No abstract

Protandry (the emergence of males before females) is currently explained either as a mating strategy to maximize number of matings in the males, or a way to minimize pre-reproductive mortality in females. Models of protandry have generally ignored variation in female quality (reproductive potential). We recorded the sex ratio, female body mass, wing length and potential fecundity (number and mass of eggs) of the tropical butterfly Brassolis sophorae through the emergence period. Temporal variation in female size and fecundity correlated with male potential for acquiring mates. Females from the end of the emergence period showed lower fecundity and size. Males emerging before and close to the median date of the female emergence period had greater mating opportunities. Males emerging either very early or late were penalized by few mating opportunities, or by encounters with small, low-quality females, respectively.

Mortality factors were determined in over 20000 pupal skins of Brassolis sophorae and Opsiphanes invirae, collected from 55 sites in the urban area of Campinas, São Paulo, southeast Brazil. Almost 50% of B. sophorae pupae and 30% of O. invirae pupae were killed by various identifiable factors, which may have an appreciable influence in determining adult population size. Mortality was related to type of attachment site, distance from the center of the city, area occupied by buildings and houses, vegetation cover, and other urban variables. Exposed pupation sites such as outside walls had a lower frequency of successful eclosions than darker or more sheltered sites, such as offset skirting boards, garages, or mailboxes, which act as partial refuges against parasitoids. Mortality levels were higher in regions of the city with high vegetation cover. Vegetation cover and distance from the city center were the best predictors of parasitism level of B. sophorae by the chalcidid wasp Spilochalcis morleyi. The viability of S. morleyi (data from parasitized B. sophorae) did not differ significantly among different regions of the city. These data do not support an exclusive model of "escape from parasites" (or other natural enemies) for explaining the abundance of urban butterflies.

Comparou-se o número médio de adultos emergidos, número de imaturos mortos e a freqüência com que ocorre a morte de toda a prole nos parasitóides Spilochalcis morleyi (Hymenoptera, Chalcididae) e Xanthozona melanopyga no hospedeiro, Brassolis sophorae (Lepidoptera, Nymphalidae). O número de parasitóides (Spilochalcis) que completaram seu desenvolvimento e emergiram foi significativamente maior em pupas femininas do hospedeiro. O número médio de imaturos de Spilochalcis mortos por pupa não diferiu entre os sexos do hospedeiro. Entretanto, nas pupas femininas de B. sophorae ocorreu uma freqüência significativamente maior de morte de toda a prole em ambas as espécies de parasitóides.

Biology of Methona themisto (Hübner, 1818) (Lepidoptera, Nymphalidae, Ithomiinae) adults in public plazas in Uberlândia, Minas Gerais, BrazilFrom April 1992 to September 1993 Methona themisto (Hübn.) adults were weekly marked and recaptured in two downtown plazas in Uberlândia, MG. Females accounted for a third of the 637 individuals marked. Nearly 10% of the butterflies were recaptured, with the maximum residence time of 62 days. The presence of the larval host plant (Brunfelsia uniflora (Pohl) D. Don, Solanaceae) in one of the plazas enhanced a higher abundance of the butterfly throughout the research and a higher proportion of new individuals, and frequency of migrants than the other plaza which lacked the host plant. Methona themisto adults were active through the sampling period with overlapping generations. Its abundance in plazas with polluted air and exotic flora, long adult life, and tolerance to humans in its vicinities place M. themisto among the ones indicated to have its life conditions improved in downtown areas of brazilian cities. Simple managing practices which benefit the lepitopteran are suggested.Key words: Lepidoptera, Methona themisto, urban habitat, mark-recapture, insect conservation. RESUMONo período de abril de 1992 a setembro de 1993, os adultos de Methona themisto (Hübn.) foram semanalmente marcados e recapturados em duas praças centrais de Uberlância (MG). Dos 637 indivíduos marcados nas duas praças, um terço era fêmea. Aproximadamente 10% dos indivíduos foram recapturados, sendo de 62 dias o máximo tempo de residência registrado. A presença da planta hospedeira das larvas (Brunfelsia uniflora, (Pohl) D. Don, Solanaceae) em uma das praças proporcionou maior abundância do lepidóptero ao longo da pesquisa, maiores porcentagens de indivíduos novos e maior freqüência de migrantes do que a outra praça pesquisada, que não continha a planta hospedeira. Methona themisto manteve-se ativa no estágio adulto durante todo o período de amostragem com sobreposição de gerações. Sua abundância em praças com ar poluído e flora exótica, vida adulta longa e tolerância à proximidade do homem, colocam M. themisto entre as espécies indicadas para ter suas condições de vida melhoradas em áreas centrais das cidades brasileiras. Simples práticas de manejo que beneficiam esse lepidóptero são sugeridas.Palavras-chave: Lepidoptera, Methona themisto, hábitat urbano, marcação e recaptura, conservação de insetos.