Low Reproductive Rates Research Articles

Treatment strategies for sheep scab: An economic model of farmer behaviour

Ovine psoroptic mange (sheep scab) is a debilitating and damaging condition caused by a hypersensitivity reaction to the faecal material of the parasitic mite Psoroptes ovis. Farmers incur costs from the use of prophylactic acaricides and, if their sheep become infected, they incur the costs of therapeutic treatment plus the economic loss from reduced stock growth, lower reproductive rate, wool loss and hide damage. The unwillingness of farmers to use routine prophylactic treatment has been cited as a primary cause of the growing incidence of sheep scab in the United Kingdom (UK) since the disease was deregulated in 1992. However, if farmers behave rationally from an economic perspective, the optimum strategy that they should adopt will depend on the risk of infection and the relative costs of prophylactic versus therapeutic treatment, plus potential losses. This calculation is also complicated by the fact that the risk of infection is increased if neighbours have scab and reduced if neighbours treat prophylactically. Hence, for any farmer, the risk of infection and optimum approach to treatment is also contingent on the behaviour of neighbours, particularly when common grazing is used. Here, the relative economic costs of different prophylactic treatment strategies are calculated for upland and lowland farmers and a game theory model is used to evaluate the relative costs for a farmer and his/her neighbour under different risk scenarios. The analysis shows that prophylaxis with organophosphate (OP) dipping is a cost effective strategy, but only for upland farmers where the risk of infection is high. In all other circumstances prophylaxis is not cost effective relative to reliance on reactive (therapeutic) treatment. Hence, farmers adopting a reactive treatment policy only, are behaving in an economically rational manner. Prophylaxis and cooperation only become economically rational if the risk of scab infection is considerably higher than the current national average, or the cost of treatment is lower. Should policy makers wish to reduce the national prevalence of scab, economic incentives such as subsidising the cost of acaricides or rigorously applied financial penalties, would be required to make prophylactic treatment economically appealing to individual farmers. However, such options incur their own infrastructure and implementation costs for central government.

Selection and characterization of Spodoptera frugiperda (Lepidoptera: Noctuidae) resistance to MON 89034 × TC1507 × NK603 maize technology

The transgenic maize MON 89034 × TC1507 × NK603 expressing Cry1A.105, Cry1F and Cry2Ab2 proteins has been used for controlling fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), in Brazil since 2010. To design resistance management strategies, we selected and characterized the resistance to MON89034 × TC1507 × NK603 maize in a field-derived strain of FAW and investigated fitness costs associated with resistance. In greenhouse assays, more than 64% of neonates from resistant strain (RR) survived on MON 89034 × TC1507 × NK603 maize plants and produced fertile adults. In contrast, neonates from susceptible (SS) and heterozygous strains did not survive on MON 89034 × TC1507 × NK603 maize plants, indicating that resistance is functionally recessive. In laboratory assays, individuals from the RR strain fed on MON 89034 × TC1507 × NK603 maize presented similar life table parameters of those fed on non-Bt maize. However, life history studies with non-Bt maize to investigate fitness costs revealed that the RR strain had a ∼4 d longer egg-to-adult period, 9% reduction in the survival rate until adult stage, and ∼ 35% lower reproductive rate than SS and heterozygous strains. In summary, our results showed that the resistance of FAW to MON 89034 × TC1507 × NK603 maize is functionally recessive and associated with relevant fitness costs. Therefore, the adoption of refuge areas as a resistance management strategy can prolong the lifetime of MON 89034 × TC1507 × NK603 maize in Brazil.

113 DEVELOPING A CRYOPRESERVATION PROTOCOL FOR DESERT TORTOISE SPERM (GOPHERUS AGASSIZZII)

The desert tortoise (Gopherus agassizzii) is listed as threatened by the USA Fish and Wildlife Service and population declines continue to occur throughout most of their range. This species’ low reproductive rate, combined with the advanced age at which they reach sexual maturity, makes them vulnerable to multiple threats. Although assisted reproductive technologies can enhance breeding of many species, they are not widely used in tortoises. The objective of this study was to identify effective sperm cryopreservation protocols for the desert tortoise and possibly to other members of Testudinidae. We compared the effects of various concentrations of the cryoprotectants dimethyl sulfoxide (DMSO) and glycerol (6–20%) using 3 freezing devices at 4 freeze rates (CryoCooler, Ops Diagnostics, 2.3°C/m, 6.4°C/m; CryoMed, Thermo Scientific, 0.3°C/m or 1.0°C/m; and CoolCell, Biocision, 1.0°C/m) on several sperm parameters. Sperm was collected postmortem from the vas deferens of 9 individuals and tested either individually (n = 2), combined into 1 pool of 3 individuals, or 2 pools of 2 individuals. Sperm was extended in TEST-yolk buffer. Initial motility score (IMS; % motile × speed of progression2), plasma membrane integrity (IPL), and acrosome integrity (IAC) were recorded before cryoprotectant addition and freezing. For each treatment group, triplicate vials were thawed at 37°C for 60 s. Cryoprotectant was removed by centrifugation and the sperm pellet was resuspended in M199 + HEPES. Sperm were evaluated immediately following resuspension (T0), as well as 30 (T30) and 60 (T60) minutes postincubation at 22°C. All data were expressed as a percentage of initial (%IMS, %IPL, and %IAC). A sperm quality index (SQI) was calculated as (%IMS × %IPL × %IAC)/1,000, giving equal weight to each indicator of cryosurvival. The effects of freeze method on %IMS, %IPL, %IAC, and SQI were analysed by ANOVA and Tukey’s test. The effect of freeze method was significant at T0 and T60, with the 16% DMSO, 6.4°C/m method resulting in the highest %IMS at T0 (46.1%) and T30 (33.8%) and the 12% glyercol at 0.3°C/m highest at T60 (48.7%). Sperm frozen in 16% glycerol at 0.3°C/m had the highest %IPL at T0, T30, and T60 (91.9, 90.4, and 85.4%, respectively). Acrosome integrity was best maintained when sperm were frozen in 16% DMSO at 6.4°C/min (91.9%). The SQI was highest at T0 when sperm was frozen at 1.0°C/min in the CryoMed with highest post-thaw sperm parameters in 16% (T0) or 12% glycerol (T30 and T60). Interestingly, there were significant differences in SQI between the two 1.0°C/min freeze methods at each period, indicating that freezing device affected sperm cryosurvival, perhaps due to different freezing curves. This study indicates that mid-range (12 and 16%) cryoprotectant concentrations and slow freeze rates (0.3°C/m and 1.0°C/m) are optimal for desert tortoise sperm frozen in TEST-yolk buffer. Future studies will determine fertilizing capability of these sperm. These results may serve as a starting point for the study of sperm cryopreservation in other Testudinidae species.

Kori bustard (Ardeotis kori struthiunculus) occurrence in the Serengeti grass plains, northern Tanzania

The kori bustard (Ardeotis kori struthiunculus) is indigenous to grasslands and lightly wooded savannahs of southern and eastern Africa. The species is categorized as near threatened in its entire range due to anthropogenic factors and low reproductive rates. The aim of this study was to analyse the impact of grass colour, grass height, season and location on the density/occurrence of this bird species in the Serengeti grass plains, Tanzania. Data were collected from January 2014 to June 2015 using transect counts in four seasons: (i) short dry, (ii) long rain, (iii) long dry and (iv) short rain seasons, respectively. The mean density of kori bustard in the grass plains was 0.25 ± 1.01 per 0.2 km2 with near-significant differences among the study sites. The occurrence of kori bustard was high in the medium height (11–30 cm) during the long rain and short dry seasons. The kori bustard density is relatively low, and the distribution varies with grass height and season. We suggest that conservation efforts should be directed at preventing its local extinction by protecting the habitat from excessive human activities, such as livestock grazing and illegal offtake.

Intraspecific genetic variation in hosts affects regulation of obligate heritable symbionts

Symbiotic relationships promote biological diversification by unlocking new ecological niches. Over evolutionary time, hosts and symbionts often enter intimate and permanent relationships, which must be maintained and regulated for both lineages to persist. Many insect species harbor obligate, heritable symbiotic bacteria that provision essential nutrients and enable hosts to exploit niches that would otherwise be unavailable. Hosts must regulate symbiont population sizes, but optimal regulation may be affected by the need to respond to the ongoing evolution of symbionts, which experience high levels of genetic drift and potential selection for selfish traits. We address the extent of intraspecific variation in the regulation of a mutually obligate symbiosis, between the pea aphid (Acyrthosiphon pisum) and its maternally transmitted symbiont, Buchnera aphidicola Using experimental crosses to identify effects of host genotypes, we measured symbiont titer, as the ratio of genomic copy numbers of symbiont and host, as well as developmental time and fecundity of hosts. We find a large (>10-fold) range in symbiont titer among genetically distinct aphid lines harboring the same Buchnera haplotype. Aphid clones also vary in fitness, measured as developmental time and fecundity, and genetically based variation in titer is correlated with host fitness, with higher titers corresponding to lower reproductive rates of hosts. Our work shows that obligate symbiosis is not static but instead is subject to short-term evolutionary dynamics, potentially reflecting coevolutionary interactions between host and symbiont.

A long‐term study of bottlenose dolphins (Tursiops aduncus) in an Australian industrial estuary: Increased sightings associated with environmental improvements

AbstractDelphinids are long‐lived, have delayed maturity and low reproductive rates which necessitate long‐term monitoring programs to detect changes in abundance. Between 1990 and 2013, an observational study of bottlenose dolphins (Tursiops aduncus) was conducted in the Port River estuary (Adelaide, Australia). The estuary has received pollution from industry, sewage plants and storm water. In recent years, pollution entering the system has reduced and the establishment of the Adelaide Dolphin Sanctuary (ADS) increased dolphin protection from harassment and deliberate attacks. Nevertheless, the estuary remains a busy port. Over a 24 yr period, we conducted boat‐based surveys (n = 735) for dolphin groups (n = 3,634) along a predetermined route in the Inner and Outer Estuary of Adelaide's Port River estuary. It is our conjecture that major infrastructure changes and pollution abatement have yielded a more favorable marine environment for dolphins, resulting in an estimated 6% annual increase in sightings, from a near absence of sightings in the 1980s. Increased dolphin numbers were likely the result of improved water quality, augmented by surveillance and education arising from the proclamation of the ADS. This study highlights the importance of long‐term monitoring and has implications for dolphin conservation in heavily impacted urban areas and their protection via protected areas.

Bovine reproductive characteristics of the Nelore breed in the middle northern Brazil

The Brazilian Court consists of cattle in its majority by animals of zebuínas breeds, with high level of adaptation to the tropical environment that favors its exploitation is primarily pasture production system, making Brazil a major competitor in the beef export market, nevertheless, this sector still find yourself submerged in low reproductive rates, which forces the industry to undergo great transformations in order to seek ways to increase productivity and economic efficiency in the industry. Reproductive efficiency of livestock is one of the determining factors for total system efficiency of meat production, therefore, must be considered as one of the main selection criteria within the animal genetic improvement programs for high rates of production, associated with the high efficiency of reproductive, herds which targets to bring technicians and designers to achieve greater productivity and achieve greater cost-effectiveness in the activity. Many scientific studies have also been developed for estimating genetic parameters characteristics of age at first calving (IPP) that has the purpose of expressing sexual precocity in female, influencing directly on the productive efficiency and the range of parts (PID) which is one of the most important features for assessing reproductive efficiency in cutting herds, being constituted by gestation period Open days, or dry period and period of lactation. The interest of this study is to show for students and researchers the importance of studying the reproductive features emphasizing the age the first lambing and calving interval.

Wildlife population trends in protected areas predicted by national socio-economic metrics and body size.

Ensuring that protected areas (PAs) maintain the biodiversity within their boundaries is fundamental in achieving global conservation goals. Despite this objective, wildlife abundance changes in PAs are patchily documented and poorly understood. Here, we use linear mixed effect models to explore correlates of population change in 1,902 populations of birds and mammals from 447 PAs globally. On an average, we find PAs are maintaining populations of monitored birds and mammals within their boundaries. Wildlife population trends are more positive in PAs located in countries with higher development scores, and for larger-bodied species. These results suggest that active management can consistently overcome disadvantages of lower reproductive rates and more severe threats experienced by larger species of birds and mammals. The link between wildlife trends and national development shows that the social and economic conditions supporting PAs are critical for the successful maintenance of their wildlife populations.

Effects of common raven and coyote removal and temporal variation in climate on greater sage-grouse nesting success

Predator removal has been simultaneously proposed and criticized as a mitigation measure for low reproductive rates of prey species, including greater sage-grouse (Centrocercus urophasianus; hereafter “sage-grouse”). Depredation of sage-grouse nests can limit their productivity. In Wyoming, lethal removal of common ravens (Corvus corax: hereafter “ravens”) and coyotes (Canis latrans) has been conducted by USDA/APHIS/Wildlife Services (WS) for the protection of livestock. During 2008–2011, we evaluated sage-grouse nest success in study sites (1) where WS initiated a raven removal program, (2) WS removed coyotes, and (3) WS did not manipulate ravens and/or coyotes. Precipitation and temperature were analyzed individually and as interactive effects with coyote removal numbers as sources of annual variation in nest success. Over the course of our study, raven densities decreased at study sites with WS raven removal, while sage-grouse nest success in those study sites was higher during years with reduced raven density. Temperature effects on nest success were dependent on timing with successful nests having cooler temperatures prior to the nesting season (conditions promoting water retention and grass growth) and warmer temperatures the week before nest fate (conducive to degradation of sage-grouse odorants used by mammalian predators). Lower nest success was associated with more lethally removed coyotes interacting with greater precipitation suggesting mesopredator release. Raven removal may have a place in sage-grouse management as an interim mitigation measure when sage-grouse populations are subjected to high densities of ravens. However, long-term solutions are necessary, such as reducing supplemental food sources and perch structures used by ravens.

Reproduction in moose at their southern range limit

Abstract Reproduction is a critical fitness component in large herbivores. Biogeographic models predict that populations occurring at the edges of the range may have compromised reproductive rates because of inferior habitat at range peripheries. When reproductive rates are chronically low, ungulate populations may lack the resiliency to rebound quickly after periods of environmental stress, and this effect may be greatest for heat-sensitive organisms at their southern range limit. To assess the demographic vulnerability of moose (Alces alces), we studied relationships between reproductive rates, maternal age, and rump fat in the southernmost naturally occurring moose population in North America. For prime-aged moose in our study, pregnancy rates were high (92%), but moose aged < 3 or > 9 years had low pregnancy rates (32% and 38%, respectively). The relationship between rump fat and pregnancy was nonlinear such that a threshold of at least 2mm of rump fat yielded a high probability of being pregnant midwinter. In contrast, among pregnant moose, the probability of both producing a calf and recruiting it until spring increased linearly with rump fat. We also conducted a meta-analysis of pregnancy and twinning rates for adult (≥ 2 years) moose across a latitudinal gradient to compare reproductive rates from our study to other populations in North America. Moose living at southern latitudes tended to have lower reproductive rates than those living in the core of moose range, implying that southern moose populations may be demographically more vulnerable than northern moose populations.

Effects of a mining‐altered environment on individual fitness of amphibians and reptiles

AbstractPollution can affect wildlife directly through toxicity and indirectly through changes in biotic and abiotic factors, however, how these mechanisms interact in affecting free‐ranging animals remains poorly understood. By examining effects on individual fitness proxies, we aimed to determine the mechanisms behind documented amphibian and reptile declines in barren landscapes where vegetation was nearly decimated due to atmospheric metal and sulfur deposition from smelting operations in Sudbury, Ontario, Canada. We examined individual characteristics of snakes (Thamnophis sirtalis, Storeria occipitomaculata) and frogs (Lithobates clamitans, L. pipiens, L. septentrionalis) in replicated barren and reference sites, including standard metabolic rates (in snakes), body condition (all species), female reproductive status (snakes), limb deformity (frogs), and fluctuating asymmetry (all species). Frogs in barren sites (except L. septentrionalis) were in poor body condition, and all but one case of limb deformities in frogs were found in barren sites. However, neither frogs nor snakes exhibited elevated frequency of fluctuating asymmetry in barren sites. Standard metabolic rates (SMR) were not elevated in either snake species, suggesting that metal toxicity does not present an energetic burden. Instead, female T. sirtalis from barren sites exhibited lower SMR and were in poor body condition, which is a predicted response to reduced food intake. By contrast, SMR and body condition of S. occipitomaculata were not different between barren and reference sites. While physiological responses differed between T. sirtalis and S. occipitomaculata, both species exhibited lower reproductive rates (proportion of pregnant females) in barren sites compared to reference sites. Thus, energy deficiency may explain reduced reproduction in T. sirtalis while reduced availability of suitable gestation microhabitat may be a limiting factor for S. occipitomaculata. Populations in smelting‐impacted habitats include individuals with potentially compromised fitness. The low values of our measured fitness proxies appear to have resulted from pollution‐induced changes in biotic and abiotic factors, in addition to (for frogs) or rather than (for snakes) from the direct toxicity. These results suggest that impact assessment based solely on toxicological data and species distributions can underestimate the full impacts of pollution, highlighting the need for integrated examination at multiple levels of biological organization.

Prioritizing Avian Species for Their Risk of Population-Level Consequences from Wind Energy Development.

Recent growth in the wind energy industry has increased concerns about its impacts on wildlife populations. Direct impacts of wind energy include bird and bat collisions with turbines whereas indirect impacts include changes in wildlife habitat and behavior. Although many species may withstand these effects, species that are long-lived with low rates of reproduction, have specialized habitat preferences, or are attracted to turbines may be more prone to declines in population abundance. We developed a prioritization system to identify the avian species most likely to experience population declines from wind facilities based on their current conservation status and their expected risk from turbines. We developed 3 metrics of turbine risk that incorporate data on collision fatalities at wind facilities, population size, life history, species’ distributions relative to turbine locations, number of suitable habitat types, and species’ conservation status. We calculated at least 1 measure of turbine risk for 428 avian species that breed in the United States. We then simulated 100,000 random sets of cutoff criteria (i.e., the metric values used to assign species to different priority categories) for each turbine risk metric and for conservation status. For each set of criteria, we assigned each species a priority score and calculated the average priority score across all sets of criteria. Our prioritization system highlights both species that could potentially experience population decline caused by wind energy and species at low risk of population decline. For instance, several birds of prey, such as the long-eared owl, ferruginous hawk, Swainson’s hawk, and golden eagle, were at relatively high risk of population decline across a wide variety of cutoff values, whereas many passerines were at relatively low risk of decline. This prioritization system is a first step that will help researchers, conservationists, managers, and industry target future study and management activity.

Population growth of Varroa destructor (Acari: Varroidae) in honey bee colonies is affected by the number of foragers with mites

Varroa mites are a serious pest of honey bees and the leading cause of colony losses. Varroa have relatively low reproductive rates, so populations should not increase rapidly, but often they do. Other factors might contribute to the growth of varroa populations including mite migration into colonies on foragers from other hives. We measured the proportion of foragers carrying mites on their bodies while entering and leaving hives, and determined its relationship to the growth of varroa populations in those hives at two apiary sites. We also compared the estimates of mite population growth with predictions from a varroa population dynamics model that generates estimates of mite population growth based on mite reproduction. Samples of capped brood and adult bees indicated that the proportion of brood cells infested with mites and adult bees with phoretic mites was low through the summer but increased sharply in the fall especially at site 1. The frequency of capturing foragers with mites on their bodies while entering or leaving hives also increased in the fall. The growth of varroa populations at both sites was not significantly related to our colony estimates of successful mite reproduction, but instead to the total number of foragers with mites (entering and leaving the colony). There were more foragers with mites at site 1 than site 2, and mite populations at site 1 were larger especially in the fall. The model accurately estimated phoretic mite populations and infested brood cells until November when predictions were much lower than those measured in colonies. The rapid growth of mite populations particularly in the fall being a product of mite migration rather than mite reproduction only is discussed.

Selection and characterization of resistance to the Vip3Aa20 protein from Bacillus thuringiensis in Spodoptera frugiperda.

Spodoptera frugiperda is one the main target pests of maize events expressing Vip3Aa20 protein from Bacillus thuringiensis (Bt) in Brazil. In this study, we selected a resistant strain of S. frugiperda on Bt maize expressing Vip3Aa20 protein and characterized the inheritance and fitness costs of the resistance. The resistance ratio of the Vip3Aa20-resistant strain of S. frugiperda was >3200-fold. Neonates of the Vip3Aa20-resistant strain were able to survive and emerge as fertile adults on Vip3Aa20 maize, while larvae from susceptible and heterozygous strains did not survive. The inheritance of Vip3Aa20 resistance was autosomal recessive and monogenic. Life history studies to investigate fitness cost revealed an 11% reduction in the survival rate until adult stage and a ∼50% lower reproductive rate of the Vip3Aa20-resistant strain compared with susceptible and heterozygous strains. This is the first characterization of S. frugiperda resistance to Vip3Aa protein. Our results provide useful information for resistance management programs designed to prevent or delay resistance evolution to Vip3Aa proteins in S. frugiperda. © 2016 Society of Chemical Industry.

Impacto de la educación no formal en el desarrollo del sector ganadero del departamento de Olancho, Honduras 2013-2015

El presente documento constituye un estudio que se centró en evaluar el impacto que causa la educación no formal en el desarrollo de la ganadería en el departamento de Olancho, Honduras en el periodo de 2013 a 2015. En donde se relacionaron aspectos sociales, productivos y económicos de las familias productoras. Se utilizó una revisión de bibliografía de diversos autores especialistas en el área bajo estudio. Encontrando que el sistema de producción extensivo de doble propósito (leche y carne) es el modelo de explotación ganadera predominante en el país. De igual manera se refleja que la ganadería en Honduras a sufrido un decrecimiento constante por diversos factores, sobresaliendo los bajos precios del mercado nacional y los bajos índices de producción y reproducción en las fincas, lo cual es atribuido a la baja preparación escolar que tienen los productores, administradores de fincas y empleados, así mismo atribuido a la baja adopción de tecnologías en las unidades de producción por motivos de desconocimiento y la inadecuada utilización de los recursos locales en el sector rural.

Performances of survival, feeding behavior, and gene expression in aphids reveal their different fitness to host alteration.

Insect populations feeding on different plant species are under selection pressure to adapt to these differences. A study integrating elements of the ecology, behavior, and gene expression of aphids on different host plants has not yet been well-explored. The present study explores the relationship between host fitness and survival, feeding behavior, and salivary gland gene expression of a pea (Pisum sativum) host race of Acyrthosiphon pisum feeding on a common host Vicia faba and on three genetically-related hosts (Vicia villosa, Medicago truncatula, and Medicago sativa). Life table data indicated that aphids on non-favored hosts exhibited small size, low reproduction rate, slow population increase and individual development, and long lifespan. Electrical penetration graph results showed that the aphids spent significantly less time in passive ingestion of phloem sap on all non-preferred host plants before acclimation. After a period of acclimation on M. truncatula and V. villosa, pea host race individuals showed improved feeding behavior. No individuals of the pea host race completed its life history on M. sativa. Interestingly, the number of host-specific differentially-expressed salivary gland genes was negatively correlated with the fitness of aphids on this host plant. This study provided important cues in host plant specialization in aphids.

Distribución, ciclo biológico y tabla de vida de Eumaeus toxea (Lepidoptera: Lycaenidae) en la provincia fisiográfica Costa de Oaxaca, México

The butterfly Eumaeus toxea is an herbivore that feeds on Zamia paucijuga, an endangered and vulnerable cycad with their populations trending to decline and disappear. The objectives of this study were to determine the geographic distribution of the butterfly and to determine the duration of their life cycle, as well as its survival and reproduction rate when reared with its natural host under field conditions in the physiographic province of Oaxaca Coast. The work was conducted during the period of June 2010 to May 2011. Butterfly distribution coincided with the distribution of their host. Using the technique of single decrement and abridged life table by stages, 47±0.5 days were required for adult emergence, a mean generation time of 51 days, a survival rate of 0.027 to adult emergence with a mortality of 28.4% for the egg stage and 68.8% for the larval stage, and a net reproductive rate of 0.014. Due to the host specificity, low population density and net reproduction rate, the conservation of E. toxea depends on the preservation of its host and the canopy where their populations survive.

Terrestrial dissolved organic matter supports growth and reproduction ofDaphnia magnawhen algae are limiting

We experimentally show that Daphnia magna can use terrestrial-derived dissolved organic matter (t-DOM) to support growth and reproduction when alternative food sources are limiting or absent. Unlike previous studies, we restricted available food to limiting algae (0.1 mg C L−1 of Scenedesmus obliquus, provided to all treatments) and bacteria (conditions were not sterile) by excluding heterotrophic protists and running our experiment in darkness to prevent algal growth. Daphnia receiving 10 mg t-DOC L−1 leached from either beech (Fagus sylvatica, t-DOMbeech) or hazel leaves (Corylus maxima, t-DOMhazel) had significantly higher juvenile growth rates and deposited larger clutch sizes across a range of realistic temperatures (15, 20, 25°C) than Daphnia receiving no t-DOM, which failed to deposit eggs. Growth rates of t-DOM-supplied Daphnia were similar (0.10 ± 0.01 d−1) and clutch sizes were low (<2 eggs female−1) across temperatures. Our experimental leachate additions mimic fresh t-DOM inputs in natural systems (e.g. during runoff or precipitation) and suggest that t-DOM and t-DOM-supported bacteria can supplement Daphnia growth and reproduction across a range of temperatures even when algae are strongly limiting. Low growth and reproduction rates, however, indicate that t-DOM based resources are unlikely to sustain Daphnia populations independently from sufficient algal contributions.

DUGONG (Dugong dugon) FEEDING BEHAVIOUR IN SEA WORLD INDONESIA, TAMAN IMPIAN JAYA ANCOL, JAKARTA

&lt;p&gt;Dugongs is a protected herbivorous marine mammals (Suwelo et al., 1992) and included in vulnerable category of IUCN(International Union for the Conservation of Nature and Natural Resources) and Appendix I CITES (Convention on International Trade in Endangered Species) (IUCN 2012). Dugong population continues to decline due to the human threat (Suwelo et al., 1992). Another factor is because Dugong has a low reproductive rate (Hindell &amp;amp; Kirkword 2003). Ex-situ conservation of dugong is become important and has conducted by Sea World Indonesia, Taman Impian Jaya Ancol, Jakarta. Research on dugong feeding behaviour can help the ex-situ conservation of dugong. This because feeding behaviour is a main daily behaviour of dugong in the sea (Chilvers et al., 2003). The aim of this research was to describe feeding behaviour of two dugong in Sea World Indonesia. Observations were made in SWI Dugong aquarium with a diameter of 10 meters and two different depth (2 meters and 5 meters). Observations were made during two weeks on December 2012. Behavioral observation time was divided into morning (9:15 to 09:35), (11:30 to 11:50) and &lt;br /&gt;(14:30 to 14:50) observations. The feeding behavior observed was hand-fed, surface-fed and bottom-fed. Daily observations of dugong feeding behavior were done using focal animal sampling and ad libitum sampling. The data obtained was displayed in the form of tables and graphs. The data was analyzed using descriptive analysis reinforced with statistical tests. The statistical tests used were the t-test and ANOVA test. Hand-fed behavior of male dugong (31,30%) was higher than female (29,67%). Results from t-test showed that the hand-fed behaviors of both dugongs were not significantly different. Meanwhile, the other t-test result for surface-fed behavior and bottom-fed behavior of both dugongs was significantly different. Surface-fed behavior of male dugong (65.83%) was higher than female (32.08%). Bottom-fed behavior of male dugong (6.23%) was lower than females (36.63%). Hand-fed behaviour and feed on surface are the adaptation of feeding behavior in captivity. Feed on bottom behaviour is the behavior that similar to dugong feeding in the wild, which is grazing. Based on the observation, it is known that both dugong, male dugong especially, have a good adaptation on hand-fed seagrass behaviour and feed on surface, while the female dugong maintain its natural feeding behavior.&lt;/p&gt;&lt;p&gt;&lt;br /&gt;&lt;strong&gt;Keywords&lt;/strong&gt;: Dugong dugon, Sea World Indonesia, feeding behaviour, captive&lt;/p&gt;

Responses of adult Hydrellia lagarosiphon to a revised diet: implications for life cycle studies and laboratory culturing techniques

AbstractPreservation of an insect culture under laboratory conditions is essential for its study. Numerous diets have been developed for entomophagous insects undergoing screening as biological control agents in attempts to improve the nutritional quality of food provided in laboratory settings. However, less emphasis has been given to developing a more effective laboratory diet for phytophagous insects with the adult life stage not dependant on the target species. The larvae of Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) mine the leaves of Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae). This species is currently under consideration as a biological control agent of this aquatic invasive. Rearing techniques for the adult stage of other Hydrellia species have been developed but current diets are not ideal as they result in relatively low reproduction rates. We compared alternative nutritional regimes and quantified their impact on life history attributes of H. lagarosiphon. The diets included the previously developed yeast‐sugar diet, a newly developed insect‐derived diet, and a diet that combined the two. Total fecundity was significantly higher for females on an insect‐derived diet compared with the traditional carbohydrate diet and the net reproductive rate (Ro) was also higher. Population doubling time (Td) was lower, decreasing by 30% compared to the traditional laboratory diet developed for Hydrellia species. Adult females fed the combination diet, including both insect and non‐insect foods, laid 30% fewer eggs than those reared on an insect diet alone. Consequently, insect‐derived nutritional regimes could improve culturing techniques significantly and if permission to release the agent is granted, this diet may benefit mass rearing efforts potentially saving time and reducing associated costs.