Queen number influences the timing of the sexual production in colonies of Cardiocondyla ants

Wingless males of the ant genus Cardiocondyla engage in fatal fighting for access to female sexual nestmates. Older, heavily sclerotized males are usually capable of eliminating all younger rivals, whose cuticle is still soft. In Cardiocondyla sp. A, this type of local mate competition (LMC) has turned the standard pattern of brood production of social insects upside down, in that mother queens in multi-queen colonies produce extremely long-lived sons very early in the life cycle of the colony. Here, we investigated the emergence pattern of sexuals in two species with LMC, in which males are much less long-lived. Queens of Cardiocondyla obscurior and Cardiocondyla minutior reared their first sons significantly earlier in multi-queen than in single-queen societies. In addition, first female sexuals also emerged earlier in multi-queen colonies, so that early males had mating opportunities. Hence, the timing of sexual production appears to be well predicted by evolutionary theory, in particular by local mate and queen-queen competition.     

Effects of Sward Height, Gap Size, and Slug Grazing on Emergence and Establishment of Trollius europaeus (Globeflower)

Abstract To determine the effects of sward height and gap size on the emergence and subsequent development of Trollius europaeus, seeds were introduced into artificially created gaps in mown and unmown wet meadow grassland in Ayr, Scotland. Emergence and establishment of nondormant seed (previously leached in running tap water and soaked in gibberellic acid) placed in a range of circular gaps (25 mm, 50 mm with and without root barrier, 100 and 200 mm diameter) were monitored over 305 days. Trollius demonstrated high field emergence (mean, 46% of viable seed sown) in this experiment. Emergence was not significantly affected by either sward height or gap size, although emergence was greater in mown swards. The critical factor determining subsequent survival of seedlings was slug predation rather than sward height or gap size. However, losses due to slug predation were significantly greater in unmown swards, resulting in more seedlings in mown swards. One hundred eleven days after sowing (September) seedling numbers had declined substantially in both unmown and mown swards, and by day 305 (April) seedlings were extinct in both sward types. The implications of the research for the restoration and management of T. europaeus are discussed.     

Taking the bait: in situ voluntary ingestion of acoustic transmitters by Atlantic cod (Gadus morhua)

Voluntary ingestion of acoustic transmitters by Atlantic cod (Gadus morhua) was investigated under field conditions in the shallow inshore waters off Newfoundland. A surface-controlled tagging frame was used to suspend and monitor baited transmitters (16×45 mm up to 16×108 mm) near the seafloor at depths ranging from 12.5 to 39.0 m. The behaviour of cod toward the transmitters was quantified using an underwater video camera. Cod ranging in size from 11 to 92 cm approached and touched the transmitters. Both biting and ingestion were size-dependent. Eight successful taggings were completed with cod ranging in size from 34 to 92 cm. Transmitters deployed in the morning were consumed faster (mean soak time = 3.3 h) than transmitters deployed in the afternoon (mean soak time = 9.1 h). Tracking revealed that cod were active immediately following tagging, suggesting no effect of the tagging procedure. Individual fish were tracked for periods ranging from 5.6 to 18.8 d, with none of the fish regurgitating transmitters during the period for which they were tracked.     

Spawning and emergence phenology of bull trout Salvelinus confluentus under differing thermal regimes

Median bull trout Salvelinus confluentus breeding was 2 weeks earlier in a cool stream than in a proximate warmer stream, aligning with expectations for salmonids, followed by emergence timing calculated to be 6 weeks later in the cool stream than the warm stream. This pattern is consistent with both site-specific adaptation and thermal spawning threshold hypotheses for life-history event timing in this threatened species.     

The effects of Ramadan intermittent fasting on the underlying mechanisms of force production capacity during maximal isometric voluntary contraction

The aim of the present study was to investigate the effects of Ramadan intermittent fasting (RIF) on the underlying mechanisms of force production capacity during maximal voluntary isometric contraction (MVIC) using the superimposed twitch technique. Ten healthy male physical education students performed three MVIC of the knee extensor superimposed with nerve electrical stimulation during four testing phases: one week before Ramadan (BR), at the end of the first week of Ramadan (R-1), during the fourth week of Ramadan (R-4) and two weeks after Ramadan (AR). This study was performed during Ramadan 2016. MVIC values, voluntary activation level (VAL), potentiated resting twitch and electromyography signals were recorded during each MVIC. The French version of the Profile of Mood States questionnaire (POMS-f) was used to evaluate the subjective mood states in each testing session. The results showed that MVIC values (890.57 ± 67.90 vs. 816.46 ± 54.72 N) and VAL (87.73 ± 3.27 vs. 77.32 ± 7.87%) decreased at R-1 compared to BR (p < 0.001). However, the neuromuscular efficiency and the potentiated resting twitch remained unchanged during Ramadan (R). Results showed that depression (p < 0.01; 6.3 ± 1.57 vs. 4.7 ± 1.25), fatigue (p < 0.001; 9.2 ± 1.93 vs. 4.6 ± 2.01) and anxiety (p < 0.001; 6.4 ± 1.51 vs. 11.8 ± 1.23) scores of POMS-f were higher during R-1 compared to BR. In conclusion, RIF-related impairment of maximal muscle force seems to be related to nervous alterations of the VAL, whereas the RIF did not adversely affect peripheral mechanisms.

Abbreviations’ List: ANOVA: Analysis of variance; AR: After Ramadan; BMI: Body-mass index; BR: Before Ramadan; EMG: Electromyography; ER: End of Ramadan; MF: Mean frequency; M_max: Peak-to-peak M-wave amplitudes; MVIV: Maximal voluntary isometric contraction; NES: Nerve electrical stimulation; NME: Neuromuscular efficiency; POMS-f: French version of the Profile of Mood States questionnaire; R: Ramadan; R-1: First week of Ramadan; R-4: Fourth week of Ramadan; RF: Rectus femoris; RIF: Ramadan intermittent fasting; RMS: Root mean square; VAL: Voluntary activation level; VL: Vastus lateralis; VM: Vastus medialis.     

Segregation in spawning and early life history among polymorphic Arctic charr, Salvelinus alpinus, in Thingvallavatn, Iceland

The relationships among time of spawning, incubation temperature, timing of first feeding and early growth were examined in four sympatric morphs of Arctic charr in Thingvallavatn, Iceland. Large benthivorous charr spawn in July-August at sites with cold ground-water flow. Planktivorous and piscivorous charr spawn in September-November and are not confined to ground-water sites. The spawning of small benthivorous charr overlaps with that of other morphs. Progeny of large benthivorous charr start feeding 2-3 months earlier than the progeny of autumn spawners. This results in differential size distribution and growth rates of young in the spring.     

埋深和播种密度对豚草种子出苗及幼苗生长的影响

豚草是一种全球性的恶性入侵杂草,给我国生物多样性及经济发展造成了巨大威胁。为研究豚草种子出苗和幼苗生长的影响因素,采用盆栽实验分析了种子大小（L、M、S）与埋深（2、4 cm和6 cm）或播种密度（2、4粒/盆和8粒/盆）对豚草（Ambrosia artemisiifolia）种子的出苗和幼苗生长的影响。研究结果表明,埋深对豚草种子出苗的影响高于播种密度及种子大小的影响,较浅的埋深有利于豚草种子出苗;出苗率在不同播种密度下均具有较高水平,达到67.9%-100%,这种高出苗率是豚草在不同生境成功定植的原因之一。豚草的幼苗生长受埋深或播种密度的影响大于种子大小的影响,且小种子更易受埋深或播种密度的影响。种子大小显著影响豚草幼苗的株高和基径（P<0.05）,总体上较大种子的株高和基径高于小种子,此外更小的种子会将生物量更多的分配给根以促进幼苗的生长。幼苗的株高和基径在较浅的埋深下更高,而豚草幼苗的单株生物量、单株地上和地下生物量随埋深的增加而增加。播种密度的增加会加剧豚草幼苗之间对水分、营养、光照等资源的竞争,导致其单株地上、地下及总生物量显著降低（P<0.05）。研究发现豚草在浅埋深、低密度生境中更容易入侵成功,因此可以通过对土壤进行深翻,采取替代控制,种植竞争能力强的本地植物等手段有效管理和防治豚草。     

White grubs,Holotrichia rustica and Holotrichia mucida (Coleoptera: Scarabaeidae) as pests of teak (Tectona grandis L. f.) seedlings

Abstract Field observations were carried out between 2002 and 2005 on bio‐ecology of white grubs infesting teak (Tectona grandis Linn. f.) seedlings at Ramdongari Forest Nursery, Forest Development Corporation of Maharashtra, Nagpur in central India. The study collected the data required for an integrated pest management strategy against the white grubs. The species damaging teak seedlings were Holotrichia rustica (Burmeister) and H. mucida Gyllenhal. The beetles (adults) of both these species began to emerge just after the pre‐monsoon showers and when the relative humidity had risen rapidly over several days, but before the first monsoon rains. While the adults fed and mated on naturally growing bushes of Ziziphus jujuba, Z. mauritiana, Z. xylopyra, Acacia leucophloea and A. catechu immediately after the emergence from the teak beds in the nursery, the immature stages (grubs) of both species fed on roots of the teak seedling, leading to plant death. This is the first report of (i) damage caused to teak seedlings by grubs of H. rustica and H. mucida, and (ii) of Z. jujuba and Z. mauritiana being hosts for the beetles of H. mucida and H. rustica. It is also the first detailed report on the field bio‐ecology of the H. rustica and H. mucida as major pests of teak. White grubs are among the toughest‐to‐manage pests of economic importance and information presented here on the pest incidence and damage of H. rustica and H. mucida is important to researchers and nursery field managers for the management of these pests on teak.     

Seed bank dynamics and tree‐fall gaps in a northwestern Mexican Quercus‐Pinus forest

Questions: How does the seed bank respond to different types of tree‐fall gaps and seasonal variations? How does the soil seed bank influence recovery of the standing vegetation in the mature forest and tree‐fall gaps? Location: 1800 — 2020 m a.s.l., Quercus‐Pinus forest, Baja California Sur, Mexico. Methods: Seed size, species composition and germination were estimated under different environmental conditions during dry and rainy seasons: a mature forest plot and gaps created by dead standing trees, snapped‐of f trees and uprooted trees. The soil seed bank was investigated using direct propagule emergence under laboratory conditions, from soil cores obtained during both seasons. Results: 21 species, 20 genera and 14 families constitute the seed bank of this forest community. Fabaceae, Asteraceae, Euphorbiaceae and Lamiaceae were the most frequently represented families in the seed bank. Floristic composition and species richness varied according to the different modes of tree death. Species composition of seed banks and standing vegetation had very low similarity coefficients and were statistically different. Seed bank sizes varied between 164 and 362 ind.m^‐2 in the mature forest plot for the dry and rainy seasons, respectively, while soil seed bank sizes for gaps ranged between 23–208 ind.m^‐2 forthe dry season and between 81–282 ind.m^‐2 for the rainy season. Conclusions: Seed bank sizes and germination response were always higher in the rainy season under all the environmental conditions analysed. Results suggest that timing responses to gap formation of the soil seed bank could be more delayed in this temperate forest than expected.