Periodical crossing of the laboratory population with the natural population would improve fitness in S. sunia (Lepidoptera: Noctuidae)

Abstract

Background The research focused on evaluating the biological and reproductive parameters of the species Spodoptera sunia with the introduction of field genetic material, in the Noctuid Insect Breeding Laboratory. Methods The experiment consisted of three treatments and three repetitions involving 30 individuals each. Field-collected S. sunia population was reared in the laboratory under semi-controlled conditions of temperature and humidity for three generations. The progeny of the third generation was crossed with the laboratory population and the resulting progeny was observed for growth and reproductive fitness. Results The results revealed that the hybrid progeny (T3) has a sex ratio (F: M) of 0.82, as against 1.22 and 0.76 observed in the field (T1) and lab populations (T2) respectively. The T1 females oviposited 196 egg masses as against 160 and 59 egg masses by T3 and T2 females respectively. The larval growth was more in hybrid progeny with shorter larval duration. However, no variation was observed in the incubation and pupal periods. Conclusions Since the most optimal results were obtained in T2 and T3, it is recommended to introduce genetic material every six months to maintain a good laboratory population of the insect host under study and better breeding of its natural enemies.