Proboscis behavioral response of four honey bee Apis species towards different concentrations of sucrose, glucose, and fructose

Sugar response and gustatory gene expression in the stingless bee Tetragonisca fiebrigi

Sugar detection and gustatory responsiveness are critical for foraging success in bees, influencing their ability to locate and exploit nectar and pollen sources. Here, we investigated the sugar response thresholds and the expression of two candidate gustatory receptor genes (TfieGr1 and TfieGr3) in the antennae and proboscises of foragers of the stingless bee Tetragonisca fiebrigi. Proboscis extension assays revealed that returning pollen foragers (PF) exhibited lower sugar response thresholds and higher sensitivity to sucrose, glucose, and fructose than returning nonpollen foragers (NPF), suggesting that NPF could be mainly engaged in finding high-quality nectar sources. In addition, more than 60 % of PF responded to all sugars tested, while NPF showed a strong preference for sucrose and glucose, with only 4 % responding to fructose. Molecular experiments revealed no significant differences in TfieGr1 and TfieGr3 expression levels between PF and NPF in either sensory tissue. These findings suggest that other gustatory receptors or mechanisms, such as central processing or internal nutrient sensing, may underlie the observed behavioral differences. Our results highlight potential species-specific adaptations in sugar detection mechanisms and underscore the importance of integrating behavioral, molecular, and ecological approaches to understanding foraging strategies in stingless bees.

Single and Synergistic Effects of Microplastics and Difenoconazole on Oxidative Stress, Transcriptome, and Microbiome Traits in Honey Bees

Microplastics (MPs) and pesticides are identified as two environmental pollutants. In the present study, we showed evidence of toxic effects on honey bees from chronic oral exposure to food containing difenoconazole alone (Dif) and in a binary mixture with polystyrene (PS)-MPs (Dif + PS). We observed a disrupted gut microbial community structure in bees after difenoconazole exposure, and the gut microbiota structure richness increased at the phylum and genus levels in Dif + PS group. Transcriptomic analysis revealed that difenoconazole exposure caused 98 differentially expressed genes (DEGs), while 41 DEGs were identified in Dif + PS group. PS-MPs seemed to mitigate oxidative damage and changes in the transcriptome profile in honey bees caused by difenoconazole to some extent. However, coexposure increased the disordered microbial community composition. Our study highlights the importance of investigating possible additive and synergic activities between stressors to comprehensively understand the effects of pollutants on pollinating insects.

Botanical Antifeedants: An Alternative Approach to Pest Control

Plant protection against phytophagous pests still largely relies on the application of synthetic insecticides, which can lead to environmental and health risks that are further exacerbated by the development of resistant pest populations. These are the driving forces behind the current trend of research and the development of new ecological insecticides. The mode of action does not have to rely exclusively on acute or chronic toxicity. Another promising approach is the use of plant antifeedants, which can significantly reduce the food intake of phytophagous insects. However, the information on antifeedant substances has not yet been sufficiently evaluated. The aim of this review was to find the most promising plants that provide potent extracts, essential oils (EOs), or isolated compounds with antifeedant properties. The selection was based on a comparison of effective concentrations or doses. Effective extracts were obtained from 85 plant species belonging to 35 families and the EOs came from 38 aromatic plant species from 11 families. Based on the results, Angelica archangelica, Caesalpinia bonduc, Grindelia camporum, Inula auriculata, Lavandula luisieri, Mentha pulegium, Piper hispidinervum, and Vitis vinifera were selected as promising plants with antifeedant potential. These plants are potent antifeedants, and at the same time provide sufficient biomass for industrial use in the development and production of botanical antifeedants.

Field Exploration for Colony Selection: Evaluating Hygienic Behavior in Apis cerana indica Colonies

Hygienic behavior (HB) emerges as a pivotal trait, impacting colony resistance to diseases. This study aimed to understand the behavioral traits of Apis cerana indica colonies, with a focus on HB and other key characteristics crucial for colony health, and to screen and identify colonies with superior hygienic behavior and better performance to combat prevailing diseases and pests. This research spans a comprehensive field analysis with different seasons and locations, encompassing the distinct environmental and management factors that influence honey bee behavior. The inclusion of A. cerana indica colonies from various locations provides a novel perspective, offering valuable insights regarding the hygienic behavior of A. cerana indica. Several statistical analyses, including descriptive statistics, principal component analysis (PCA), and Aligned Rank Transformation-Analysis of Variance (ART-ANOVA) for repeated measures, shed light on the distribution of hive metrics, emphasizing the significance of considering seasonality and location-specific factors. PCA highlights unique characteristics in Tirupur and Coimbatore colonies, while correlation analyses uncover relationships among HB, honey, pollen, brood area, and adult population. Moreover, the study's nuanced findings gave the status of hygienic behavior of A. cerana indica colonies and identified colonies with better colony performance, which will be useful for future breeding programs with A. cerana indica.

Effects of Artificial Sugar Supplementation on the Composition and Nutritional Potency of Honey from Apis cerana

In the global apiculture industry, reward feeding and supplementary feeding are essential for maintaining bee colonies. Beekeepers provide artificial supplements to their colonies, typically in the form of either a honey-water solution or sugar syrup. Owing to cost considerations associated with beekeeping, most beekeepers opt for sugar syrup. However, the effects of different types of artificial sugar supplements on bee colonies and their subsequent impact on honey composition remain unclear. To address this gap, this study compared the chemical composition, antioxidant capacity, and nutritional potency of three types of honey: honey derived from colonies fed sugar syrup (sugar-based product, SP) or a honey-water solution (honey-sourced honey, HH) and naturally sourced honey (flower-sourced honey, FH), which served as the control. The results revealed that FH outperformed HH and SP in terms of total acidity, sugar content, total protein content, and antioxidant capacity, and HH outperformed SP. Regarding nutritional efficacy, including the lifespan and learning and memory capabilities of worker bees, FH exhibited the best outcomes, with no significant differences observed between HH and SP. This study underscores the importance of sugar source selection in influencing honey quality and emphasizes the potential consequences of substituting honey with sugar syrup in traditional apiculture practices.

Gustation in insects: taste qualities and types of evidence used to show taste function of specific body parts

The insect equivalent of taste buds are gustatory sensilla, which have been found on mouthparts, pharynxes, antennae, legs, wings, and ovipositors. Most gustatory sensilla are uniporous, but not all apparently uniporous sensilla are gustatory. Among sensilla containing more than one neuron, a tubular body on one dendrite is also indicative of a taste sensillum, with the tubular body adding tactile function. But not all taste sensilla are also tactile. Additional morphological criteria are often used to recognize if a sensillum is gustatory. Further confirmation of such criteria by electrophysiological or behavioral evidence is needed. The five canonical taste qualities to which insects respond are sweet, bitter, sour, salty, and umami. But not all tastants that insects respond to easily fit in these taste qualities. Categories of insect tastants can be based not only on human taste perception, but also on whether the response is deterrent or appetitive and on chemical structure. Other compounds that at least some insects taste include, but are not limited to: water, fatty acids, metals, carbonation, RNA, ATP, pungent tastes as in horseradish, bacterial lipopolysaccharides, and contact pheromones. We propose that, for insects, taste be defined not only as a response to nonvolatiles but also be restricted to responses that are, or are thought to be, mediated by a sensillum. This restriction is useful because some of the receptor proteins in gustatory sensilla are also found elsewhere.

Slow-Fast Cognitive Phenotypes and Their Significance for Social Behavior: What Can We Learn From Honeybees?

Cognitive variation is proposed to be the fundamental underlying factor that drives behavioral variation, yet it is still to be fully integrated with the observed variation at other phenotypic levels that has recently been unified under the common pace-of-life framework. This cognitive and the resulting behavioral diversity is especially significant in the context of a social group, the performance of which is a collective outcome of this diversity. In this review, we argue about the utility of classifying cognitive traits along a slow-fast continuum in the larger context of the pace-of-life framework. Using Tinbergen’s explanatory framework for different levels of analyses and drawing from the large body of knowledge about honeybee behavior, we discuss the observed interindividual variation in cognitive traits and slow-fast cognitive phenotypes from an adaptive, evolutionary, mechanistic and developmental perspective. We discuss the challenges in this endeavor and suggest possible next steps in terms of methodological, statistical and theoretical approaches to move the field forward for an integrative understanding of how slow-fast cognitive differences, by influencing collective behavior, impact social evolution.