Abstract: Local mate competition (LMC) theory had developed in many aspects, including that the offspring sex ratio should be more female-biased when the foundress oviposited with related females than with unrelated females. We studied the influence of relatedness of Diaziella yangi females oviposited on a fig on sex ratio of offsprings, which was a species of non-pollinator hosting on Ficus curtipes. Treatment 1: The 2 foundresses of D. yangi were from the same fig of maturing tree No. 1； treatment 2:  the 2 foundresses were from the same fig of maturing tree No. 2; treatment 3:  one foundress was from maturing tree No. 1, and the other one was from maturing tree No. 2.The experimental results, however, were not consistent with the predicted values. In the experimental results, the sex ratio of offsprings in two treatments with two foundresses of sister relationship were 0.195±0.028 and 0.189±0.043, respectively; the sex ratio of offsprings produced by two foundresses of non-sister relationship was 0.240±0.030; and there were no significant difference among the three treatments. The results suggest that fig-wasps have no capabilities of kin recognition and adjusting the sex ratio of offsprings accordingly, and this is consistent with many other studies.

Key words: Ficus curtipes, Diaziella yangi, evolutionary biology, sex ratio, foundress relatedness, local mate competition