Inbreeding depression in captive-raised diamondback moths
Author of the article:PU Yu-Chen** HUANG Bin HOU You-Ming***
Author's Workplace：Key Laboratory of Insect Ecology in Fujian, Key Laboratory of Integrated Pest Management on Crops in Fujian-Taiwan, Ministry of Agriculture, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
Key Words：diamondback moth, inbred lines, mating behavior, production, depression
Abstract： [Objectives] To investigate the effects of inbreeding on the diamondback moth (DBM) in order to improve the captive rearing of DBM. [Methods] DBM were continuously reared for 6 generations under laboratory conditions, and differences in mating behavior, reproductive capacity, pupal weight, adult longevity and morphology etc. between inbred and outbred populations compared. [Results] The pupal weight of inbred populations decreased significantly, especially after the third generation. Mating frequency and mating duration of inbred generations of male and female adults also markedly decreased, especially after the fourth generation. These decreases were very obvious; the mating frequency and mating duration of females of the F6 generation were, respectively, 12.9% and 8.3% those of the F0 generation, whereas the corresponding data for males were 13.8% and 8.9% those of the F0 generation. This indicates that the fitness of the inbred population had undergone a significant decline since the F4 generation. Similarly, the preoviposition period, oviposition period, fecundity, hatching rate and adult longevity etc. all significantly decreased in the post-F4 inbred population, but the developmental period significantly increased. Inbreeding also had significant effects on the size of male and female adults, the body length of male and female adults in the F6 generation being only about 60% of that of the F0 generation. [Conclusion] Changes in reproductive behavior and morphology were apparent in DBM after just 3 generations of inbreeding. These changes became more obvious after 4 generations, after which they became sufficient to cause populations to decline. Wild-caught moths should be incorporated into captive DBM breeding populations at least every 3 generations to avoid the deleterious effects of inbreeding.