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Nature Jul 2023Whereas progress has been made in the identification of neural signals related to rapid, cued decisions, less is known about how brains guide and terminate more...
Whereas progress has been made in the identification of neural signals related to rapid, cued decisions, less is known about how brains guide and terminate more ethologically relevant decisions in which an animal's own behaviour governs the options experienced over minutes. Drosophila search for many seconds to minutes for egg-laying sites with high relative value and have neurons, called oviDNs, whose activity fulfills necessity and sufficiency criteria for initiating the egg-deposition motor programme. Here we show that oviDNs express a calcium signal that (1) dips when an egg is internally prepared (ovulated), (2) drifts up and down over seconds to minutes-in a manner influenced by the relative value of substrates-as a fly determines whether to lay an egg and (3) reaches a consistent peak level just before the abdomen bend for egg deposition. This signal is apparent in the cell bodies of oviDNs in the brain and it probably reflects a behaviourally relevant rise-to-threshold process in the ventral nerve cord, where the synaptic terminals of oviDNs are located and where their output can influence behaviour. We provide perturbational evidence that the egg-deposition motor programme is initiated once this process hits a threshold and that subthreshold variation in this process regulates the time spent considering options and, ultimately, the choice taken. Finally, we identify a small recurrent circuit that feeds into oviDNs and show that activity in each of its constituent cell types is required for laying an egg. These results argue that a rise-to-threshold process regulates a relative-value, self-paced decision and provide initial insight into the underlying circuit mechanism for building this process.
Topics: Animals; Female; Calcium Signaling; Decision Making; Drosophila melanogaster; Neural Pathways; Neurons; Oviposition; Presynaptic Terminals; Psychomotor Performance
PubMed: 37407812
DOI: 10.1038/s41586-023-06271-6 -
Cell Reports Oct 2023Comparative studies of related but ecologically distinct species can reveal how the nervous system evolves to drive behaviors that are particularly suited to certain...
Comparative studies of related but ecologically distinct species can reveal how the nervous system evolves to drive behaviors that are particularly suited to certain environments. Drosophila melanogaster is a generalist that feeds and oviposits on most overripe fruits. A sibling species, D. sechellia, is an obligate specialist of Morinda citrifolia (noni) fruit, which is rich in fatty acids (FAs). To understand evolution of noni taste preference, we characterized behavioral and cellular responses to noni-associated FAs in three related drosophilids. We find that mixtures of sugar and noni FAs evoke strong aversion in the generalist species but not in D. sechellia. Surveys of taste sensory responses reveal noni FA- and species-specific differences in at least two mechanisms-bitter neuron activation and sweet neuron inhibition-that correlate with shifts in noni preference. Chemoreceptor mutant analysis in D. melanogaster predicts that multiple genetic changes account for evolution of gustatory preference in D. sechellia.
Topics: Animals; Drosophila melanogaster; Drosophila; Drosophila Proteins; Taste; Fatty Acids
PubMed: 37864792
DOI: 10.1016/j.celrep.2023.113297 -
Journal of Comparative Physiology. A,... Mar 2024Plants and herbivorous insects as well as their natural enemies, such as predatory and parasitoid insects, are united by intricate relationships. During the long period... (Review)
Review
Plants and herbivorous insects as well as their natural enemies, such as predatory and parasitoid insects, are united by intricate relationships. During the long period of co-evolution with insects, plants developed a wide diversity of features to defence against herbivores and to attract pollinators and herbivores' natural enemies. The chemical basis of insect-plant interactions is established and many examples are studied, where feeding and oviposition site selection of phytophagous insects are dependent on the plant's secondary chemistry. However, often overlooked mechanical interactions between insects and plants can be rather crucial. In the context of mechanoecology, the evolution of plant surfaces and insect adhesive pads is an interesting example of competition between insect attachment systems and plant anti-attachment surfaces. The present review is focused on mechanical insect-plant interactions of some important pest species, such as the polyphagous Southern Green Stinkbug Nezara viridula and two frugivorous pest species, the polyphagous Mediterranean fruit fly Ceratitis capitata and the monophagous olive fruit fly Bactrocera oleae. Their ability to attach to plant surfaces characterised by different features such as waxes and trichomes is discussed. Some attention is paid also to Coccinellidae, whose interaction with plant leaf surfaces is substantial across all developmental stages in both phytophagous and predatory species that feed on herbivorous insects. Finally, the role of different kinds of anti-adhesive nanomaterials is discussed. They can reduce the attachment ability of insect pests to natural and artificial surfaces, potentially representing environmental friendly alternative methods to reduce insect pest impact in agriculture.
Topics: Female; Animals; Insecta; Coleoptera
PubMed: 38480551
DOI: 10.1007/s00359-024-01698-2 -
EFSA Journal. European Food Safety... Oct 2023The EFSA Panel on Plant Health performed a pest categorisation of (Hemiptera: Auchenorrhyncha: Ricaniidae) for the EU following commodity risk assessments of , , and...
The EFSA Panel on Plant Health performed a pest categorisation of (Hemiptera: Auchenorrhyncha: Ricaniidae) for the EU following commodity risk assessments of , , and plants for planting from Türkiye in which was identified as a pest that could potentially enter the EU. The native range of is China (Shaanxi, Shandong and Zhejiang provinces), but around 2010, the species entered the Republic of Korea and rapidly spread. Small and localised populations were also recently found in Türkiye (Marmara) and southern Russia (Krasnodyarskiy kray). Within the EU, a few individuals have been recorded in Italy (Pistoia province, Tuscany), in one locality in southern France (Alpes-Maritimes), in the Netherlands (Western Netherlands) and in one garden in Germany (Baden-Württemberg) where it was eradicated. is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is polyphagous, feeding on plants belonging to more than 200 species including many crop and ornamental plants. Economically important hosts in the EU include apple (), citrus ( spp.), walnut ( sp.) and ornamentals such as hibiscus ( spp.) and camellia (), as well as forest trees, mostly deciduous. In the Republic of Korea, the species has one generation per year. It overwinters as eggs and goes through five nymphal instars. Its impact is due to oviposition obstructing the vascular system of its hosts, depletion of the host resources and egestion of honeydew promoting the development of sooty moulds. Plants for planting constitute the main pathway for entry into the EU and for spread. Climatic conditions in southern EU countries and host plant availability in those areas would allow establishment and spread. The introduction of is expected to have an economic impact in the EU through the reduction in yield, quality and commercial value of fruits and ornamental plants. Phytosanitary measures are available to reduce the likelihood of entry and further spread. meets the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.
PubMed: 37915980
DOI: 10.2903/j.efsa.2023.8320 -
Microbiome Sep 2023The influence of microbiota in ecological interactions, and in particular competition, is poorly known. We studied competition between two insect species, the invasive...
BACKGROUND
The influence of microbiota in ecological interactions, and in particular competition, is poorly known. We studied competition between two insect species, the invasive pest Drosophila suzukii and the model Drosophila melanogaster, whose larval ecological niches overlap in ripe, but not rotten, fruit.
RESULTS
We discovered D. suzukii females prevent costly interspecific larval competition by avoiding oviposition on substrates previously visited by D. melanogaster. More precisely, D. melanogaster association with gut bacteria of the genus Lactobacillus triggered D. suzukii avoidance. However, D. suzukii avoidance behavior is condition-dependent, and D. suzukii females that themselves carry D. melanogaster bacteria stop avoiding sites visited by D. melanogaster. The adaptive significance of avoiding cues from the competitor's microbiota was revealed by experimentally reproducing in-fruit larval competition: reduced survival of D. suzukii larvae only occurred if the competitor had its normal microbiota.
CONCLUSIONS
This study establishes microbiotas as potent mediators of interspecific competition and reveals a central role for context-dependent behaviors under bacterial influence. Video Abstract.
Topics: Female; Animals; Drosophila; Drosophila melanogaster; Fruit; Lactobacillus; Larva; Microbiota
PubMed: 37679800
DOI: 10.1186/s40168-023-01617-8 -
Frontiers in Zoology Aug 2023Various chalcidoid wasps can actively steer their terebra (= ovipositor shaft) in diverse directions, despite the lack of terebral intrinsic musculature. To...
Various chalcidoid wasps can actively steer their terebra (= ovipositor shaft) in diverse directions, despite the lack of terebral intrinsic musculature. To investigate the mechanisms of these bending and rotational movements, we combined microscopical and microtomographical techniques, together with videography, to analyse the musculoskeletal ovipositor system of the ectoparasitoid pteromalid wasp Lariophagus distinguendus (Förster, 1841) and the employment of its terebra during oviposition. The ovipositor consists of three pairs of valvulae, two pairs of valvifers and the female T9 (9th abdominal tergum). The paired 1st and the 2nd valvulae are interlocked via the olistheter system, which allows the three parts to slide longitudinally relative to each other, and form the terebra. The various ovipositor movements are actuated by a set of nine paired muscles, three of which (i.e. 1st valvifer-genital membrane muscle, ventral 2nd valvifer-venom gland reservoir muscle, T9-genital membrane muscle) are described here for the first time in chalcidoids. The anterior and posterior 2nd valvifer-2nd valvula muscles are adapted in function. (1) In the active probing position, they enable the wasps to pull the base of each of the longitudinally split and asymmetrically overlapping halves of the 2nd valvula that are fused at the apex dorsally, thus enabling lateral bending of the terebra. Concurrently, the 1st valvulae can be pro- and retracted regardless of this bending. (2) These muscles can also rotate the 2nd valvula and therefore the whole terebra at the basal articulation, allowing bending in various directions. The position of the terebra is anchored at the puncture site in hard substrates (in which drilling is extremely energy- and time-consuming). A freely steerable terebra increases the chance of contacting a potential host within a concealed cavity. The evolution of the ability actively to steer the terebra can be considered a key innovation that has putatively contributed to the acquisition of new hosts to a parasitoid's host range. Such shifts in host exploitation, each followed by rapid radiations, have probably aided the evolutionary success of Chalcidoidea (with more than 500,000 species estimated).
PubMed: 37553687
DOI: 10.1186/s12983-023-00503-1 -
Royal Society Open Science Aug 2023Behavioural avoidance has obvious benefits for animals facing environmental stressors such as pathogen-contaminated foods. Most current bioinsecticides are based on the...
Behavioural avoidance has obvious benefits for animals facing environmental stressors such as pathogen-contaminated foods. Most current bioinsecticides are based on the environmental and opportunistic bacterium () that kills targeted insect pests upon ingestion. While food and oviposition avoidance of bioinsecticide by targeted insect species was reported, this remained to be addressed in non-target organisms, especially those affected by chronic exposure to bioinsecticide such as species. Here, using a two-choice oviposition test, we showed that female flies of three species (four strains of , and ) avoided laying eggs in the presence of var. bioinsecticide, with potential benefits for the offspring and female's fitness. Avoidance occurred rapidly, regardless of the fraction of the bioinsecticide suspension (spores and toxin crystals versus soluble toxins/compounds) and independently of the female motivation for egg laying. Our results suggest that, in addition to recent findings of developmental and physiological alterations upon chronic exposure to non-target , this bioinsecticide may modify the competitive interactions between species in treated areas and the interactions with their associated natural enemies.
PubMed: 37650056
DOI: 10.1098/rsos.230565 -
Vavilovskii Zhurnal Genetiki I Selektsii Jul 2023The honey bee Apis mellifera is a rather difficult object for selection due to the peculiarities of its biology. Breeding activities in beekeeping are aimed at obtaining...
The honey bee Apis mellifera is a rather difficult object for selection due to the peculiarities of its biology. Breeding activities in beekeeping are aimed at obtaining bee colonies with high rates of economically useful traits, such as productivity, resistance to low temperatures and diseases, hygienic behavior, oviposition of the queen, etc. With two apiaries specializing in the breeding of A. m. mellifera and A. m. carnica as examples, the application of genetic methods in the selection of honey bees is considered. The first stage of the work was subspecies identification based on the analysis of the polymorphism of the intergenic mtDNA locus tRNAleu-COII (or COI-COII) and microsatellite nuclear DNA loci Ap243, 4a110, A24, A8, A43, A113, A88, Ap049, A28. This analysis confirmed that the studied colonies correspond to the declared subspecies. In the apiary with A. m. mellifera, hybrid colonies have been identified. A method based on the analysis of polymorphisms of the tRNAleu-COII locus and microsatellite nuclear DNA loci has been developed to identify the dark forest bee A. m. mellifera and does not allow one to differentiate subspecies from C (A. m. carnica and A. m. ligustica) and O (A. m. caucasica) evolutionary lineages from each other. The second stage was the assessment of the allelic diversity of the csd gene. In the apiary containing colonies of A. m. mellifera (N = 15), 20 csd alleles were identified. In the apiary containing colonies of A. m. carnica (N = 44), 41 alleles were identified. Six alleles are shared by both apiaries. DNA diagnostics of bee diseases showed that the studied colonies are healthy. Based on the data obtained, a scheme was developed for obtaining primary material for honey bee breeding, which can subsequently be subjected to selection according to economically useful traits. In addition, the annual assessment of the allelic diversity of the csd gene will shed light on the frequency of formation of new allelic variants and other issues related to the evolution of this gene.
PubMed: 37465190
DOI: 10.18699/VJGB-23-44 -
Bulletin of Mathematical Biology Dec 2023We propose a two stages mosquito egg-larvae model with seasonality as a simplification of a four stages one. For the simplified model we characterize the dynamics in...
We propose a two stages mosquito egg-larvae model with seasonality as a simplification of a four stages one. For the simplified model we characterize the dynamics in terms of the vectorial reproduction number, [Formula: see text], obtaining extinction if [Formula: see text] and convergence to a unique positive periodic orbit if [Formula: see text]. We illustrate each case with an example, by providing general conditions on the periodic coefficients for its occurrence. These examples are further developed using numerical simulations where the periodic parameters satisfy the conditions obtained. In the [Formula: see text] case, real climatic data is used for inferring the parameter behaviour. For the four stage system, using alternative oviposition rate functions, we present a result which generalizes others given for models with delays and even with diffusion to the case in which competition between the larvae is introduced. The analytical study of our initial four stages system when [Formula: see text] remains open, since we were not able to prove that in this case the system is dissipative.
Topics: Animals; Female; Mathematical Concepts; Models, Biological; Culicidae; Diffusion; Larva
PubMed: 38108949
DOI: 10.1007/s11538-023-01238-0 -
Journal of Comparative Physiology. A,... Nov 2023Polarization vision is used by a wide range of animals for navigating, orienting, and detecting objects or areas of interest. Shallow marine and semi-terrestrial...
Polarization vision is used by a wide range of animals for navigating, orienting, and detecting objects or areas of interest. Shallow marine and semi-terrestrial crustaceans are particularly well known for their abilities to detect predator-like or conspecific-like objects based on their polarization properties. On land, some terrestrial invertebrates use polarization vision for detecting suitable habitats, oviposition sites or conspecifics, but examples of threat detection in the polarization domain are less well known. To test whether this also applies to crustaceans that have evolved to occupy terrestrial habitats, we determined the sensitivity of two species of land and one species of marine hermit crab to predator-like visual stimuli varying in the degree of polarization. All three species showed an ability to detect these cues based on polarization contrasts alone. One terrestrial species, Coenobita rugosus, showed an increased sensitivity to objects with a higher degree of polarization than the background. This is the inverse of most animals studied to date, suggesting that the ecological drivers for polarization vision may be different in the terrestrial environment.
Topics: Female; Animals; Anomura; Ecosystem
PubMed: 37043013
DOI: 10.1007/s00359-023-01631-z