Physiological Entomology最新文献

Molecular studies on odorant receptors (ORs), odorant-binding proteins (OBPs) and the functioning of the receptor and pheromone signal transduction in fruit fly Bactrocera species have expanded exponentially during the past few decades. OBPs contribute to the sensing of the olfactory system (OS) via the transduction of odorants through the sensillum lymph. However, ORs, a family of G-protein-coupled receptors in Bactrocera and various other species, exhibit heightened responsiveness to multiple chemical odours such as hormones, sensory stimuli and neurotransmitters. The apparent mechanism involves a combinatorial code encompassing both peripheral and antennal lobe processing, facilitating the reception of sexual pheromones and environmental cues. The OS is specifically designed to recognize and process information from volatile chemical signals, and these chemical signals play an important function in various flies. Insects rely on these chemicals to navigate and comprehend their surroundings. A mature insect OS is composed of two pairs of sensillae-covered palps, antennae and two primary pairs of olfactory appendages on the anterior head. It has been shown that chemosensory gene families contribute in odour perception. These include various neuroreceptor families, such as OBPs, chemosensory proteins and sensory neuron membrane proteins. Additionally, there are three divergent chemoreceptors, namely ORs, ionotropic receptors and gustatory receptors. Methods based on systematic biology, molecular biology and bioinformatics tools have rapidly emerged to investigate the insect communication systems and provide new insights for the management of many agricultural pest. Several aromatic compounds, including semiochemicals and pheromones, have been employed to defend crops and animals from destructive fruit flies and other invasive and frugivorous species. To promote the expansion of the cropping system, the utilization of phytochemical lures can be convenient for sustainable agriculture production and enhance food security. Hence, this review examined the state of the art in chemical communication of insects with a focus on fruit fly pest species to identify OS and their semiochemical receptors, protein receptors and chemosensory receptors (CSRs), as well as their practical applications for biological control and integrated pest management are highlighted.

Worldwide spread in the incidence of diabetes justified the need of extensive research in an appropriate model system to develop an effective treatment strategy for diabetology. In recent years, because of animal ethical issues and limitations, the silkworm (Bombyx mori) has emerged as a perfect invertebrate model for various biomedical experiments. However, there are several issues related to induce hyperglycaemia in the mammalian system that have not been studied in the silkworms. In the present study, we investigated the consequences of induced hyperglycaemia by oral and intravascular administration of streptozotocin (STZ) and glucose in the silkworms. Interestingly, results confirmed the competence of STZ to induce hyperglycaemia when administered through intravascular route, but suppress the glucose concentration if administrated orally in the silkworms. Comparatively, the severity of induced hyperglycaemia in the silkworms remained nearly the same in response to the oral and intravascular administration of glucose. Furthermore, prolonged administration of STZ has recorded negative effect on the growth rate of the silkworms, whereas a drastic decline in the same was reported in the silkworms administered with glucose. Notably, these results confirm that the response shown by the silkworms to STZ is very similar to that of mammals, making it an excellent model to study diabetic complications and consequences associated with STZ in diabetology.

Ectotherm predators and their prey could potentially respond differently to habitat temperatures. Predators might select higher temperatures to increase their probability of capture while prey could select lower or higher temperatures that may enhance their escape capability. We used a combination of field and laboratory analyses to characterise the thermal niches of predator species and their potential arthropod prey. We studied a predator–prey system in northern Chile using a common desert-dwelling spider Loxosceles laeta and three potential prey: a tenebrionid beetle Psammetichus costatus (Coleoptera), Pycnoscelus surinamensis (Blattodea) and Porcellio laevis (Isopoda). Results showed that the predator L. laeta selects warmer temperatures (T_p = 27.22 ± 4.87°C) in laboratory and lower temperatures in field conditions (T_s = 20.8 ± 1.59°C), with low temperatures in the morning and high temperatures at night. The three prey species had lower and different preferred temperatures than the predator in laboratory conditions. However, we found a high overlap in the thermal niche between the predator and their prey in field conditions, whereby the predator selected similar temperatures to its prey, one exception being P. laevis that chooses completely different habitat temperatures. This suggests that predators look for their prey in places with low temperatures that are not thermally suitable for them, whereas the prey may use this strategy of selecting low temperatures to evade potential predators.

The Asian citrus psyllid, Diaphorina citri, is a vector of the bacterial pathogen, Candidatus Liberibacter asiaticus (CLas) that is believed to cause huanglongbing (HLB), also known as citrus greening disease. This phytopathogen can manipulate its vectors directly by modifying behaviour and altering fitness and indirectly by reducing host plant quality, which may affect the predation efficiency of natural enemies. Little is known about how this phytopathogen may affect third tropic level predators. The purpose of this investigation was to determine if the CLas pathogen modifies interactions between D. citri and its predators. We tested whether CLas infection of psyllids indirectly affects fitness of a key predator, the lady beetle Harmonia axyridis. We provided ladybeetles with 10 infected or uninfected adult psyllids in choice bioassays and measured the consumption rate over 24 h. Similarly, 15 infected or uninfected adult psyllids were provided to ladybeetles in no-choice bioassays and feeding rates and net weight gain of male and female beetles were measured over 5 consecutive days. Fecundity and fertility of lady beetles feeding on CLas-infected D. citri was reduced compared with those feeding on uninfected D. citri, and oocyte development appeared diminished in those beetles feeding on infected compared with uninfected psyllids. However, in choice assays, beetles did not distinguish between CLas-infected and uninfected psyllids. We postulate that CLas may reduce the nutritional quality of psyllids diminishing fecundity and fertility of their predatory beetles. Our results lead us to speculate that under conditions of near 100% HLB infection, as occurs endemically in Florida, effectiveness of biological control for D. citri may benefit from provisioning ladybeetle predators with alternative hosts of higher nutritional quality or augmentative releases of laboratory-reared predators.

Heliothine moths represent some of the world's most important agricultural pest species. Helicoverpa zea (Corn Earworm) and Heliothis virescens (Tobacco Budworm) cause billions in damage and control costs worldwide each year. Given their economic importance, sex pheromones of many species have been studied for the development of management techniques such as trapping for population monitoring. The majority of pheromones identified and studied to date have been female-produced sex pheromones. Less emphasis has been placed on male sex pheromones, associated with abdominal hairpencil structures that often function in courtship or to attract females. The present study examines the composition, detection and behavioural role of male H. zea hairpencil compounds in male autodetection and in courtship. Comparative examination of the hairpencil effluvia of H. zea and H. virescens did not reveal distinct differences in pheromone blend composition produced by males of these species. Electrophysiological testing demonstrated broad antennal neuron response in both males and females of H. zea to nine key stimuli, with sexual dimorphism present in each species. Behavioural assays suggested that odours released by male hairpencils are important in mate acceptance by female H. zea and may play a role in mate choice and species isolation. Wind tunnel observations indicated that key H. zea hairpencil odours (hexadecanyl acetate and octadecanyl acetate) also function in mate competition, antagonising responses of downwind conspecific males following a synthetic female sex pheromone plume. This finding provides insight regarding male–male detection and response to hairpencil compounds in H. zea.

The biological complexity of leaf-cutting ants is determined in part by both positive and negative associations with microorganisms. These ants constantly face microorganisms that can compromise workers’ survival and the integrity of their symbiont fungus. The ability to produce antimicrobial compounds within the colony, both by the workers and by associated microorganisms, is an adaptive response that protects against these natural enemies. Atta cephalotes (Linnaeus, 1758) is an ecologically successful species with a great capacity to overcome pathogenic microorganisms. In contrast to the Acromyrmex genus, the evidence suggests that it does not maintain an association with antibiotic-producing actinobacteria raising the question of whether this species maintains associations with bacterial communities that can potentially protect the colony against prejudicial microorganisms. In this direction, the diversity and composition of the culturable bacterial microbiota associated with A. cephalotes developmental stages were evaluated, as well as their potential to inhibit the growth of the entomopathogenic fungus Metarhizium anisopliae and the mycoparasite Trichoderma sp. Six nests were collected, of which a total of 900 larvae, 900 pupae and 900 adult workers were analysed. Culture-dependent and molecular methods were used to identify the strains to genus level. To determine differences in bacterial composition in the development stages, analysis of the contribution to dissimilarity (SIMPER) were performed. Seventy-seven strains corresponding to 18 genera were documented. Acinetobacter was the dominant one. On the other hand, Acinetobacter, Bacillus, Enterobacter, Serratia and Microbacterium were maintained from the larval to the adult stage. Furthermore, except for Acinetobacter, different strains of these bacterial groups significantly inhibited pathogenic fungi growth. The results suggest the existence of a persistent association of A. cephalotes with strains of these bacterial genera and a potential role in defence at the collective level.

The grain chinch bug (Macchiademus diplopterus Distant) is a phytosanitary pest, endemic to the Western Cape in South Africa. At the start of the aestivation phase of their lifecycle, grain chinch bugs seek sheltering sites, which potentially include fruit and fruit trees if orchards are near host plants. Aestivating grain chinch bug on export fruit is considered contaminant or hitchhiker phytosanitary pests. Previous studies have indicated that the grain chinch bug has the ability to become more tolerant of thermal stresses as they progress through their aestivation cycle. To examine the potential physiological changes that occur during aestivation, molecular (soluble protein identification) and biochemical (macromolecule) analyses were performed on the insects before entering aestivation, as well as early, mid, mid-late and late aestivation periods. Analyses provided useful information on the abundance and identity of individual soluble proteins and concentration of macromolecules, indicating whether compounds are up- or down-regulated throughout the aestivation cycle. The focus of this investigation was to examine the influence of heat shock proteins and proteins involved in energy production and metabolism throughout the aestivation period. Results provide insight into the thermo-tolerance capabilities or mechanisms of the grain chinch bug. The significant decrease in the number of individual proteins identified in samples before aestivation compared to early aestivation indicated the insects' progression into a hypometabolic state. During the early, mid and mid-late aestivation periods (from December to May), large volumes of fruit are exported from South Africa. An increase in abundance of proteins, such as smHsp20, Hsp10, 70, 80 and 90, occurred during the mid/mid-late aestivation period compared with the early period. This indicated the potential role of heat shock proteins in the insect's ability to increase its thermo-tolerance at a later stage within the aestivation cycle.

The study of insect flight is important for conservation and sustainability efforts, as predicting insect dispersal can aid management programmes in tackling economic and ecological harm from, for example, invasive species. Flight mills are invaluable tools for measuring the factors of insect flight under laboratory conditions, as they lower several technical and financial barriers to conduct experiments. It is especially difficult, however, to make assumptions about the energetic cost of tethered flights conducted using different tethers, or even on different flight mills, due to the mechanical variability of the bearing friction and air resistance of the rotating assembly. This additional uncertainty necessitates a larger number of replicates for any given standard of statistical confidence. By characterising flight mill friction, this uncertainty can both be reduced in magnitude and assigned a specific, well-defined numerical value. We present a simple methodology to characterise this friction through dynamic calibration of the flight mill, at a high statistical confidence. This study uses videography of a flight mill undergoing free velocity decay due to friction, using an in-house developed software to extract angular velocity from video data. However, the technique is readily adaptable to other measurement techniques. Using the velocity, alongside the mass moment of inertia of the flight mill, allows us to determine the rotational friction coefficient. This friction coefficient provides precise measurements of thrust production, and therefore the energy expenditure of flight, by the tethered insect.

Bombyx mori Linnaeus, 1758 (Lepidoptera: Bombycidae), a very important economical insect and backbone of the silk industry, is fully reliant on humans for its life cycle. It has short life span, possessing many genes having high degree of homology with human disease-causing genes, low breeding and maintenance cost, has less ethical issues associated with it and has also got its genome fully sequenced. Because of these characteristics, it has been recognized as an alternate invertebrate model organism candidate for use in life science research. It has been successfully used as an alternative invertebrate model organism in a variety of scientific domains, including human disease models, environmental monitoring models, epigenetic models and microbial drug screening and discovery models, since the last decade. This newly emerged model has given promising results so far in its short journey and has a tremendous future prospect of establishing itself as a successful model just like the classical invertebrate models, Drosophila melanogaster Meigen, 1830 (Diptera: Drosophilidae) and Caenorhabditis elegans Maupas, 1900 (Rhabditida: Rhabditidae). The use of the silkworm B. mori as a model organism in areas linked to human health and disease is reviewed here.