Cockroach Periplaneta Americana Research Articles

Insecticidal effect of Quinolizidine and phenolic compounds extracted from lupines luteus against American cockroach (Periplaneta Americana) and German cockroach (Blattella germanica)

Insecticidal effect of Quinolizidine and phenolic compounds extracted from lupines luteus against American cockroach (Periplaneta Americana) and German cockroach (Blattella germanica)

The Cocoon of the Developing Emerald Jewel Wasp (Ampulex compressa) Resists Cannibalistic Predation of the Zombified Host

Introduction: To reproduce, the parasitoid emerald jewel wasp (Ampulex compressa) envenomates an American cockroach (Periplaneta americana) and barricades it in a hole with an egg on the host’s leg. The larval wasp feeds externally before entering the host and consuming internal organs before forming a cocoon inside the host carcass. Methods: The vulnerability of jewel wasp larvae to predation by juvenile cockroaches was investigated, and data were recorded with time-lapse videography. Results: Cockroaches were found to be predators of parasitized hosts. When parasitized cockroaches were exposed to hungry cockroaches on days 0–8 of development, the developing larva was killed. Eggs were dislodged or consumed, larvae on the leg were eaten, and larvae inside the host were eaten along with the host. On day 9, 80% of the wasp larvae were killed and eaten along with the host. Conversely, on day 10, 90% of the larvae survived. On developmental day 11 or later, the wasp larva always survived, although the host carcass was consumed. Survival depended entirely on whether the cocoon had been completed. Conclusion: The results highlight the vulnerability of larvae to predation and suggest the cocoon defends from insect mandibles. This may explain the unusual feeding behavior of the jewel wasp larvae, which eat the host with remarkable speed, tapping into the host respiratory system in the process, and consuming vital organs early, in contrast to many other parasitoids. Results are discussed in relation to larval wasp behavior, evolution, and development, and potential predators are considered.

Non-Invasive Recording of the Electroretinogram from Both Compound Eyes in the Cockroach Periplaneta Americana L. in Response to Light Stimuli

Non-Invasive Recording of the Electroretinogram from Both Compound Eyes in the Cockroach Periplaneta Americana L. in Response to Light Stimuli

The complex neurochemistry of the cockroach antennal heart

The innervation of the antennal heart of the cockroach Periplaneta americana was studied with immunocytochemical techniques on both the light and electron microscopic levels. The antennal heart is innervated by two efferent systems, both using one biogenic amine in combination with neuropeptides. In one, we found co-localization of serotonin with proctolin and allatostatin. These fibers most likely originate from paired neurons located in the suboesophageal ganglion. In the second system, we found octopamine co-localized with the short neuropeptide F. The source of this second system is dorsal unpaired median (DUM) neurons, also located in the suboesophageal ganglion. The possible effects of these neuromediators on different targets are discussed.

Purified fibers in chemically defined synthetic diets destabilize the gut microbiome of an omnivorous insect model.

The macronutrient composition of a host's diet shapes its gut microbial community, with dietary fiber in particular escaping host digestion to serve as a potent carbon source for gut microbiota. Despite widespread recognition of fiber's importance to microbiome health, nutritional research often fails to differentiate hyper-processed fibers from cell-matrix derived intrinsic fibers, limiting our understanding of how individual polysaccharides influence the gut community. We use the American cockroach (Periplaneta americana) as a model system to dissect the response of complex gut microbial communities to diet modifications that are impossible to test in traditional host models. Here, we designed synthetic diets from lab-grade, purified ingredients to identify how the cockroach microbiome responds to six different carbohydrates (chitin, methylcellulose, microcrystalline cellulose, pectin, starch, xylan) in otherwise balanced diets. We show via 16S rRNA gene profiling that these synthetic diets reduce bacterial diversity and alter the phylogenetic composition of cockroach gut microbiota in a fiber-dependent manner, regardless of the vitamin and protein content of the diet. Comparisons with cockroaches fed whole-food diets reveal that synthetic diets induce blooms in common cockroach-associated taxa and subsequently fragment previously stable microbial correlation networks. Our research leverages an unconventional microbiome model system and customizable lab-grade artificial diets to shed light on how purified polysaccharides, as opposed to nutritionally complex intrinsic fibers, exert substantial influence over a normally stable gut community.

Changes in Prevalence of IgE Sensitization and Allergenic Exposition over a 10-Year Period in a Tropical Region.

Multiple antigen environmental sources have been identified as possible causes of allergies, but few studies have evaluated changes in the sensitization profiles over time. The aim of this study was to evaluate the changes in IgE sensitization and exposure to dust mites, cats, dogs, and cockroaches over a 10-year period. During a period of 10 years among patients with asthma, rhinitis and/or atopic dermatitis, we evaluated the annual frequency of atopy to Dermatophagoides farinae, Dermatophagoides pteronyssinus, Blomia tropicalis, Canis familiaris, Felis domesticus and cockroaches (Periplaneta americana and Blatella germanica). Exposure to sources was also assessed using questionnaires (Pets) or direct counts (House dust mites and cockroaches). The association between some risk factors and the prevalence of atopy was explored. A total of 6,000 records were included. Among the patients, 82% had IgE sensitization to at least one of the six allergenic sources. Sensitization to Dermatophagoides spp. was the most frequent (>78%). Exposure and sensitization in the first decade of life to Dermatophagoides spp. seem to determine the molecular spreading to other allergenic sources. Exposure to Blomia tropical increases significantly over time (year 2015; 38% vs. year 2022; 51%, p 0.03). Exposure to dogs was higher than with cats but association between atopy and exposure was stronger with cats (OR 27.4, 95% CI: 22.3-33.6, p < 0.01). Exposure and sensitization in the first decade of life to Dermatophagoides spp. determine the molecular spreading of IgE antibodies to other allergenic sources. Household exposure to dogs and cats seems to be important for the subsequent development of atopy. Sensitization to B. tropicalis and cockroach appears to be mostly from cross-reactivity rather than direct exposure.

Use of Periplaneta americana as a Soybean Meal Substitute: A Step towards Sustainable Transformative Poultry Feeds.

Insects are becoming increasingly popular as a sustainable and nutritious alternative protein source in poultry feeds, due to their high protein content, low environmental impact, and efficient feed conversion rates. Using insect-based feeds can reduce the need for traditional protein sources like soybean meal (SBM), which often contribute to environmental issues such as deforestation and high water consumption. The current experiments were devised to assess the impacts of the partial replacement of SBM with the American cockroach Periplaneta americana and black soldier fly Hermetia illucens on the performances, hematology, gut morphometry, and meat quality of male broilers (Ross 308). A total of 350, 1-day-old chicks weighing 40.05 ± 0.27 g were divided into 7 dietary treatments (5 pens/treatment and 10 birds/pen) at random, i.e., a 4, 8, or 12% SMB replacement with P. americana and H. illucens. Soybean meal was used as a basal diet and taken as a control. The results indicated that broilers fed on 12% P. americana or H. illucens showed significant improvements (p < 0.05) in feed conversion ratio, live weight, and daily weight gain. Hematological traits significantly improved (p < 0.05). A gut histology showed increased villus height, villus width, crypt depth, and villus height/crypt depth ratios, indicating improved nutrient absorption. Broiler meat fed on 12% P. americana meal had significantly higher redness and yellowness (p < 0.05). Substituting soybean meal with up to 12% P. americana or H. illucens meal in poultry feed can enhance the broilers' growth performance, hematology, gut morphometry, and meat quality. Hence, these findings imply that P. americana or H. illucens meal are viable and constructive alternative protein sources in poultry nutrition, offering a sustainable approach to meet the increasing demand for animal protein across the world.

Cockroaches (Periplaneta americana Linnaeus [Dictyoptera: Blattidae]) as Potential Vectors of Bacteria in Federal University Wukari, Nigeria

Cockroaches (Periplaneta americana Linnaeus [Dictyoptera: Blattidae]) as Potential Vectors of Bacteria in Federal University Wukari, Nigeria

Isolation and Diagnosis of Parasites from Domestic Cockroach Periplaneta americana in Mosul city, Iraq

Cockroaches are the greatest potential mechanical vector of various pathogenic microorganisms, some of which cause serious diseases in humans and domestic animals. The high prevalence of human pathogens carried by the cockroach has been reported in many countries. This study aimed to determine the prevalence of internal and external parasites parasitizing the American cockroach, Periplaneta americana, the effect of the sex of the cockroach and the area of sample collection on The type, number and types of parasites isolated, The current study was conducted for the period from July 2023 until April 2024, A samples of 111 male Periplaneta americana cockroaches were collected from some homes and schools in the city of Mosul. After the samples arrived at the laboratory, by placing them in clean, sterilized tubes in a refrigerator set at -4°C for 10 minutes Subsequently, 10 ml of normal saline solution was added to each tube. The tubes were then vigorously shaken for 5 minutes to dislodge parasites a salt solution was added to centrifuge tubes, which were spun at 2000 rotations per minute for 5 minutes. This mixture was shaken for 5 minutes and then, Cockroaches were dissected to isolate internal parasites The contents of the digestive tract were taken, and the solution was filtered through a mesh. Each sample was prepared by placing a drop of sediment on a glass slide, adding Lugol's iodine dye, and examining it under a microscope. The majority of the samples were infected with one or more types of parasites on their body surfaces and within their digestive tracts, infection rate of 96.40 %. This study involved the isolation and diagnosis of 19 parasitic species, including five types of worms: Ancylostoma duodenale, Leidynema, Strongyloides stercoralis, Hammerschmidtiella male, and Thelastoma. and six types of protozoan parasites, including both active and Nyctotherus ovalis cyst, active and cyst stages of Lophmonas, cyst stage of Entamoeba coli, and Gregarine. and Seven types of eggs, comprising eggs of each of Ancylostoma duodenale, Thelastoma, Leidynema, Strongyloides stercoralis, Hammerschmidtiella , Gryllophila, and in addition to the external parasitic Mite, The highest infection rate was recorded in worms, with 91 out of 111 samples i.e. (81.98% ). This was followed by protozoa, with a rate of 72% out of 80 samples. Finally, external mites, 52 samples i.e. (46.84%). In this study, it was observed that the number of parasites harbored by cockroaches in their digestive tracts exceeds more than that found on their external surfaces. Cockroaches collected from households were found to harbor a greater number of parasites compared to those collected from schools, underscoring the necessity of raising awareness about the dangers of cockroach presence in homes and keeping them away from food sources due to the parasites they carry, which may cause various diseases.

The American cockroach (Periplaneta americana) residue could partially replace the dietary puffed soybean meal in the Three-yellow chickens

Periplaneta americana residue is a byproduct of using Periplaneta americana in pharmaceutical research and development for extracting active ingredients. Three hundred Three-yellow chickens were selected for the experiment and randomly divided into 6 groups (5 replications per group, 10 chickens per replicate): the control group (group A) was fed a basal ration, and the experimental groups (groups B, C, D, E, and F) were fed experimental diets in which P. americana residue replaced puffed soybean meal at proportions of 20, 40, 60, 80, and 100%, respectively, for a period of 42 d. The aim was to assess the impact of different levels of P. americana residue on the growth, survival, intestinal morphology, digestive enzyme activity, intestinal flora, and intestinal transcriptional responses of Three-yellow chickens. The results indicated that the increase in P. americana residue levels had a linear and quadratic impact on the average daily gain (ADG) and feed conversion ratio (FCR), respectively. The ADG was notably greater in the 40% group than in the 100% group, while the FCR was significantly lower in the 20% and 40% groups than in the 100% group (P < 0.05). Protease, lipase, and amylase activities exhibited a quadratic increase with increasing concentrations of P. americana residue (P < 0.05). Protease and lipase activities were notably greater in the 20% and 40% groups than in the 0% group (control group), amylase activity was significantly greater in the 40% group than in the 0% group (control group) (P < 0.05). Duodenal crypt depth (CD) decreased quadratically with increasing P. americana residue (P < 0.05). The duodenal villus height/crypt depth ratio (V/C) was significantly lower in the 100% group than in the 60% group (P < 0.05). The intestinal villus height (VH) increased quadratically with increasing levels of P. americana residue. The VH in the 60% group was significantly greater than that in the 0% (control group), 20, 80, and 100% groups (P < 0.05). The Chao and Ace indices demonstrated linear and quadratic increases with increasing levels of P. americana residue, while the Pd index showed a quadratic increase with increasing levels of P. americana residue (P < 0.05). The relative abundance profile of Lactobacillus exhibited a linear and quadratic decrease with increasing levels of P. americana residue, with the 100% group showing a significantly lower abundance than the 0% (control group) and 40% groups (P < 0.05). The transcriptome results showed that P. americana residue could enhance the digestive system by promoting vitamin, fat, carbohydrate digestion and absorption, cholesterol metabolism, etc. In conclusion, P. americana residue can replace puffed soybean meal without negatively affecting the growth performance of three-yellow chickens. The low and medium groups had positive effects on the growth performance, digestive enzyme activity, intestinal morphology, intestinal flora, and substance digestion and absorption of three-yellow chickens. The recommended replacement of P. americana residue for puffed soybean meal in the diets of three-yellow chickens ranged from 20% to 60%.

Invasive vegetation encroachment modulates dual threats faced by island-endemic scaly crickets

The mechanisms by which non-native species impact island-endemic populations are varied and often convoluted. For effective invertebrate conservation where capacity is limited, it is vital to understand both direct and indirect species interactions. Those interactions define specific threats and therefore highlight possible solutions. We quantified several of the non-native species threats faced by an endemic scaly cricket, Discophallus ascension (family: Mogoplistidae), found on Ascension Island’s naturally barren coastlines. We hypothesized that encroaching non-native Mexican thorn Prosopis juliflora (1) directly reduced microclimate suitability, (2) indirectly increased resource competition with non-native species, and (3) indirectly increased non-native predation. Our aim was to assess how rapidly spreading Mexican thorn might reduce endemic cricket populations. Lab trials first confirmed the temperature and diet preferences of D. ascension. Mexican thorn significantly increased ground-level temperature but not above the estimated optimum for D. ascension within key habitat. Observed interspecific resource competition was significantly greater in habitat degraded by Mexican thorn and was driven by non-native ants, house crickets Gryllodes sigillatus and cockroaches Periplaneta americana. Recorded cricket predation was almost entirely by non-native rats Rattus rattus in barren habitat but primarily by ants in Mexican thorn habitat. Threats to D. ascension were therefore modulated by invasive vegetation, but driven by non-native insects and rats at all sites. We conclude that removal of vegetation alone is likely to reduce resource competition but not predation. Managing multiple invasive species is likely necessary for successful species conservation.

OXIDATIVE EFFECTS OF MAHANARAYAN TAILA ON AMERICAN COCKROACH, PERIPLANETA AMERICANA L. (BLATTIDAE: BLATTODEA)

The American cockroach (Periplaneta americana), a prevalent household pest originating from tropical regions like India, poses a significant public health risk as a carrier of human pathogens. The present study investigated the effectiveness of ?Mahanarayan Taila (MT),? an herbal oil, as an alternative solution. The repellent activity of the oil and its impact on biomolecules such as lipids and proteins in cockroaches was determined. Cockroaches were exposed to sub-lethal concentrations of MT over 24, 48, 72, and 96 h to assess repellency. The oil at 1% concentration resulted in a 50% mortality of adults. Mortality data were analyzed using GraphPad software. The study revealed significant changes in lipid peroxide levels, correlating with the oil concentration, and a dose-dependent depletion in protein sulfhydryl levels alongside the formation of protein carbonyls. Behavioral changes were also documented, including a knockdown effect and the appearance of black residues on cockroaches. These findings highlight the potential of MT herbal oil as an effective and safer alternative for cockroach control. With its complex mixture of phenols, monoterpenes, and sesquiterpenes, MT shows promise for surface treatments or fumigation in cockroach control programs.. KEYWORDS :Lipid peroxidation, Mahanarayan Taila, Mortality, Oxidative stress, Periplaneta americana

Systemic Anti-inflammatory Activity of American Cockroach (Periplaneta americana) Extract: A Molecular Docking Study

Surgery can trigger systemic inflammatory response syndrome. This study aims to determine the effectiveness of Periplaneta americana cockroach extract as an oral systemic anti-inflammatory agent using molecular docking. The molecular docking method consisted of five steps. The first step was preparing the TNF-α converting enzyme (TACE) receptor as a native ligand, dexamethasone as a control ligand, and three test ligands of Periplaneta americana cockroach extract. The second step was docking preparation. The third step was analyzing Gibbs free energy (∆G) and root mean square deviation (RMSD). The fourth step was docking the test and control ligands with TACE. The fifth step was analyzing ∆G, inhibition constant (Ki), visualization of two- and three-dimensional interactions, percentage of binding site similarity (%BSS), and the rule of five (Ro5) on test ligands. The ∆G results for the native, control, and test ligands 1, 2, and 3 were -12.8, -7.1, -7.7, -6.9, and -9.0 kcal/mol, respectively. The Ki values for the native, control, and test ligands 1, 2, and 3 were 4.091, 6.205, 2.253, 9.521, and 2.507 µM, respectively. The results of the Ro5 analysis suggested that the three test ligands satisfied Lipinski’s rule of five. This study concluded that Periplaneta americana cockroach extract is an effective oral systemic anti-inflammatory agent.

Domestic pest control of cockroaches (Periplaneta americana) by using food-based non-chemical baits.

The purpose of this experiment was to study the food preference of the household cockroaches (Periplaneta americana) in respect of Domestic Pest Control. These collected cockroaches were given choices among nine food items (three carbohydrate-rich foods: banana, bread, potato; three protein-rich foods: crushed peanuts, cottage cheese, walnut and three mixed diet). Modified nine-chambered olfactometers were used for this food preference experiment. Each kind of food was placed in each chamber of olfactometer with 10 cockroaches in each replica were placed in the center of olfactometer. 2 replicas of olfactometer were constructed of same kind. The olfactometers were observed for continuous 5 days i.e. 120 hours. The cockroaches were checked during day and night time each day, the amount of food consumed by them was recorded of each duration and the simple biostatistics mean and standard deviation were used for inferring the food preference of the cockroaches. The results show that the maximum of the cockroaches preferred walnut as compared to other offered baits. Bread was the second most preferred food followed by peanuts, cottage cheese, mixed diet, banana, and potato. Furthermore, the feeding behavior of these cockroaches occurred during the day hours 12:00-4:00 pm and night hours 01:00-04:00 am. The feeding gets of the cockroaches was started by swinging their antenna followed by touching the food baits offered.

Identification and sensitization to environmental fungal spores in Lima City, Peru

To identify and registry the most important fungal spores trapped in our aerobiology station, as well as to report the prevalence of skin sensitization to these allergens. The pollen counts were made according to standardized technique with a Burkard seven days spore trap, following the American Academy of Allergy, Asthma and Immunology (AAAAI) through National Allergy Bureau (NAB) recommendations. The trap was installed on the roof of Clinica SANNA, El GOLF, San Isidro, which is 20 m high, 12°5'54"S 77°3'6"W in the west-south of the Lima urban area. The sampling period was performed from September 2020 to October 2021. Skin prick tests were carried out according to the recommendations of the Spanish Society of Allergology and Clinical Immunology (SEAIC) in 200 patients (18 to 60 years old) with symptoms of rhinoconjunctivitis and/or asthma, who were evaluated in the Allergology Service of Clinica SANNA el Golf. Allergenic extracts were applied, dust mites (Dermatophagoides pteronyssinus, Dermatophagoides farinae, Blomia tropicalis), cat and dog danders, cockroach (Periplaneta americana), grass 6 mix, weed mix, molds (Cladosporium herbarum, Alternaria alternata, Aspergillus fumigatus, Penicillium notatum, Nigrospora spp.), INMUNOTEK-Spain provided the extracts. We also tested other fungal allergens such as Fusarium spp, Stemphylium spp, Curvularia spp, a mixture of Helmintosporum/Dreschlera spp. from the DIATER-Argentina laboratory. We identified spores of Alternaria alternata, Cladosporium spp., Nigrospora spp., Stemphylium spp., Fusarium spp., Curvularia spp., Dreschlera/Helmintosporum spp. The patients showed sensitization to Cladosporium herbarum (14%), Fusarium spp. (13,5%), Nigrospora spp. (8%), Alternaria Alternata (7%), Stemphylium (6%), Dreschlera/Helmintosporium spp. (5,5%), Curvularia spp. (3%), Aspergillus fumigatus (2,5%). The inhabitants of the south-western area of the urban city of Lima are exposed to different fungal spores with allergenic potential, with a higher concentration being identified during the summer/autumn months. Cutaneous sensitization is demonstrated in variable percentages to the fungal spores identified in this aerobiological sampling. The results of this study should be expanded and compared with data in the forthcoming years, identify seasonal and annual fluctuations and extend the traps to other locations in Lima.

Interactive parallel sex pheromone circuits that promote and suppress courtship behaviors in the cockroach.

Many animals use multicomponent sex pheromones for mating, but the specific function and neural processing of each pheromone component remain unclear. The cockroach Periplaneta americana is a model for studying sex pheromone communication, and an adult female emits major and minor sex pheromone components, periplanone-B and -A (PB and PA), respectively. Attraction and courtship behaviors (wing-raising and abdominal extension) are strongly expressed when adult males are exposed to PB but weakly expressed when they are exposed to PA. When major PB is presented together with minor PA, behaviors elicited by PB were impaired, indicating that PA can both promote and suppress courtship behaviors depending on the pheromonal context. In this study, we identified the receptor genes for PA and PB and investigated the effects of knocking down each receptor gene on the activities of PA- and PB-responsive sensory neurons (PA- and PB-SNs), and their postsynaptic interneurons, and as well as effects on courtship behaviors in males. We found that PB strongly and PA weakly activate PB-SNs and their postsynaptic neurons, and activation of the PB-processing pathway is critical for the expression of courtship behaviors. PA also activates PA-SNs and the PA-processing pathway. When PA and PB are simultaneously presented, the PB-processing pathway undergoes inhibitory control by the PA-processing pathway, which weakens the expression of courtship behaviors. Our data indicate that physiological interactions between the PA- and PB-processing pathways positively and negatively mediate the attraction and courtship behaviors elicited by sex pheromones.

Anti-Inflammatory, Antipyretic, and Analgesic Potential of Chitin and Chitosan Derived from Cockroaches (Periplaneta americana) and Termites.

The chitin and chitosan biopolymers are extremely valuable because of their numerous industrial and pharmacological uses. Chitin and chitosan were extracted from the exoskeleton of Periplaneta americana (cockroaches) and termites using various acid and alkali techniques. The extraction process involves an initial demineralization step, during which integument dry powder was subjected to 500 mL (2.07 mol/L) of concentrated HCl at 100 degrees Celsius for 30 min, followed by meticulous rinsing with distilled water to restore the pH to its baseline. Deproteinization was conducted at 80 degrees Celsius using 500 mL (1 mol/L) of NaOH solution, which was repeated for 24 h. A total of 250 mL (0.06 mol/L) of NaOH was added at 100 degrees Celsius for 4 h to obtain chitosan, followed by extensive washing and subsequent drying. FTIR analysis was used to identify the functional groups in Periplaneta americana and termites. The crystallinity of these biopolymers, which have a face-centered cubic structure, was determined by X-ray diffraction analysis. This study assessed the analgesic properties of chitin and chitosan via an acetic-acid-induced writhing test in mice, revealing a significant reduction in writhing behavior following the chitin and chitosan extract. Notably, chitin exhibits the highest degree of analgesic activity compared to chitosan. Both chitin and chitosan show anti-inflammatory effects, with chitosan absorbing proton ions at sites of inflammation, while chitin effectively inhibits ear edema and elicits an analgesic response in mice. Furthermore, the present study revealed antipyretic activity, with termite chitin demonstrating the most significant effect at a concentration of 500 µL/mL, followed by chitosan and chitin at 100 µL/mL. These findings indicate the potential of using chitin and chitosan derived from termites and Periplaneta americana as natural anti-inflammatory compounds, implying prospective uses in anti-inflammatory, antipyretic, and analgesic capabilities.

Digestibility of Cockroach (Periplaneta americana) Insect Meal Diet By African Catfish (Clarias gariepinus) Juvenile and Its Effects on growth Performance

The use of Cockroach (Periplaneta americana) meal was studied to ascertain its digestibility and effect on growth performance of Clarias gariepinus. A 40% protein basal and test diets using fish and cockroach meal respectively with inert biomarker at 70:30% were fed for 42 days to Clarias gariepinus of average weight 29.22±0.18g. Catfish response to diets in terms of growth parameters revealed the following for reference diet fed and basal diet fed fish: weight gain (52.59g vs. 36.31g); specific growth rate (2.46%/g/day vs. 1.91%/g/day); feed conversion ratio (1.71 vs. 2.13); and percentage weight gain (181.44% vs. 123.35%). Apparent digestibility values of test diet were higher significantly (P&lt;0.05) than basal diet. Digestibility coefficient in reference diet fish and basal diet fish showed that: protein (88.48% vs 87.01%); dry matter (87.35% vs. 86.82%); energy (86.88% vs. 85.48%); and fat (39.67% vs. 27.75%). African catfish responded positively to CIM diet with improved growth performance up to 30% inclusion level. Apparent digestibility of the CIM diet was superior to the fishmeal reference diet.

A novel class of insecticidal alkylsulfones are potent inhibitors of vesicular acetylcholine transport

Pyridine alkylsulfone derivatives typified by oxazosulfyl (Sumitomo Chemical Company Ltd.) and compound A2 (Syngenta) represent a new class of insecticides, with potent activity against several insect orders. Whilst the MOA of this class has been attributed to interaction with the voltage-gated sodium channel (VGSC), here we present strong evidence that their toxicity to insects is mediated primarily through inhibition of the vesicular acetylcholine transporter (VAChT). Alkylsulfone intoxication in insects is characterised by (i) a reduction in cholinergic synaptic transmission efficiency demonstrated by a depression of cercal afferent activity in giant-interneurone preparations of American cockroach (Periplaneta americana), (ii) selective block of cholinergic-transmission dependent post-synaptic potentials in the Drosophila giant-fibre pathway and (iii) abolition of miniature excitatory post-synaptic currents (mEPSCs) in an identified synapse in Drosophila larvae.Ligand-binding studies using a tritiated example compound ([3H]-A1) revealed a single saturable binding-site, with low nanomolar Kd value, in membrane fractions of green bottle fly (Lucilia sericata). Binding is inhibited by vesamicol and by several examples of a previously identified class of insecticidal compounds known to target VAChT, the spiroindolines. Displacement of this binding by analogues of the radioligand reveals a strong correlation with insecticidal potency. No specific binding was detected in untransformed PC12 cells but a PC12 line stably expressing Drosophila VAChT showed similar affinity for [3H]-A1 as that seen in fly head membrane preparations. Previously identified VAChT point mutations confer resistance to the spiroindoline class of insecticides in Drosophila by Gal-4/UAS directed expression in cholinergic neurones and by CRISPR gene-editing of VAChT, but none of these flies show detectable cross-resistance to this new chemical class.Oxazosulfyl was previously shown to stabilise voltage-gated sodium channels in their slow-inactivated conformation with an IC50 value of 12.3μM but inhibits binding of [3H]-A1 with approximately 5000 times greater potency. We believe this chemistry class represents a novel mode-of-action with high potential for invertebrate selectivity.

Using RNA interference targeting a nicotinic acetylcholine receptor subunit to counteract insecticide accommodation mechanisms: example of the β1 subunit in the imidacloprid-accommodated American cockroach, Periplaneta americana.

Insecticide accommodation and resistance are limiting factors to the much-needed increase in agricultural production. Various physiological and cellular modifications, such as the changes of insecticide molecular targets, have been linked to these events. Thus, a previous study demonstrated that the imidacloprid accommodation set up by the cockroach Periplaneta americana after an exposure to a sublethal dose of this insecticide involves functional alterations of two nicotinic acetylcholine receptor (nAChR) subtypes. As RNA interference (RNAi) is one of the most promising strategies for controlling pest insects, we evaluated, in this study, the use of RNAi that targets the β1 nAChR subunit to counteract the imidacloprid accommodation phenomenon in cockroaches. Interestingly, we showed that ingestion of dsRNA-β1 increased the sensitivity to imidacloprid of accommodated cockroaches. Thus, we have demonstrated for the first time that RNAi that targets an nAChR subunit can counteract the accommodation mechanism to insecticide targeting nAChRs set up by an insect.