POPULATION BIOLOGY AND SPECIES INTERACTIONS IN HERBIVOROUS INSECTS

草食性雌甲虫在寄主植物丰度方面表现出较高的种群密度稳定性。田间试验表明，具有生殖能力的雌蜂在子房中吸收卵子是对寄主植物退化的反应。雌虫择优产卵，在卵量较少的植物上产卵。这些特定的产卵策略导致种群的时间资源跟踪，通过密度依赖减少每只雌性实现的卵。随着卵密度的增加，子代终生适合度降低。这表明在卵密度较低的植物上产卵可以提高雌性产卵的终生繁殖成功率。当繁殖季节后期资源恶化或淹没等生境干扰导致后代适合度显著下降时，卵的吸收可能具有适应意义。它还增加了在第二个繁殖季节产卵的机会，通过增加随后的卵子吸收雌性的存活率。因此，生殖雌性的产卵行为在时间和空间上与其后代的终生适合度高度相关。

An herbivorous lady beetle Epilachna niponica exhibited a high stability of population densities in terms of host plant abundance. Field experments revealed that reproductive females resorbed eggs in the ovary in response to host plant deterioration. Also, females selected oviposition site carefully, by laying eggs on plants with less egg load. These specified oviposition tactics resulted in a temporal resource tracking of populations, through density-dependent reduction in realized eggs per female. Lifetime fitness of offspring decreased with increasing egg density. This implies that oviposition on plants with less egg density improves lifetime reproductive success of an ovipositing female. Egg resorption could have adaptive significance when offspring fitness drops considerably due to resource deterioration late in the reproductive season or habitat disturbance such as inundation. It slso enhances a chance of future oviposition in the second reproductive season, through increasing subsequent survival of egg-resorbed females. Consequently, the oviposition behavior of reproductive females in time and space is highly correlated with lifetime fitness of their offspring.