Deltamethrin contact exposure mediated toxicity and histopathological aberrations in tissue systems of cockroach species Periplaneta americana and Blatella germanica

Cockroach species Periplaneta americana and Blatella germanica potentially survive in locations close to human activity. Besides spoiling food material, cockroaches also transfer pathogens of different diseases among human. Since the insecticides have been used extensively to control cockroaches, information on their insecticide susceptibility and toxicity at cellular level may be crucial. In the study, deltamethrin toxicity as well as the deltamethrin-mediated cytomorphological changes in brain, ovary and midgut of the two important cockroach species has been assessed. Different concentrations [0.00025% (0.0025mg/ml), 0.0025% (0.025mg/ml), 0.025 (0.25mg/ml), 0.25% (2.5mg/ml), 0.5% (5mg/ml), 1% (10mg/ml)] of deltamethrin in acetone were used to expose test species in WHO bottle assay. Knockdown was recorded after 5 min interval while delayed mortality was observed after 24 hr. Brain, ovary and gut were dissected post 1 hr exposure and 24 hr holding (for 0.25%, 0.5% and 1% concentration), and tissues were processed for microscopic analysis. Deltamethrin exposed cockroaches and dissected tissues were used to estimate deltamethrin using HPLC. At 0.00025% (lowest concentration), the percentage knock-down observed was 66.7% for P. americana and 80% B. germanica respectively (R2= 0.78; p=0.0001) in 1 hr. KDT50 value was found to be 8.7 min (95% CI: 7.3-10.2), while KDT99 was 20.7 min (95% CI: 16.0-35.7) in P. americana at 1% concentration. Whereas, the KDT50 and KDT99 values for B. germanica were 7.4 min (95% CI: 5.4-9.1) and 27.4 min (95% CI: 18.2-80.0) at similar concentration. LD50 and LD95 values (for 60 min standard exposure) were 0.0006 % (95% CI: 0.00-0.001) and 0.034% (95% CI: 0.013-0.49) respectively for P. americana, while these values were 0.0005 (95% CI: 0.00-0.001) and 0.04 (95% CI: 0.01-0.23) for B. germanica. Exposure to 1% deltamethrin induced considerable toxic effect in the epithelial cells in the midgut. HPLC estimated 0.21±0.05 mg (95% CI - 0.18-0.25; CoV 23.9%) deltamethrin in P. americana post 1% exposure. Even short term exposure of low concentration of synthetic pyrethroid deltamethrin displayed immediate knockdown and delayed mortality in both the test species. Considerable histological damage was observed in both the insects at 1% exposure. In India, resistance to deltamethrin may have been reported among different insects due its extensive use, however the formulations such as insecticide paints, attractant baits etc. developed using deltamethrin as active ingredient could be useful in cockroach control operations.

Immediate and Delayed Mortality of Four Stored-Product Pests on Concrete Surfaces Treated with Chlorantraniliprole

Chlorantraniliprole is an effective pesticide against a plethora of pests, but its efficacy against stored-product pests is very poorly explored. In this study we treated concrete surfaces with four different doses of chlorantraniliprole (0.01, 0.05, 0.1, and 0.5 mg a.i./cm2) against the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) adults and larvae, the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults, the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) adults, and the flour mite, Acarus siro L. (Sarcoptiformes: Acaridae) adults and nymphs, to examine the immediate mortalities after 1, 2, 3, 4, and 5 days of exposure. Additionally, the delayed mortality of the individuals that survived the 5-day exposure was also evaluated after a further 7 days on untreated concrete surfaces. We documented high mortality rates for all tested species and their developmental stages. After 5 days of exposure to 0.5 mg a.i./cm2, T. castaneum larvae and A. siro adults exhibited the highest immediate mortality levels, reaching 96.7% and 92.2%, respectively. Delayed mortality was also very high for all tested species and their developmental stages. Nymphs of A. siro displayed a 96.3% delayed mortality followed by the adults of R. dominica (98.6%) after exposure to 0.5 mg a.i./cm2. All other tested species and their developmental stages reached complete (100.0%) delayed mortality, where even 0.01 mg a.i./cm2 caused ≥86.6% delayed mortality in all species and their developmental stages. Taking into consideration the effectiveness of chlorantraniliprole on this wide range of noxious arthropods, coupled with its low toxicity towards beneficial arthropods and mammals, this pesticide could provide an effective management tool for stored-product pests in storage facilities.

Unconventional secretion of unglycosylated ORF8 is critical for the cytokine storm during SARS-CoV-2 infection

Coronavirus disease 2019 is a respiratory infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidence on the pathogenesis of SARS-CoV-2 is accumulating rapidly. In addition to structural proteins such as Spike and Envelope, the functional roles of non-structural and accessory proteins in regulating viral life cycle and host immune responses remain to be understood. Here, we show that open reading frame 8 (ORF8) acts as messenger for inter-cellular communication between alveolar epithelial cells and macrophages during SARS-CoV-2 infection. Mechanistically, ORF8 is a secretory protein that can be secreted by infected epithelial cells via both conventional and unconventional secretory pathways. The unconventionally secreted ORF8 recognizes the IL17RA receptor of macrophages and induces cytokine release. However, conventionally secreted ORF8 cannot bind to IL17RA due to N-linked glycosylation. Furthermore, we found that Yip1 interacting factor homolog B (YIF1B) is a channel protein that translocates unglycosylated ORF8 into vesicles for unconventional secretion. Blocking the unconventional secretion of ORF8 via a YIF1B knockout in hACE2 mice attenuates inflammation and yields delayed mortality following SARS-CoV-2 challenge.

Efficacy of targeted indoor residual spraying with the pyrrole insecticide chlorfenapyr against pyrethroid-resistant Aedes aegypti

Background There is an increased need to mitigate the emergence of insecticide resistance and incorporate new formulations and modes of application to control the urban vector Aedes aegypti. Most research and development of insecticide formulations for the control of Ae. aegypti has focused on their peridomestic use as truck-mounted ULV-sprays or thermal fogs despite the widespread knowledge that most resting Ae. aegypti are found indoors. A recent modification of indoor residual spraying (IRS), termed targeted IRS (TIRS) works by restricting applications to 1.5 m down to the floor and on key Ae. aegypti resting sites (under furniture). TIRS also opens the possibility of evaluating novel residual insecticide formulations currently being developed for malaria IRS. Methods We evaluated the residual efficacy of chlorfenapyr, formulated as Sylando 240SC, for 12 months on free-flying field-derived pyrethroid-resistant Ae. aegypti using a novel experimental house design in Merida, Mexico. On a monthly basis, 600 female Ae. aegypti were released into the houses and left indoors with access to sugar solution for 24 hours. After the exposure period, dead and alive mosquitoes were counted in houses treated with chlorfenapyr as well as untreated control houses to calculate 24-h mortality. An evaluation for these exposed cohorts of surviving mosquitoes was extended up to seven days under laboratory conditions to quantify “delayed mortality”. Results Mean acute (24-h) mortality of pyrethroid-resistant Ae. aegypti ranged 80–97% over 5 months, dropping below 30% after 7 months post-TIRS. If delayed mortality was considered (quantifying mosquito mortality up to 7 days after exposure), residual efficacy was above 90% for up to 7 months post-TIRS application. Generalized Additive Mixed Models quantified a residual efficacy of chlorfenapyr of 225 days (ca. 7.5 months). Conclusions Chlorfenapyr represents a new option for TIRS control of Ae. aegypti in urban areas, providing a highly-effective time of protection against indoor Ae. aegypti females of up to 7 months.

Open Pelvic Fracture with Rectal Laceration: A Case Report

Open pelvic fractures are rare but represent a serious clinical problem with high mortality rates. Acute mortality is often associated with haemorrhage and delayed mortality is most often associated with sepsis and multiple organ failure. An aggressive multidisciplinary approach is of paramount importance to prevent catastrophe. It involves emergency resuscitation, stabilization of unstable fracture with an external fixator, and faecal diversion for rectal injury. Here, a case of open pelvic fracture with rectal laceration has been presented.

Effect of wall type, delayed mortality and mosquito age on the residual efficacy of a clothianidin-based indoor residual spray formulation (SumiShield™ 50WG) in southern Mozambique

Indoor residual spraying (IRS) is one of the main malaria vector control strategies in Mozambique alongside the distribution of insecticide treated nets. As part of the national insecticide resistance management strategy, Mozambique introduced SumiShield™ 50WG, a third generation IRS product, in 2018. Its residual efficacy was assessed in southern Mozambique during the 2018–2019 malaria season. Using a susceptible Anopheles arabiensis strain, residual efficacy was assessed on two different wall surfaces, cement and mud-plastered walls, using standard WHO (World Health Organization) cone bioassay tests at three different heights. Female mosquitoes of two age groups (2–5 and 13–26 day old) were exposed for 30 minutes, after which mortality was observed 24h, 48h, 72h, and 96h and 120h post-exposure to assess (delayed) mortality. Lethal times (LT) 90, LT50 and LT10 were estimated using Bayesian models. Mortality 24h post exposure was consistently below 80%, the current WHO threshold value for effective IRS, in both young and old mosquitoes, regardless of wall surface type. Considering delayed mortality, residual efficacies (mosquito mortality equal or greater than 80%) ranged from 1.5 to ≥12.5 months, with the duration depending on mortality time post exposure, wall type and mosquito age. Looking at mortality 72h after exposure, residual efficacy was between 6.5 and 9.5 months, depending on wall type and mosquito age. The LT50 and LT10 (i.e. 90% of the mosquitoes survive exposure to the insecticides) values were consistently higher for older mosquitoes (except for LT10 values for 48h and 72h post-exposure mortality) and ranged from 0.9 to 5.8 months and 0.2 to 7.8 months for LT50 and LT10, respectively. The present study highlights the need for assessing mosquito mortality beyond the currently recommended 24h post exposure. Failure to do so may lead to underestimation of the residual efficacy of IRS products, as delayed mortality will lead to a further reduction in mosquito vector populations and potentially negatively impact disease transmission. Monitoring residual efficacy on relevant wall surfaces, including old mosquitoes that are ultimately responsible for malaria transmission, and assessing delayed mortalities are critical to provide accurate and actionable data to guide vector control programmes.

Delayed Tree Mortality After Prescribed Fires in Mixed Oak Forests in Northwestern Ohio

Delayed tree mortality can contribute to variability in fire effects in forests, but its prevalence is not well understood in eastern North American oak forests where a management goal is using prescribed fire to shape forest density and composition. To assess potential delayed mortality after prescribed fires, we tracked the fates of 690 trees of four species in burned and 542 trees in unburned oak forests in northwestern Ohio, USA, and modeled survival using tree diameter and bole char. Delayed mortality, occurring 3–4 growing seasons after fire and in addition to initial mortality (1–2 growing seasons after fire), varied with species and tree diameter. Compared to initial mortality, delayed mortality resulted in eleven times more small-diameter (1–13 cm) red maple (Acer rubrum) dying after fire. White oak (Quercus alba), 1–25 cm in diameter, also incurred delayed mortality (five-times increase in dead trees). Neither sassafras (Sassafras albidum) nor black oak (Quercus velutina) displayed delayed mortality. Background tree mortality in unburned sites was minimal (0.4% per year across species). Logistic regression to model canopy survival selected only stem diameter for burned red maple trees, whereas both diameter and bole char related to survival in other species. Results suggest that (1) monitoring postfire tree mortality in oak forests should extend for at least four growing seasons to detect delayed mortality in some species, and that (2) single surface fires may eventually reduce encroaching red maple in oak forests more than initial postfire years indicate. Study Implications Delayed tree mortality, a poorly understood phenomenon in eastern North American oak forests, varied with species and stem diameter after prescribed fires in northwestern Ohio oak forests. Accompanied by minimal mortality of large oaks (>25 cm in diameter), single surface fires appear capable of reducing density of encroaching red maple stems, but these reductions may not appear for at least 3–4 growing seasons after fires.