Short Emergence Period Research Articles

Rapid emergence of African swine fever virus variants with different numbers of a tandem repeat sequence in South Korea.

African swine fever virus variants with different numbers of a 10‐bp tandem repeat were isolated in South Korea soon after being identified in wild boar. The short emergence periods and sympatric distributions within a narrow geographical region suggest that the variants were sporadically generated in the pre‐existing viral population.

Life cycles of dominant mayflies (Ephemeroptera) on a torrent of the high Bolivian Andes

The mayflies of the temperate and cold zones have well-synchronized life cycles, distinct cohorts, short emergence and flight periods. In contrast, aquatic insects from the tropical zones are characterized by multivoltine life cycles, “non-discernible cohorts” and extended flight periods throughout the year. This report is the first observation of life cycle patterns made of two species of mayflies on a torrent in the high elevation Bolivian Andes. The samples were taken from four sites and four periods during a hydrological season. The life cycle of each species was examined using size-class frequency analysis and a monthly modal progression model (von Bertalanffy’s model) to infer the life cycle synchrony type. These first observations showed a moderately synchronized univoltine life cycle for Andesiops peruvianus (Ulmer, 1920), whereas Meridialaris tintinnabula Pescador and Peters (1987), had an unsynchronized multivoltine life cycle. These results showed that the generalization of all aquatic insects as unsynchronized multivoltine species in the Andean region may not be entirely accurate since there is still a need to further clarify the life cycle patterns of the wide variety of aquatic insects living in this high elevation tropical environment.

A trait-based approach to explain weed species response to agricultural practices in a simulation study with a cropping system model

The objective of the present study was to use a cropping system model to evaluate the potential impacts of modified agricultural practices ex ante on weeds and to adapt ecological analytical methods to analyse simulation output to identify species traits selected by cropping techniques. Cropping systems typical of three French regions were determined from farm surveys and a French data base monitoring agricultural practices and weeds (“Biovigilance-Flore”). Current scenarios as well as recent and probable future changes were identified in surveys and by expert opinion were simulated in each region, using the FlorSys model and a weed flora consisting of sixteen major annual weed species. Each scenario was simulated over 24 years and repeated 10 times with randomly chosen regional weather series. The simulated weed flora was analysed with RLQ-analyses and fourth-corner analyses. These showed that longer rotations selected weed species with elongated/flattened seeds; spring crops and late-sown autumn crops favoured round seeds and species with short emergence periods; frequent mouldboard ploughing selected species with thick-coated seeds; frequent tillage favoured monocotyledons and species with a late and/or short emergence period; glyphosate before sowing in direct-drilled fields selected seeds with low area/mass ratios. The identified selection pressures could be explained by effects on life-cycle processes (e.g. thick-coated seeds survive better in the soil after burial, low area/mass ratios delay germination because of slower imbibition). The trait×practice relationships were then used to predict the behaviour of additional weed species in cropping systems.

The genus Hybos Meigen (Diptera: Empidoidea: Hybotidae) in Thailand.

The genus Hybos Meigen in Thailand is revised and full descriptions and keys provided for all 41 species. Thirty-four new species are recognized: H. aceriformis sp. nov., H. ancyclochiles sp. nov., H. anisoserratus sp. nov., H. bispinatus sp. nov., H. chaweewani sp. nov., H. daugeroni sp. nov., H. divisus sp. nov., H. grootaerti sp. nov., H. hylobates sp. nov., H. inthanonensis sp. nov., H. kaluang sp. nov., H. khamfui sp. nov., H. konkaogwang sp. nov., H. lannaensis sp. nov., H. mangraii sp. nov., H. meeamnat sp. nov., H. men sp. nov., H. merzi sp. nov., H. ngachang sp. nov., H. paknok sp. nov., H. phahompokensis sp. nov., H. pisadaanus sp. nov., H. saenmueangmai sp. nov., H. shamshevi sp. nov., H. sinclairi sp. nov., H. songbai sp. nov., H. steatopygus sp. nov., H. stigmaticus sp. nov., H. subapicalis sp. nov., H. tetricus sp. nov., H. thaosaeo sp. nov., H. thepkaisoni sp. nov., H. tilokarati sp. nov., H. yungyak sp. nov. Seven species known previously from China are recognized: H. ancistroides Yang & Yang, H. apicihamatus Yang & Yang, H. longus Yang & Yang, H. particularis Yang, Yang & Hu, H. serratus Yang & Yang, H. xishuangbannaensis Yang & Yang, and H. zhejiangensis Yang & Yang. Eight informal species-groups are tentatively proposed based on characters of male and female terminalia and attention is drawn to the many previously overlooked taxonomically useful characters of the female terminalia. Distribution maps of all species are presented and distributions categorised as ‘widespread’, ‘eastern’, ‘southern’, north-eastern’ or ‘northern and western’. Species richness and endemicity are greatest in mid to high elevation evergreen forest biotopes of the northern mountains and areas of endemism are identified on the Luang Prabang, Daen Lao, Thanon Thong-chai ranges and on the Isaan Plateau at least. Adult phenology is correlated with the rainy season in many species and preliminary analyses reveal that many high-elevation species have short emergence periods and restricted distributions, whereas some lowland species have longer emergence periods and wider distributions.

Potential impact of climate change on aquatic insects: A sensitivity analysis for European caddisflies (Trichoptera) based on distribution patterns and ecological preferences

We analysed the sensitivity of European Trichoptera (caddisfly) species to climate change impacts based on their distribution and ecological preferences, and compared the fraction of species potentially endangered by climate change between the European ecoregions. The study covers 23 European ecoregions as defined by Illies (1978). For 1134 Trichoptera species and subspecies, we coded 29 parameters describing biological and ecological preferences and distribution based on the evaluation of more than 1400 literature references. Five parameters served to describe the species’ sensitivity to climate change impacts: endemism, preference for springs, preference for cold water temperatures, short emergence period, and restricted ecological niches in terms of feeding types. Of the European Trichoptera species and subspecies, 47.9% are endemic, 23.1% have a strong preference for springs, 21.9% are cold stenothermic, 35.5% have a short emergence period, and 43.7% are feeding type specialists. The fraction of endemic species meeting at least one of the four other sensitivity criteria mentioned above is highest in the Iberic-Macaronesian Region (30.2% of all species), about 20% in several other south European ecoregions, and about 10% in high mountain ranges. In 15 out of 23 ecoregions (including all northern European and lowland ecoregions) the proportion is less than 3%.

Forecasting emergence and movement of overwintering hazelnut big bud mites from big buds

Eriophyoid big bud mites are key pests of hazelnut throughout the world, but they are difficult to control with chemicals or other methods because they are protected inside the bud. The most effective time for control is during the relatively short emergence period which is difficult for growers to predict. The key objectives of this study were to monitor mite emergence from big buds in spring, determine the phenology of mites in relation to tree phenology and weather, and identify the optimum timing for control measures. Mite emergence was found to occur between early and late spring in Canterbury, New Zealand. Mite emergence and movement occurred when daily maximum temperatures were >15 degrees C and when mean temperatures were >9 degrees C, with mite emergence increasing with temperature. The developmental status of new buds during mite emergence was a crucial factor in the infestation of new buds. An accumulated heat sum model (DD), starting at Julian date 152 and using a lower threshold temperature of 6 degrees C, predicted the onset of emergence on two cultivars and at two sites at approximately 172 DD. A regression model based on leaf number, bud length, bud width, DD and Julian date provided a more satisfactory prediction of percent accumulated mite emergence. It is recommended both peak mite emergence and the developmental status of hazelnut buds be used to optimise the time to apply control measures. The optimum time to apply a control was predicted to be before buds measure 0.5 x 0.5 mm (width x length), are enclosed within the axil, and have a rounded tip, or, when 50% accumulated mite emergence has occurred, whichever occurs first.

The life cycle of Podmosta macdunnoughi (Ricker) in the Lower Laurentians, Quebec (Plecoptera: Nemouridae), with a discussion on embryonic diapause

Podmosta macdunnoughi (Ricker) is a small nemourid stonefly distributed over the glaciated areas of eastern Canada and northern New England, but more abundant in the boreal zone. In the outlet stream of Lake Pitt in the Lower Laurentians of Quebec, near the southern edge of its range, the species has a univoltine cycle. The adults emerged in late April and early May. The eggs, however, did not hatch till September and the first nymphs were collected in October. Growth continued throughout the winter and ended just before the emergence period. Though a wide range of sizes was present during the winter, there was a resynchronisation of the population before emergence and a short emergence period due to rapid growth of the smaller nymphs. Mature female nymphs were larger than males. The significance of the embryonic diapause in this northern species is discussed.

Planning for Institutional Change in Utilization of Sub-Saharan Africa's Common Property Range Resources

Attempts to increase food productivity, make the agricultural sector more cost efficient, improve diets of lower income people, and increase net incomes of farmers and livestock owners are receiving considerable interest on a worldwide basis. In many areas, however, these goals are not being met. In particular, livestock development programs in arid and semi-arid pastoral and sedentary regions in Africa have been especially discouraging. The general problem confronted in this article is to determine why the livestock industry is not developing, and to analyze alternatives related to one major source of concern: communally grazed areas. Africa warrants a special place in development planning due to a multitude of non-economic factors. Political instability, language differences, and tribal and racial tensions have often tended to overshadow economic considerations (Bates, 1981). Perhaps most striking has been the heavy emphasis on equity considerations, possibly because many nations have recently emerged from colonial rule. The relatively short post emergence period (two to three decades in most cases) combined with the continent's economic and natural resource diversity, and a host of other factors such as trade policies, make analysis of economic development potential very difficult (World Bank, 1981). It is evident that there is no one problem and no unique solution in defining policies related to Sub-Saharan Africa's livestock sector.' Perhaps most important is to recognize that the various kinds of livestock systems themselves, as well as associated social institutions, are dynamic forces. Furthermore, it is crucial that the industry and associated problems be understood in the context of human population growth and pressure which has only recently emerged as a source of concern (Development Forum, 1984). In fact, it is population growth which is bringing about a shift in emphasis from livestock production as a primarily ethical or sociological problem to one of determining the role which livestock can play in meeting basic food needs. In this article, a perspective of Sub-Saharan Africa's livestock industry is developed by explaining the dynamic setting in which it is now found. Discussion then turns to communal grazing, a topic we feel has not been properly

The nymphal development of Paraleptophlebia adoptiva (McDunnough) and Paraleptophlebia mollis (Eaton) (Ephemeroptera: Leptophlebiidae) and the possible influence of temperature

Nymphal development of Paraleptophlebia adoptiva (McDunnough) and Paraleptophlebia mollis (Eaton) was studied in the West and East branches of the Credit River, Peel County, Ontario. Nymphs of P. adoptiva were found only in the cooler water of the West branch; they continued to grow during winter months and had a short emergence period in mid-May. Paraleptophlebia mollis nymphs occurred in both branches, nymphs in the West branch being significantly smaller than those of the East. No growth was observed for P. mollis nymphs in winter and a protracted emergence period for this species throughout June was evident. Both mayfly species are univoltine.

Phénologie de Tanypodinae de ruisseaux des Laurentides (Diptera; Chironomidae)

Emergence of Tanypodinae (Diptera; Chironomidae) was monitored in 1972 and 1973 in several streams in the Laurentides. Only summer species occurred. All species appeared to be univoltine, except perhaps Paramerina fragilis which may be bivoltine. Two types of emergence pattern were observed: four species had a short and synchronous emergence period; eight others emerged over many weeks. Arctopelopia flavifrons and Arctopelopia americana have different emergence patterns when they coexist in the same section and when they occur alone. Considerable variations in emergence patterns between stations were often observed for the same species. Weather conditions most affected the emergence of species with extended emergence periods.

Five-Year Patterns of Emergence in Tetragoneuria cynosura and Gomphus exilis (Odonata)1

Emergence patterns were studied in 2 dragonfly species, Tetragoneuria cynosura (Say) and Gomphus exilis Selys, over a 5-year period in North Carolina. Data were based on systematic collections of exuviae; a total of 4,942 T. cynosura exuviae and 6,499 G. exilis exuviae were obtained. Both forms showed characteristics of “spring species” by emerging early in the year and having a short synchronous emergence period and an early emergence peak. The diurnal emergence peak for T. cynosura occurred earlier in the morning than did that for G. exilis. In both species, males emerged significantly earlier in the emergence period than females; males comprised about 47% of both populations. There is some indication that duration of emergence and the timing of emergence peaks may be temperature-dependent.

Causes and effects of short emergence periods in insects

Causes and effects of short emergence periods in insects