Search Results (117)

The flesh fly, Wohlfahrtia nuba (Wiedemann) (Diptera: Sarcophagidae), is one of the first necrophagous insects to arrive on a cadaver and is vital for understanding decomposition. Environmental factors, especially temperature, influence insect development, which is crucial for estimating postmortem interval (PMI) in forensic entomology. This study explored how seasonal temperature variations affect the survival and development of W. nuba’s immature stages. The W. nuba colony was reared in the laboratory for four seasons from 3 October 2023 to 30 September 2024. The duration of the larval and pupal phases, the percentage of survival and mortality of the larvae and pupae, the larval growth rate, the percentage of emergence, fecundity, the sex ratio, and the pre-larviposition period were among the many life cycle characteristics that were documented during the study. Research indicates that seasonal changes affect development, shortening the growth period as temperatures rise. Flies raised at an average temperature of 38.3 °C grew faster but experienced higher larval mortality and lower survival rates. The average duration of larval and pupal stages was reduced, with an optimal development temperature of 27.9 °C showing higher survival rates, maximum body weight, and fecundity. The largest mortality rate occurred during winter at an average temperature of 18.5 °C, with males and females showing significant pupal elongation. The findings could help forensic entomologists working on legal investigations to ascertain PMI. Full article

The pine wood nematode (Bursaphelenchus xylophilus, PWN) is a globally significant quarantine pest that causes severe economic and ecological damage to coniferous forests worldwide. Additionally, PWNs continue to expand into higher latitudes. However, studies on their cold tolerance remain limited. This study investigated the overwintering environment of PWNs in epidemic areas of Liaoning Province, China. It established a protocol to induce anhydrobiosis in PWNs, evaluated their low-temperature resistance, observed morphological changes during anhydrobiosis, and explored potentially involved key genes. The results showed that (1) there was no significant difference in thermal insulation between infected and healthy wood in Liaoning Province; both effectively reduced temperature fluctuation rates, providing a protective function for PWN overwintering. (2) PWNs significantly enabled their cold tolerance through anhydrobiosis, accompanied by significant morphological changes and substantial lipid droplet depletion. (3) Eleven anhydrobiosis-related genes were identified. Among these, the collagen gene family showed consistent expression patterns throughout dehydration and rehydration. This suggests a potential role in cuticle structural changes and osmoregulation during anhydrobiosis. These findings provide a theoretical basis for understanding how PWNs survive winter conditions in high-latitude regions. Additionally, they offer valuable insights for future research into PWN anhydrobiosis and the development of effective control strategies. Full article

Migration is a diverse behavior exhibited by a wide array of organisms. Variability in the type of movements is rooted in their purpose, environmental factors, demographics, and individual physiological condition. The ability of caribou (Rangifer tarandus granti) to efficiently move long distances and have a high degree of plasticity in their movements allows them to respond and be resilient to dynamic and dramatic differences in environmental conditions. I used 88 collared, sympatric, adult, female, barren-ground Nelchina Caribou Herd caribou in east-central Alaska to assess their migratory strategy (as indexed by the distance between winter and summer ranges) and how this might affect their movements. Employing 41,682 movement vectors from 39 of these individuals equipped with GPS collars, I compared the annual and monthly movements of caribou that were found on different winter ranges. Distances between winter and summer ranges for individual caribou were correlated with their annual movement, but not for caribou that wintered within the same area. As expected, caribou with the greatest distance between their winter and summer ranges (300 km) traveled the most annually (2132 km/year), whereas caribou with the shortest distance between ranges (71 km) traveled the least annually (1368 km/year). However, caribou that migrated the furthest exhibited greater movement rates in all non-migratory summer months and most non-migratory winter months, as well as during migration. Movement rates were the greatest in summer, peaking in July, regardless of where caribou wintered. During the winter months, movement rates were similar among caribou found on different winter ranges and decreased over the winter, reaching minimums in January-March. Caribou that migrated the shortest distance and had lower movement rates tended to be found in smaller groups in summer. The connection between group size and movement rates may be a function of competition or a small-scale example of the larger-scale phenomenon of range expansion of large herds. Environmental factors, such as snow depth and temperature, were also correlated (negatively and positively, respectively) with caribou movement rates. Survival was not significantly different for caribou utilizing different winter ranges, which implies that the benefits of this long-distance migration can be offset by its costs. A more detailed understanding of the drivers and variability of caribou movement should help improve the management of this declining species. Full article

Alfalfa (Medicago sativa) is a globally distributed economic legume crop used for forage and ecological restoration. We aimed to explore the mechanisms underlying the cold acclimation observed in this species. Our results for fall plant growth showed that non-dormant alfalfa (SD) maintained a vigorous growth rate compared to that of fall-dormant alfalfa (ZD); however, the winter survival rate of ZD was higher than that of SD. Among the ZD samples, the starch content first accumulated and then decreased; the sucrose content was consumed first along with simultaneous raffinose accumulation, which was followed by sucrose content accumulation, with consistent changes in the corresponding related synthase and hydrolase activity. SD exhibited the opposite trend. The transcriptome data showed that most of the differentially expressed genes were involved in carbon metabolism (ko01200), amino acid biosynthesis (ko01230), and starch and sucrose metabolism (ko00500). Our data clearly show that alfalfa’s cold acclimation mechanism is a complex process, with the establishment of stable carbon homeostasis; sucrose is first converted into starch and raffinose, and then, starch is converted into sucrose, which enables alfalfa’s cold resistance. The process is accompanied by CBF/DREB1A TF regulation. This study provides important insights into the cold acclimation mechanisms of alfalfa. Full article

Echinops gmelinii Turcz. is a winter annual species of the Asteraceae family, distributed in sandy areas of northern China, and is crucial for wind avoidance and sand fixation. To understand the inter- and intra-annual population dynamics of E. gmelinii in its cold desert habitats, we conducted long- and short-term demographic studies to investigate the timing of germination, seedling survival, soil seed bank and seed longevity of natural populations on the fringe of the Tengger Desert. Cypselae (seeds) of E. gmelinii can germinate in both July and August, but this process is heavily affected by precipitation amount and timing. Early emerging seedlings died rapidly under the high temperature and drought stress, before completing their life cycle. Later emerging seedlings could survive to complete their life cycle due to more suitable conditions for plant growth. In short, seedling survival dynamics were affected by precipitation distribution, and the survival rates were low (<4%). In addition, we found that the high seed production (1328 seeds·m⁻²) of E. gmelinii depended mainly on the production of seeds by individuals rather than high plant density (35 individuals·m⁻²). The contribution of newly ripened seeds and soil seed banks to seedlings emergence was 57.7% and 42.3%, respectively. Thus, only a small amount of the newly matured seeds was depleted during the year. Only 23.6% of the annual seeds germinated, and the remainder accumulated in a persistent soil seed bank (seed longevity was ≥2 y). The amount and timing of precipitation distribution were the key factors affecting the population dynamics of E. gmelinii in our study area. This species can cope with the uncertain precipitation patterns though a “cautious” germination strategy, varying the timing of germination and forming a persistent soil seed bank. Full article

The increasing reliance of modern agriculture on honey bee (Apis mellifera) pollination has driven efforts to preserve and enhance bee populations. The cryopreservation of drone semen presents a promising solution for preserving genetic diversity and supporting breeding programs without live animal transport risks. This study aimed to evaluate a one-step dilution antibiotic-free drone semen slow-freezing protocol under field conditions with in vitro and in vivo parameters. Semen viability was tested by two different mixes of dyes, and both techniques gave similar results, showing a post-thaw viability drop of 37%. Virgin queens were inseminated either with fresh or frozen–thawed semen. Survival rates until egg-laying onset and female brood production were similar for both groups; however, colonies with queens inseminated with fresh semen were more likely to go into wintering. Results suggest that frozen–thawed semen can support viable queen insemination, with potential for female brood production even without antibiotics in the diluent. This study highlights the need for further refinement of cryopreservation protocols, particularly regarding semen quality and queen longevity, to improve the feasibility of cryobanking for Apis mellifera conservation and breeding. Full article

Aleurocanthus spiniferus not only damages plant leaves directly but also causes a sooty blotch due to the honeydew secreted by the nymphs and adults. This pest is widespread and seems to be spreading from low latitude to higher latitude areas where winters are typically colder, indicating an increase in its cold tolerance. Changes in temperature help insects to anticipate the arrival of winter, allowing them to take defensive measures in advance. This study examines the impacts of brief warm pulses on the low-temperature tolerance of A. spiniferus, and analyzes the physiological and biochemical mechanisms underlying its cold adaptation, utilizing seasonal differences in cold tolerance. Intermittent training at 25 °C significantly improved the survival rate of overwintering nymphs (third and fourth instar) at −7 °C. Analysis of seasonal differences in the supercooling point (SCP) and freezing point (FP) revealed that overwintering nymph had the highest cold tolerance in November. Seasonal variation in levels of cold-resistant substances were also observed, with moisture decreasing during overwintering, while fat and glycerol levels increased. Conversely, glucose, sorbitol, and trehalose levels rose significantly at the end of the overwintering period. The expression profile of cold-resistant genes indicated that the aldo-keto reductase family 1 member B1 in Aleurocanthus spiniferus (AspiAKR1B1) shows a significant decrease at the end of the overwintering period. Knocking down AspiAKR1B1 led to a marked reduction in the cold tolerance of A. spiniferus. Therefore, brief warm pulses and AspiAKR1B1 are key factors contributing to the enhanced cold tolerance of A. spiniferus. This research provides theoretical support for preventing the further spread of A. spiniferus to higher latitudes, and offers technical guidance for developing effective pest control measures. Full article

Little brown bats (Myotis lucifugus) cluster in hibernacula sites over winter, in which they use metabolic rate depression (MRD) to facilitate entrance and exit of hibernation. This study used small RNA sequencing and bioinformatic analyses to identify differentially regulated microRNAs (miRNAs) and to predict their downstream effects on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) terms in the skeletal muscle of torpid M. lucifugus as compared to euthermic controls. We observed a subset of ten miRNAs whose expression changed during hibernation, with predicted functional roles linked to cell cycle processes, downregulation of protein degradation via ubiquitin-mediated proteolysis, downregulation of signaling pathways, including MAPK, p53, mTOR, and TGFβ, and downregulation of cytoskeletal and vesicle trafficking terms. Taken together, our results indicate miRNA regulation corresponding to both widely utilized MRD survival strategies, as well as more hibernation- and tissue-specific roles in M. lucifugus, including skeletal muscle atrophy resistance via myostatin inhibition and insulin signaling suppression. Full article

The Horqin Sandy Land in China is a key alfalfa production base, challenged by low winter temperatures and large diurnal temperature shifts, affecting alfalfa’s winter survival. Alfalfa roots are the primary organs responsible for winter adaptability; consequently, by investigating the changes in the root physiology and nutritional components of alfalfa during the overwintering period, we can enhance our understanding of its mechanisms for cold resistance. Over the course of two years (2022–2023), field trials were conducted on 40 alfalfa varieties selected from both domestic and international sources for their potential cold resistance. This study assessed winter survival rates and analyzed root contents, including soluble sugars, starch, soluble proteins, and the concentrations of carbon (C), nitrogen (N), phosphorus (P) and their stoichiometric ratios. Principal component analysis, subordinate function analysis, and cluster analysis were employed for comprehensive evaluation. Biochemical markers varied significantly across varieties. The C, N, and starch contents in the roots were the main factors determining cold resistance. The varieties were categorized into four groups: Category I included five highly resistant varieties (‘Baimu 202’, ‘WL168HQ’, ‘Zhongmu No. 1’, ‘Gongnong No. 1’, and ‘Legacy’); Category II consisted of six moderately resistant varieties; Category III included twenty-eight slightly resistant varieties; and Category IV contained one non-resistant variety (‘3010’). This study recommends the adoption of the five varieties in Category I to enhance alfalfa cultivation in the Horqin region. This research provides valuable theoretical and practical guidance for improving the cultivation of alfalfa in the cold regions of northeastern China, supporting the development of the local livestock industry. Full article

Honey bee (Apis mellifera) population declines have been associated with the parasitic mite, Varroa destructor, which is currently primarily controlled by the use of acaricides. An alternative is to breed for resistance to Varroa, which was conducted in this study by bidirectional selection for mite fall to obtain colonies with low (resistant) or high (susceptible) Varroa population growth (LVG and HVG, respectively). Selection for three generations resulted in approx. 90% lower Varroa population growth in LVG than in HVG colonies. In addition, late summer Varroa infestation rates of brood and adults were both significantly lower in LVG colonies (p < 0.01), which was also significantly associated with lower Deformed Wing Virus (DWV) infection levels (p < 0.01). Survival of Varroa-parasitized bees was almost 50% higher for LVG bees compared to HVG bees (p < 0.01). Also, colony winter survivorship was significantly higher for LVG colonies than for HVG colonies (p < 0.05). However, the higher colony populations observed for LVG colonies were not significantly different from those of HVG colonies. Overall, individual and colony health was improved by selecting colonies for LVG, demonstrating its effectiveness as a means of breeding for controlling Varroa populations in honey bee colonies. Full article

This study investigates morbidity, mortality, and weight gain in pre-weaned female dairy calves, which pose economic and animal welfare challenges for farms, particularly in family-run operations in southern Brazil. We aimed to identify the rates and factors associated with these outcomes in Alto Uruguai, Rio Grande do Sul, Brazil, tracking 547 calves from 70 farms across 27 municipalities from July 2015 to September 2016. We assessed calf-rearing practices, nutrition, health, and the environment using farmer questionnaires, direct observations, and systematic weight and health monitoring of female calves from birth to weaning. The association between predictors and perinatal mortality (stillbirths and deaths within 24 h), postnatal mortality (deaths from 25 h after birth to weaning), calf morbidity, and weight gain was analysed through regression models. The participating farms had 25 (9–70) (median and range) lactating cows and produced 411 (96–1631) L/d of milk (median and range). Total mortality rate was 6.8% (median 0, range 0–50%/range), of which 2.4% (median 0, range 0–50%/range) was perinatal and 4.5% (median 0, range 0–40%/range) postnatal. Average morbidity was one case for every five calves born alive (106/538), 83% of which were reported as diarrhoea cases. Weight gain was 570 ± 212 g/d (mean and standard deviation). The postnatal mortality rate was highest in the first few weeks of life and among calves with at least one case of diarrhoea. Younger and winter/spring-born calves became sick more frequently. The calves of purebred bulls, fed with cow’s milk, which received at least 4 L of milk and 0.5 kg of feed daily, had greater weight gain. The calf mortality rate was at the lower end of the range reported in international research. The main disease affecting calves was diarrhoea, and weight gain was insufficient for calves to double their weight by the time they were weaned. The results of the present study suggest that the quality of the management adopted in calf rearing in many of the family-run dairy farms of southern Brazil may be compromising the welfare, health, performance, and survival of the calves and possibly the productivity of dairy herds. Full article

Relative humidity (RH) is measured in vivaria with a broad range to accommodate seasonal fluctuations. It is assumed that measurements in the room (macroenvironment) reflect those in the cage (microenvironment). However, there is limited data comparing RH in the macroenvironment to the microenvironment and how the mice may be affected by variations in RH that fall within husbandry recommendations. This study aimed to compare RH in the macroenvironment to that of the microenvironment in various group sizes of laboratory mice; and examine how variation in microenvironmental RH impacts pup survival. Temperature and RH were measured using a temperature/humidity data logger attached to a solid top cage lid. The lid was rotated across N = 48 breeding trios and N = 33 same sex cages on a C57BL/6J background. Further, once a week, a single breeding trio was selected (N = 23) to compare RH readings to weekly rates of pup loss in a larger breeding colony. Across all cages, RH was higher in the microenvironment than the macroenvironment. RH was universally higher in the summer than in the winter, and increased with group size. For breeding cages, as microenvironmental RH increased, the proportion of pups lost each week decreased in a linear relationship. No threshold of decreased mortality could be identified. These data highlight RH as a potential extrinsic factor. While these patterns are correlational, they warrant further research focused on the causative role of RH on mouse welfare. Full article

This study examined the survival rates of Anadara broughtonii and Chlamys farreri with varying heights throughout winter and summer aquaculture periods under varying ratios of mixed-culture conditions in marine environments. The aim was to assess the viability and economic advantages of mixed-culture practices among different bivalve species. Results indicate that the winter (from December to February of the following year) mortality rate for A. broughtonii in mixed culture ranges from 12.04% to 16.85%, markedly lower than in single-species cultures. Mixed-culture A. broughtonii measuring 2.5–4.0 cm exhibit a significantly reduced summer (from July to September) mortality rate compared to those in single-species cultures (p < 0.05). No significant mortality difference was observed between the monoculture and polyculture of C. farreri. Growth rates of C. farreri and A. broughtonii showed no significant differences between monoculture and polyculture conditions. The optimal size for combining two different species of bivalves is 2.5 cm, with a 1:1 ratio being the most effective. An equal number of seedlings were cultivated across various seawater aquaculture systems for a period of one year. The survival rates of monoculture seedlings of Anadara broughtonii and Chlamys farreri were 60.34% and 86.55%, respectively. In contrast, polyculture seedlings exhibited higher survival rates after one year of mariculture, with Anadara broughtonii at 73.36% and Chlamys farreri at 89.74%. The polyculture of A. broughtonii and C. farreri in suspension cages demonstrates a favorable input–output ratio of 1:2.02. This approach effectively reduces winter and summer mortality rates of A. broughtonii, representing an efficient new method for marine bivalve aquaculture. Full article

Annual ryegrass (Lolium rigidum) is a problematic weed in winter crops and fallows in the southeastern cropping region (SCR) of Australia. This weed has evolved resistance to multiple herbicide groups, globally. In Australia, L. rigidum is more prevalent in the western and southern regions than in SCR. To assess the herbicide resistance status of L. rigidum, the response of five L. rigidum populations (collected from the SCR) to glyphosate, glufosinate, paraquat, haloxyfop-P-ethyl, and clethodim is determined using dose–response curves. Three parametric logistic models are used to determine the herbicide dose required to achieve 50% survival (LD₅₀) and 50% growth reduction (GR₅₀). The LD₅₀ values for 50% survival at 28 days after treatment range from 1702 g a.e. ha⁻¹ to 8225 g a.e. ha⁻¹ for glyphosate, 1637 g a.i. ha⁻¹ to 1828 g a.i. ha⁻¹ for glufosinate, 141 g a.i. ha⁻¹ to 307 g a.i. ha⁻¹ for paraquat, 11 g a.i. ha⁻¹ to 107 g a.i. ha⁻¹ for haloxyfop-P-ethyl, and 17 g a.i. ha⁻¹ to 48 g a.i. ha⁻¹ for clethodim. The resistance factor, based on GR₅₀ value, is highest in the S7 population (2.2 times) for glyphosate, the S11 population (2.3 times) for glufosinate, the S11 population (2.0 time) for paraquat, the S7 population (3.9 times) for haloxyfop-P-ethyl, and the S3 population (3.1 times) for clethodim, compared with the susceptible or less tolerant population. The S11 population is found to be resistant to five tested herbicides, based on resistance factors. Similarly, the S3 population is highly resistant to glyphosate, haloxyfop-P-ethyl, and clethodim compared with the W4 population. These results suggest that L. rigidum populations in the SCR exhibit resistance to multiple herbicide groups at labelled field rates. The findings highlight the necessity of adopting an integrated management approach, including the use of residual herbicides, tank mixing herbicides with different modes of action, and rotating herbicides in conjunction with cultural and mechanical control methods. Full article

This study investigated the tolerance of resting eggs of Eurytemora pacifica to storage under low temperatures, which is of particular interest in light of the recent use of nauplii as living food in aquaculture, other than conditions experienced also in the wild during winter cold events in the Northern Hemisphere. Sediment samples collected in August 2020 were used to store the resting eggs at two different freezing temperatures (−5 and −20 °C) for five different durations (1, 3, 6, 9, and 12 months). The mean hatching success rates of the resting eggs after one month of storage were 85.3 ± 1.5% (−5 °C) and 85.0 ± 3.6% (−20 °C), with no significant difference between freezing temperatures. However, significant differences emerged over time, with the mean hatching success rate remaining at 85.0 ± 3.6% at −5 °C after three months, while it dropped sharply to 1.7 ± 2.1% at −20 °C. For the non-freezing conditions, the hatching success at 10 °C increased gradually over the one-month incubation period, ultimately reaching 71.0%. These findings demonstrate the remarkable cold tolerance of E. pacifica but also indicate a limit to this tolerance at longer durations. These results underscore the importance of considering the adoption of storage freezing for resting eggs to be used for aquaculture and also suggest the possibility of the species better surviving the extreme weather events in comparison with other species. Full article