Physiological Entomology最新文献

Insects are known to dominate adverse ecological conditions due to their diverse adaptations and resilient biological traits, with their immune systems playing a crucial role in this dominance. Traditionally, insects were thought to lack adaptive immune responses due to their inability to produce antibodies and transfer immunity across generations. However, recent research using insects as model organisms has challenged this notion, revealing that prior exposure to sublethal doses of pathogens or pathogen-derived materials can protect against subsequent lethal exposures—a phenomenon known as ‘immune priming’. Evidence of bacterial, fungal and viral immune priming across different insect species highlights various types of priming, including trans-stadial (across life stages) and trans-generational (across generations) priming. Despite differing views on immune priming, its potential applications in agriculture are considerable, especially in biological control, the utilization of beneficial insects and sustainable pest management. This review explores the intricate dynamics of immune priming in insects, comparing it to vertebrate immunity and investigates its mechanisms, potential agricultural applications and future prospects.

Disease tolerance is an infection phenotype where hosts show relatively high health despite harbouring elevated pathogen loads. Variation in the ability to reduce immunopathology may explain why some hosts can tolerate higher pathogen burdens with reduced pathology. Negative immune regulation would therefore appear to be a clear candidate for a mechanism underlying disease tolerance. Here, we examined how the negative regulation of the immune deficiency (IMD) pathway affects disease tolerance in Drosophila melanogaster when infected with four doses of the gram-negative bacterial pathogen Pseudomonas entomophila. We find that while flies unable to regulate the IMD response exhibited higher expression of antimicrobial peptides and lower bacterial loads as expected, this was not accompanied by a proportional reduction in mortality. Instead, ubiquitous UAS-RNAi knockdown of negative regulators of IMD (pirk and caudal) substantially increased the per-pathogen-mortality in both males and females across all tested infectious doses. Our results therefore highlight that in addition to regulating an efficient pathogen clearance response, negative regulators of IMD also contribute to disease tolerance.

All animal species, from arthropods to vertebrates, must deal with occasional stressors in their lives, though most research on this has been focused on vertebrates. Meanwhile, our understanding of stress reactions in arthropod species like spiders is nascent. In the United States, a non-native orb-weaving spider, Trichonephila clavata (‘jorō’ spider), is spreading as is its already-established cousin in the United States, T. clavipes (golden silk spider). Prior study has revealed how these two species have a unique behavioural reaction to physical stressors, whereby they remain in a thanatosis state for a prolonged period compared with other species. Here, we investigate the physiological stress reactions of these Trichonephila spiders by evaluating how each species' dorsal vessel contractions (heart rates) become elevated after being subjected to a non-lethal stressor. For comparison, we also evaluate two similarly-sized orb weavers, Argiope aurantia (garden spider) and A. trifasciata (banded garden spider). We record baseline heart rates of inactive, resting, spiders in our lab, then restrain them under an electronic, ‘optocardiographic’, sensor for 10 min, to record their ‘stressed’ heart rates. Argiope aurantia has a pronounced heart rate elevation, for reasons unknown. We observe that all spider heart rates increase during restraint, though each has a species-specific pattern of elevation over time under restraint. Notably, heart rates of both Trichonephila spiders are less variable under stress, since they tend not to struggle during restraint. Meanwhile, both Argiope spiders frequently struggle, leading to marked fluctuations in cardiac output. The stress reactions of Trichonephila spiders could be characterized as ‘even-tempered’, which may factor into their ability to live in habitats with frequent disturbances.

In insects, temperature and diet quality during larval development are two fundamental factors affecting key life history traits that, in turn, determine an individuals' fitness. Life-history theory predicts that within species, individuals attain larger sizes when developing under colder temperatures (i.e., temperature—size rule) or on high-quality diet (i.e., allowing for more effective resource acquisition and development). Here, I studied how temperature and host-plant identity affect growth rate, larval development time and size at maturity in Aglia tau L. (Lepidoptera: Saturniidae: Agliinae), a univoltine capital breeding moth. I further examined whether and to what extent these environmental variables influence the degree of sexual size dimorphism. Caterpillars were reared under two contrasting temperature regimes (constantly 18 and 23°C) and fed with three natural host plants, that is, Carpinus betulus L. (Betulaceae), Fagus sylvatica L. (Fagaceae) and Prunus padus L. (Rosaceae). A full-factorial analysis of variance design was used to test for effects of temperature and host identity on life history traits and to account for possible interactive effects. Contrary to theory, the body sizes of males and females were maintained at higher temperatures or even increased when reared on the highest quality host plant (Prunus padus). As predicted, the high-quality host allowed for overall larger body sizes in both sexes and further resulted in a higher degree of sexual size dimorphism. The study highlights the need to account for diet effects when studying temperature-induced life history responses in insects and to consider further traits that may influence species-specific reaction norms.

The Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae), is a global vector of dengue, chikungunya and zika viruses. With extreme adaptability of survival as diapause eggs, this mosquito has invaded and established in temperate climatic zones. The diapause eggs are specially programmed to overcome the harsh winter conditions in temperate habitats. In the laboratory, diapausing females are reared from early larval instars under short-day conditions (21°C and 16D:8 L photoperiods). Aedes albopictus is normally fed on Guinea pigs for the rearing of diapause mosquitoes which requires ethical approval from the animal use committee and costly arrangements. Therefore, the present study was conducted to find whether bovine serum albumin protein (10%) with sucrose (5%) solution (SAP-10) offered through a membrane-free feeding system would result in an alternative diet for the production of diapause eggs in comparison to blood-feeding. This feeding system shows a considerable rate of engorgement of diapausing females under short-day conditions and produced 30.8 diapause eggs/female in comparison to blood-feeding on a guinea pig (40.9 eggs/female). The diapause rate of viable eggs for the SAP-10 diet (95.28%) was similar to the blood-feeding (96.32%). The findings suggest that the present diet feeding system is a promising tool for the rearing of diapause Ae. albopictus mosquitoes under short-day conditions. Further studies are suggested to evaluate the physiological and developmental aspects of mosquitoes reared on the diet.

Caloric intake can greatly affect many aspects of an organism's life. A deficiency of calories can lead to stress resulting in decreased fecundity, insufficient calories to maintain tissues and increased lifespan. Conversely, increasing caloric density increases fecundity and decreases lifespan. Despite decades of work exploring food quality and quantity on physiology in the model species Drosophila melanogaster Meigan 1830 (Diptera: Drosophilidae) and the melanogaster group in general, relatively little work explores the physiological responses to diet manipulation in other Drosophila species, like the obscura species group. Here, we looked at the effects of five different caloric densities (0.5×, 0.75×, 1.0×, 1.5× and 3.0×) on food intake, body weight, body fat, fecundity and longevity in D. pseudoobscura Frolova & Astaurov, 1929 (Diptera: Drosophilidae). Comparing longevity and fecundity across diets, we found that heavy caloric concentration (3.0×) decreases lifespan and that calorie restriction (0.5× and 0.75×) led to significant decreases in fecundity and body weight. However, calorie concentration did not significantly increase D. pseudoobscura body fat. By expanding our understanding of the physiological responses to diet stress to D. pseudoobscura, we establish the framework for comparative work across Drosophila species. With this information, we can then identify which physiological responses to diet manipulation might be most conserved and comparable across species.

Rice leaffolder, Cnaphalocrocis medinalis (Lepidoptera: Plutellidae) is an important migratory pest in Asia. While many lepidopteran species are known to enhance adult life history by obtaining supplementary nutrition, little is known about the effects of adult diet on C. medinalis. We first examined the effects of offering five dilutions of honey solution (0%, 5%, 10%, 15% and 20%) on the longevity, fecundity and ovary development of adult C. medinalis. We then compared the effects of 10% honey solution to 25% glucose solution, which was previously reported to be the best adult diet for C. medinalis. We found that adult male and female C. medinalis fed 5%–20% honey solution lived significantly longer than those fed just water. Importantly, a honey–based diet accelerated and increased ovary development and prolonged the oviposition period, leading to higher fecundity. More specifically, females fed 5%–15% honey solution had the highest fecundity, followed by 20% honey solution, and the lowest when fed only water. In addition, the oviposition rate was 100% in females fed 10% and 15% honey solution. When we compared 10% honey solution to 25% glucose solution, those fed honey solution had significantly higher estimated female performance, which is a composite measure consisting of fecundity, percentage of egg-laying females and percentage of eggs that hatched. Overall, our findings indicate that adult diet quality significantly impacts C. medinalis performance and that using a 10%–15% honey solution is optimal for mass-rearing under laboratory conditions.

This study investigates the impact of imidacloprid insecticide, on the flesh fly Sarcophaga ruficornis, (Diptera: Sarcophagidae), a medically and veterinary significant species associated with myiasis. Lethal (0.02%) and sub-lethal (0.004%) doses were administered over 24 and 48 h, focusing on midgut histopathological, ultrastructural and biochemical alterations. Imidacloprid-induced disruptions in physiological and metabolic functions, leading to adult fly mortality. Histological and cytological analyses revealed significant cellular changes, including cell degeneration, cytoplasmic vacuolization, chromatin condensation, irregular epithelial borders, disrupted peritrophic membrane and the release of cell components into the midgut lumen. Biochemical analyses demonstrated a decrease in total protein, carbohydrate and lipid contents, correlating with insecticide concentration and duration. Antioxidant enzymes, particularly glutathione S-transferase (GST) and superoxide dismutase (SOD), resulted in a significant increase compared to the control, proportional to time and concentration. This research provides a comprehensive understanding of imidacloprid-induced toxicity in the midgut of Sarcophaga ruficornis, emphasizing its potential for effective pest population management.

Sensory mechanotransduction is the process of deciphering physical stimuli into neural electrical receptor potentials, essential to Drosophila, the fruit fly. Nearly every aspect of an adult Drosophila intricate behavioural repertoire that involves the senses of proprioception, hearing, touch, olfaction, balancing and graviception. Mechanotransduction are mediated by a wide variety of specialized sensilla and sensory neurons that comprise the antenna. The eye and antenna of Drosophila melanogaster are derived from a cluster of approximately 23 cells that are set aside during embryonic development and are constantly divided during the three larval stages, organizing into an epithelial sac known as the eye-antennal imaginal disc. During late larval and pupal development, the forward lobe of this epithelium, known as the antennal disc, gives rise to the antenna (an organized tripartite structure), whereas the posterior lobe, known as the eye disc, gives rise to the eye. The development of the antenna is a complex and intricate process that relies on the interplay of numerous genes. Each gene involved contributes to the regulatory network that governs the formation, differentiation, and patterning of specific structures within the antenna, ensuring its proper functionality. Thus, aberrant expression or mutation of any gene results in a faulty antenna. The defectiveness appears in terms of antennal structure leading to loss of function including defective behaviour found in an organism. A similar kind of structure–function relation of hearing with a behavioural defect has been reported in vertebrates. Some of the behavioural defects associated with genes are conserved in both vertebrates and Drosophila. Thus, a behavioural assay is an adaptable approach to studying the functionality of various genes associated with the antennae. Here a crucial relationship is established between the genetic regulation of mechanosensory neurons and an organism's behaviour. The current review summarizes antennae development, function and several methods used to study the mechanosensory behaviour associated with Drosophila antennae.

Cockroaches, ubiquitous pests known for significant reproduction and as potential vectors of diseases, are notorious for their adoptability to a variety of insecticides that cause substantial challenges in pest control. The present research evaluated the LC₅₀ concentrations of imidacloprid (0.65 mg/L) and clothianidin (2.5 μg/L) for Blattella germanica using topical and bait methods. The cockroaches were exposed to one-third concentration of LC₅₀ at a regular interval of 1, 2, 4, 8, 12, 16 and 20 days. During exposure, the activity of P450 monooxygenase increased, whereas the activity of brain acetylcholinesterase decreased. Lactate dehydrogenase, alkaline and acid phosphatase activity were highest on day 4, with a slight recovery on day 20. The elevated activities for superoxide dismutase and catalase, as well as increased lipid peroxidation levels on day 4, followed by a significant recovery in activity on day 20. The glutathione-S-transferase activity was elevated while the glutathione content was reduced, and a significant restoration was observed at the end of the experiment. The biochemical mechanisms of the organisms such as P450, esterase enzymes and oxidative systems, are actively involved in the detoxification mechanism. The study elucidated that the insecticide defence mechanism triggers detoxification pathways that encompass the metabolism of endogenous insecticidal compounds, with clothianidin showing greater efficacy and lower detoxification compared with imidacloprid.