correlated with the number of mature oocytes per ovary (egg load). Ovarian index maximized the differences between sexually mature and immature ovaries, and ovary length provided the best separation of immature stages. All four characters were positively correlated with egg load, but ovarian index and ovary width were the two best indicators of mature oocytes. Use of these parameters to assess egg load eliminates the need to tease apart ovaries and count mature oocytes, thereby providing an efficient method for processing large samples of flies. Currently, we are using the six-stage ovary classification system, in conjunction with assessment of egg load in mature stages, to evaluate the physiological age structure of Anastrepha populations captured in field-deployed traps.