Effect of temperature on the reproduction of Glossina pallidipes, with reference to G. m. morsitans

The reproductive biology of G. pallidipes Austen was studied at 28°, 25° and 22° C. Experiments showed that incubation of puparia at 28° C resulted in sterility of both males and females. Incubation at 22° C resulted in a reduced fecundity of the females due to egg retention; the fertility of the males was not affected.Comparative studies with G. m. morsitans Westw. showed that G. m. morsitans puparia are less affected by a temperature of 28° C than are G. pallidipes puparia.

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Effet de la température sur la reproduction de Glossina pallidipes, avec référence à G. m. morsitans

Résumé Les productivités de G. pallidipes Austen élevés au laboratoire pendant tout leur cycle à 22, 25 et 28° C, ont été comparées.A 28° C, la vie intrapupale est réduite à environ 23 jours, contre 30 jours environ à 25° C; la survie des adultes est plus brève qu'à 25° C et les mouches ne s'accouplent pas. Les ovaires présentent une rétention d'oeufs et seulement 1/3 des mâles contient des spermatozoïdes mobiles. A 22° C, le cycle est considérablement prolongé, la vie intrapupale durant environ 40 jours. Les femelles s'accouplaient environ 14 jours après l'émergence. Les ovaires présentaient une rétention d'oeufs, bien que moins souvent qu'à 28° C. Les mâles contenaient des spermatozoïdes mobiles.Des expériences avec changements de température à différents moments du cycle ont montré que la stérilité des mâles et des femelles est provoquée par l'incubation de pupes de G. pallidipes à 28° C. La mensuration des ovocytes montre à 28° C un effet nocif sur leur maturation. Des observations sur les testicules dans les pupes révèlent, par comparaison avec 25° C, que l'enroulement des testicules et des spermatozoïdes est retardé à 28° C, tandis que la pigmentation des testicules est retardée à 22° C. Les pupes de G. m. morsitans sont moins affectées à 28° C que celles de G. pallidipes.

     

Potential geographical distribution of Actinidia spp. and its predominant indices under climate change

Kiwifruit (Actinidia ssp.) is an economically and nutritionally important fruit crop with a remarkably high vitamin C content. Shaanxi Province, China, has the world's largest production base for kiwifruit; hence, it is necessary to accurately assess the potential geographic distribution of kiwifruit in this area for planting planning and government management. To perform this analysis, we selected three categories of environmental indices (climate, soil, and topographical) for a total of 18 ecological suitability assessment indices. Based on fuzzy mathematic theory, we built 18 membership functions to show the quantitative relationship between kiwifruit yield and these 18 assessment indices. Furthermore, an assessment model of kiwifruit suitability for cultivation was constructed using a combination of the weighted average method and GIS spatial analysis of the present land-use map of Shaanxi. The results show that 5860.1 km² (14.0%) of arable land and orchard can be demarcated as highly suitable for kiwifruit cultivation, 7868.9 km² (18.7%) suitable for rapeseed cultivation; 11,392.1 km² (27.1%) marginally suitable for rapeseed cultivation; and 16,892.5 km² (40.2%) as unsuitable for kiwifruit cultivation in this province. We provide a useful assessment system for ecological zoning of kiwifruit suitability and identify the highly suitable planting area of kiwifruit in Shaanxi Province. south Shannan and south Guanzhong. These results provide a reference tool for distribution rationalization and resource optimization of kiwifruit-planting areas.     

Polytene chromosome maps in four species of tsetse flies Glossina austeni, G. pallidipes, G. morsitans morsitans and G. m. submorsitans (Diptera: Glossinidae): a comparative analysis

Photographic polytene chromosome maps from pupal trichogen cells of four tsetse species, Glossina austeni, G. pallidipes, G. morsitans morsitans and G. m. submorsitans were constructed and compared. The homology of chromosomal elements between the species was achieved by comparing banding patterns. The telomeric and subtelomeric chromosome regions were found to be identical in all species. The pericentromeric regions were found to be similar in the X chromosome and the left arm of L1 chromosome (L1L) but different in L2 chromosome and the right arm of L1 chromosome (L1R). The L2 chromosome differs by a pericentric inversion that is fixed in the three species, G. pallidipes, G. morsitans morsitans and G. m. submorsitans. Moreover, the two morsitans subspecies appeared to be homosequential and differ only by two paracentric inversions on XL and L2L arm. Although a degree of similarity was observed across the homologous chromosomes in the four species, the relative position of specific chromosome regions was different due to chromosome inversions established during their phylogeny. However, there are regions that show no apparent homology between the species, an observation that may be attributed to the considerable intra—chromosomal rearrangements that have occurred following the species divergence. The results of this comparative analysis support the current phylogenetic relationships of the genus Glossina.     

Thermal tolerance in a south-east African population of the tsetse fly Glossina pallidipes (Diptera, Glossinidae): implications for forecasting climate change impacts

For tsetse (Glossina spp.), the vectors of human and animal trypanosomiases, the physiological mechanisms linking variation in population dynamics with changing weather conditions have not been well established. Here, we investigate high- and low-temperature tolerance in terms of activity limits and survival in a natural population of adult Glossina pallidipes from eastern Zambia. Due to increased interest in chilling flies for handling and aerial dispersal in sterile insect technique control and eradication programmes, we also provide further detailed investigation of low-temperature responses. In wild-caught G. pallidipes, the probability of survival for 50% of the population at low-temperatures was at 3.7, 8.9 and 9.6 degrees C (95% CIs: +/-1.5 degrees C) for 1, 2 and 3 h treatments, respectively. At high temperatures, it was estimated that treatments at 37.9, 36.2 and 35.6 degrees C (95% CIs: +/-0.5 degrees C) would yield 50% population survival for 1, 2 and 3 h, respectively. Significant effects of time and temperature were detected at both temperature extremes (GLZ, p<0.05 in all cases) although a time-temperature interaction was only detected at high temperatures (p<0.0001). We synthesized data from four other Kenyan populations and found that upper critical thermal limits showed little variation among populations and laboratory treatments (range: 43.9-45.0 degrees C; 0.25 degrees C/min heating rate), although reduction to more ecologically relevant heating rates (0.06 degrees C/min) reduce these values significantly from approximately 44.4 to 40.6 degrees C, thereby providing a causal explanation for why tsetse distribution may be high-temperature limited. By contrast, low-temperature limits showed substantial variation among populations and acclimation treatments (range: 4.5-13.8 degrees C; 0.25 degrees C/min), indicating high levels of inter-population variability. Ecologically relevant cooling rates (0.06 degrees C/min) suggest tsetses are likely to experience chill coma temperatures under natural conditions (approximately 20-21 degrees C). The results from acute hardening experiments in the Zambian population demonstrate limited ability to improve low-temperature tolerance over short (hourly) timescales after non-lethal pre-treatments. In flies which survived chilling, recovery times were non-linear with plateaus between 2-6 and 8-12 degrees C. Survival times ranged between 4 and 36 h and did not vary between flies which had undergone chill coma by comparison with flies which had not, even after factoring body condition into the analyses (p>0.5 in all cases). However, flies with low chill coma values had the highest body water and fat content, indicating that when energy reserves are depleted, low-temperature tolerance may be compromised. Overall, these results suggest that physiological mechanisms may provide insight into tsetse population dynamics, hence distribution and abundance, and support a general prediction for reduced geographic distribution under future climate warming scenarios.     

Artificial larviposition sites for field collections of the puparia of tsetse flies Glossina pallidipes and G. m. morsitans (Diptera: Glossinidae)

Tsetse flies Glossina pallidipes Austen and G. morsitans morsitans Westwood deposit their larvae in warthog burrows, in August-November, at Rekomitjie Research Station, Zambezi Valley, Zimbabwe. Artificial burrows, made from 200-l steel drums, were used to sample these flies and to collect their puparia. Sand-filled plastic trays in the burrows served as a substrate for larval deposition. The sand was covered with c. 2 cm of leaf litter after it was shown that only 3% of larvae were deposited on bare sand if both substrates were available. Other burrow modifications - artificially shading the burrow entrance, increasing the relative humidity inside the burrow, or reducing the size of the burrow entrance - significantly decreased deposition rates. The use of burrows in the hot season results in a reduction in the temperature experienced by the puparium towards an assumed optimum level of 26 degrees C. Artificial burrows maintained a mean temperature of 28.5 degrees C during October-November 1998, c. 2.5 degrees C cooler than ambient; earlier work has shown that natural burrows can be c. 5 degrees C cooler than ambient at these times. This may explain why natural burrows in full sunlight were used for larviposition, whereas artificial burrows were used only when they were in deep shade, and why significantly higher proportions of G. pallidipes were found in natural (66%) than in artificial burrows (34%). Better-insulated artificial burrows might produce more puparia with higher proportions of G. pallidipes. Burrows become waterlogged during the rains and may be too cool for optimum puparial development during the rest of the year. The percentages of G. m. morsitans in catches of females from artificial burrows, refuges and odour-baited traps were 34, 26 and < 10% respectively. Traps are biased in favour of G. pallidipes; artificial burrows may show a bias in favour of G. m. morsitans that is a function of temperature. Artificial warthog burrows provide a convenient way of studying the puparial stage in tsetse and for the first time facilitate the capture of females as they deposit their larvae.     

Potential distribution of Avena sterilis L. in Europe under climate change

Avena sterilis (sterile oat) is one of the most extended and harmful weeds in Mediterranean cereal crops. A process‐based niche model for this species was developed using CLIMEX. The model was validated and used to assess the potential distribution of A. sterilis in Europe under the current climate and under two climate change scenarios. Both scenarios represent contrasting temporal patterns of economic development and CO₂ emissions. The projections under current climate conditions indicated that A. sterilis does not occupy the full extent of the climatically suitable habitat available to it in Europe. Under future climate scenarios, the model projection showed a gradual advance of sterile oat towards Northeastern Europe and a contraction in Southern Europe. The infested potential area increases from the current 45.2% to 51.3% in the low‐emission CO₂ scenario and to 59.5% under the most extreme scenario. These results provide the necessary knowledge for identifying and highlighting the potential invasion risk areas and for establishing the grounds on which to base the planning and management measures required. The main actions should be focused on controlling the large‐scale seed scattering, preventing seed dispersal into potentially suitable areas.     

气候变化情景下孑遗植物绵刺在中国的潜在地理分布

绵刺(Potaninia mongolica Maxim.)为我国西北干旱、半干旱地区孑遗濒危荒漠植物,具有重要的生态作用。预测过去、当代及未来气候变化情景下绵刺植物在中国的潜在地理分布区和迁移路线,将为绵刺的保护利用及种群合理建立提供一定的科学依据。基于绵刺在中国的73个有效分布点和8个环境因子变量,利用MaxEnt模型和ArcGIS软件预测末次间冰期、末次盛冰期、当代及未来绵刺在中国的潜在地理分布变化,综合分析影响绵刺分布的主要环境因子及其适宜范围,并用检验受试者工作特征(ROC)曲线下面积(AUC)评估模型的精确度。结果表明：(1)MaxEnt模型预测精确度极高,受试者工作特征(ROC)曲线下面积(AUC)值为0.988,预测显示当代绵刺主要分布在内蒙古中西部地区(阿拉善地区)、宁夏东北部和西北部、甘肃中东部、新疆中部和西部少量狭长分布区,潜在地理分布的总适生区面积约是51.94×10⁴ km~2;(2)影响绵刺潜在地理分布的重要环境因子变量是降雨(最干月降雨量、年均降雨量、最湿月降雨量、最冷季度平均降雨量)和温度(最热月的最高温);(3)从末次间冰期到末次...     

Potential impacts of climate change on distribution range of Nabis pseudoferus and N. palifer (Hemiptera: Nabidae) in Iran

Nabis pseudoferus Remane and N. palifer Seidenstucker are predators that feed on a wide range of insect pests. To reveal their current potential habitats, the effects of climate change and their future distribution in various areas of Iran we used maximum entropy modeling (Maxent). To produce the models, samples were collected from 218 areas of Iran resulting in discovering 271 points where the nabids were found. The accuracy and performance of distribution models were also evaluated by the area under receiver operating characteristic curve and jack‐knife analysis. In the Maxent model, the climatic, elevation and land cover layers were the major bases for the current models. In modeling future distribution, the land cover layer was excluded. The distribution of N. pseudoferus was independent of the type of vegetation while the distribution of N. palifer varied according to differences in type of vegetation. Using jack‐knife analysis, the land cover and precipitation were the most effective predictors driving the two Nabis species range expansion. From 2013 to 2050 the impacts of climate change on N. pseudoferus distribution was predicted to have a negative impact but have a positive effect on N. palifer range expansion. Results could be used in preparation of predators' conservation, translocation and reintroduction programs and application in pest management strategies.     

Lutzomyia (Nyssomyia) whitmani s.l . (Antunes & Coutinho, 1939)(Diptera: Psychodidae: Phlebotominae): geographical distribution and the epidemiology of American cutaneous leishmaniasis in Brazil--mini-review

The aim of the present study, in view of the widespread geographical distribution of Lutzomyia (Nyssomyia) whitmani s.l. in Brazil, in close association with the regions of transmission of Leishmania (Viannia) braziliensis and L. (V.) shawi, is to investigate the distribution of this sand fly species and American cutaneous leishmaniasis (ACL) in relationship to vegetation and landscape ecology throughout Brazil. Thematic maps were elaborated by the MapInfo programme, giving information on the spatial distribution of L. whitmani s.l., in accordance with types of vegetation and foci of ACL. With regards to the known areas of transmission of ACL in Brazil, it is notable that L. (N.) whitmani s.l. occurs in most of them, where it has been implicated as a possible vector of L. (V.) braziliensis. The presence of L. whitmani s.l. has been registered in 26 states, the one exception being Santa Catarina; in some states such as Roraima, Acre, Tocantins, and Mato Grosso do Sul this sand fly species has been recorded in a large number of municipalities. L. whitmani s.l. has been found in association with a variety of vegetation types, including the Amazonian forest, savanna ("campos cerrados"), and northeastern savanna ("caatingas nordestinas" or "savana estépica").