幼虫密度对井上蛀果斑螟生长发育和生殖的影响

Effects of larval density on growth and development and reproduction of Assara inouei

为明确井上蛀果斑螟种内竞争密度效应对种群增长的影响,在室内饲养条件下,设置1、5、10、15、20和25头·皿-(1Φ=9 cm)6种不同幼虫密度处理,测定井上蛀果斑螟各虫态发育历期、存活率、繁殖率和种群增长指数等生物学参数。结果表明,井上蛀果斑螟雌、雄蛹质量和平均单雌产卵量随幼虫密度增加显著减少;幼虫密度对预蛹期、成虫羽化率、雌雄性比和子代卵孵化率无显著影响。幼虫密度为15头·皿-1,幼虫发育最好,其存活率和化蛹率分别为65.67%和98.83%,幼虫和蛹发育历期分别为18.32 d和7.01 d,成虫产卵期为7.61 d,种群增长指数最高,为26.52。当幼虫密度大于15头·皿^(-1),随幼虫密度增加,幼虫存活率和化蛹率显著减少,幼虫和蛹发育历期显著延长,成虫产卵期显著缩短。幼虫密度为25头·皿^(-1),幼虫发育最差,其存活率和化蛹率分别为36.12%和76.67%,幼虫和蛹发育历期分别为20.36 d和8.56 d,成虫产卵期为5.29 d,种群增长指数最低,仅为4.57。井上蛀果斑螟幼虫期存在密度制约效应及密度临界值;在特定空间,幼虫密度超过临界值时发生密度效应,使该虫种群数量显著减少。

In order to explore the density effects of intraspecific competition on the population growth of Assara inouei,the biological charactristics of the developmental duation,survival rate,reproduction rate and life table parameters were examined by rearing larvae at the densities of 1,5,10,15,20 and 25 larvae·dish-1(Φ=9 cm)under laboratory conditions.The results showed that pupal mass of male and female and the average number of eggs per female decreased significantly as the larval density increased.Larval density had no significant effect on pre-pupal duration,adult eclosion rate,female to male adult sex ratio and hatching rate of offspring eggs.When the larval density was 15 larvae·dish^(-1),the larval development was the best,the survival rate and pupation rate were 65.67%and 98.83%,respectively,the larval duation and pupal duration were 18.32 d and 7.01 d,respectively,oviposition duration of adult was 7.61 d,and the population growth index was the highest(26.52).When the larval density was greater than 15 larvae·dish^(-1),the survival rate and pupation rate of larvae were significantly reduced,the larval duation and pupal duration were significantly prolonged,and the oviposition duration of adult was significantly shortened with the increase of larval density.When the larval density was 25 larvae·dish-1,the larval development was the worst,the survival rate and pupation rate were 36.12%and 76.67%,respectively,the larval duation and pupal duration were 20.36 d and 8.56 d,respectively,oviposition duration of adult was 5.29 d,and the population growth index was the lowest(4.57).The larval stage of Assara inouei had a density restriction effect and a density critical value.When the larval density was higher in a limited space,an obvious density effect would occur,which significantly reduced the population of this pest.