Diapause is a common dormancy strategy exhibited by many species of invertebrates and insects to temporarily avoid seasonally recurring unfavourable conditions for their development, most usually in winter. Less frequently, a prolonged diapause lasting two or more years is described in species living in unpredictable environments where it is adaptive, but with significant costs. In this paper we examine the occurrence of prolonged diapause in the lycaenid butterfly Tomares ballus. Pupae of this species undergo an obligate diapause from mid-May to late January the following year. However, during our rearing experiments (from 2009 to 2016) the emergence of adults occurred sequentially and a fraction of the pupae remained in diapause for up to seven years. The annual percentage emergence after the first year of diapause was 45.6%, and only barely exceeded 50.0% in 2015. Remarkably, 12 pupae (11.4% of the initial brood) remained in diapause in their eighth year. The negative exponential equation fitted to the emergence data suggests that further emergences may occur within the next five years. Therefore, the potential for successful prolonged diapause of T. ballus pupae may be more than 10 years. The adaptive value of this strategy is discussed in relation to the effects of adverse and unpredictable weather during the flight period of the butterfly, intra-guild competition, parasitoids and changes in habitat quality. We suggest that this strategy may also be exhibited by other species of Mediterranean lycaenids., Rafael Obregón, Juan Fernández Haeger, Diego Jordano., and Obsahuje bibliografii
Parasitoid females may adjust offspring sex allocation according to the number and quality of hosts available. Because in solitary species only one offspring survives per host, already parasitized hosts are of low quality and generally rejected. Superparasitism (i.e., sequential oviposition by the same or different females) results in aggressive interactions and competition for nutritional resources among larvae. We examined variations in the offspring sex ratio of Dendrocerus carpenteri (Curtis) (Hymenoptera: Megaspilidae), a solitary ectoparasitoid developing as a hyperparasitoid on the prepupae and pupae of primary aphid parasitoids inside mummified aphids. Mated females produced a female-biased sex ratio of 0.433 (proportion of sons) when caged singly and provided with 12 mummies for 2 h; they parasitized an average of four mummies/h and rarely superparasitized. Superparasitism increased when two females were caged together and provided with 12 mummies, from 1.18 to 1.24 and 1.38 eggs/host parasitized in 1, 2 and 3 h, respectively. The offspring sex ratio became increasingly more female-biased with increase in superparasitism; however, sex ratio variations were not correlated with cohort size. One mated and one unmated female provided with 12 mummies and caged together for 1 h produced a mean cohort sex ratio of 0.645, which differed from the one predicted (0.717) by an algebraic model incorporating the assumptions that both females contribute equal numbers of offspring and that the mated female does not change her offspring-sex allocation strategy. The observed shift in the cohort sex ratio to an increased female-bias indicates that mated females of D. carpenteri change their behaviour when encountering parasitized mummies or a conspecific competitor in the same patch. By depositing fertilized rather than unfertilized eggs, a female can increase the proportion of her daughters among parasitoids competing for a diminishing host supply., Manfred Mackauer, Andrew Chow., and Obsahuje bibliografii
In the parthenogenetic monogeneans of the genus Gyrodactylus Nordmann, 1832, the genetic diversity within or between hosts is determined by the relative roles of lateral transmission and clonal propagation. Clonality and limited transmission lead to high-amplitude metapopulation dynamics and strong genetic drift. In Baltic populations of the three-spined stickleback Gasterosteus aculeatus Linnaeus, the local mitochondrial diversity of Gyrodactylus arcuatus Bychowsky, 1933 is very high, and spatial differentiation weak. To understand the transmission dynamics in a single location, the transmission of the parasite from adults to next generation sticklebacks was investigated in a northern Baltic brackish water location. By sequencing 777 nt of cox1, as many as 38 separate mitochondrial haplotypes were identified. In August, the intensity of gyrodactylid infection on adult hosts was high, the haplotype diversity (h) was extreme and differentiation between fish was negligible (total h = 0.926, mean h = 0.938). In October, only 46% of the juvenile sticklebacks carried G. arcuatus. The number of parasites per young fish followed a Poisson distribution 0.92 ± 1.04 (mean ± SD) on October 2, and was clearly overdispersed 2.38 ± 5.00 on October 25. The total haplotype diversity of parasites on juveniles was nearly as high as in adults (h = 0.916), but the mean per fish was only h = 0.364 (FST = 0.60), due to low intensity of infection and rapid clonal propagation of early arrivals. The initial first come first served advantage of the first gyrodactylid colonisers will be lost during the host adulthood via continuous transmission. Nesting and polygamy are suggested as factors maintaining the high genetic diversity of the parasite population. The transmission dynamics and, consequently, the population structure of Baltic G. arcuatus is fundamentally different from that of G. salaris Malmberg, 1957, on the Baltic salmon Salmo salar Linnaeus., Jaakko Lumme, Marek S. Ziętara., and Obsahuje bibliografii
In mammalian carnivore guilds (order Carnivora), spatiotemporal partitions play a major role in reducing competitive confrontations and facilitating successful sympatry. Using camera-trapping techniques, the present study aimed to elucidate patterns of spatial distribution and diel activities among medium- and large-sized carnivore species across central Bulgaria. We obtained 3,364 images of nine focal carnivores from 13,988 camera-trapping days between 2015 and 2020. Our findings indicated that the spatial distribution of the focal carnivore guilds varied with changes in altitudinal gradient, ruggedness, and forest-agricultural landscape changes. Specifically, the two largest species, the grey wolf (Canis lupus Linnaeus, 1758) and the brown bear (Ursus arctos Linnaeus, 1758), were found only in the Balkan Mountains, whereas the largest mesocarnivore, the golden jackal (Canis aureus Linnaeus, 1758), was mainly distributed agricultural lowlands. The European wildcat (Felis sylvestris Schreber, 1777) was found in forests inside protected areas, and other mesocarnivores were distributed at intermediate levels between wooded-mountains and agricultural lowlands. Brown bear, golden jackal, and domestic dog (Canis lupus familiaris Linnaeus, 1758) showed cathemeral, crepuscular, and diurnal activity, respectively, whereas the remaining six carnivores showed nocturnal activity in synchrony with their main prey. Our findings indicated that anthropogenic landscape modifications and potential interspecific competition resulted in patterns of spatial distribution and temporal activity in this carnivore guild.
Coprophagous insect communities play a critical role in the decomposition of vertebrate dung and provide ecosystem
functions fundamental to modern agriculture. While the ecology of dung beetles is rather well understood, niche differentiation in
coprophagous fl ies is poorly studied. Sepsid fl ies (Diptera: Sepsidae) are a vital part of the European community of coprophages,
with 6–7 widespread species of Sepsis often found co-occurring in the same pasture. To advance our ecological understanding of
the mechanisms that enable species to coexist, we investigated the oviposition preferences and larval performance of 7 common
species of Sepsis in the dung of different large domestic and wild mammals. Substrate preferences and subsequent performance
of larvae in laboratory experiments did not vary greatly. All species did very well on cow dung, the most common substrate in
Central Europe, but also on dung of horse and wild boar. In contrast, fl ies did not prefer or grow well in dung of red and roe deer,
two of the most common wild vertebrates. Thus there were only minor differences among the species tested along the specialistgeneralist (dung) gradient, indicating that differences in the choice of oviposition sites by the adults of the different fl y species
and larval performance do not constitute a major axis of ecological differentiation. Nevertheless, there was a positive correlation
between substrate choice and larval performance indicating the preference of gravid females for particular oviposition sites is
adaptive. We conclude that sepsids are common in Europe because they are well adapted to the dung of herbivorous livestock
rather than wild animals. Nevertheless, specialization on particular types of dung does not defi ne the niche of Sepsis dung fl ies
and hence plays a minor role in mediating their species diversity.