Biologia reprodutiva de Diachasmimorpha longicaudata criado sobre Ceratitis capitata e Anastrepha fraterculus

Abstract

Biological control with the use of parasitoids has been one of the most used methods for the control of tefritids. Diachasmimorpha longicaudata is one of the most important biological agents used in inundative release programs to control fruit flies Bactrocera, Anastrepha and Ceratitis species. Thus, the aim of this study was to evaluate the anatomical, morphometric and histological characteristics of the male and female reproductive system of D. longicaudata reared on Ceratitis capitata and Anastrepha fraterculus larvae and their relationship with the production of oocytes in the progenies. For the morphological and histological description of the male and female reproductive systems of D. longicaudata, virgin and copulated males and females aged six days, raised on C. capitata larvae. For morphometric analysis, females of two strains were used, females reared on C. capitata (LC) and females raised on A. fraterculus (LA). Four different progenies were evaluated, for this, larvae of A. fraterculus and C. capitata were offered for the LA line, and larvae of C. capitata and A. fraterculus for the LC line, thus obtaining the progenies (LAA, LAC, LCC and LCA). For the morphometric analysis of the progenies of each lineage, measurements of the body length and wingspan of 50 females of each group were performed, with the aid of a micrometer ruler coupled to the microscope eyepiece, in a 10-fold magnification. To count the number and morphometry of oocytes, reproductive systems of virgin and copulated females with three, six and nine days old were used. The reproductive systems were dissected, fixed, dehydrated and included in Historesin (Leica), sectioned at 2μm thick and stained with Toluidine Blue to be analyzed under a light microscope. The male reproductive system of D. longicaudata presents morphological diversity capable of differentiating it from other species. D. longicaudata can present the two testicles together, covered by a single capsule of connective tissue, or they can be encapsulated separately. It consists of a pair of testicles, two seminal vesicles, a pair of vas deferens, two accessory glands and an ejaculatory duct. Each testicle consists of only one follicle. Testicular follicles are filled with cysts at different stages of spermatogenesis. The histological and morphological characteristics of the male reproductive system of D. longicaudata, one and six days old, do not differ. The female reproductive system of the parasitoid D. longicaudata is composed of a pair of ovaries with two ovarioles each, two lateral oviducts connected to the common oviduct, an elongated accessory gland and two sperm cells. There are no differences in the histological and morphological characteristics of the reproductive system between virgin and copulated females of D. longicaudata. Females from the host A. fraterculus are larger (body length and wingspan) and have a greater number of oocytes than females reared in C. capitata larvae. Virgin females from the progenies (LAA and LCA) produced more immature oocytes, whereas copulated females from the same progenies produced immature and mature oocytes. Females six days old had more mature oocytes than females three days old.