天敌宽体金线蛭胁迫对不同性比福寿螺种群特征的影响

Effects of stress by the natural enemy Whitmania pigra on population characteristics of Pomacea canaliculata Lamarck with different sex ratios

  • 摘要: 【目的】研究天敌宽体金线蛭胁迫下不同性比福寿螺种群的响应,探明福寿螺在天敌胁迫下的种群特征变化,为揭示福寿螺在天敌胁迫下快速入侵策略以及在繁殖环节通过调控其性比例来防控福寿螺的危害提供科学依据。【方法】采用3重复随机区组试验,将3种不同性比福寿螺种群(雌雄比分别为2∶1、1∶1和1∶2)与天敌宽体金线蛭置于水族箱中共养21 d,以不投放宽体金线蛭为对照,定期调查福寿螺的存活、摄食、行为活动和繁殖特征(产卵量、孵化率、孵化历期等)。【结果】宽体金线蛭的存在抑制了福寿螺的存活,不同性比福寿螺种群存活率均降低50.0%以上,但不影响存活个体的日均摄食量;雌多雄少福寿螺种群的存活率和日均摄食量高于雌雄等量和雌少雄多种群,分别高于后两者20.0%和40.0%以上;福寿螺通过减少摄食(降幅达58.0%)和增加闭厣(增幅达194.0%)行为以应对宽体金线蛭的捕食,而性比对福寿螺行为活动影响不明显;雌性占比越低,种群产卵量越少,受天敌抑制越明显,雌多雄少福寿螺种群在天敌胁迫下产卵量未见明显减少,而雌少雄多种群产卵量锐减近90.0%;宽体金线蛭的存在提升了福寿螺卵孵化率(增幅达32.0%),并缩短了孵化历期(降幅达8.0%)。【结论】宽体金线蛭的存在会抑制福寿螺生存和繁殖,雌多雄少的性比结构有利于福寿螺种群应对天敌威胁。

     

    Abstract: 【Objective】 The purpose of the study was to investigate the response of Pomacea canaliculata Lamarck population with different sex ratios under the stress of the natural enemy Whitmania pigra,to explore changes of population characteristics of P. canaliculata under the natural enemy stress,and to provide scientific basis for revealing the rapid invasion strategies of P. canaliculata under natural enemy stress as well as for preventing and controlling P. canaliculata damage through the regulation of its sex ratios in breeding period.【Method】 By using three repeated randomized block experiments,three P. canaliculata populations with different sex ratios(2:1,1:1,and 1:2 for males and females,respectively) were put to coexist with the natural enemy W. pigra in aquaria for 21 d,with no W. pigra put in aquaria as the control,and the survival,feeding,behavior and reproductive characteristics(egg-laying amount,hatching rate,incubation period,etc.) of the P. canaliculata were regularly surveyed.【Result】 The survival of P. canaliculata was inhibited by the presence of W. pigra,and the survival rate of P. canaliculata populations with different sex ratios decreased by more than 50.0%, but the average daily intake of P. canaliculata was unaffected. The survival rate and average daily intake of P. canaliculata populations with a female-biased sex ratio were higher than those with an equal number of males and females and those with a male-biased sex ratio,which were higher than those of the latter two by more than 20.0% and 40.0% respectively. Reduced feeding(58.0% decline) and increased closed operculum(194.0% increase) in behavior of P. canaliculata were emerged in response to predation by W. pigra,but the impact of sex ratios was not distinct in the behavior of P. canaliculata. The lower the proportion of female in P. canaliculata,the lesser the egg-laying amount of the population, and the more obvious the inhibition of natural enemy. The egg-laying amount for female-biased population of P. canaliculata was not reduced under natural enemy stress,but egg-laying amount for male-biased population of P. canaliculata slumped by nearly 90.0%. The hatching rate of P. canaliculata eggs was enhanced by 32.0% and the incubation period was shortened by 8.0% in the presence of W. pigra.【Conclusion】 The presence of W. pigra can inhibit the survival and reproduction of P. canaliculata,but female-biased sex ratio is beneficial for P. canaliculata population to cope with natural enemy stress.

     

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