INVERSION POLYMORPHISM,LONGEVITY, AND BODY SIZE IN A NATURAL POPULATION OF DROSOPHILA BUZZATII

In this study we present the results of an analysis of differential longevity associated with Drosophila buzzatii second chromosome inversion karyotypes based on the assessment of more than 1000 individuals collected in a natural population. Comparisons of inversion frequencies between emerged and bait-collected flies showed not only that inversion arrangements were associated with differential longevity, but also that selection was sex specific. Because each individual fly was scored for thorax length and karyotype, we were able to show that longevity selection favoring larger flies coupled with the average effect of inversions on thorax length can account for the change of inversion frequencies due to longevity in females. The observed genotypic-by-sex interaction could be an important mechanism involved in the maintenance of the polymorphism. Arrangement 2Jz³, which was shown to impaired fecundity in two independent previous studies, exhibited a positive effect on longevity. This pattern of negative pleiotropy may be another plausible mechanism accounting for the maintenance of the polymorphism.     

POLLEN LONGEVITY AND STIGMA PRE-EMPTION IN CLARKIA

The ability of pollen to effect seed set decreases with age when stored at room temperature or on the plant, but not when stored at 5 C. Seed set declines rapidly with pollen stored 10 days or more at room temperature. Seed set declines rapidly with pollen stored 4 days or more on the plant. The degree of pollen germination on the stigma and the number of pollen tubes in the style correlate positively with seed set. Pollen germination on the stigma and pollen tube growth in the style are strongly correlated with seed set for pollen stored at room temperature, but not, or only weakly, correlated for pollen stored at 5 C. In the latter case, seed sets are lower than expected, indicating a possible viability reduction associated with a post-pollination function. Inviable pollen grains temporarily interfere with normal pollen germination on the stigma. Essentially no seeds are produced when in viable pollen, immediately followed by viable pollen, is placed on a fresh stigma. However 27 to 65 seeds are produced when in viable pollen, followed in 1 to 6 days by viable pollen, is placed on fresh stigmas. New stigma surface is exposed at the center as expanding stigma surfaces carry the interfering inviable pollen toward the edge of the stigma.     

温、湿度对亚洲玉米螟成虫繁殖力及寿命的影响

温度和湿度的变化对亚洲玉米螟0strinia furnacalis(Guenee)成虫的交配和产卵及寿命都具有极显著的影响。在16℃～32℃和RH20%～100%的温湿范围中,亚洲玉米螟成虫繁殖力在20℃～28℃恒温和RH70%～100%的温湿组合中较大,其中在24℃恒温和28℃～20℃变温与RH90%～100%的组合中为最大,在32℃和RH20%的组合中为最小。单雌抱卵量、产卵量和产出卵率及交配次数均与温度呈抛物线曲线关系,与湿度呈正相关。温、湿度对成虫繁殖力具有极显著的交互作用。成虫寿命与温湿度密切相关,温度越高,成虫寿命越短;而湿度越高,成虫寿命越长。但雄蛾比雌蛾较耐低湿,在16℃～24℃下雄蛾寿命比雌蛾较长。此外,雄蛾较强的交配能力可促进卵的发育和产出。以上结果对玉米螟种群动态消长的分析和预测预报提供了参考依据。