Autumnal moth – why autumnal?

1. As for some other spring‐feeding moths, adult flight of Epirrita autumnata (Lepidoptera: Geometridae) occurs in late autumn. Late‐season flight is a result of a prolonged pupal period. Potential evolutionary explanations for this phenological pattern are evaluated. 2. In a laboratory rearing, there was a weak correlation between pupation date and the time of adult emergence. A substantial genetic difference in pupal period was found between two geographic populations. Adaptive evolution of eclosion time can thus be expected. 3. Metabolic costs of a prolonged pupal period were found to be moderate but still of some ecological significance. Pupal mortality is likely to form the main cost of the prolonged pupal period. 4. Mortality rates of adults, exposed in the field, showed a declining temporal trend from late summer to normal eclosion time in autumn. Lower predation pressure on adults may constitute the decisive selective advantage of late‐season flight. It is suggested that ants, not birds, were the main predators responsible for the temporal trend. 5. Egg mortality was estimated to be low; it is thus unlikely that the late adult period is selected for to reduce the time during which eggs are exposed to predators. 6. In a laboratory experiment, oviposition success was maximal at the time of actual flight peak of E. autumnata, however penalties resulting from sub‐optimal timing of oviposition remained limited.     

Endophytic fungi in wild and cultivated grasses in Finland

We examined the occurrence of vertically via host seeds transmitted endophyte infections of 14 grass species in natural populations in Finland and totally 97 agricultural cultivars of 13 grass species. Although endophyte infections were widespread in native grass species, overall endophyte occurrence and frequencies were lower than published reports have suggested. In natural populations, 10 out of 14 grass species examined harbor fungal endophytes in their seeds. The highest species-specific mean incidences of endophyte infected plants in infected populations were found in Agrostis capillaris. Festuca arundinacea. F. ovina. F. Pratensis. F. rubra and Phleum pratense (67%, 98%, 29%., 42%. 32% and 33%, respectively). Mean incidences were < 20% in Dactylis glomerata. Deschampsia flexuosa. D. cespitosa and Elymus repens. and no infections were detected in Calamagrostis lapponica. C. epigejos. Alopecurus pratensis and Phalaris arundinacea. However, we detected a very high variation in infection incidences among natural populations and a large proportion of populations was, indeed, endophyte-free. This supports the ideas that 1) endophytic fungi provide selective advantage of infected grasses to their uninfected eonspecifics in some habitats, and/or 2) fungi are occasionally transmitted horizontally by spores. In grass cultivars, endophyte infected seeds were detected only in F. Pratensis and Lolium perenne. and endophyte frequencies were either very high or very low. Cultivars of 11 other grass species were endophyte-free.     

Alien aquatic vascular plants in Hungary (Pannonian ecoregion): Historical aspects,data set and trends

Estimating the extent of biological invasions is critical in predicting the effect of exotic species. We investigated the occurrence and number of alien freshwater plants and give information on the composition of alien aquatic flora, their trend in time, invasion pathway, and their invasive character.     

Life history tradeoffs in relation to the degree of polyandry and developmental pathway in Pieris napi (Lepidoptera, Pieridae)

Pieris napi females have different heritable reproductive tactics. Polyandrous females have higher lifetime fecundity, whereas monandrous ones start to reproduce at a faster rate. Butterfly larvae are time‐constrained in seasonal environments. Thus, polyandry is expected to be associated with fast juvenile development, which may result in biased mortality due to physiological costs. We compared how females with varying degrees of polyandry allocate between duration of larval period and achievable size in directly developing and over‐wintering generations. Offspring survival and growth were monitored under a high density and low quality diet. Polyandrous females developed at a faster rate than monandrous ones, regardless of developmental pathway. The growth rate of female offspring correlated with their mothers’ degree of polyandry, which underpins polyandry and monandry as distinct strategies with life history differences reaching beyond mating frequency. The high growth rate of polyandrous females resulted in a short larval period among directly developing females, and in large size within an over‐wintering cohort. A change in either the duration of the larval period or pupal mass had no significant effect on the other, emphasising that growth rate is not necessarily a simple outcome of the tradeoff between development time and size at maturity. The correlation between the degree of polyandry and juvenile growth rate diminished when larvae were exposed to environmental stress, which offers an explanation why juvenile mortality was decoupled from mating tactic. We conclude that polyandry is a strategy that allows larvae to utilise optimal conditions in a more effective way than monandry. As a consequence, polyandrous females either achieve larger size or they mature faster. This gives them a double advantage over monandrous ones within an over‐wintering generation or diminishes the effects of asynchronous hatching of offspring within a directly developing generation. Possible costs of high growth rate are discussed.     

Smaller Microtus vole species competitively superior in the absence of predators

Interspecific competition is assumed to generate negative effects on coexisting species, possibly including slower population growth and lower survival. The field vole ( Microtus agrestis ) and the sibling vole ( M. rossiaemeridionalis ) are sympatric close relatives which compete for similar resources. Previous non-experimental studies suggest that the smaller sibling vole is a superior competitor, yet more vulnerable to predation than the larger field vole. We studied the effects of coexistence on population densities, reproductive parameters, and survival in these two species by means of experimentation in large, predator-free outdoor enclosures. While populations of both species reached higher densities in the absence of the other, field voles appeared to suffer more from interspecific competition than sibling voles. The proportion of young individuals in the population was higher in the sibling vole than in the field vole at the end of the experiment. The presence of a coexisting species reduced the survival of field voles. Sibling voles, on the other hand, appeared to suffer more from intraspecific competition than interspecific competition. On a population level, the sibling vole seems to be a superior competitor in the absence of predators due to better survival and possibly a higher reproductive capacity. However, predation probably has a profound influence on the interspecific dynamics of these two species indicating that in natural surroundings apparent competition (i.e. competition via shared predators) is stronger than direct competition.     

Effect of ethanol on thromboxane and prostacyclin synthesis by fetal platelets and umbilical artery

The effect of ethanol (10-500 mmol/l) on platelet thromboxane production and on vascular thromboxane and prostacyclin was studied in human fetal tissues. The release of thromboxane B2 (a metabolite of thromboxane A2) during thrombin-induced spontaneous aggregation of fetal platelets was inhibited by ethanol concentrations of 50 mmol/l or higher. Ethanol at concentration from 100 mmol/l also inhibited umbilical artery production of thromboxane B2 and that of 6-keto-prostaglandin F1 alpha (a metabolite of prostacyclin). However, it stimulated the conversion of exogenous arachidonic acid to thromboxane B2 in fetal platelets and to 6-keto-prostaglandin F1 alpha in the umbilical artery. This suggests that ethanol inhibits phospholipase A2, but stimulates the enzymes distal from phospholipase A2 in the prostaglandin-synthesizing enzyme cascade.     

Dietary shifts,niche relationships and reproductive output of coexisting Kestrels and Long-eared Owls

Summary Food samples of breeding Kestrels (Falco tinnunculus) and Long-eared Owls (Asio otus) were collected in the peak and low phase of their preferred prey (Microtus voles) in western Finland. Diets of pairs that bred as neighbours (1 km) with interspecifics were compared with those of non-neighbours. In both species, neighbouring pairs fed less on Microtus voles and more on alternative prey than did non-neighbours. Competition theory predicts that diet overlap should be lower during prey shortage and that diet similarity should be especially reduced in neighbouring pairs. Observations were consistent with expectations: diet similarity was lower in the low vole years and neighbouring pairs showed less diet overlap that non-neighbours. Differences in habitat composition and prey availability at the sample sites should not confuse the results. In addition to the high diet similarity, hunting habitats and nest sites of the species overlapped almost completely; they only showed clear temporal segregation in hunting. Probably because of food competition, the neighbouring pairs of both species produced significantly fewer young than the non-neighbours. These results contrast with the view that the diet composition and dietary shift of rodent-feeding predatory birds can be interpreted in terms of simple opportunistic foraging. In the breeding season, interspecific competition for food seems to be an important factor that affects the niches of these species, especially in northern areas, where the seasonal low phase of voles in spring and the number of alternative prey are lower than in more southern areas.     

Septal deafferentation produces continuous rhythmic slow activity (theta) in the rat hippocampus

Hippocampal EEG was recorded in behaving rats in which the brain stem afferents to the septal region were previously damaged. In these animals rhythmic slow activity (RSA or theta) was continuously present, including drinking and immobility. The average frequency of RSA, however, was significantly higher during running (8-9 Hz) than during drinking or awake motionless state (6-8 Hz). In normal rats irregular sharp waves, rather than RSA were present during drinking and immobility. The results suggest that brain stem afferents are necessary to suppress the rhythmic firing of septal "pacemaker" cells.