Effects of Heat Stress on the Main Organs of the Male Reproductive Tract of Anisopteromalus calandrae Howard (Hymenoptera: Pteromalidae)

The success of biological control against agricultural insect pests, which is one of the alternative methods to chemicals, requires bio-controlling organisms to have a good reproductive capacity. Considering insects, the reproductive capacity of the male of Anisopteromalus calandrae Howard (Hymenoptera: Pteromalidae), a cowpea bruchid parasitoid, depends essentially on the condition of development of the genital tract. In order to predict influence of current climate change on insect reproduction, the objective of this study is to determine the effects of heat stress on the dimensional and structural characteristics of the main organs of the genital tract of male of A. calandrae according to their age in lab conditions. Experimentation was carried out on nymphs and males aged 1 and 10 days and reared at 28�C and 38�C. Observations of the male genital tract structure were made with photonic microscopy. Heat stress disorganized the structure of the testis and the anterior portions of the seminal vesicles resulting to reduction of stock of spermatozoa in the lumens of the seminal vesicles. These experiments prove that a heat stress affects the structure of the reproductive system of A. calandrae which may explain the decrease of fertility of heat stressed males and then the disequilibrium of the sex ratio in this haplo-diploid insect.