Stability of environment and of insect populations

Summary The abundance of moths was monitored with light-traps in two sites in southern Bohemia, České Budějovice for 22 years and in Černiš for 9 years. In these sites, that are vastly different in environmental stability and predictability, stability of insect populations was studied. The amplitude of fluctuations in abundance of the insect populations, as measured by the coefficient of variation (CV), varied a great deal between species so that there was a large overlap between the two sites. Nevertheless there was a highly significant tendency for species at Černiš, the more stable site, to have smaller values of CV, i.e., to be less fluctuating. Also in species co-occurring in the two sites, the CV at Černiš tended to be smaller. Trends in abundance of individual species over time, both increases and decreases, were common in both sites and did not differ between habitats. Environmental stability begets insect population stability in terms of the amplitude of the fluctuations, but trends in time occur irrespective of stability of the habitat.     

蝴蝶研究对纳博科夫小说美学的发生学意义

作为后现代主义文学先驱,纳博科夫对蝴蝶的痴迷及科学研究活动是其小说美学思想生发的最根本的内在动因,即他的科学活动对他的小说美学思想具有发生学意义：对蝴蝶的迷恋与研究培育出纳博科夫独特的“元学精神”,并让他发现科学与艺术之间异质同构的“审美狂喜”的特征,由此而导引出他独特的艺术本源论与艺术本质论。     

广州地区及其近郊蛾类初步调查

从1993年7月至1996年5月,通过对广州市地区及近郊13个点的蛾类调查共采得标本650余号,分属于19科,190种。     

Lepidoptera-habitat relationships in urban parks

We examined the relationships among Lepidopteran species richness and relative abundance, field and park size, and herbaceous plant richness and cover in parks of New York, NY. Lepidopteran populations and habitats were quantified from 1 June–30 September 2002 in fields of 8 New York City (NYC) parks. We observed 42 species of Lepidoptera, with park size, field size, and plant species richness positively related to Lepidopteran abundance and species richness. Several plant species received heavy use and appeared to be important to Lepidoptera in this urban environment, particularly butterfly-bush (Buddleia davidii), mugwort (Artemisia vulgaris), knapweed (Centaurea maculosa), and clover (Trifolium spp.).     

Persistence of abnormal females that produce only female progeny with occasional recovery to normal females in Lepidoptera

In Lepidoptera, females that produce only female progeny have been found in wild populations of at least 12 species. In some species, recoveries, where abnormal females return to normal females, have been observed. A mathematical model of the population dynamics with recovery was developed to identify the conditions for realizing the persistence of abnormal females. Analysis indicated normal and abnormal females coexist and reach an equilibrium state at certain recovery rate values. The equilibrium values of normal and abnormal females were determined. When a population was in equilibrium it was shown that the ratio of normal to abnormal females and the sex ratio after reproduction are always functions of the recovery rate and the proportion of female offspring from an abnormal female to that from a normal female. Using the simulation it was found that, even when a population fluctuates under variable environmental conditions, the two ratios mentioned above reach equilibrium. Equilibrium relationships were applied to published data, and it was concluded that recovery from abnormal to normal females explains the persistence of abnormal females in some species of Lepidoptera. The model developed in this paper can also be used for analysing the persistence of abnormal females of other insect species.     

Persistence of females that produce only female progeny in lepidoptera

Summary In Lepidoptera females that produce only female progeny, can be found in wild populations of at least 11 species. The genetic variation is passed on to each generation of female offspring. If genetically abnormal females produce more female offspring than normal females do and mating is random, then populations containing these abnormal females will have a biased population sex ratio. Unmated females will increase due to the scarcity of males and so the population as a unit will die out. Several possible biological explanations for the persistence of the genetic variation have been proposed. But experiments and observations have not verified those hypotheses. Simulations of Heuch's model (1978), however, have shown that the variation persists if the population is distributed, in patches and there is dispersal among patches, even when insects disperse at random. Abnormal females tend to persist at both low and high migration rates, but the probability of persistence is higher at high migration rates. It has been suggested that abnormal females in a population are an adaptation, but the results of this investigation show that this explanation, may not be plausible.     

Effects of urbanization on butterfly species richness,guild structure,and rarity

We evaluated the effects of landscape characteristics associated with urbanization, as well as local features, on butterfly species richness at four spatial scales (50, 150, 500, and 1,000 m from survey plots). We also evaluated these effects separately by butterfly guilds based on their region-wide rarity and on degree of specialization. The distribution of abundances of the 44 species observed showed an excess of uncommon species compared to a log-normal distribution, and the two most abundant species were exotic (Thymelicus lineola and Pieris rapae). We used an information theoretic approach to model selection to determine the most important correlates of butterfly species richness. Models of mean butterfly richness per visit explained greater variance than did models of cumulative richness across the season. Cumulative butterfly species richness was affected more at larger spatial scales, while richness per visit was affected similarly at all spatial scales. The most consistent local factor affecting butterfly diversity was the number of nectar producing plants that were flowering. The most consistent landscape-level correlates of species richness were number of people (at small spatial scales) and green space. Measures of increased urbanization were associated with decreased butterfly species richness, and rare and specialized species were most affected. Species that were regionally rare, and those that specialized both in host plants and had few broods, disappeared with declining richness across sites 2.9–4.5 times faster than did generalists and less restricted specialists.