Spatial Distribution Of Adults Research Articles

Spatial and temporal patterns in Arctic mosquito abundance

Abstract Organisms that undergo a shift in ontogeny and habitat type often change their spatial distribution throughout their life cycle, but how this affects population dynamics remains poorly understood. We examined spatial and temporal patterns in Aedes nigripes abundance, a widespread univoltine Arctic mosquito species (Diptera: Culicidae), hypothesizing that the spatial distribution of adults would be closely tied to aquatic habitat. We tracked adult densities of A. nigripes near Kangerlussuaq, Greenland using emergence traps, CO2‐baited traps, and sweep‐nets. In back‐to‐back years of sampling (2017 and 2018) we found two‐fold variation in overall abundance. Adults were spatially patchy when first emerging from aquatic habitats but within a week, mean capture rates for host‐seeking adult females were similar across locations, even in places far from larval habitat. Daily variation in mosquito captures was primarily explained by weather, with virtually no mosquito activity when temperatures averaged less than 8°C or wind speeds exceeded 6 m/s. Gravid females (3% of resting adults) were spatially patchy on the landscape, but not always in the same places where most adults emerged. The spatial distribution of adults is quickly uncoupled from the spatial distribution of larvae because A. nigripes females may disperse far from their natal habitats in search of a blood‐meal and high‐quality oviposition habitat. 8. This research highlights the value of studying ecological processes that act at disparate life stages for understanding the population biology of organisms with complex life cycles.

Agroecological basis for the design of biotechnological traps based on Isaria fumosorosea for the biological control of Bemisia tabaci in strawberry crops

ABSTRACTIsaria fumosorosea is an entomopathogenic fungus that is used as a control alternative for nymphs and adults of Bemisia tabaci. Currently there are some commercial products, however, in greenhouse or field, these do not reach the levels of control as in the laboratory because the viability of the spores decreases as a result of the conditions of application of these products in situ. The objective of this work is to implement, through agroecological data, a system of biotechnological traps based on I. fumosorosea to increase the control efficiency mainly of adults of B. tabaci in strawberry greenhouses. One way to quantify the degree of infestation of a crop is the use of yellow traps, likewise to determine the spatial distribution of adults. The Taylor method [(1984). Assessing and interpreting the spatial distributions of insect populations. Annual Reviews of Entomology, 29, 321–357) was used in five different strawberry cultivation models, finding aggregate and regular distributions. Finally, once the crop model with the highest degree of infestation was selected, the designed traps were tested and mortalities were obtained between 50% and 90% in both the laboratory and the greenhouse. The biotechnological traps based on I. fumosorosea both in the laboratory and in the greenhouse had statistically the same effect as those used under the traditional method used in the field that is aspersion; therefore, this alternative method of application can be a tool important for the biological control of this pest.

Can the Dispersal Behavior of Halyomorpha halys (Hemiptera: Pentatomidae) Inform the Use of Insecticide-Treated Netting to Mitigate Homeowner Issues From its Fall Invasion?

Brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a serious agricultural pest and can be a significant nuisance when it invades human dwellings during its fall dispersal to overwintering sites. Methods informed by behavioral data to exclude or reduce its entry into buildings are needed. The temporal and spatial distribution of adults on an invaded building was assessed over multiple years, revealing its seasonal dispersal pattern and that its numbers varied by wall aspect. Moreover, its density was higher in recessed doorways than on associated walls, raising questions about its behavioral response to dark, contrasting surfaces. This response was evaluated using black, framed panels of deltamethrin-incorporated netting, non-treated netting, and an open frame with no netting, deployed in pairs on the wall of a private residence. More dispersing adults landed on panels of non-treated netting than on open panels, but there was no difference between panels with treated and non-treated netting. Adults remained on treated panels for less time than on non-treated panels, and most walked rather than flew from both. Adult male and female H. halys collected during the dispersal period were exposed to panels of treated and non-treated netting in a laboratory, using durations derived from field recordings. Exposures to treated panels intoxicated but did not kill them over a 7-d assessment period. The deployment of insecticide-treated netting, guided by the behavior of adult H. halys alighting on buildings, is discussed in relation to potential options to mitigate homeowner issues from this serious annual problem.

Scale-dependent resource use in the Euphydryas aurinia complex

Butterflies of the European Euphydryas aurinia complex include a series of taxa, showing morphological and eco-ethological differences. All of them are threatened by changes in land use affecting both the structural and functional connectivity of habitat patches, as well as habitat quality. In this framework, we analysed the use of resources by two of the three taxa occurring in Italy, E. (a.) glaciegenita (Alpine) and E. (a.) provincialis (Mediterranean), at ‘landscape’, ‘patch’ and ‘microhabitat’ scale. We collected data on spatial distribution of adults by Mark-Release-Recapture to understand which parameters affect adult distributions at landscape scale and to test the degree of adult aggregation at patch scale. We sampled first instar larvae within fixed plots and compared the microhabitat characteristics of occupied vs. unoccupied host plants. We found that both populations were affected by management at landscape scale, with contrasting patterns depending on both sites and sex. The food plants were not a limiting factor for adult distribution, probably because they were abundant in the study areas. Within patches, males of E. (a.) glaciegenita showed aggregate distributions in comparison to those of E. (a.) provincialis, suggesting the existence of a “lek strategy”. At microhabitat scale, we observed that females carefully chose their egg-laying sites according to host plant density and microclimatic cues, even though selection was driven by distinct factors in the two populations. Understanding the ecological requirements of all life stages is essential to develop appropriate conservation strategies to preserve butterflies of the E. aurinia complex in Italy.

The taxocene of lichen-feeding darkling beetles (Coleoptera, Tenebrionidae: Helopini) in a forest-steppe ecotone

The taxocene of lichen-feeding darkling beetles from the tribe Helopini is studied in the steppes of the south of Rostov Province. The species of lichens grazed on by the representatives of this tribe are identified for the first time and dependence of circadian activity and spatial distribution of adults on temperature and air humidity is shown. Global warming and human activities may have caused degradation of steppe lichen communities that formed the dietary base for the lichen-feeding darkling beetles in natural ecosystems. As a result, 3 out of 4 beetle species completely left steppe biotopes for tree shelterbelts. This caused a change in the trophic relationships (transition from epigeic to epiphytic lichens) and in the spatial distribution of darkling beetles, promoted the establishment of competitive interactions, and increased the duration of circadian and seasonal activity due to the lengthening of the periods with optimum temperature and air humidity for each species.

Birth and life of tree aggregates in tropical forest: hypotheses on population dynamics of an aggregated shade‐tolerant species

AbstractQuestionsSeveral studies have described aggregated spatial patterns in tropical tree species. This study investigates aggregate dynamics of Vouacapoua americana (Aublet), a climax species whose spatial pattern is not simply related to light and soil conditions or to its short seed dispersal range.LocationTwo rain forest sites: Nouragues and Paracou, in the Guiana Shield.MethodsWe described the spatial pattern of tree locations and spatial autocorrelation of tree diameters, using statistics derived from Ripley's K. We particularly used methods to define analysis subplots according to local density or local mean diameter. We investigated relationships between spatial distributions of adults and saplings.ResultsAt both sites, populations of Vouacapoua demonstrated several nested levels of aggregation. Tree diameters were spatially autocorrelated, revealing the existence of clusters with similar diameters. In the largest aggregates, tree diameters declined from the centre to the edge. Regeneration was aggregated and occurred mainly at cluster edges and around rare isolated trees, and sapling densities and basal area of adults were negatively correlated. We show that long‐distance dispersal events are rare.ConclusionsEnvironmental factors and seed dispersal only explain part of the observed spatial patterns. We provide two main hypotheses about Vouacapoua population dynamics. First, the lack of regeneration in aggregate centres results in the ageing of existing aggregates. We suggest that this lack of recruitment close to mature trees is due to a Janzen–Connell effect. However, aggregates can continue to grow along colonization fronts. Second, long‐distance dispersal events allow the formation of new clusters and play a crucial role in the colonization process.

Cohabitation patterns of the San Marcos salamander (Eurycea nana)

AbstractSocial interactions of conspecifics are a function of complex relationships involving resource defense, antipredatory tactics, and mate acquisition. Consequently, individuals often associate non-randomly with conspecifics in their habitats, with spatial distributions of adults ranging from territorial spacing to aggregations. Site tenacity and cohabitation patterns have been well studied in many species of terrestrial salamander; however, less is understood about these behaviors in aquatic species. We examined the cohabitation patterns of intrasexual and intersexual pairs of the federally threatened, paedomorphic San Marcos salamander (Eurycea nana) under artificial shelters in a laboratory setting over a 20-day period. We found that intrasexual female pairs and intersexual pairs were found cohabiting more often than intrasexual male pairs. We also assessed site tenacity by examining shelter affinity and found that both males and females inhabited one of the two shelters more often than expected from random habitation, regardless of whether they were in intersexual or intrasexual pairings. Our results indicate that although both sexes of Eurycea nana exhibit site affinity, the sex of individuals is an important determinant of cohabitation patterns.

Seed shadow, seedling recruitment, and spatial distribution of Buchenavia capitata (Combretaceae) in a fragment of the Brazilian Atlantic Forest

Here we describe the seed shadow, seedling recruitment, ontogenetic structure and spatial distribution of Buchenavia capitata (an emergent canopy tree) in a 380-ha fragment of the Atlantic forest in northeast Brazil. In particular, we examine seed distribution around 10 parental trees and both seedling recruitment and mortality, during an 18 month period beneath and around parental trees. Moreover, we describe: (1) B. capitata occurrence within treefall gaps; (2) population structure in terms of ontogenetic stages for the whole site; and (3) spatial distribution of adults within an area of 51 hectares. 99% of seeds were found beneath parent crowns (n = 4,236) and seed density reached 14.6 +/- 29.9 seeds/m2 (0-140 seeds/m2). 49% of all seeds germinated but seedling mortality reached 100% after an 18 month period. In addition, saplings of B. capitata were not found in forest understory and within 30 treefall gaps (94-2,350 m2). The adults showed an average DBH of 69.3 +/- 22.1 cm, were 19.2 +/- 2.9 m tall and presented a clumped spatial distribution. B. capitata matched some of the features presented by shade intolerant trees or large-gap specialists, and we hypothesize that low rates or even lack of long distance seed dispersal events may be reducing the probability of B. capitata seeds reaching suitable habitats for successful seedling recruitment and growth. Because of that (1) seedlings face high levels of early mortality; (2) there is no sapling recruitment at the study site; and (3) local population faces senility and it is threatened by local extinction.

Biodiversidade e uso de hábitat da anurofauna em Santa Fé do Sul, região noroeste do estado de São Paulo

The aim of present study was to initiate a database about the frogs in eight water bodies located in an open area and pronounced dry season. For that, were determined: richness and species diversity; the temporal and spatial distribution of adults and tadpoles; the similarity on the vocalization sites and in the males advertisement calls and the relation between heterogeneity descriptors and the richness of species. The field activities were developed trough september of 2003 to august of 2004, monthly during the dry season and twice a month during the rainy season. During the studied period, 20 species of anuran were recorded in the studied area, distributed in nine genus of four families: Leptodactylidae (9), Hylidae (8), Microhylidae (2) and Bufonidae (1). From these, Bufo schneideri, Physalaemus centralis and Physalaemus fuscomaculatus were registered only by collection of tadpoles. The registered species are known by their ample geographic distribution and for colonize altered areas in other localities. There was no correlation between species richness and structural complexity of water bodies. However, the greater richness was registered in temporary environments of long duration. The preponderant use of long duration temporary water bodies is related, probably, to the less abundance of aquatic predators on those environments than in the permanent water bodies and to the less chance of desiccation than in water bodies of short duration. The temporary puddles of unstable hydroperiod were colonized initially by leptodactylids, while the permanent or temporaries puddles of stable hydroperiod were colonized by hylids. The vocalization and reproduction activity of most species was restricted to the warm and rainy period of the year, a typical pattern of communities in the tropical seasonal regions. Five species (Bufo schneideri, Hyla albopunctata, H. nana, Leptodactylus podicipinus and Pseudopaludicola aff. saltica) vocalized during the dry and rainy season

Species and sex ratio differences in mixed populations of hybridogenetic water frogs: The influence of pond features

Among closely related species with overlapping fundamental niches, usually one species excludes the other(s) unless they differ in their realized niches. In some instances, however, niche overlap is inevitable. One example is European water frogs of the Rana lessonae / R. ridibunda / R. esculenta-complex, where the hybrid R. esculenta is reproductively dependent on one or the other of the two parental species. Hence, it has to live in close sympatry with them, but species and sex ratios in such mixed populations vary widely among ponds. In this paper we investigate the spatial and temporal distribution of the three species by comparing nine ponds with different ecological conditions and frog proportions. All three species occurred in all ponds, but in significantly different absolute and relative numbers. R. lessonae proportions are higher in smaller, more structured ponds with rich vegetation under water while R. ridibunda dominates in larger, less structured ponds with little vegetation under water. The hybrid R. esculenta is intermediate in its distribution; it occurs in larger ponds than R. lessonae, but in more vegetated ones than R. ridibunda. The sex ratios of the three species differ also within the ponds. In R. esculenta, the proportion of females decreased with increasing fluctuation in water temperature. The observed spatial distribution of adults is best explained through species differences in the habitat-related development and survival of their progeny, which is known from several experiments. Temporal changes in species proportions were not related to pond characteristics. This, however, is not surprising, as year-to-year changes in pond features were small, and strong site fidelity, combined with high annual survival, creates substantial temporal autocorrelation between population compositions of successive years.

Seed dispersal, plant recruitment and spatial distribution of Martius (Arecaceae) in a remnant of Atlantic forest in northeast Brazil

Seed dispersal ecology of Bactris acanthocarpa Mart. (Arecaceae), an Atlantic forest understory palm, was investigated during two years as an attempt to test the following predictions: (i) seeds of Bactris are dispersed by mammals and large-gaped birds; (ii) Bactris benefits from seed dispersal in terms of seed predation avoidance, improvement of seed germination and seedling survival; and (iii) spatial distribution of adults is related to patterns of seed dispersal. The study was conducted at Dois Irmãos Reserve, a 387.4-ha reserve of Atlantic forest in northeastern Brazil (8º S–35º W). Black–rumped agoutis ( Dasyprocta prymnolopha ) and Guianan squirrels ( Sciurus aestuans ) were identified as the seed dispersers/predators, moving seeds short distances (< 4 m from parents) and at low rates (0.04-0.05 diaspore/palm/day). Pyrene burial prevented seed predation by vertebrates and reduced by half seed infestation by Scolytidae beetles. Only buried pyrenes germinated. Pyrene predation was not correlated with distance from conspecific adults. In contrast, early seedling mortality was higher near conspecific adults. Most adults (64%) had their nearest conspecific adult neighbour > 4 m away in contrast to 96% of seedlings that occurred concentrated within 4 m from adults (77% under the palm crowns). Here, we present evidence that spatial distribution of B. acanthocarpa is partly due to low rates of seed removal, short-distance seed dispersal by agoutis and squirrels, and early seedling mortality associated with presence of seedlings under palm crowns.

The Regular Alternation of Short and Long Foraging Trips in the Blue Petrel Halobaena caerulea: A Previously Undescribed Strategy of Food Provisioning in a Pelagic Seabird

The food-provisioning strategy of a pelagic seabird, the blue petrel Halobaena caerulea was assessed on Kerguelen Island by the simultaneous recording of individual trip duration, feed mass and change in adult mass. Dietary analysis provided information on the energetic value of meals and on the spatial distribution of adults at sea. Males and females brought large meals (average 62 g), representing 36% of their unladen mass, and contributed equally to the feeding of the chick. Adults regularly alternated long trips (LT, average duration 7.2 days) over oceanic waters with short trips (ST, 1.8 days) probably restricted to the Kerguelen shelf. They systematically gained mass during LT, but lost this stored energy during the following ST

Determinants of spatial distribution in a population of the subalpine butterfly Oeneis chryxus.

This paper describes temporally varying determinants of the spatial distribution of adults in an insect population and the relationship between that distribution and the mating system. Male Oeneis chryxus butterflies were distributed nonrandomly throughout a sloping Colorado meadow divided horizontally by a dirt road into an upper and lower slope. Over an eight-year period of intensive study, the proportion of males located on the road, the upper slope, and the lower slope varied as a function of population size and sex ratio. In each year, more than half of the male population aggregated on sections of the road in a distinct and recurring pattern that was not correlated with the distribution of any food resource or thermal regime. Females were usually extremely scarce and not distributed in any pattern apparent from the few observations of them. Areas densely occupied by males were associated with visual landmarks. We hypothesize that the male distribution is determined by a pattern of movement of receptive females toward these landmarks. The road offers a thermally favorable environment with an unobstructed view in which to await the passage of scarce females. The mating system in this population has several lek-like features and supports the prediction that landmark mating is a favored strategy under conditions of female scarcity and wide dispersal of resources.

Dispersal Properties of Mangrove Propagules

Characteristics of dispersal and establishment for water-borne mangrove propagules, including period and pattern of floating, period of obligate dispersal, time to root firmly, longevity, and vigor, are estimated for six species in Panama (Laguncularia racemosa, Avicennia germinans, A. bicolor, Rhizophora mangle, R. harrisonii, and Pelliciera rhizophorae). Dispersal properties correlate with the spatial distribution of adults within the swamp. Genera whose adults are found on higher ground, on the landward edge of the intertidal zone, have propagules that require a period of freedom from tidal inundation of approximately five days in order to establish firmly in the substrate. Genera whose adults are found on the seaward edge of the swamp, in deeper water, have large, heavy propagules. MANGROVES ARE WOODY PLANTS that grow on quiet seashores in the tropics and subtropics (Walter 1971). Swamps composed of mangroves form an extensive component of tropical vegetation. Because vegetative propagation is an insignificant aspect of mangroves' spread and colonization, a knowledge of the dispersal and establishment of their propagules is a prerequisite to understanding the habitat division that results in adult distributions. This paper presents field and laboratory observations on some aspects of dispersal in four genera of Panamanian mangroves. Mangrove species show a characteristic zonation within the swamp (Watson 1928, Davis 1940, West 1956, Schnell 1971, Walter 1971, Thom et al. 1975). Some species are found predominately on the lower ground or more seaward portions of the swamp; whereas other species are on the higher ground or more landward portions of the swamp. mangrove species on both coasts of the Isthmus of Panama and their zonational tendencies are shown in table 1. These trees constitute the entire higher flora of the swamps, except for epiphytic orchids, bromeliads, and a fern. Most mangrove species share two traits: dispersal in water (van der Pijt 1972) and vivipary. Macnae (1968) describes this latter phenomenon: The zygote, once formed, develops uninterruptedly through the embryo into the seedling without the intervention of any resting stage. Gill and Tomlinson (1969) also discuss . . the continuous development of the embryo without any dormant period. In the usual sense, there is therefore no true seed. Essentially, the dispersal unit is a small tree, for which the term propagule is convenient. continual growth of the embryo during dispersal is a unique aspect of mangrove establishment. NATURAL HISTORY Laguncularia racemosa.-Laguncularia is a monotypic genus in the Combretaceae. L. raceniosa ranges from Florida and the West Indies to Brazil, from northwestern Central America to Peru, and from Senegal to Angola (Exell 1958). Laguncularia propagules are and flattenedobovoid-ellipsoid (lens-shaped) (table 2 and figs. 1 and 2). They are pea-green (Munsell 2.5 7/10) when they fall from the parent tree but turn mnudbrown (Munsell 2.5 3/4) in two days or so. TABLE 1. Mangrove species in Panama. Zone Pacific coast Atlantic coast Family Seaward Rhizophora harrisonii Leechman R. mangle L. Rhizophoraceae (lower ground) (= R. brevistyla Salvoza) Pelliciera rhizophorae Triana & Theaceae Planchon Landward Laguncularia racemosa Gaertn. L. racemosa Gaertn. Combretaceae (higher ground) Avicennia germinans L. A. germinans L. Avicenniaceae A. bicolor Stanley (formerly Verbenaceae) 1 Present address: Division of Biological Science, University of Michigan, Ann Arbor, Michigan 48109, U.S.A. BIOTROPICA 10(1): 47-57 1978 47 This content downloaded from 157.55.39.220 on Fri, 02 Sep 2016 05:18:39 UTC All use subject to http://about.jstor.org/terms pericarp serves as a float and is not shed until the propagule is firmly rooted or nearly dead. propagules germinate while dispersing, the radide pushing out a plug surrounded by the calyx and elongating. Dispersing propagules commonly bear roots. stages by which they take root in the soil are illustrated in figure 3.