Population dynamics of Bradysia difformis Frey on different host plants
Author of the article:ZHANG Yan-Xia** GUO Su-Fan LIU Chang-Zhong***
Author's Workplace：Gansu Agricultural University, Collage of Plant Protection, Lanzhou 730070, China
Key Words：Bradysia difformis Frey, plant, developmental duration, survival rate, parameters of population dynamics
Abstract：[Objectives] To clarify the growth, development and reproductive rhythm of Bradysia difformisFrey on Chinese chives, broad beans, lettuce, chinese cabbage and wild cabbage. [Methods] B. difformis damages the underground parts of economic crops, which causes heavily losses of growing production. Experiments were conducted in an artificial climate chamber where B. difformis larvae were raised on different host plants and their growth, development and reproductive rhythm were measured to calculate population dynamics parameters. [Results] The developmental duration from egg to pupa was longest on wild cabbage, followed by Chinese cabbage, Chinese chives and lettuce, and shortest on broad bean. There was no significant difference in the longevity of females and males on different plants, but different plants had a significant effect on the average number of eggs per female and pupal weight. The maximum and minimum number of eggs laid per female were on leeks and wild cabbage, respectively. Pupae were heaviest on Chinese chives, the lightest on lettuce. The survival rates of B. difformis decreased with development, the survival rate of each instar was highest on leeks, and lowest on lettuce. Net reproductive rate (R0) and intrinsic rate of increase (rm) were highest on Chinese chives and lowest on wild cabbage. Mean generation time (T) as shortest on broad beans and longest on Wild cabbage. Population doubling time (t) was shortest on Chinese chive and longest on Wild cabbage. [Conclusion] Although B. difformis could complete its growth and reproduce on all five plants tested, these can be ranked in descending order of suitability as follows: Chinese chive, then broad bean, Chinese cabbage, wild cabbage, lettuce.