Choice Assays Research Articles

Examining imidacloprid behaviorally resistant house flies (Musca domestica L.) (Diptera: Muscidae) for neonicotinoid cross-resistance.

The house fly (Musca domestica L.) is a ubiquitous fly species commonly associated with confined animal and urban waste storage facilities. It is known for its pestiferous nature and ability to mechanically vector numerous disease-causing pathogens. Effective control of adult house fly populations has traditionally relied upon insecticidal food baits; however, due to the overuse of insecticides, resistance has proven to yield many insecticidal baits and chemical classes less effective. Imidacloprid, the most widely used neonicotinoid, has been formulated and commonly used in house fly baits for over 2 decades. However, widespread evidence of physiological and behavioral resistance to imidacloprid has been documented. While previous studies have investigated the mechanisms of behavioral resistance to imidacloprid in the house fly, it remains unclear whether behavioral resistance is specific to imidacloprid or if behavioral cross-resistance exists to other compounds within the neonicotinoid class of insecticides. The current study used no-choice and choice-feeding bioassays to examine a lab-selected imidacloprid behaviorally resistant house fly colony for cross-resistance to other insecticides in the neonicotinoid chemical class. All flies exhibited high mortality (97-100%) in no-choice assays, even when exposed to imidacloprid, indicating physiological susceptibility to all tested neonicotinoids. House flies exhibited high mortality (98-100%) in choice assays when exposed to all neonicotinoid insecticides tested besides imidacloprid. These results confirm that imidacloprid behavioral resistance is specific to the compound imidacloprid and that alternative neonicotinoids remain viable options for control. Our study showed no evidence of behavioral cross-resistance to other compounds in the neonicotinoid class.

Novo plant-based mosquito repellent shows promise for exclusion of Aedes mosquitoes from "window" entry.

Mosquitoes threaten over half of the world's population through vectored diseases such as malaria, zika, yellow fever, dengue, and chikungunya. Mosquitoes have a highly developed olfactory system attuned to chemotaxis relating to host-seeking, mating, and oviposition behavior. In this study, we aimed to determine the spatial efficacy of 2 plant-based repellent blends (Blend3 and Blend4that had previously been found to successfully repel Aedes, Anopheles and Culex mosquitoes in wind tunnel assays)in excluding Aedes aegypti from the window entry. A new cage system was developed for parallel "no-choice" and "choice" olfactometric assays. In the no-choice trial, Blends 3 and 4, as well as commercial products (N, N-diethyl-3-methylbenzamide, p-menthane-3,8-diol [PMD], 3-(N-n-butyl-N-acetyl)-amino-propionic acid ethyl ester, and 2-(2-hydroxyethyl)-1-methylpropylstyrene 1-piperidine carboxylate), were adsorbed into filter papers of different sizes and placed in a window created between 2 attached bug dorms. Then, the number of mosquitoes entering the window was counted through a 6-min period. In choice olfactometric assays, Blends 3, 4, and PMD were adsorbed into filter paper and the number of mosquitoes moving away from Blend 3 and PMD were compared. No-choice assays showed that Blend3 (P < 0.001) and Blend4 (P = 0.0012) were more repellent than the best commercial product PMD. Additionally, while Blend 4 was significantly more repellent than Blend 3 (P = 0.012) in the choice assay, overall, these 2 blends show promise as new repellents for the spatial exclusion of Aedes aegypti from window entry alone or as part of a "push-pull'' strategy.

Efficacy of Melia azedarach leaf extract in different solvents against Heterotermes indicola Wasmann (Blattodea: Rhinotermitidae) using non-durable wooden blocks under laboratory and field conditions

Hetertermes indicola Wasman (Blattodea: Rhinotermitidae) is a highly wood-destructive termite species in the urban settings of Pakistan. This study evaluated the biocidal action of Melia azedarach leaf extract in different solvents on H. indicola by conducting choice and no-choice feeding deterrence assays using impregnated palatable wood under field and laboratory conditions. Dose-dependent and time-dependent trends were observed in the leaf extracts of M. azedarach at different concentrations (500, 1000, and 1500 ppm) using solvent water and methanol with 80–100 % termite mortality after 6 days of exposure. A key outcome was the higher termiticidal efficacy of methanolic extract compared to aqueous extract under both field and laboratory conditions. The LC50 values of 358 ppm for methanol and 466 ppm for aqueous extract after 15 days in a laboratory no-choice experiment exhibit a quantitative measure of chinaberry leaf extract toxicity. A significant reduction in mean percent weight loss (8.26 %) of treated wood with 1500 ppm of M. azedarach leaf extract in methanol was observed under field conditions. In conclusion, triterpenoids and phytol present in methanolic leaf extract demonstrated higher efficacy in both lab and field conditions making a solid foundation for the further development of natural wood preservatives. Since they induced rapid lethargic conditions in termites and digestive toxicity which leads to minimum loss of treated wood.

Signal Detection Theoretic Estimates of the Murine Absolute Visual Threshold Are Independent of Decision Bias.

Decision bias influences estimates of the absolute visual threshold. However, most psychophysical estimates of the murine absolute visual threshold have not taken bias into account. Here we developed a one-alternative forced choice (1AFC) assay to assess the decision bias of mice at the absolute visual threshold via the theory of signal detection and compared our approach with the more conventional high-threshold theoretic approach. In the 1AFC assay, mice of both sexes were trained to signal whether they detected a flash stimulus. We directly measured both hit and false alarm rates, which were used to estimate d' Using the theory of signal detection, we obtained absolute thresholds by interpolating the intensity where d' = 1 from d'-psychometric functions. This gave bias-independent estimates of the absolute visual threshold which ranged over sixfold, averaging ∼1 R* in 1,000 rods (n = 7 mice). To obtain high-threshold theoretic estimates of the absolute visual threshold from the same mice, we estimated threshold intensities from the frequency of seeing curves, corrected for guessing. This gave us thresholds that were strongly correlated with decision bias, ranging over 13-fold and averaged ∼1 R* in 2,500 rods. We conclude that the theory of signal detection uses false alarms to overcome decision bias and narrow the range of threshold estimates in mice, providing a powerful tool for understanding detection behavior near absolute visual threshold.

Transgenic cotton expressing Allium sativum leaf agglutinin exhibits resistance to whiteflies and aphids without negative effects on ladybugs

Cotton (Gossypium hirsutum L.) is of great economic importance as a cultivated crop in many parts of the world. In addition to being a pillar of the textile industry, cotton and its byproducts are used for livestock feed, seed oil, and other products. Bacillus thuringiensis crystal toxin (Bt) expression in cotton provides effective protection against chewing insects but does not defend plants from piercing/sucking insect pests. With the aim to create transgenic plants with resistance against piercing/sucking pests, we used Agrobacterium-mediated genetic transformation of cotton cultivar Coker 312 to express the Allium sativum leaf agglutinin (ASLA) gene from the phloem-specific rolC promoter. The ASLA transgene was stably inherited and showed Mendelian segregation in the T1 generation. Transgenic lines, expressing the ASLA gene, showed explicit resistance against major sap-sucking pests. Green peach aphid (Myzus persicae Sulzer) choice assays showed that 75% of aphids preferred untransformed cotton plants relative to those expressing the ASLA gene. In detached leaf bioassays, plants expressing ASLA caused 82% aphid mortality and 44–53% reduction in fecundity. Clip cage bioassays with whiteflies (Bemisia tabaci Gennadius) showed 74–82% mortality and 44–60% decrease in fecundity due to ASLA gene expression. In whole plant bioassays, whiteflies showed 77% mortality and a 54% decrease in fecundity on ASLA transgenics. Importantly, we did not observe a negative effect of the ASLA gene on ladybugs (Coccinella septempunctata) that consumed these whiteflies. Together, our findings demonstrate the potential of ASLA-transgenic cotton for providing protection against two devastating insect pests, whiteflies and aphids. The ASLA-transgenic cotton appears promising for direct commercial cultivation besides serving as a potential genetic resource in recombination breeding.

Compensation of physiological traits under simulated drought and herbivory has functional consequences for fitness in soybean (Glycine max (L.) Merrill)

Soybean (Glycine max (L.) Merrill), one of the most valuable crops in the world, faces serious challenges due to drought and insect herbivory. Although well studied independently, we lack a comprehensive understanding of interactive effects of drought × herbivory on both soybean and herbivore traits. A holistic examination of soybean morpho-physiology (above and below-ground traits including root morphology) and herbivore performance can help us understand the potential consequences of these two major stressors on soybean yield and fitness. To this end, we imposed simulated-drought and herbivory by soybean looper (SBL) (Chrysodeixis includens Walker) and assessed both host and herbivore performance. Morpho-physiological traits of soybean including shoot height, chlorophyll content, root morphology, photosynthesis, stomatal conductance, and transpiration were measured. Additionally, growth and feeding behavior of SBL were also assessed to analyze the impacts of drought × herbivory on both host and herbivore. Our results show that certain physiological traits were significantly upregulated under drought × herbivory indicating compensation. We also observed that SBL frass weight, and scale of damage was lower on simulated-drought-experienced plants and, in choice assays, SBL preferred well-watered plants. In addition to lower yields observed under simulated-drought and herbivory interaction, soybeans that experienced both drought and herbivory had the highest number of aborted pods. Our study shows that simulated drought and herbivory have synergistic negative impacts on soybean morpho-physiology and support plant vigor hypothesis. Simulated drought negatively impacted SBL performance and made them less attracted to the soybeans that experienced water stress. Ultimately, the interactive effects of these stressors have negative consequences on soybean yield and fitness. This study demonstrates the need to integrate biotic and abiotic stressors for a better understanding of interactive effects on host and herbivores to make informed decisions for breeding and pest management strategies.

Seasonal variation in attraction to plant volatiles by Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae).

Pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae), occurs as 2 seasonal morphotypes. Summerforms occur on pear (Pyrus communis L.; Rosales: Rosaceae) where they are a significant pest. The larger and darker winterform morphotype develops in response to shortening daylengths and begins winter in reproductive diapause characterized by the absence of ovarian development. Diapausing winterforms often leave pear to overwinter on coniferous shelter plants and then return to pear in late winter and early spring to begin depositing the eggs that produce the first summerform generation. Cacopsylla pyricola adults are attracted to the color of foliage most of the year, but little is known about the role of plant volatiles in host finding and in seasonal dispersal between host and shelter plants by the psyllid. We used a Y-tube olfactometer and choice assays to investigate the response by C. pyricola adults to volatiles emitted by pear and an evergreen tree (cypress) often used as a shelter plant by wintering C. pyricola. Attraction to pear and cypress volatiles varied by season, tree phenology, and psyllid physiology. Cacopsylla pyricola were attracted to cypress volatiles and preferred to settle on cypress shoots during winter and early spring but then shifted to a marked preference for the pear developmental host in late spring and summer. Female C. pyricola exhibited stronger responses to pear volatiles than did males. Our study is the first to show that plant volatiles have a role in host finding by C. pyricola and provides a foundation for research on chemical ecology and management of C. pyricola.

Sensitive and Accurate Quantification of Enterovirus-D68 (EV-D68) Viral Loads Using Droplet Digital PCR (ddPCR).

Enterovirus-D68 (EV-D68) is a reemerging virus that has been associated with numerous outbreaks in children in the past 10 years. Most assays examining viral infection kinetics have relied on the use of quantitative RT-PCR (qRT-PCR) assays as an assay of choice. Though valuable, there are inherent limitations that introduce variability, thereby reducing its value when comparing results across the field. Unlike the qRT-PCR assay that uses a standard curve to determine the copy number of viral RNA, the droplet digital PCR assay (ddPCR) directly quantifies the absolute number of copies within a given sample, which in turn makes the assay highly sensitive and accurate. Here, we have developed an EV-D68-specific ddPCR assay that effectively quantifies EV-D68 RNA copies in both cells and supernatants within a dynamic range of 6.7 × 10-3 copies/μL to 1.2 × 104 copies/μL of the sample. The assay was highly specific for a broad range of EV-D68 isolates (Fermon, US/MO/14-18947, US/MO/14-18949, US/KY/14-18953, USA/2018-23088, USA/2020-23336 and EV-D68-infected human nasal turbinate samples from the 2022 outbreak) without cross-reactivity to other viruses such as Enterovirus-A71 (EV-A71), Human Parechovirus (HPeV)-1 and -2, Coxsackievirus (CV)-B1, Human Coronavirus (HCoV)-NL63, SARS-CoV-2, Influenza-A and B, Rhinovirus, and Respiratory Syncytial Virus (RSV)-A2, which are known to cause infection in children. The assay was able to readily quantify EV-D68 in infected cells and supernatants along with nasal turbinate samples collected from children during the 2022 outbreak. Our results suggest that the assay can be readily translated to accurately quantify viral loads in tissues and body fluids such as plasma and lung or nasal aspirates.

Making a healthy choice: Tactical host selection behaviour of a parasitoid wasp

Abstract Host selection behaviour plays a pivotal role in determining the success of parasitoids, especially in environments where host quality varies. In heterogeneous environments, parasitoids frequently encounter hosts that are infected. We conducted experiments to ascertain whether the ecto‐parasitoid Bracon brevicornis can differentiate between healthy caterpillars and those infected with Bacillus thuringiensis (Bt) and examined the implications of this host selection behaviour. In an olfactometer choice assay, B. brevicornis avoided Bt‐infected Spodoptera litura hosts. In a no‐choice assay, the female parasitoid displayed a lower paralysis rate on infected hosts, indicating a strong selection behaviour. Furthermore, we explored the impact of infection duration by exposing female wasps to larvae infected for 24, 48 and 72 h with Bt. Both choice and no‐choice assays demonstrated that female B. brevicornis refrains from ovipositing on infected larvae, regardless of the infection duration. Direct exposure to Bt through consumption did not affect the fitness of the tested parasitoid wasp. However, post‐24‐h Bt infection, host larvae showed an increased total hemocyte density, particularly high phagocytic cell numbers, and enhanced melanization, rendering the host larva unsuitable for parasitoid development. Taken together, our study underscores that parasitoids exhibit robust host selection behaviour by actively avoiding infected hosts. This insight is valuable for devising new pest control strategies in agriculture that safeguard beneficial parasitoids.

Co-stimulation of muscarinic M1 and M4 acetylcholine receptors prevents later cocaine reinforcement in male and female mice, but not place-conditioning

Acute stimulation of M1 or M4 muscarinic cholinergic receptors reduces cocaine abuse-related effects in mice and rats. The combined activation of these receptor subtypes produces synergistic effects on some behavioural endpoints in mice. M1 and M1 + M4 receptor stimulation in a cocaine vs. food choice assay in rats and microdialysis in rats showed delayed and lasting “anticocaine effects”. Here, we tested whether these putative lasting neuroplastic changes are sufficient to occlude the reinforcing effects of cocaine at the behavioural level in mice. Mice were pre-treated with the M1 receptor partial agonist VU0364572, M4 receptor positive allosteric modulator VU0152100, or VU0364572 + VU0152100 two weeks prior to acquisition of cocaine intravenous self-administration (IVSA). Male C57BL/6JRj mice received vehicle, VU0364572, VU0152100, or VU0364572 + VU0152100. Female mice were tested with two VU0364572 + VU0152100 dose combinations or vehicle. To attribute potential effects to either reduced rewarding effects or increased aversion to cocaine, we tested VU0364572 alone and VU0364572 + VU0152100 in acquisition of cocaine-conditioned place preference (CPP) in male mice using an unbiased design. The acquisition of cocaine IVSA was drastically reduced and/or slowed in male and female mice receiving VU0364572 + VU0152100, but not either drug alone. Food-maintained operant behaviour was unaffected, indicating that the treatment effects were cocaine-specific. No treatment altered the acquisition of cocaine-CPP, neither in the post-test, nor in a challenge 14 days later. The cocaine IVSA findings confirm unusual long-lasting “anticocaine” effects of muscarinic M1 + M4 receptor stimulation. Thus, in mice, simultaneous stimulation of both receptor subtypes seems to produce potential neuroplastic changes that yield lasting effects.

Trichomes and unique gene expression confer insect herbivory resistance in Vitis labrusca grapevines

BackgroundGrapevine (Vitis) is one of the world’s most valuable fruit crops, but insect herbivory can decrease yields. Understanding insect herbivory resistance is critical to mitigating these losses. Vitis labrusca, a wild North American grapevine species, has been leveraged in breeding programs to generate hybrid grapevines with enhanced abiotic and biotic stress resistance, rendering it a valuable genetic resource for sustainable viticulture. This study assessed the resistance of V. labrusca acc. ‘GREM4’ and Vitis vinifera cv. ‘PN40024’ grapevines to Popillia japonica (Japanese beetle) herbivory and identified morphological and genetic adaptations underlying this putative resistance.Results‘GREM4’ displayed greater resistance to beetle herbivory compared to ‘PN40024’ in both choice and no-choice herbivory assays spanning periods of 30 min to 19 h. ‘GREM4’ had significantly higher average leaf trichome densities than ‘PN40024’ and beetles preferred to feed on the side of leaves with fewer trichomes. When leaves from each species that specifically did not differ in trichome densities were fed on by beetles, significantly less leaf area was damaged in ‘GREM4’ (3.29mm2) compared to ‘PN40024’ (9.80mm2), suggesting additional factors beyond trichomes contributed to insect herbivory resistance in ‘GREM4’. Comparative transcriptomic analyses revealed ‘GREM4’ exhibited greater constitutive (0 h) expression of defense response and secondary metabolite biosynthesis genes compared to ‘PN40024’, indicative of heightened constitutive defenses. Upon herbivory, ‘GREM4’ displayed a greater number of differentially expressed genes (690) compared to ‘PN40024’ (502), suggesting a broader response. Genes up-regulated in ‘GREM4’ were enriched in terpene biosynthesis, flavonoid biosynthesis, phytohormone signaling, and disease defense-related functions, likely contributing to heighted insect herbivory defense, while genes differentially expressed in ‘PN40024’ under herbivory were enriched in xyloglucan, cell wall formation, and calcium ion binding. The majority of genes implicated in insect herbivory defense were orthologs with specific expression patterns in ‘GREM4’ and ‘PN40024’, but some paralogous and genome-specific genes also likely contributed to conferring resistance.ConclusionsOur findings suggest that ‘GREM4’ insect herbivory resistance was attributed to a combination of factors, including trichomes and unique constitutive and inducible expression of genes implicated in terpene, flavonoid, and phenylpropanoid biosynthesis, as well as pathogen defense.

Fatally impaired glucose digestion by propylene glycol in Aedes aegypti (Diptera: Culicidae) and co-formulation with terpenoids for enhancing attractive toxic sugar baits.

Propylene glycol (PG) demonstrates greater efficacy than other sugar polyols. However, the attributes it confers for toxicity and possible co-formulation with other ingredients are unknown. To evaluate this, α-glucosidase and glucose oxidase reactions were performed in Aedes aegypti (L.) (Diptera: Culicidae) to categorize if PG behaves similarly to prior studied sugar alcohols. A combination of no-choice and choice assays was used to determine effective ratios of PG and sucrose, competitiveness against a control of 10% sucrose, and whether mosquitoes recovered from PG consumption. The final trials included β-cyclodextrin encapsulated cinnamon leaf oil, clove stem oil, patchouli oil, garlic oil, cedarwood oil, and papaya seed oil formulated with 5% sucrose + 5% PG. PG functioned as a linear competitive inhibitor of α-glucosidase. The efficacy of PG was synergized by co-ingestion with equivalent ratios of sucrose. Unlike the high diuretic response to other sugar alcohols, PG resulted in diminished excretion regardless of being co-formulated with sucrose or terpenoids. PG is not especially competitive against unadulterated sugar meals but is likewise not clearly repellent. Although mosquitoes did not recover from ingestion of the glycol meals, there was no indication that mortality would continue to accumulate once the treatments were removed. Of the terpenoids tested, cinnamon and patchouli caused ~50% or less mortality; garlic, cedarwood, and clove caused 80-90% mortality; and papaya seed caused 100% mortality, exceeding all other test groups and the formulation blank. PG is a useful supporting ingredient in attractive toxic sugar bait formulations with flexibility in formulation.

The rat telemetry assay and venous catheter access buttons for use in cardiovascular safety pharmacology assessments – Surgical methods, refinements and colony maintenance

IntroductionRat telemetry is the assay of choice to assess the potential effects of novel drug candidates on cardiovascular parameters during early drug discovery. Telemetry device implantation can be combined with venous catheter and access button implantation when intravenous administration of the drug substance is required. MethodsRats (Sprague Dawley or Han Wistar) were implanted with telemetry devices for arterial blood pressure measurement using either direct aortic catheterisation (n = 131) or aortic catheterisation via the femoral artery (n = 17). Bipolar leads for ECG recording were also implanted in some of the animals (n = 102). Femoral vein catheters and access buttons were implanted as a separate surgery after the initial telemetry implantation (n = 43). Results128 animals (86%) were implanted successfully with telemetry devices without any notable surgical or post-surgical problems. When considering the 2 different catheterisation methods separately, the success rate of the direct aortic approach was 88% compared to 76% with the aortic placement via the femoral artery. Lameness was the most common post-surgical problem. Blood loss during surgery and ischaemic patches on the tail were also observed at a low incidence with the direct aortic approach. Catheter pull-out occurred in some rats before the first signal check reducing the overall success rate for blood pressure measurement using the direct aortic approach to 85%. A 95% success rate was observed for catheter and access button implantation. DiscussionA high success rate is possible when implanting telemetry devices in rats with and without venous catheters and access buttons. We have attempted to provide solutions to problems and describe refinements to the procedure which may further improve surgical outcomes.

Assessment of the efficacy of Piper methysticum (Micrembryeae: Piperaceae) as a bioinsecticide, and/or spinosad combined with attractive plant volatiles for a novel lure and kill strategy against Bactrocera tryoni (Diptera: Tephritidae) in laboratory.

The Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), is a crop pest of global economic importance because of its wide range of hosts and its invasiveness capacities. To develop a novel integrated and sustainable crop protection, we have investigated the insecticidal properties of different varieties of kava (Piper methysticum [Frost]) extracted by two methods and the attractive effects of six plant volatiles identified from B. tryoni host plants to female, mated or not. We did not identify any significant insecticidal effect of the traditional Pacific kava plant at the tested concentrations. Among mated females, ethyl acetate compared to the no odor control elicited the highest attraction (87%, of which 60% for this odor), while ethyl butyrate was preferred compared with ethyl acetate in dual choice assays. Flies' preferences for specific odors depended on their mating status and the odor landscape they were confronted with. Combination with the commercial ingestion insecticide (Success 4: spinosad, 480 g/l, Dow AgroSciences, Valbonne, France) with the plant volatiles were tested to detect an increase in mortality related to the addition of an attractant. The 2-heptanone slightly showed a tend to increase the attractiveness of mated females within 4-6 h to the food bait, but the results were not statistically significant after 8 h. Further tests should be performed with other concentrations or mixtures of the identified host plant volatiles to develop a strong lure and kill strategy.

A single pair of pharyngeal neurons functions as a commander to reject high salt in Drosophila melanogaster.

Salt (NaCl), is an essential nutrient for survival, while excessive salt can be detrimental. In the fruit fly, Drosophila melanogaster, internal taste organs in the pharynx are critical gatekeepers impacting the decision to accept or reject a food. Currently, our understanding of the mechanism through which pharyngeal gustatory receptor neurons (GRNs) sense high salt are rudimentary. Here, we found that a member of the ionotropic receptor family, Ir60b, is expressed exclusively in a pair of GRNs activated by high salt. Using a two-way choice assay (DrosoX) to measure ingestion volume, we demonstrate that IR60b and two co-receptors IR25a and IR76b are required to prevent high salt consumption. Mutants lacking external taste organs but retaining the internal taste organs in the pharynx exhibit much higher salt avoidance than flies with all taste organs but missing the three IRs. Our findings highlight the vital role for IRs in a pharyngeal GRN to control ingestion of high salt.

A single pair of pharyngeal neurons functions as a commander to reject high salt in Drosophila melanogaster

Salt (NaCl), is an essential nutrient for survival, while excessive salt can be detrimental. In the fruit fly, Drosophila melanogaster, internal taste organs in the pharynx are critical gatekeepers impacting the decision to accept or reject a food. Currently, our understanding of the mechanism through which pharyngeal gustatory receptor neurons (GRNs) sense high salt are rudimentary. Here, we found that a member of the ionotropic receptor family, Ir60b, is expressed exclusively in a pair of GRNs activated by high salt. Using a two-way choice assay (DrosoX) to measure ingestion volume, we demonstrate that IR60b and two co-receptors IR25a and IR76b are required to prevent high salt consumption. Mutants lacking external taste organs but retaining the internal taste organs in the pharynx exhibit much higher salt avoidance than flies with all taste organs but missing the three IRs. Our findings highlight the vital role for IRs in a pharyngeal GRN to control ingestion of high salt.

Effects of Xenorhabdus and Photorhabdus bacterial metabolites on the ovipositional activity of Aedes albopictus

AbstractViral diseases like yellow fever, dengue, and Zika have an alarming impact on public health. These diseases can be transmitted by Aedes mosquito species, such as Ae. albopictus, which is now found in many countries outside its original range. Xenorhabdus and Photorhabdus spp. are enteric bacterial symbionts of insect-preying nematodes and are known to produce an array of natural products with various activities including larvicidal activity. In this study, the effects of natural products produced by four Xenorhabdus and one Photorhabdus bacteria on the ovipositional behavior of Ae. albopictus mosquitoes were assessed. Utilizing a binary choice assay in insect cages, gravid female mosquitoes were presented with two oviposition cups containing water supplemented with varying concentrations of bacterial supernatants (50–1% concentrations) versus control medium. After 72 h, the eggs deposited on filter papers were counted. The oviposition attractant index (OAI) feature of the bacterial supernatant was evaluated using the number of eggs laid in the cups. Notably, all tested supernatants exhibited concentration-dependent deterrence of oviposition. Xenorhabdus cabanillasii displayed the strongest deterrent effect, inhibiting egg-laying at 50–5% concentrations (OAI: − 0.87 to − 0.35), followed by X. nematophila (50–10%, OAI: − 0.82 to − 0.52). Xenorhabdus szentirmaii, X. doucetiae, and P. kayaii showed significant deterrence at ≥ 20% concentrations. Using promoter exchange mutants generated by the easyPACId approach, fabclavine from X. szentirmaii was identified as the bioactive compound with evident deterrent effects. Such deterrents targeting egg-laying could be valuable for controlling populations by disrupting their breeding in suitable habitats.

Search for Snail Repellents: Antimollusc Activities from Stemona parviflora and Six Other Chinese Stemona Species.

Snails are important agricultural pests difficult to control, but data regarding molluscicidal assays are scant. Stemona alkaloids are typical secondary metabolites for the taxa and have been broadly investigated for their pharmacological and toxicological effects. This makes it possible for us to further develop the toxicities of these compounds to snails. In this work, we tested the antifeedant properties of leaves from seven Chinese Stemona species against the land snail species Bradybaena ravida in choice and non-choice feeding assays. The tested leaves Stemona parviflora exhibited the most deterrent effects, and a further phytochemical investigation of aerial parts led to the identification of 16 alkaloids. Among them, three novel alkaloids could be identified. The alkaloidal fraction and single alkaloids were further assayed against this snail species, and the results suggest a cocktail effect because the impact of the alkaloidal fraction was higher than the effects caused by single alkaloids. The study can promote the search process of natural antimollusc products from plants to control snails.

Surgical incision pain induced an increase in alcohol consumption in mice

IntroductionLarge population-based studies have suggested a link between increased alcohol use and reduced pain. In addition, these studies suggest that higher levels of pain intensity are associated with an increase in alcohol consumption and rates of hazardous drinking which potentiates the risk of developing alcohol use disorders (AUD). The mechanisms and determinants of the alcohol–pain interaction can be studied in preclinical studies. MethodsThe overall goal of this study is to use animal models to explore the impact of acute postoperative pain on alcohol intake. To achieve this, we characterized the timeline and levels of alcohol intake and preference in mice after laparotomy in the 2-bottle choice paradigm. ResultsOur results show that laparotomy surgery increased alcohol intake and preference in male mice but not females in the 2-bottle choice and 3-bottle choice assays. In addition, ketoprofen administration blocked the increase in alcohol consumption in male mice after laparotomy. We also found that changes in alcohol initial sensitivity and acute functional tolerance, using loss of righting reflex (LORR) response, occur after surgery in mice. ConclusionTaken together, these findings suggests that sex, pain and alcohol sensitivity-related factors may modulate the relationship between alcohol consumption and pain.

Production of protein hydrolysate from four plant sources and its optimization with α-pinene and tea seed saponin to control olive fruit fly

Types, source of production and optimization with some attractive compounds are the main requirements to produce a commercially efficient protein hydrolysate. The current study was designed to produce protein hydrolysate for the first time from Camelia sinensis (Tea) seeds, Cyamopsis tetragonoloba (Guar) seeds, Cucurbita pepo (Summer squash) seeds, Glycine max (Soybean) seeds and Olea europaea Kernels (Olive) optimized with α-pinene and Camelia sinensis saponin (CSS) aiming to availability of the products from the sources with low economic value and more attractance. Results revealed the highest extracted protein from Guar while the highest inhibition of DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) and hydroxyl radicals were recorded in the protein hydrolysates extracted from Summer squash, Soybean and Olive. The highest reduction potential of Fe3+ ion and radical scavenging activity were found in the protein hydrolysate extracted from Olive and Soybean, respectively. Exposure of protein hydrolysates extracted from plant sources were determined in choice and no choice assays. In choice experiment, the highest amount of ingestion was recorded on Tea, Guar and Summer squash but the adults ingested the most protein hydrolysate extracted from tea optimized with α-pinene. In no choice experiment, the highest ingestion was recorded on Guar while optimization with α-pinene caused the highest ingestion on both Tea and Guar. Bioassay of C. sinensis saponin against the adults of B. oleae demonstrated the LC50 and LT50 values of 0.35% and 1.41 days, respectively. Also, CSS decreased activities of digestive enzymes in B. oleae except for TAG-lipase and trypsin. The adults of B. oleae fed on protein hydrolysate containing CSS showed elevated activity of antioxidant enzymes including catalase, peroxidase, superoxide dismutase and ascorbate peroxidase except for glucose-6-phosphate dehydrogenase. Results of the present study showed that protein hydrolysate can be extracted from plant sources that have little commercial value like tea seeds and olive kernels. In addition, their optimization with compounds that are attractive to the olive fruit fly can provide products with the higher efficiency than the products available in the market.