Brood Development Research Articles

Beyond thermal limits: comprehensive metrics of performance identify key axes of thermal adaptation in ants

Summary How species respond to temperature change depends in large part on their physiology. Physiological traits, such as critical thermal limits (CTmax and CTmin), provide estimates of thermal performance but may not capture the full impacts of temperature on fitness. Rather, thermal performance likely depends on a combination of traits—including thermal limits—that vary among species. Here, we examine how thermal limits correlate with the main components that influence fitness in ants. First, we compare how temperature affected colony survival and growth in two ant species that differ in their responses to warming in the field—Aphaenogaster rudis (heat‐intolerant) and Temnothorax curvispinosus (heat‐tolerant). We then extended our study to compare CTmax, thermal requirements of brood and yearly activity season among a broader set of ant species. While thermal limits were higher for workers of T. curvispinosus than A. rudis, T. curvispinosus colonies also required higher temperatures for survival and colony growth. This pattern generalized across 17 ant species, such that species whose foragers had a high CTmax also required higher temperatures for brood development. Finally, species whose foragers had a high CTmax had relatively short activity seasons compared with less heat‐tolerant species. The relationships between CTmax, thermal requirements of brood and seasonal activity suggest two main strategies for growth and development in changing thermal environments: one where ants forage at higher temperatures over a short activity season and another where ants forage at lower temperatures for an extended activity season. Where species fall on this spectrum may influence a broad range of life‐history characteristics and aid in explaining the current distributions of ants as well as their responses to future climate change. A lay summary is available for this article.

Nutritional value of bee-collected pollens of hardy kiwi, Actinidia arguta (Actinidiaceae) and oak, Quercus sp. (Fagaceae)

Bee-collected pollens have gained attention as natural dietary supplement for human nutrition over the honeybee feed, and become important commercial hive products for beekeepers. Oak trees, Quercus sp. (Family: Fagaceae) and hardy kiwi, Actinidia arguta (Family: Actinidiaceae) are important pollen sources for honey bees. During collection and storage through the addition of nectar and salivary secretions the chemical composition of pollen is changed. We analyzed nutrient contents of bee collected oak and hardy kiwi pollens and compared with recommended requirement of essential amino acids for honey bee brood development. The results revealed that protein content was found 23.2% for oak and 26.5% for hardy kiwi pollen. All the determined essential amino acid contents of both oak and kiwi pollen satisfied the minimum individual amino acid requirement of honey bee. Threonine was present in marginal level in hardy kiwi pollen. Fat content of oak and hardy kiwi pollen were found 7 and 4.5% respectively. The higher value of polyunsaturated fatty acid/saturated fatty acid - stearic acid, lower AI and TI value, presence of essential fatty acid n-3 linolenic acid indicated these pollens as superior sources of fat. The most abundant mineral was found potassium in both the pollens followed by phosphorus. In contrast sodium content was found very less. In vitro digestibility of oak and kiwi pollen were found 69.5 and 37.8% suggesting the difficulty of nutrient uptake directly from pollen grains.

Nurse honeybee workers tend capped brood, which does not require feeding, around the clock.

'Nurse' honeybees tend brood around the clock with attenuated or no circadian rhythms, but the brood signals inducing this behavior remain elusive. We first tested the hypothesis that worker circadian rhythms are regulated by brood pheromones. We monitored locomotor activity of individually isolated nurse bees that were exposed to either various doses of larval extract or synthetic brood ester pheromone (BEP). Bees orally treated with larval extract showed attenuated circadian rhythms in one of four tested colonies; a similar but statistically non-significant trend was seen in two additional colonies. Nurse bees treated with synthetic BEP showed rhythm attenuation in one of three tested colonies. Next, we tested the hypothesis that capped brood, which does not require feeding, nevertheless induces around-the-clock activity in nurses. By combining a new protocol that enables brood care by individually isolated nurse bees, detailed behavioral observations and automatic high-resolution monitoring of locomotor activity, we found that isolated nurses tended capped brood around the clock with attenuated circadian rhythms. Bees individually isolated in similar cages but without brood showed strong circadian rhythms in locomotor activity and rest. This study shows for the first time that the need to feed hungry larvae is not the only factor accounting for around-the-clock activity in nurse bees. Our results further suggest that the transition between activity with and without circadian rhythms is not a simple switch triggered by brood pheromones. Around-the-clock tending may enhance brood development and health in multiple ways that include improved larval feeding, thermoregulation or hygienic behavior.

Effects of neem (Azadirachta indica) on honey bee workers and queens, while applied to control Varroa destructor

The objective of this study was to determine the effect of neem (Azadirachta indica) oil on mortality and development of honey bee worker brood, queen oviposition, colony performance, and Varroa destructor mortality. As a hypothesis it was indicated that adequate concentrations of neem oil may control V. destructor without affecting bee colonies. Neem oil at concentrations of 0.33–21.1%, with 7.26–464.64 mg l−1 azadirachtin, was sprayed on bee (Apis mellifera) combs. Their effects on mortality and developmental time of the brood, worker bee response on feeding and capping the larvae, and number of eggs laid by the queen were quantified. A 21.1% oil concentration resulted in 100% egg mortality, but lower concentrations resulted in minimal egg mortality. Larvae that reached the fifth instar were capped and survived the presence of the oil, but when 21.1% was applied, their development was delayed one to two days. With concentrations of 5.3 and 10.6% (116.2 and 232.3 mg l−1 of azadirachtin, respectively), queen oviposition was not significantly different from the control, but 10.6% slightly decreased oviposition. The highest V. destructor mortality (85%) was proportional to the concentration and number of spray applications. When neem oil was applied to hives, none of the concentrations used decreased bee population, capped worker larvae or the reserves of honey and pollen. However, two queens died after one application of 5.3% and three applications of 10.6%.

Floral Diversity of Pollen Collected by Honey Bees (Apis mellifera L.) – Validation of the Chromatic Assessment Method

Abstract Pollen collected from flowers by forager bees is the only natural protein source for the hive. This nutritional compound is fundamental for the nurse bee and brood development, and for the queen activity. Pollen has a strong influence on colony health. It is also known that the pollen quality, in terms of the amino acid profile and total protein content, varies significantly according to the floral origin. For this reason, the palynological diversity assessed in corbicular pollen is a good measure of the quality of the environment the bees live in, in terms of available food. An international research initiative “C.S.I. Pollen” aims to elaborate a pollen diversity map for all of Europe, carried out by beekeepers. Chromatic assessment of pellet colours will be used as a method. In our study, we wanted to validate this idea, through the comparison between the two methods: chromatic assessment of the diversity of pollen pellet colours and palynological assessment of the real pollen type diversity. In other words, we wanted to verify whether the pellet-colour profile reflects the palynological one. We found a significant correlation between results obtained from the two methods but some improvements are also proposed in order to increase the determination coefficient and to reduce the differences given by the two answers.

Life Inside an Acorn: How Microclimate and Microbes Influence Nest Organization in Temnothorax Ants

AbstractNests provide a buffer against environmental variation, but conditions may also vary at different locations within a nest. Conditions can vary based on abiotic factors, such as moisture and temperature, as well as biotic factors, such as the presence of microbes and potential pathogens. Therefore, characterizing how animals adjust their position inside their nests to track microclimate preferences while at the same time preventing pathogen exposure is necessary to understand the benefits nests provide. Here we studied how colonies of the acorn‐nesting ant Temnothorax curvispinosus responded to experimental manipulation of moisture, temperature, and microbial growth inside their nests. Colonies showed no response to differences in moisture and moved to the bottom of the acorn regardless of moisture treatment. When nests were heated from the top to simulate warming by the sun, workers preferentially moved brood to the warm, upper half of the acorn, which would stimulate brood development. Finally, the strongest factor that influenced colony position was the presence of microbes inside the nest—colonies avoided the bottom of the nest when it was inoculated with microbes, and colonies in new acorns shifted to the top of the acorn over time as mold and other microbes had time to grow. The relatively strong response of T. curvispinosus to microbial growth inside their nests suggests that pathogen pressures—in addition to microclimate—have a significant impact on how colonies use nest spaces. Social insects are known to invest heavily in antimicrobial compounds that kill or slow the growth of microbes, but avoidance may represent an additional line of defense to prevent pathogen exposure.

Is the initial nest depth adapted to favorable conditions for the incipient colony in leaf-cutting ants?

The nest dug by the leaf-cutter ant queen of the genus Atta is a vertical tunnel interconnected to a small chamber to hold its offspring and the symbiotic fungus. The depth of the initial chamber of the Atta sexdens rubropilosa ranges from 10 to 30 cm below the soil surface. This available information, could it be that the ideal initial nest depth is adapted to favorable conditions for the initial colony? We hypothesized this depth can provide a minimum temperature range with almost constant temperature, leading to the development of symbiotic fungus and brood yet to emerge. To test this hypothesis, laboratory experiments were carried out and the soil temperature was measured at different depths. The colony development at different temperatures was studied in the laboratory and the brood production (number of eggs, larvae, pupae and adults) was measured until the first workers emergency. Additionally, lipid content and the survival of queens at different temperatures were determined. Our results show an suitable temperature range (ranging from 24.82±3.14°C to 24.11±1.30°C) at a depth of 5 to 25 cm from the ground, an ideal brood development at temperatures of 24 and 28 °C, and consequently a reduction in lipid content of the queens at high temperatures, without affecting their survival in the trial period. These results indicate that the depth of the initial chamber excavated by the queen is suitable for the success of the incipient colony.

Escape to the high canopy-thermal deficiency causes niche expansion in a forest-floor ant.

The small formicoxenine ant Temnothorax saxonicus was known from about 40 localities in Central Europe nesting in anorganic substrates on floor of xerothermous forests whereas investigations of 198 tree canopies in 19 forest sites of the same region provided no indication for arboreal nesting or foraging. We present the first evidence for canopy-nesting populations of T. saxonicus on old Quercus trees in 3 sites having maximum calibrated topsoil temperatures of 17.9 ± 0.3 °C which were significantly (P < 0.007) lower than 22.8 ± 2.0 °C measured in 5 sites with ground-nesting populations. The thermal deficit on forest floor inhibits brood development in ground nests and caused a moving to canopy were maximum calibrated temperatures of the, now wooden, substrates are at least 26.1 °C for the whole canopy and 30.8 °C in more sun-exposed spots. T. saxonicus competed here successfully with the obligatory canopy ants T. affinis and T. corticalis. The distributional data of this rope-climbing study support former results that highest nest densities of small arboreal ants occur in temperate climate over the entire canopy mantle of single trees situated in open land or in park-like environments but occur in the top of the canopy in tree stands with high degree of canopy closure.

Spatiotemporal Spawning Patterns of Smallmouth Bass at Its Upstream Invasion Edge

AbstractClimate change and land‐use practices are causing widespread warming of streams, forcing resident species to adapt or migrate. For instance, in the John Day River, Oregon (Columbia River basin), rising temperatures are facilitating the range expansion of Smallmouth Bass Micropterus dolomieu into critical salmon rearing habitat. Understanding Smallmouth Bass reproductive ecology at its range boundaries is integral to understanding and ultimately predicting its upstream range expansion. We addressed this knowledge gap by exploring potential temperature‐mediated effects on Smallmouth Bass reproduction at the leading edge of its nonnative riverine distribution in the Pacific Northwest. We used continuous snorkel surveys to characterize its upstream extent in the North Fork John Day River, where we observed spawning patterns and measured adult nest‐guarding male size, fecundity, brood development, habitat attributes, and nest success over 2 years (2014, 2015). We found a pattern of asynchronous and protracted spawn timing across the leading invasion edge, &gt;90% nest success, and few changes in reproductive attributes (e.g., fecundity, brood development) as the thermal regime became increasingly colder. We also found increased selectivity of nest substrata and decreased guarding requirements in upstream habitats. These results suggest that reproductive success does not limit the upstream range expansion of Smallmouth Bass and highlight potential ecological benefits that may offset the energetic demands associated with dispersing upstream. Overall, our findings enhance the current understanding of how reproduction influences range expansion of nonnative Smallmouth Bass populations in streams, enabling us to better guide managers tasked with minimizing the spread of this nonnative species in the future.Received November 2, 2015; accepted February 1, 2016 Published online June 15, 2016

Honeybees Produce Millimolar Concentrations of Non-Neuronal Acetylcholine for Breeding: Possible Adverse Effects of Neonicotinoids.

The worldwide use of neonicotinoid pesticides has caused concern on account of their involvement in the decline of bee populations, which are key pollinators in most ecosystems. Here we describe a role of non-neuronal acetylcholine (ACh) for breeding of Apis mellifera carnica and a so far unknown effect of neonicotinoids on non-target insects. Royal jelly or larval food are produced by the hypopharyngeal gland of nursing bees and contain unusually high ACh concentrations (4–8 mM). ACh is extremely well conserved in royal jelly or brood food because of the acidic pH of 4.0. This condition protects ACh from degradation thus ensuring delivery of intact ACh to larvae. Raising the pH to ≥5.5 and applying cholinesterase reduced the content of ACh substantially (by 75–90%) in larval food. When this manipulated brood was tested in artificial larval breeding experiments, the survival rate was higher with food supplemented by 100% with ACh (6 mM) than with food not supplemented with ACh. ACh release from the hypopharyngeal gland and its content in brood food declined by 80%, when honeybee colonies were exposed for 4 weeks to high concentrations of the neonicotinoids clothianidin (100 parts per billion [ppb]) or thiacloprid (8,800 ppb). Under these conditions the secretory cells of the gland were markedly damaged and brood development was severely compromised. Even field-relevant low concentrations of thiacloprid (200 ppb) or clothianidin (1 and 10 ppb) reduced ACh level in the brood food and showed initial adverse effects on brood development. Our findings indicate a hitherto unknown target of neonicotinoids to induce adverse effects on non-neuronal ACh which should be considered when re-assessing the environmental risks of these compounds. To our knowledge this is a new biological mechanism, and we suggest that, in addition to their well documented neurotoxic effects, neonicotinoids may contribute to honeybee colony losses consecutive to a reduction of the ACh content in the brood food.

Daily Thermal Fluctuations Experienced by Pupae via Rhythmic Nursing Behavior Increase Numbers of Mushroom Body Microglomeruli in the Adult Ant Brain.

Social insects control brood development by using different thermoregulatory strategies. Camponotus mus ants expose their brood to daily temperature fluctuations by translocating them inside the nest following a circadian rhythm of thermal preferences. At the middle of the photophase brood is moved to locations at 30.8°C; 8 h later, during the night, the brood is transferred back to locations at 27.5°C. We investigated whether daily thermal fluctuations experienced by developing pupae affect the neuroarchitecture in the adult brain, in particular in sensory input regions of the mushroom bodies (MB calyces). The complexity of synaptic microcircuits was estimated by quantifying MB-calyx volumes together with densities of presynaptic boutons of microglomeruli (MG) in the olfactory lip and visual collar regions. We compared young adult workers that were reared either under controlled daily thermal fluctuations of different amplitudes, or at different constant temperatures. Thermal regimes significantly affected the large (non-dense) olfactory lip region of the adult MB calyx, while changes in the dense lip and the visual collar were less evident. Thermal fluctuations mimicking the amplitudes of natural temperature fluctuations via circadian rhythmic translocation of pupae by nurses (amplitude 3.3°C) lead to higher numbers of MG in the MB calyces compared to those in pupae reared at smaller or larger thermal amplitudes (0.0, 1.5, 9.6°C), or at constant temperatures (25.4, 35.0°C). We conclude that rhythmic control of brood temperature by nursing ants optimizes brain development by increasing MG densities and numbers in specific brain areas. Resulting differences in synaptic microcircuits are expected to affect sensory processing and learning abilities in adult ants, and may also promote interindividual behavioral variability within colonies.

Effects of an insect growth regulator and a solvent on honeybee (Apis mellifera L.) brood development and queen viability.

Honeybee toxicology is complex because effects on individual bees are modulated by social interactions between colony members. In the present study, we applied high doses of the insect growth regulator fenoxycarb to honeybee colonies to elucidate a possible interplay of individually- and colony-mediated effects regarding honey bee toxicology. Additionally, possible effects of the solvent dimethyl sulfoxide (DMSO) were assessed. We conducted studies on egg hatching and brood development to assess brood care by nurse bees as well as queen viability. Egg hatching was determined by the eclosion rate of larvae from eggs originating from colonies (i) treated with sugar syrup only, (ii) treated with sugar syrup containing DMSO and (iii) treated with sugar syrup containing fenoxycarb (dissolved in DMSO). To evaluate brood development, combs with freshly laid eggs were reciprocally transferred between colonies, and development of brood was examined in the recipient hive. Brood reared inside DMSO- and fenoxycarb-treated colonies as well as brood from DMSO- and from fenoxycarb-exposed queens showed higher mortality than brood not exposed to the chemicals. No differences were found in egg hatching among the treatments, but there was a higher variability of eclosion rates after queens were exposed to fenoxycarb. We also observed queen loss and absconding of whole colonies. Based on our results we infer that fenoxycarb has queen- as well as nurse bee-mediated effects on brood quality and development which can lead to the queen's death. There also is an effect of DMSO on the nurse bees' performance that could disturb the colony's equilibrium, at least for a delimited timespan.

Mountain pine beetle (Dendroctonus ponderosae) can produce its aggregation pheromone and complete brood development in naïve red pine (Pinus resinosa) under laboratory conditions

Mountain pine beetle (Dendroctonus ponderosae Hopkins; Coleoptera: Curculionidae, Scolytinae) has killed millions of hectares of lodgepole pine (Pinus contorta Douglas ex Loudon) forest in western Canada, where it has recently established in the novel host jack pine (Pinus banksiana Lamb.) and threatens naïve red pine (Pinus resinosa Aiton) forests as the current outbreak expands eastward. It is therefore crucial to understand whether red pine is a suitable host for D. ponderosae. Host suitability was assessed by comparing the ability of beetles to produce pheromones and complete their development in red pine bolts inoculated with mating beetle pairs. We detected two of four primary pheromones, including trans-verbenol and verbenone, but not exo-brevicomin or frontalin. Beetle brood successfully developed in bolts, with reproductive parameters (e.g., female and larval galleries, pupal chamber, and number of broods emerged per mated pair of adults) that were similar to those reported from the beetle’s historical host lodgepole pine and the novel host jack pine. These results provide initial evidence that red pine is a suitable host for D. ponderosae. However, it is unclear how either low concentrations or an absence of exo-brevicomin, frontalin, and the synergistic monoterpene myrcene could affect host colonization and establishment of beetles.

Honeybee Colony Vibrational Measurements to Highlight the Brood Cycle.

Insect pollination is of great importance to crop production worldwide and honey bees are amongst its chief facilitators. Because of the decline of managed colonies, the use of sensor technology is growing in popularity and it is of interest to develop new methods which can more accurately and less invasively assess honey bee colony status. Our approach is to use accelerometers to measure vibrations in order to provide information on colony activity and development. The accelerometers provide amplitude and frequency information which is recorded every three minutes and analysed for night time only. Vibrational data were validated by comparison to visual inspection data, particularly the brood development. We show a strong correlation between vibrational amplitude data and the brood cycle in the vicinity of the sensor. We have further explored the minimum data that is required, when frequency information is also included, to accurately predict the current point in the brood cycle. Such a technique should enable beekeepers to reduce the frequency with which visual inspections are required, reducing the stress this places on the colony and saving the beekeeper time.

Bacteria influence mountain pine beetle brood development through interactions with symbiotic and antagonistic fungi: implications for climate-driven host range expansion.

Bark beetles are associated with diverse communities of symbionts. Although fungi have received significant attention, we know little about how bacteria, and in particular their interactions with fungi, affect bark beetle reproduction. We tested how interactions between four bacterial associates, two symbiotic fungi, and two opportunistic fungi affect performance of mountain pine beetles (Dendroctonus ponderosae) in host tissue. We compared beetle performance in phloem of its historical host, lodgepole pine (Pinus contorta), and its novel host recently accessed through warming climate, jack pine (Pinus banksiana). Overall, beetles produced more larvae, and established longer ovipositional and larval galleries in host tissue predominantly colonized by the symbiotic fungi, Grosmannia clavigera, or Ophiostoma montium than by the opportunistic colonizer Aspergillus and to a lesser extent, Trichoderma. This occurred in both historical and naïve hosts. Impacts of bacteria on beetle reproduction depended on particular fungus-bacterium combinations and host species. Some bacteria, e.g., Pseudomonas sp. D4-22 and Hy4T4 in P. contorta and Pseudomonas sp. Hy4T4 and Stenotrophomonas in P. banksiana, reduced antagonistic effects by Aspergillus and Trichoderma resulting in more larvae and longer ovipositional and larval galleries. These effects were not selective, as bacteria also reduced beneficial effects by symbionts in both host species. Interestingly, Bacillus enhanced antagonistic effects by Aspergillus in both hosts. These results demonstrate that bacteria influence brood development of bark beetles in host tissue. They also suggest that climate-driven range expansion of D. ponderosae through the boreal forest will not be significantly constrained by requirements of, or interactions among, its microbial associates.

Neonicotinoid-Coated Zea mays Seeds Indirectly Affect Honeybee Performance and Pathogen Susceptibility in Field Trials.

Thirty-two honeybee (Apis mellifera) colonies were studied in order to detect and measure potential in vivo effects of neonicotinoid pesticides used in cornfields (Zea mays spp) on honeybee health. Honeybee colonies were randomly split on four different agricultural cornfield areas located near Quebec City, Canada. Two locations contained cornfields treated with a seed-coated systemic neonicotinoid insecticide while the two others were organic cornfields used as control treatments. Hives were extensively monitored for their performance and health traits over a period of two years. Honeybee viruses (brood queen cell virus BQCV, deformed wing virus DWV, and Israeli acute paralysis virus IAPV) and the brain specific expression of a biomarker of host physiological stress, the Acetylcholinesterase gene AChE, were investigated using RT-qPCR. Liquid chromatography-mass spectrometry (LC-MS) was performed to detect pesticide residues in adult bees, honey, pollen, and corn flowers collected from the studied hives in each location. In addition, general hive conditions were assessed by monitoring colony weight and brood development. Neonicotinoids were only identified in corn flowers at low concentrations. However, honeybee colonies located in neonicotinoid treated cornfields expressed significantly higher pathogen infection than those located in untreated cornfields. AChE levels showed elevated levels among honeybees that collected corn pollen from treated fields. Positive correlations were recorded between pathogens and the treated locations. Our data suggests that neonicotinoids indirectly weaken honeybee health by inducing physiological stress and increasing pathogen loads.

Giant freshwater prawn (Macrobrachium rosenbergii) brood development in winter season

Realizing the importance of giant freshwater prawn, Macrobrachium rosenberbii supply mature brood for extending the culture period for the successful production of marketable size, a study was conducted for development of broods of the species in the winter season by increasing temperature of water using green house concept. For this purpose, two ponds were covered with transparent polyethylene sheet fastened in bamboo frame and two ponds with no such covering. The ponds were equally stocked with prawn @ 5000 indv./ha (female:male::8:1) on 8th December 2009 and reared up to 9th March 2010. Temperature of water of the green house ponds was much higher than that of open ponds. Prawns started to be gravid after stocking in the green house ponds and 45-55% prawn became berried up to 9th March. But no remarkable development of gonad except a very few (2.5%) gravid prawn at the later part of rearing in one of the open pond was observed.Bangladesh J. Zool. 42(2): 153-159, 2014

Brood cells, life-cycle stages and development of some earth-borer beetles in the generaBolborhachium, BlackburniumandBolboleaus(Coleoptera: Geotrupidae), with notes on captive rearing and a discussion of larval diet

Studies in Western Australia have revealed new information on the natural history of beetles in the genera Blackburnium, Bolboleaus and Bolborhachium (Bolboceratinae), all of which are notable for their relatively enormous eggs. Most of the information concerns Bolborhachium recticorne (Guérin-Méneville 1838), which was studied at a perennial nesting site. This species (with two exceptions), and some congeners, constructed built-in brood cells using transported surface soil. By contrast, Blackburnium reichei (Guérin-Méneville 1838) and Bolboleaus hiaticollis Howden 1985 excavated simple chambers for their eggs. Egg to adult development in all species occurred in the brood cells. Eggs and larvae collected in the field were reared in their original cells and in artificial cells made in soil. Of three instars, the first contained the already developed second instar and did not feed. Second and third instars nibbled at the walls of their cells as if feeding, grew in size and increased their weight 2.5–3.0 times. However, they turned over little soil, ingested little solid material and rarely passed faeces, so ingestion and digestion of ‘humus’ (finely divided plant detritus) is unlikely to account for all (if any) of their weight gain. As the contents of the larval intestine were hygroscopic, perhaps larvae ingest salts and/or humic and fulvic acids that enable them to absorb water. Soil bacteria are suggested as a source of nutrition for the larvae.

Respiration in wood ant (Formica aquilonia) nests as affected by altitudinal and seasonal changes in temperature

Wood ants build large, long-lasting nests and maintain stable high temperatures in nest centers from April to September to support brood development. Similar nest temperatures have been recorded regardless of latitude and altitude, suggesting that nests from colder environments produce more heat than nests from warmer environments. We measured changes in temperature and in situ respiration in nests from 700 and 1000 m a.s.l. We also sampled ants and nest materials from the same nests and measured their respiration at 10 and 20 °C in the laboratory. Both ant and microbial respiration increased greatly as temperature increased in spring, especially at 1000 m, resulting in the increase in nest temperature in spring. Metabolic activity greatly increased for ants in March and for nest microorganisms in April when nutrient contents also increased because of input of plant material and food. Nests from 1000 m maintained similar temperatures as nests from 700 m in summer but were colder in winter. Ants were responsible for the maintenance of high temperatures during summer but metabolic activity did not differ between the two altitudes, suggesting that the increased respiration and heat production in summer by ants at the higher altitude resulted from an increase in numbers of ants per colony.

The Effect of Temperature on Synchronization of Brood Development of the Bopyrid Isopod Parasite Probopyrus pandalicola with Molting of Its Host, the Daggerblade Grass Shrimp Palaemonetes pugio.

The bopyrid isopod Probopyrus pandalicola is a hematophagous ectoparasite that sexually sterilizes some palaemonid shrimps, including female daggerblade grass shrimp Palaemonetes pugio. The reproduction of parasitic isopods is thought to occur synchronously with host molting because the brood would be unsuccessful if molting occurred before the larvae were free swimming. Temperature affects the length of the molting cycle of shrimp, and therefore may also affect the incubation time of isopod broods. The purpose of the present study was to determine the effect of temperature on brood development of the parasite and on the degree of synchronization with the molting of its host. Parasitized P. pugio were monitored daily at 2 experimental temperatures, 23 and 15 C, in temperature-controlled chambers for the duration of a full parasite reproductive cycle. Developmental stage was determined by the visible coloration of the brood through the exoskeleton of the host, and was designated as egg, embryo I, embryo II, or epicaridium larvae. Temperature significantly affected median brood incubation time, which was only 11 days at 23 C, as compared to 35 days at 15 C. The final developmental stage (epicaridium larvae) was 3 times shorter at 23 C (median 3 days; n = 45) than at 15 C (median 9 days; n = 15). Temperature significantly affected the intermolt period of parasitized shrimp, which was shorter at 23 C (median 12 days) than at 15 C (median 37 days). A smaller percentage of the intermolt period elapsed between larval release and shrimp molting at 23 C (0.0%) than at 15 C (3.1%), indicating closer synchronization between host molting and parasite reproduction at the warmer temperature. At 15 C, the isopods utilized a smaller proportion of the time that was available for brood incubation during the intermolt period of their host. Brood size ranged from 391 to 4,596 young and was positively correlated with parasite and host size. Because development progressed more rapidly at 23 C, warmer temperatures could increase the prevalence of P. pandalicola. The corresponding reduction in the abundance of ovigerous grass shrimp as a result of sexual sterilization by bopyrids could adversely impact estuarine ecosystems, as grass shrimp are a crucial link in transferring energy from detritus to secondary consumers.