Efecto de la regulación de la cabecera del río Genil (Sierra Nevada, España) sobre la comunidad de macroinvertebrados acuáticos y la dieta larvaria de Rhyacophila nevada (Insecta : Trichoptera)

Se analiza el efecto que un embalse (Embalse de Canales), situado en la parte alta de un río de montaña (Río Genil, Sierra Nevada, Granada, España), tiene sobre la comunidad de macroinvertebrados, y en especial sobre la dieta de las larvas del tricóptero depredador Rhyacophila nevada Zamora-Muñoz, C. & Alba-Tercedor, 1992. Para ello se establecieron estaciones de muestreo aguas arriba y abajo del embalse, realizándose muestreos cuantitativos de macroinvertebrados con una periodicidad mensual. Los macroinvertebrados (MIB) se identificaron hasta el máximo nivel taxonómico posible (en la mayoría de los casos a nivel de especie). La mayor diversidad específica se encontró en los dípteros quironómidos. Se estimó también la biomasa por especie (PSLC) y los ciclos de vida de las especies de depredadores, efemerópteros y dípteros. El contenido de los tractos digestivos fue analizado y cuantificado. La diversidad de los MIB estuvo determinada por los cambios de flujo y los ciclos de vida de las presas. Rhyacophila nevada es el depredador más abundante, presenta un ciclo multivoltino, comportándose como un depredador que busca activamente sus presas que ingiere comenzando por la región caudal. El número de presas en R. nevada aumentó con su tamaño. Las diferencias significativas de la dieta entre las estaciones de muestreo son consecuencia de los cambios en la disponibilidad de recursos (presas) en el tiempo. El ancho de nicho trófico también mostró diferencias entre estaciones.The effect that a dam (the Canales dam), located in the upper part of a mountain river (Genil stream, Sierra Nevada, Spain), has on the macroinvertebrate community, is analysed, especially over the larval diet of the predator caddisfly Rhyacophila nevada Zamora-Muñoz, C. & Alba-Tercedor, 1992. To that end, sampling stations were established, upstream and downstream of the dam. Quantitative samplings of macroinvertebrates were realized every month. The macroinvertebrates were identified to the maximum taxonomical level (species level in the majority of cases). The highest specific diversity was found in the chironomidae Diptera. The biomass per species was estimated , as well as the life cycles of the predator's species, mayflies and dipterans. Gut contents were analysed and quantified. The diversity of the MIB was determined by flow shifts and prey life cycles. Rhyacophila nevada is the most abundant predator, with a multivoltine life cycle, and behaving as an active searcher of preys, ingesting them from the caudal region. The number of prey items consumed by R. nevada increased with its size. Significant differences on the diet between the sampling stations are a consequence of the shift in the resource availability of preys in time. The trophic niche breadth was different among sites

Observing the devastating coffee berry borer (Hypothenemus hampei) inside the coffee berry using microcomputed tomography

The coffee berry borer is the most devastating insect pest of coffee throughout the world. The insect spends most of its life cycle inside the coffee berry, which makes it quite difficult to observe its behaviour. Micro-computed tomography (micro-CT) was used to observe all developmental stages of the coffee berry borer inside coffee berries (Coffea canephora). An interesting oviposition pattern involving a sequential placement of eggs starting in the periphery of the seed and moving inwards was observed. Micro-CT should be useful in elucidating unknown life history aspects of other seed-feeding bark beetles as well as of bark and ambrosia beetles in general

Anatomical damage caused by Bacillus thuringiensis variety israelensis in yellow fever mosquito Aedes aegypti (L.) larvae revealed by micro‑computed tomography

With micro-computed tomography techniques, using the single-distance phase-retrieval algorithm phase contrast, we reconstructed enhanced rendered images of soft tissues of Aedes aeqypti fourth instar larvae after Bti treatment. In contrast to previous publications based on conventional microscopy, either optical or electron microscopy, which were limited to partial studies, mostly in the form of histological sections, here we show for the first time the effects of Bti on the complete internal anatomy of an insect. Using 3D rendered images it was possible to study the effect of the bacterium in tissues and organs, not only in sections but also as a whole. We compared the anatomy of healthy larvae with the changes undergone in larvae after being exposed to Bti (for 30 min, 1 h and 6 h) and observed the progressive damage that Bti produce. Damage to the midgut epithelia was confirmed, with progressive swelling of the enterocytes, thickening epithelia, increase of the vacuolar spaces and finally cell lysis, producing openings in the midgut walls. Simultaneously, the larvae altered their motility, making it difficult for them to rise to the surface and position the respiratory siphon properly to break surface tension and breathe. Internally, osmotic shock phenomena were observed, resulting in a deformation of the cross-section shape, producing the appearance of a wide internal space between the cuticle and the internal structures and a progressive collapse of the tracheal trunks. Taken together, these results indicate the death of the larvae, not by starvation as a consequence of the destruction of the epithelia of the digestive tract as previously stated, but due to a synergic catastrophic multifactor process in addition to asphyxia due to a lack of adequate gas exchange.Consejería de Universidad, Investigación e Innovación of Junta de Andalucia (Spain)FEDER Programe through the research projects: “Caracterización de variantes de toxinas Cry activas frente a la Mosca de la Fruta del Mediterráneo (Ceratitis capitata) obtenidas mediante la tecnología del despliegue de proteínas en fagos” (B-BIO-081-UGR18)Búsqueda de nuevas toxinas Cry con actividad frente al ectoparásito de la abeja Varroa destructor mediante la evolución in vitro de proteínas y la técnica del despliegue de proteínas en fago” (A-BIO-424-UGR20

Micro-CT to Document the Coffee Bean Weevil, Araecerus fasciculatus (Coleoptera: Anthribidae), Inside Field-Collected Coffee Berries (Coffea canephora)

The coffee bean weevil, Araecerus fasciculatus (De Geer) (Coleoptera: Anthribidae), is a cosmopolitan insect with >100 hosts, and has been reported as a pest of stored coffee. During a study involving the coffee berry borer, we observed coffee bean weevils emerging from field-collected coffee berries and used micro-computerized tomography (micro-CT) scans to observe the insect inside the berry. Two eggs had eclosed inside the berry, resulting in observations of a newly eclosed adult beetle and a 5th instar larva, each feeding on one of the two seeds. This is the first time since 1775, when the insect was first described, that the insect has been observed inside a coffee berry

Asian citrus psyllid stylet morphology and applicability to the model for inter-instar stylet replacement in the potato psyllid

In Hemiptera, presumptive stylets for each consecutive postembryonic instar are manufactured prior to ecdysis to replace the ecdysial stylets discarded with the exuviae. With the discovery that the bacterium “Candidatus” Liberibacter solanacearum accesses the tissues involved in the stylet replacement process of the potato psyllid, a hypothesis was formed that the bacterium could adhere to the stylets of freshly emerged instars and hence gain access to the host plant when feeding is resumed. Although unproven, it was imperative that a model for stylet replacement be built. Stylet morphology and the stylet replacement process of the Asian citrus psyllid (ACP), vector of “C.” L. asiaticus, causal pathogen of citrus greening disease, are comparable to the potato psyllid model system. Morphology consists of a basal terminus with its tab-shaped auricle, a base, shaft, and an apical terminus. Each of the four auricles act as a platform for the replacement apparatus, which is compacted into a tight aggregate of cells, the ‘endcap’. As modeled, on apolysis of larval instar hypodermis, the aggregate ‘deconstructs’ and expands into a snail shell-shaped tube, the ‘atrium’, that houses the presumptive stylet as it is synthesized. Completed stylets then despool from the atrium and are fitted into their functional positions as the next instar emerges from its exuviae.Funding was provided by a grant from USDA-NIFA Award 2014- 70016-23028, 2015-2020, “Developing an Infrastructure and Product Test Pipeline to Deliver Novel Therapies for Citrus Greening Disease”

Anatomical study of the coffee berry borer (Hypothenemus hampei) using micro-computed tomography

Traditionally, the study of anatomy in insects has been based on dissection techniques. Microcomputed tomography (micro-CT) is an X-ray based technique that allows visualization of the internal anatomy of insects in situ and does not require dissections. We report on the use of micro-CT scans to study, in detail, the internal structures and organs of the coffee berry borer (Hypothenemus hampei), the most damaging insect pest of coffee worldwide. Detailed images and videos allowed us to make the first description of the aedeagus and the first report of differences between the sexes based on internal anatomy (flight musculature, midgut shape, hindgut convolutions, brain shape and size) and external morphology (lateral outline of the pronotum and number of abdominal tergites). This study is the first complete micro-CT reconstruction of the anatomy of an insect and is also the smallest insect to have been evaluated in this way. High quality rendered images, and additional supplementary videos and 3D models are suitable for use with mobile devices and are useful tools for future research and as teaching aids.This paper benefitted from sub-award agreement S15192.01 between Kansas State University (KSU) and the University of Granada, as part of the USDA-NIFA Award 2014-70016-23028 to Susan J. Brown (KSU), “Developing an Infrastructure and Product Test Pipeline to Deliver Novel Therapies for Citrus Greening Disease” (2015–2020)

Evidence of Different Thermoregulatory Mechanisms between Two Sympatric Scarabaeus Species Using Infrared Thermography and Micro-Computer Tomography

In endotherms insects, the thermoregulatory mechanisms modulate heat transfer from the thorax to the abdomen to avoid overheating or cooling in order to obtain a prolonged flight performance. Scarabaeus sacer and S. cicatricosus, two sympatric species with the same habitat and food preferences, showed daily temporal segregation with S. cicatricosus being more active during warmer hours of the day in opposition to S. sacer who avoid it. In the case of S. sacer, their endothermy pattern suggested an adaptive capacity for thorax heat retention. In S. cicatricosus, an active ‘heat exchanger’ mechanism was suggested. However, no empirical evidence had been documented until now. Thermographic sequences recorded during flight performance showed evidence of the existence of both thermoregulatory mechanisms. In S. sacer, infrared sequences showed a possible heat insulator (passive thermal window), which prevents heat transfer from meso- and metathorax to the abdomen during flight. In S. cicatricosus, infrared sequences revealed clear and effective heat flow between the thorax and abdomen (abdominal heat transfer) that should be considered the main mechanism of thermoregulation. This was related to a subsequent increase in abdominal pumping (as a cooling mechanism) during flight. Computer microtomography scanning, anatomical dissections and internal air volume measurements showed two possible heat retention mechanisms for S. sacer; the abdominal air sacs and the development of the internal abdominal sternites that could explain the thermoregulation between thorax and abdomen. Our results suggest that interspecific interactions between sympatric species are regulated by very different mechanisms. These mechanisms create unique thermal niches for the different species, thereby preventing competition and modulating spatio-temporal distribution and the composition of dung beetle assemblages

Morphological and histological description of the midgut caeca in true crabs (Malacostraca: Decapoda: Brachyura): origin, development and potential role

Background The decapods are a major group of crustaceans that includes shrimps, prawns, crayfishes, lobsters, and crabs. Several studies focused on the study of the digestive system of the decapods, constituted by the oesophagus, stomach, midgut tract, midgut gland, and hindgut. Nevertheless, in the midgut tract there are associated a set of organs called “midgut caeca”, which are among the most controversial and less studied digestive organs of this group. This work used the common spider crab Maja brachydactyla Balss, 1922 as a model to resolve the origin, development, and potential role of the midgut caeca. Such organs were studied in the larvae (zoea I, zoea II, megalopa), first juveniles, and adult phases, being employed traditional and modern techniques: dissection, micro-computed tomography (Micro-CT), and light and electron microscopical analyses (TEM and SEM). Results The common spider crab has a pair of anterior midgut caeca and a single posterior caecum that originate from the endoderm germ layer: they develop from the midgut tract, and their epithelium is composed by secretory cells while lacking a cuticle lining. The midgut caeca are small buds in the newly hatched larvae, enlarge linearly during the larval development, and then continue growing until became elongated and coiled blind-tubules in adults. The adult midgut caeca are internally folded to increase their inner surface. The electron microscopy observations showed that the midgut caeca are highly active organs with important macroapocrine and microapocrine secretory activity. Our results suggest that the role of the caeca might be related to the digestive enzyme secretion. The secretory activity should increase as the animal grows in size. Conclusion The present study resolves the embryonic origin of the midgut caeca (endoderm derived organs), development (general lengthening starting from small buds), and role (active secretory organs). The secretory activity of the midgut caeca should be incorporated in the current models of the digestive physiology in different decapod taxa.info:eu-repo/semantics/publishedVersio