The effect of methyl farnesoate and retinoic acid injections on some reproductive parameters in female Pontastacus leptodactylus

Pontastacus leptodactylus, one of the economically important crayfish species, lays eggs once a year. Egg number is one of the important egg quality determination parameters and studies in this direction are important. In this study, egg number, reproductive system weight, gonadosomatic index (GSI) and hepatosomatic index (HSI) values were determined in female crayfish injected with different doses of methyl farnesoate (MF) hormone and retinoic acid (RA), (Vitamin A Acid/Tretinoin). It was also aimed to investigate the effect of MF on protein, amino acids and fatty acids in the hepatopancreas of female P. leptodactylus. Crayfish were injected with MF in 3 experimental groups at doses of 250, 500 and 1000 ng g-¹ body weight, respectively, before the beginning of the mating period. At the end of the study, a significant difference was observed in the number of eggs and gonadosomatic index values of the crayfish injected with MF compared to the crayfish in the control and other experimental groups (P < 0.05). On the other hand, no significant difference was observed between the control and experimental groups in terms of hemolymph MF levels (P > 0.05). However, as a result of the studies, it was determined that there was no statistically significant difference between the amounts of 18 amino acids determined in the hepatopancreas of the control and experimental groups, except for valine and leucine amino acids (P > 0.05). In addition, there was no statistically significant difference in fatty acids between the crayfish in the control and experimental groups (P > 0.05). The protein content in the hepatopancreas was higher in the D3 group. There was no significant difference in the amount of protein in the hepatopancreas between the experimental groups (P > 0.05). Retinoic acid injection was administered to the experimental groups (D1, D2, D3) at doses of 10, 20 and 40 µg g-¹ body weight, respectively. At the end of the study, there was no statistically significant difference between the control groups (K1 and K2) and the experimental groups in terms of the number of eggs in crayfish injected with RA (P > 0.05). However, the number of eggs of D2 group was higher than the other groups. The number of eggs in the control groups were 206 and 211 for K1 and K2, respectively, and 210, 240 and 212 for D1, D2 and D3 in the experimental groups, respectively. As a result, MF injection was found to be positively effective in increasing the number of eggs in female P. leptodactylus and it was concluded that the reproductive efficiency of this species could be increased by MF injection. It was also concluded that RA injection may also be positively effective in increasing the number of eggs in female P. leptodactylus.