Consumption of spiders by the little brown bat (Myotis lucifugus) and the long-eared bat (Myotis evotis) in the Rocky Mountains of Alberta

Intraspecific variation in diet and/or foraging behaviour is one way in which species are able to occupy wide geographical areas with variable environments. <i>Myotis lucifugus</i> (Le Conte, 1831), a primarily aerial insectivorous bat, consumes spiders in low temperatures at the start and end of summer in Northwest Territories, but in Alaska, it consumes spiders all summer, even during high aerial-insect abundance. There are no competitors of <i>M. lucifugus</i> in Alaska, but there are in Northwest Territories, suggesting that aerial insect abundance and competition from gleaning bats influences when <i>M. lucifugus</i> consumes spiders. In the Kananaskis area of the Rocky Mountains of Alberta, we investigated spider consumption by <i>M. lucifugus</i>, and <i>Myotis evotis</i> (H. Allen, 1864), a species more adept at gleaning, to better understand when bats consume spiders. Fecal sample analysis indicated that <i>Myotis evotis</i> consumed spiders all season long, with greater consumption when the bats were caught near water. <i>Myotis lucifugus</i> did not consume spiders at all. This suggests that <i>M. lucifugus</i> opportunistically consumes spiders when encountered, but does not encounter them in Kananaskis where it forages primarily over open water, unlike in Northwest Territories where it forages in the interior of forests and may encounter spiders more frequently.

Massive windborne migration of Sahelian insects: Diversity, seasonality, altitude, and direction

Knowledge on long-distance migration of insects is especially important for food security, public health, and conservation–issues that are especially significant in Africa. During the wet season, the Sahel nourishes diverse life forms which are soon purged by the long dry season. Windborne migration is a key strategy enabling exploitation of such ephemeral havens. However, our knowledge of these large-scale movements remains sparse due to the virtual invisibility of insects flying at altitude. In this first cross-season investigation (3 years) of the aerial insect fauna over Africa, we sampled crepuscular and nocturnal insects flying 40–290 m above ground in four Sahelian villages in Mali, using sticky nets mounted on tethered helium-filled balloons. Nearly half a million insects were caught, representing at least thirteen insect orders following preliminary sorting of the collections. At least 100 insect families were determined to have been captured at altitude in samples collected on 222 nets, obtained in 125 collections over 96 nights. Control nets (raised momentarily to >40 m during system launch and retrieval) confirmed that the insects were captured at altitude, not near the ground. Thirteen ecologically and phylogenetically diverse species were studied in detail. The flight activity of all species peaked during the wet season every year across localities up to ~100 km apart, and occurred over multiple nights, suggesting regular migrations. Species differed in flight altitude, seasonality, and correlations with aerial temperatures, humidity, and wind speed. All taxa exhibited frequent migrations on southerly winds, accounting for the recolonization of the Sahel from southern source populations. “Return” southward movement at the end of the wet season occurred in most taxa but no selectivity for such winds was detected. Extrapolation of aerial density to estimate the seasonal number of migrants crossing Mali at latitude 14°N suggested numbers in the trillions, even for the modestly abundant taxa. Assuming 2–10 hours of flight, the nightly distances traversed exceed tens and even hundreds of kilometers. Two migration strategies were proposed: “residential Sahelian migration” and “round trip migration”. The unprecedented magnitude and diversity of long-range windborne insect migrations highlight the importance of this life strategy in their impact on Sahelian and neighboring ecosystems.

Flight dispersion in field and reproductive status of Scaptocoris castanea Perty (Hemiptera: Cydnidae)

Flight dispersion is an adaptive trait to insects, since that make possible found new habitat with resources adequate to survive and reproduction. This behavior is reported in Scaptocoris castanea Perty (Hemiptera: Cydnidae), however few is known on this issue. Herein, we propose to characterize the flight dispersion of S. castanea in field and assess your reproductive status. For this, we conducted samples in soybean and cotton crop by two years (i.e. crop station), where the insects were collected with aerial insect net and sample in soil. We assess presence and/or absence of insect at flight dispersion, sexual rate and reproductive status of females (flight and soil), which was defined as presence of sperm in the spermatheca (i.e. couple female) and number of ovules in ovaries (i.e., full eggs). Our results exhibit that dispersion by flight occurred between March and April (2014) and, February and March (2015), which indicate strong association among flight dispersion and rain period. Besides, we verified that the insects collected during flight exhibit a high proportion of female (> 0.85), and high reproductive potential from insect at flight and in soil. Therefore, the flight dispersion in S. castanea is characterized by occur after mating behavior (presence of sperm in spermatid) and with insect able to colonize new fields (presence of ovules in ovaries).Dispersão por voo em campo e status reprodutivo de Scaptocoris castanea Perty (Hemiptera: Cydnidae) Resumo. Dispersão por voo é uma característica adaptativa em insetos, pois permitem a localização de habitat favoráveis para sobrevivência e reprodução. Tal comportamento é realizado pelo percevejo-castanho, Scaptocoris castanea Perty (Hemiptera: Cydnidae), mas pouca atenção tem sido dada a esta questão. Assim, propõe-se nesta pesquisa caracterizar a dispersão por revoada e status reprodutivo de S. castanea em campo. Para isso, realizou-se coletas em áreas de soja e algodão em dois anos (safras). Estas consistiam em captura de insetos em revoadas com rede entomológica e coletas em solo. Avaliou-se a razão sexual dos adultos e o status reprodutivo das fêmeas (revoada e solo), considerando a presença de espermatozoides na espermateca e fêmeas com óvulos nos ovaríolos (óvulos formados). Nossos resultados mostraram que a dispersão por voo ocorreu entre março e abril (2014) e fevereiro e março (2015), o que indica forte associação da dispersão com período da chuva. Além disso, verificou-se que os insetos coletados durante o voo exibiam alta proporção de fêmeas (> 0,85) e alto potencial reprodutivo de fêmeas em voo e no solo. Portanto, pode-se concluir que a dispersão de S. castanea é caracterizada por ocorrer após comportamento de cópula (presença de esperma na espermateca) e com insetos aptos para colonizar novas áreas (presença de óvulos nos ovaríolos).