Metabolic and transcriptomic characterization of summer and winter dormancy in the solitary bee, Osmia lignaria.

The solitary bee Osmia lignaria is a native pollinator in North America with growing economic importance. The life cycle of O. lignaria provides a unique opportunity to compare the physiological and molecular mechanisms underlying two ecologically contrasting dormancies within the same species.

Molecular mechanisms and trade-offs underlying fluctuating thermal regimes during low-temperature storage.

Insects exposed to constant low temperatures (CLT) exhibit high rates of mortality as well as a variety of sublethal effects. In many species, interruptions of CLT with brief pulses of warm temperatures (fluctuating thermal regimes, FTR) lead to increases in survival and fewer sublethal effects. However, we still lack a complete understanding of the physiological mechanisms activated during FTR.

Identification of sex-specific markers based on gene expression in adult Colorado potato beetles.

The Colorado potato beetle, Leptinotarsa decemlineata, (Coleoptera: Chrysomelidae) is an economically important pest insect of potatoes. Understanding how the mechanisms driving its invasiveness vary between sexes will be critical for developing modern control methods. However, the currently available methods for sexing adult Colorado potato beetles are either inefficient or unsuitable for projects that require RNA as an input, like those measuring gene expression.

Effects of developmental state on low-temperature physiology of the alfalfa leafcutting bee, .

The success of agriculture relies on healthy bees to pollinate crops. Commercially managed pollinators are often kept under temperature-controlled conditions to better control development and optimize field performance. One such pollinator, the alfalfa leafcutting bee, , is the most widely used solitary bee in agriculture.

Effects of Temperature and Wildflower Strips on Survival and Macronutrient Stores of the Alfalfa Leafcutting Bee (Hymenoptera: Megachilidae) Under Extended Cold Storage.

Megachile rotundata (F.) is an important pollinator of alfalfa in the United States. Enhancing landscapes with wildflowers is a primary strategy for conserving pollinators and may improve the sustainability of M.

Timing of Diapause Initiation and Overwintering Conditions Alter Gene Expression Profiles in .

Within the United States and Canada, the primary pollinator of alfalfa is the alfalfa leafcutting bee (ALCB), . Our previous findings showed that overwintering conditions impacted gene expression profile in ALCB prepupae that entered diapause early in the season. However, ALCB are a bivoltine species, which begs the question of whether bees entering diapause later in the season also show this trend.

Environmental impacts on diapause and survival of the alfalfa leafcutting bee, Megachile rotundata.

Megachile rotundata exhibits a facultative prepupal diapause but the cues regulating diapause initiation are not well understood. Possible cues include daylength and temperature. Megachile rotundata females experience changing daylengths over the nesting season that may influence diapause incidence in their offspring through a maternal effect.

Body and Wing Allometries Reveal Flight-Fecundity Tradeoff in Response to Larval Provisioning in Osmia lignaria (Hymenoptera: Megachilidae).

Variation in body size has important implications for physical performance and fitness. For insects, adult size and morphology are determined by larval growth and metamorphosis. Female blue orchard bees, Osmia lignaria, (Say) provision a finite quantity of food to their offspring.

Overwintering conditions impact insulin pathway gene expression in diapausing Megachile rotundata.

Diapause is a non-feeding state that many insects undergo to survive the winter months. With fixed resources, overall metabolism and insulin signaling (IIS) are maintained at low levels, but whether those change in response to seasonal temperature fluctuations remains unknown. The focus of this study was to determine 1) how genes in the insulin signaling pathway vary throughout diapause and 2) if that variation changes in response to temperature.

Comparison of Fluctuating Thermal Regimes and Commercially Achievable Constant-Temperature Regimes for Short-Term Storage of the Alfalfa Leafcutting Bee (Hymenoptera: Megachilidae).

Interrupting the spring incubation of Megachile rotundata (F.) with a period of low-temperature storage for synchronizing the bees' emergence with crop bloom is an essential part of M. rotundata management.

Diet quantity influences caste determination in honeybees ().

In species that care for their young, provisioning has profound effects on offspring fitness. Provisioning is important in honeybees because nutritional cues determine whether a female becomes a reproductive queen or sterile worker. A qualitative difference between the larval diets of queens and workers is thought to drive this divergence; however, no single compound seems to be responsible.

Fluctuating thermal regimes prevent chill injury but do not change patterns of oxidative stress in the alfalfa leafcutting bee, Megachile rotundata.

In insects, prolonged exposure to unseasonably low temperatures can lead to detrimental physiological effects known as chill injury. Changes to active and passive transport across epithelia during chilling likely drive the collapse of ion gradients, metabolic imbalance and potentially oxidative stress. In the alfalfa leafcutting bee, Megachile rotundata transcriptomic evidence provides support for these responses at the level of gene expression, but variable expression profiles between life stages in M.

Thermoprofile Parameters Affect Survival of Megachile rotundata During Exposure to Low-Temperatures.

Insects exposed to low temperature stress can experience chill injury, but incorporating fluctuating thermoprofiles increases survival and blocks the development of sub-lethal effects. The specific parameters required for a protective thermoprofile are poorly understood, because most studies test a limited range of thermoprofiles. For example, thermoprofiles with a wave profile may perform better than a square profile, but these two profiles are rarely compared.

Immediate Transcriptional Response to a Temperature Pulse under a Fluctuating Thermal Regime.

The response of ectotherms to temperature stress is complex, non-linear, and is influenced by life stage and previous thermal exposure. Mortality is higher under constant low temperatures than under a fluctuating thermal regime (FTR) that maintains the same low temperature but adds a brief, daily pulse of increased temperature. Long term exposure to FTR has been shown to increase transcription of genes involved in oxidative stress, immune function, and metabolic pathways, which may aid in recovery from chill injury and oxidative damage.

Long-Distance Transportation Causes Temperature Stress in the Honey Bee, Apis mellifera (Hymenoptera: Apidae).

Pollination services provided by the honey bee, Apis mellifera (Hymenoptera: Apidae, Linnaeus, 1758) have broad economic impacts and are necessary for production of a diversity of important crops. Hives may be transported multiple times per year to provide pollination. To test how temperature may contribute to transportation stress, temperature sensors were placed in hives in different locations and orientations on the trailer during shipping.

A Precise and Autonomous System for the Detection of Insect Emergence Patterns.

Existing systems to measure insect emergence patterns have limitations; they are only partially automated and are limited in the maximum number of emerging insects they can detect. In order to obtain precise measurement of insect emergence, it is necessary for systems to be semi-automated and able to measure large numbers of emerging insects. We addressed these issues by designing and building a system that is automated and can measure emergence of up to 1200 insects.

Mechanisms underpinning the beneficial effects of fluctuating thermal regimes in insect cold tolerance.

Insects exposed to low temperature often have high mortality or exhibit sublethal effects. A growing number of recent studies have shown beneficial effects of exposing insects to recurrent brief warm pulses during low-temperature stress (fluctuating thermal regime, FTR). The physiological underpinnings of the beneficial effects of FTR on cold survival have been extensively studied over the past few years.

Micro-computed tomography of pupal metamorphosis in the solitary bee Megachile rotundata.

Insect metamorphosis involves a complex change in form and function. In this study, we examined the development of the solitary bee, Megachile rotundata, using micro-computed tomography (μCT) and volume analysis. We describe volumetric changes of brain, tracheae, flight muscles, gut, and fat bodies in prepupal, pupal, and adult M.

Environmental history impacts gene expression during diapause development in the alfalfa leafcutting bee, .

Our understanding of the mechanisms controlling insect diapause has increased dramatically with the introduction of global gene expression techniques, such as RNA sequencing (RNA-seq). However, little attention has been given to how ecologically relevant field conditions may affect gene expression during diapause development because previous studies have focused on laboratory-reared and -maintained insects. To determine whether gene expression differs between laboratory and field conditions, prepupae of the alfalfa leafcutting bee, , entering diapause early or late in the growing season were collected.

Cues for cavity nesters: investigating relevant zeitgebers for emerging leafcutting bees, .

Photoperiod is considered the universal zeitgeber, regulating physiological processes in numerous animals. However, for animals in light-restricted habitats (e.g.

Metamorphosis is induced by food absence rather than a critical weight in the solitary bee, .

Body size is an important phenotypic trait that correlates with performance and fitness. For determinate growing insects, body size variation is determined by growth rate and the mechanisms that stop growth at the end of juvenile growth. Endocrine mechanisms regulate growth cessation, and their relative timing along development shapes phenotypic variation in body size and development time.

Physiological responses to fluctuating temperatures are characterized by distinct transcriptional profiles in a solitary bee.

Exposure to stressful low temperatures during development can result in the accumulation of deleterious physiological effects called chill injury. Metabolic imbalances, disruptions in ion homeostasis and oxidative stress contribute to the increased mortality of chill-injured insects. Interestingly, survival can be significantly increased when chill-susceptible insects are exposed to a daily warm-temperature pulse during chilling.

The geometric framework for nutrition reveals interactions between protein and carbohydrate during larval growth in honey bees.

In holometabolous insects, larval nutrition affects adult body size, a life history trait with a profound influence on performance and fitness. Individual nutritional components of larval diets are often complex and may interact with one another, necessitating the use of a geometric framework for elucidating nutritional effects. In the honey bee, , nurse bees provision food to developing larvae, directly moderating growth rates and caste development.

Optimizing Fluctuating Thermal Regime Storage of Developing Megachile rotundata (Hymenoptera: Megachilidae).

The alfalfa leafcutting bee, Megachile rotundata (F.), is the primary pollinator for alfalfa seed production in North America. Under current management practice, developing pupae are incubated at 29-30°C until the adults emerge for pollination.