Effect of male to female ratio on fecundity and fertility of Hippodamia variegata (Col.: Coccinellidae)

Many of insects have re-mating behavoiur during their reproductive period. The re-mating phenomenons have been observed in many ladybirds, too. In current study, the change of proportion of male to female (sex ratio) was used in order to changing of possibility and times of re-mating in Hippodamia variegata. In previous studies it has been indicated that males make up about 50% of this predator’s population. To examine change in sex ratio, one day old and virgin females and males have been used. Treatments included: 10 females without male, 10 females with the presence of 2 males, 10 females with the presence of 4 males, 10 females with the presence of 6 males, 10 females with the presence of 8 males and 10 pairs of females and males together. Number of eggs was counted and recorded for 20 days. Then, effect of the male: female ratio on egg production and hatching rate was evaluated. The results of this research showed that there was no significant difference between treatments about egg production. In other words, decreasing the ratio of male, female have not got any negative effect on female egg production. Evaluating the fertility in different treatments showed that, despite popular perception, the presence of 10 males with 10 females not only did not increase the amount of fertility but also decreased it. This illustrates that incidence of re-mating causes declining female’s fitness. This finding has been discussed from practical point of view.