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International Journal of Molecular... May 2024The effect of pesticides on insects is often discussed in terms of acute and chronic toxicity, but an important and often overlooked aspect is the impact of sublethal... (Review)
Review
The effect of pesticides on insects is often discussed in terms of acute and chronic toxicity, but an important and often overlooked aspect is the impact of sublethal doses on insect physiology and behavior. Pesticides can influence various physiological parameters of insects, including the innate immune system, development, and reproduction, through a combination of direct effects on specific exposed tissues and the modification of behaviors that contribute to health and reproductive success. Such behaviors include mobility, feeding, oviposition, navigation, and the ability to detect pheromones. Pesticides also have a profound effect on insect learning and memory. The precise effects depend on many different factors, including the insect species, age, sex, caste, physiological condition, as well as the type and concentration of the active ingredients and the exposure route. More studies are needed to assess the effects of different active ingredients (and combinations thereof) on a wider range of species to understand how sublethal doses of pesticides can contribute to insect decline. This review reflects our current knowledge about sublethal effects of pesticides on insects and advancements in the development of innovative methods to detect them.
Topics: Animals; Insecta; Pesticides; Reproduction; Behavior, Animal
PubMed: 38892195
DOI: 10.3390/ijms25116007 -
Animals : An Open Access Journal From... May 2024Chemical communication is an important mode of communication in the courtship and breeding processes of amphibians. In caudates, multiple components of sexual pheromones...
Chemical communication is an important mode of communication in the courtship and breeding processes of amphibians. In caudates, multiple components of sexual pheromones have been identified and functionally verified. One of these pheromone systems is plethodontid modulating factor (PMF). In anurans, the pheromone called amplexin was found in nuptial pads of ranids and was considered a member of the PMF system, yet its bio-function has not been tested. In this study, we obtained 18 amplexin transcript sequences from nuptial pads of (Amphibia, Ranidae) by transcriptome sequencing and found that the proteins translated by these transcripts are diversified, hydrophilic, and relatively stable. We also acquired a amplexin isoform with the highest expression level in the transcriptome analysis through the prokaryotic expression system. Using two different animal behavioral experimental settings, we have tested the bio-function of the recombinant PMF protein (rPMF) in 's reproduction and found that the rPMF does not attract females but shortens the duration of amplexus significantly. This is the first study to verify the function of the PMF pheromone in Anura, indicating the pervasiveness of chemical communication during breeding in amphibians.
PubMed: 38891597
DOI: 10.3390/ani14111550 -
Animals : An Open Access Journal From... May 2024Although the presence of female contact sex pheromones in . has been hypothesized, to date its existence has not been proven. To gather more evidence of their...
Although the presence of female contact sex pheromones in . has been hypothesized, to date its existence has not been proven. To gather more evidence of their existence, cuticular liposoluble extracts were obtained from the following samples of adult females to be used as the experimental treatments: (1) ventral exoskeleton of immature female (VI), (2) dorsolateral exoskeleton of immature female (DI), (3) ventral exoskeleton of mature female (VM), and (4) dorsolateral exoskeleton of mature female (DM). Polyvinyl chloride tubes (artificial females; AF) were coated with each extract and the behavior displayed by sexually mature males in contact with the AF was recorded and classified as follows: 0 = no response; 1 = contact; 2 = pushing; and 3 = prolonged contact (≥10 s). To test the hypothesis that the extracts collected from the ventral portion of the abdomen exoskeleton have a higher effect on the behavior of males than the extracts collected from the dorsolateral portion of the abdomen exoskeleton, the experiment was divided into two bioassays: Bioassay I (VI vs. DI) and Bioassay II (VM vs. DM). In each bioassay, all experimental treatments were significantly different ( > 0.05) from the CTL group (AF coated with hexane). Notably, the pushing behavior was significantly higher ( < 0.05) in the VI treatment compared to the CTL and DI treatment. These results provide evidence of the existence of contact female sex pheromones with sexual recognition function located primarily in the ventral portion of the abdomen exoskeleton of . .
PubMed: 38891570
DOI: 10.3390/ani14111523 -
Biology Letters Jun 2024Social insects can sense colony size-even without visual information in a dark environment. How they achieve this is yet largely unknown. We empirically tested a...
Social insects can sense colony size-even without visual information in a dark environment. How they achieve this is yet largely unknown. We empirically tested a hypothesis on the proximate mechanism using ant colonies. In colonies, the monogynous queen is known to increase the effort devoted to queen pheromone transmission behaviour (patrolling) as the colony grows, as if she perceives colony size. The negative feedback hypothesis assumes that, through repeated physical contact with workers, the queen monitors the physiological state (fertility) of workers and increases her patrolling effort when she encounters more fertile workers. Supporting this hypothesis, we found that the queen increased her patrolling effort in response to a higher ratio of fertile workers under the experimental condition of constant colony size. Furthermore, chemical analyses and bioassays suggested that cuticular hydrocarbons have queen pheromone activity and can mediate the observed queen-worker communication of fertility state. Such a self-organizing mechanism of sensing colony size may also operate in other social insects living in small colonies.
Topics: Animals; Ants; Pheromones; Social Behavior; Female; Population Density; Hydrocarbons; Fertility; Animal Communication; Behavior, Animal
PubMed: 38889776
DOI: 10.1098/rsbl.2024.0102 -
Cellular and Molecular Life Sciences :... Jun 2024Sex pheromones play crucial role in mating behavior of moths, involving intricate recognition mechanisms. While insect chemical biology has extensively studied type I...
Sex pheromones play crucial role in mating behavior of moths, involving intricate recognition mechanisms. While insect chemical biology has extensively studied type I pheromones, type II pheromones remain largely unexplored. This study focused on Helicoverpa armigera, a representative species of noctuid moth, aiming to reassess its sex pheromone composition. Our research unveiled two previously unidentified candidate type II sex pheromones-3Z,6Z,9Z-21:H and 3Z,6Z,9Z-23:H-in H. armigera. Furthermore, we identified HarmOR11 as an orphan pheromone receptor of 3Z,6Z,9Z-21:H. Through AlphaFold2 structural prediction, molecular docking, and molecular dynamics simulations, we elucidated the structural basis and key residues governing the sensory nuances of both type I and type II pheromone receptors, particularly HarmOR11 and HarmOR13. This study not only reveals the presence and recognition of candidate type II pheromones in a noctuid moth, but also establishes a comprehensive structural framework for PRs, contributing to the understanding of connections between evolutionary adaptations and the emergence of new pheromone types.
Topics: Animals; Sex Attractants; Moths; Receptors, Pheromone; Male; Insect Proteins; Female; Molecular Docking Simulation; Amino Acid Sequence; Phylogeny; Molecular Dynamics Simulation; Sexual Behavior, Animal
PubMed: 38878072
DOI: 10.1007/s00018-024-05303-2 -
Nature Microbiology Jul 2024Initiation of development requires differential gene expression and metabolic adaptations. Here we show in the nematode-trapping fungus, Arthrobotrys flagrans, that both...
Initiation of development requires differential gene expression and metabolic adaptations. Here we show in the nematode-trapping fungus, Arthrobotrys flagrans, that both are achieved through a dual-function G-protein-coupled receptor (GPCR). A. flagrans develops adhesive traps and recognizes its prey, Caenorhabditis elegans, through nematode-specific pheromones (ascarosides). Gene-expression analyses revealed that ascarosides activate the fungal GPCR, GprC, at the plasma membrane and together with the G-protein alpha subunit GasA, reprograms the cell. However, GprC and GasA also reside in mitochondria and boost respiration. This dual localization of GprC in A. flagrans resembles the localization of the cannabinoid receptor CB1 in humans. The C. elegans ascaroside-sensing GPCR, SRBC66 and GPCRs of many fungi are also predicted for dual localization, suggesting broad evolutionary conservation. An SRBC64/66-GprC chimaeric protein was functional in A. flagrans, and C. elegans SRBC64/66 and DAF38 share ascaroside-binding sites with the fungal GprC receptor, suggesting 400-million-year convergent evolution.
Topics: Animals; Caenorhabditis elegans; Receptors, G-Protein-Coupled; Mitochondria; Ascomycota; Fungal Proteins; Pheromones; Humans; Gene Expression Regulation, Fungal
PubMed: 38877225
DOI: 10.1038/s41564-024-01731-9 -
Current Biology : CB Jun 2024While the neural basis of age-related decline has been extensively studied, less is known about changes in neural function during the pre-senescent stages of adulthood....
While the neural basis of age-related decline has been extensively studied, less is known about changes in neural function during the pre-senescent stages of adulthood. Adult neural plasticity is likely a key factor in social insect age polyethism, where individuals perform different tasks as they age and divide labor in an age-dependent manner. Primarily, workers transition from nursing to foraging tasks, become more aggressive, and more readily display alarm behavior as they get older. While it is unknown how these behavioral dynamics are neurally regulated, they could partially be generated by altered salience of behaviorally relevant stimuli. Here, we investigated how odor coding in the antennal lobe (AL) changes with age in the context of alarm pheromone communication in the clonal raider ant (Ooceraea biroi). Similar to other social insects, older ants responded more rapidly to alarm pheromones, the chemical signals for danger. Using whole-AL calcium imaging, we then mapped odor representations for five general odorants and two alarm pheromones in young and old ants. Alarm pheromones were represented sparsely at all ages. However, alarm pheromone responses within individual glomeruli changed with age, either increasing or decreasing. Only two glomeruli became sensitized to alarm pheromones with age, while at the same time becoming desensitized to general odorants. Our results suggest that the heightened response to alarm pheromones in older ants occurs via increased sensitivity in these two core glomeruli, illustrating the importance of sensory modulation in social insect division of labor and age-associated behavioral plasticity.
PubMed: 38876103
DOI: 10.1016/j.cub.2024.05.031 -
Science Advances Jun 2024Advanced social behavior, or eusociality, has been evolutionarily profound, allowing colonies of ants, termites, social wasps, and bees to dominate competitively over...
Advanced social behavior, or eusociality, has been evolutionarily profound, allowing colonies of ants, termites, social wasps, and bees to dominate competitively over solitary species throughout the Cenozoic. Advanced sociality requires not just nestmate cooperation and specialization but refined coordination and communication. Here, we provide independent evidence that 100-million-year-old Cretaceous ants in amber were social, based on chemosensory adaptations. Previous studies inferred fossil ant sociality from individual ants preserved adjacent to others. We analyzed several fossil ants for their antennal sensilla, using original rotation imaging of amber microinclusions, and found an array of antennal sensilla, specifically for alarm pheromone detection and nestmate recognition, sharing distinctive features with extant ants. Although Cretaceous ants were stem groups, the fossilized sensilla confirm hypotheses of their complex sociality.
Topics: Animals; Ants; Social Behavior; Animal Communication; Pheromones; Fossils; Behavior, Animal; Biological Evolution; Sensilla
PubMed: 38875342
DOI: 10.1126/sciadv.adp3623 -
Advances in Experimental Medicine and... Jun 2024Pheromones are utilized to a great extent in insects. Many of these pheromones are biosynthesized through a pathway involving fatty acids. This chapter will provide...
Pheromones are utilized to a great extent in insects. Many of these pheromones are biosynthesized through a pathway involving fatty acids. This chapter will provide examples where the biosynthetic pathways of fatty acid-derived pheromones have been studied in detail. These include pheromones from Lepidoptera, Coleoptera, and Hymenoptera. Many species of Lepidoptera utilize fatty acids as precursors to pheromones with a functional group that include aldehydes, alcohols, and acetate esters. In addition, the biosynthesis of hydrocarbons will be briefly examined because many insects utilize hydrocarbons or modified hydrocarbons as pheromones.
PubMed: 38874890
DOI: 10.1007/5584_2024_813 -
MBio Jun 2024Mitogen-activated protein kinase (MAPK) pathways are fundamental to the regulation of biological processes in eukaryotic organisms. The basidiomycete , known for causing...
Mitogen-activated protein kinase (MAPK) pathways are fundamental to the regulation of biological processes in eukaryotic organisms. The basidiomycete , known for causing fungal meningitis worldwide, possesses five MAPKs. Among these, Cpk1, Hog1, and Mpk1 have established roles in sexual reproduction, stress responses, and cell wall integrity. However, the roles of Cpk2 and Mpk2 are less understood. Our study elucidates the functional interplay between the Cpk1/Cpk2 and Mpk1/Mpk2 MAPK pathways in . We discovered that overexpression compensates for Δ mating deficiencies via the Mat2 transcription factor, revealing functional redundancy between Cpk1 and Cpk2. We also found that Mpk2 is phosphorylated in response to cell wall stress, a process regulated by the MAPK kinase (MAP2K) Mkk2 and MAP2K kinases (MAP3Ks) Ssk2 and Ste11. Overexpression of partially restores cell wall integrity in Δ by influencing key cell wall components, such as chitin and the polysaccharide capsule. Contrarily, overexpression cannot restore thermotolerance and cell membrane integrity in Δ. These results suggest that Mpk1 and Mpk2 have redundant and opposing roles in the cellular response to cell wall and membrane stresses. Most notably, the dual deletion of and restores wild-type mating efficiency in Δ mutants via upregulation of the mating-regulating transcription factors and , suggesting that the Mpk1 and Mpk2 cooperate to negatively regulate the pheromone-responsive Cpk1 MAPK pathway. Our research collectively underscores a sophisticated regulatory network of cryptococcal MAPK signaling pathways that intricately govern sexual reproduction and cell wall integrity, thereby controlling fungal development and pathogenicity.IMPORTANCEIn the realm of fungal biology, our study on offers pivotal insights into the roles of specific proteins called mitogen-activated protein kinases (MAPKs). Here, we discovered the cryptic functions of Cpk2 and Mpk2, two MAPKs previously overshadowed by their dominant counterparts Cpk1 and Mpk1, respectively. Our findings reveal that these "underdog" proteins are not just backup players; they play crucial roles in vital processes like mating and cell wall maintenance in . Their ability to step in and compensate when their dominant counterparts are absent showcases the adaptability of . This newfound understanding not only enriches our knowledge of fungal MAPK mechanisms but also underscores the intricate balance and interplay of proteins in ensuring the organism's survival and adaptability.
PubMed: 38874410
DOI: 10.1128/mbio.01156-24