光周期对莲草直胸跳甲生长发育和繁殖的影响

为明确莲草直胸跳甲Agasicles hygrophila Selman et Vogt的生态适应性,提高其对恶性杂草喜旱莲子草Alternanthera philoxeroides(Martius)的生物防治效率,研究了7组不同光周期对其生长发育和繁殖的影响。结果表明:不同光周期处理下,莲草直胸跳甲卵的孵化历期差异显著,在L∶D=12 h∶12 h时孵化历期最短,为4.33 d;其化蛹率无显著差异。相较于短光期,长光期条件更适合其幼虫生长发育。随着光照时数的增加,莲草直胸跳甲成虫寿命、产卵历期、雌虫产卵量呈明显单峰趋势,光周期为L∶D=12 h∶12 h时,成虫寿命和产卵历期最长,分别为41.8 d和34.0 d;光周期为L∶D=8 h∶16 h时,雌虫产卵量最高,为98.5块。不同光周期处理下其成虫后代的孵化率均高于85%,各处理间均无显著差异。在7组光周期处理下,莲草直胸跳甲均未出现生长与生殖停滞及大量死亡现象。生命表分析结果显示,光周期为L∶D=12 h∶12 h时,莲草直胸跳甲种群的净增殖率、平均世代周期及内禀增长率均最高,分别为386.88、45.36和0.13;而种群增殖时长最短,为5.27 d。表明光周期为L∶D=12 h∶12 h时最适合莲草直胸跳甲生长发育和繁殖。

Effects of different photoperiods on growth, development and reproduction of the alligator weed flea beetle Agasicles hygrophila

To clarify the alligator weed flea beetle, Agasicles hygrophila Selman et Vogt, ecological adaptability and improve its biocontrol efficiency to alligator weed Alternanthera philoxeroides (Martius), the effects of seven different photoperiod treatments on growth, development and reproduction of A.hygrophila were investigated in the laboratory. The results showed that there were significant differences in hatching duration among the seven treatments. Under the 12/12 h photoperiod, flea beetles had shortest hatching duration of 4.33 d. There was no significant difference in pupation rate among all light conditions. Compared with short light conditions, long light conditions were more suitable for larval growth and development. The longevity, oviposition duration and number of egg masses laid by females in an experimental period of 30 days showed single clear peaks with increasing illumination time. The longevity and oviposition duration of 41.8 d and 34.0 d were higher under the 12/12 h photoperiod than any other photoperiods. Under the photoperiod of 8/16 h, the fecundity in 30 days of female beetle adults was the highest of 98.5. The hatching rates were all higher than 85% among seven different photoperiods, and there were no significant difference among treatments. Flea beetles did not show growth retardation, reproduction stagnation and mass mortality under seven photoperiods. Life table of flea beetle during the different photoperiods showed that the population had the highest net reproductive rate, mean generation time, intrinsic rate of increase and the lowest doubling time under 12/12 h, with the values of 386.88, 45.36, 0.13 and 5.27 d, respectively. Therefore, the photoperiod of 12/12 h was the most suitable condition for flea beetle growth, development and reproduction.