Evaluation of organic insecticides for management of spotted‐wing drosophila (Drosophila suzukii) in berry crops

Spotted‐wing drosophila, Drosophila suzukii (Matsumura), is an invasive pest affecting fruit production in many regions of the world. Insecticides are the primary tactic for controlling D. suzukii in organic as well as conventional production systems. Organic growers have a greater challenge because fewer insecticides are approved for use in organic agriculture. The most effective organically approved product is spinosad, but alternatives are needed because of label restrictions limiting the number of applications per year, toxicity to beneficial arthropods and the risk of developing resistance. We evaluated several organically approved insecticides against D. suzukii in laboratory assays and field trials conducted on organic blueberry and raspberry farms. Spinosad was consistently the most effective insecticide, but a few other insecticides such as azadirachtin + pyrethrins, Chromobacterium subtsugae and sabadilla alkaloids showed moderate activity. None of the treatments had long residual activity. Mortality started to decline by 3 days after treatment, and by 5 days after application, the treatments were not different from the controls. These products may be useful in rotation programmes, necessary for reducing reliance on spinosad and mitigating resistance. Cultural and biological control approaches are needed in fruit production for D. suzukii management, but insecticides will likely continue to be the dominant management tactic while these other approaches are being optimized and adopted.     

Impact of phagostimulants on effectiveness of OMRI‐listed insecticides used for control of spotted‐wing drosophila (Drosophila suzukii Matsumura)

Spotted‐wing drosophila, Drosophila suzukii Matsumura, is an invasive pest in the United States that causes considerable damage to fruit crops. It is responsible for many millions of dollars of revenue loss. The female D. suzukii has a heavily sclerotized ovipositor and can lay eggs in ripening or ripe fruit. The arrival of this invasive species has disrupted existing integrated pest management programmes, and growers rely on repeated insecticide applications to protect fruit. Organic growers have few chemical control options, and their reliance on spinosad increases the risk of developing insecticide resistance. We hypothesized that combining phagostimulants with insecticides would increase insecticide efficacy by prompting flies to spend more time in contact with residues. Therefore, the objective of this study was to evaluate the effectiveness of sucrose and the yeast Saccharomyces cerevisiae as phagostimulants in combination with organic biopesticides against D. suzukii in blueberries. Adding sucrose with or without yeast did not improve insecticide efficacy in terms of adult fly mortality or fruit infestation. Spinosad was very effective in all experiments, and for this product, there is little room for improvement. The phagostimulants had no effect on residual activity of any insecticide. The addition of sucrose with or without yeast did not improve the effectiveness of organic insecticides for D. suzukii. Concentrations of these phagostimulants in our experiments (0.36%) may have been too low to elicit a response. Further research is recommended to test different types and concentrations of phagostimulants.     

Vaccination with SARS-CoV-2 variants of concern protects mice from challenge with wild-type virus

Vaccines against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) have been highly efficient in protecting against Coronavirus Disease 2019 (COVID-19). However, the emergence of viral variants that are more transmissible and, in some cases, escape from neutralizing antibody responses has raised concerns. Here, we evaluated recombinant protein spike antigens derived from wild-type SARS-CoV-2 and from variants B.1.1.7, B.1.351, and P.1 for their immunogenicity and protective effect in vivo against challenge with wild-type SARS-CoV-2 in the mouse model. All proteins induced high neutralizing antibodies against the respective viruses but also induced high cross-neutralizing antibody responses. The decline in neutralizing titers between variants was moderate, with B.1.1.7-vaccinated animals having a maximum fold reduction of 4.8 against B.1.351 virus. P.1 induced the most cross-reactive antibody responses but was also the least immunogenic in terms of homologous neutralization titers. However, all antigens protected from challenge with wild-type SARS-CoV-2 in a mouse model.

This study explores the immune response induced by wild type and variant SARS-CoV-2 spike proteins, and the protection that these immune responses provide against challenge with wild type virus in the mouse model.     

Proinflammatory agents,IL-8 and IL-10, upregulate inducible nitric oxide synthase expression and nitric oxide production in avian osteoclast-like cells

Nitric oxide synthase (NOS) isoenzymes generate nitric oxide (NO), a sensitive multifunctional intercellular signal molecule. High NO levels are produced by an inducible NOS (iNOS) in activated macrophages in response to proinflammatory agents, many of which also regulate local bone metabolism. NO is a potent inhibitor of osteoclast bone resorption, whereas inhibitors of NOS promote bone resorption both in vitro and in vivo. The possibility that osteoclasts, like macrophages, express a regulated iNOS and produce NO as a potential autocrine signal following inflammatory stimulation was investigated in well-characterized avian marrow-derived osteoclast-like cells. NO production (reflected by medium nitrite levels) was markedly elevated in these cells by the proinflammatory agents lipopolysaccharide (LPS) and the synergistic action of IL-1α, TNFα, and IFNγ. Inhibitors of NOS activity (aminoguanidine, L-NAME) or iNOS induction (dexamethasone, TGFβ) reduced LPS-stimulated nitrite production. LPS also increased the NOS-associated diaphorase activity of these cells and their reactivity with anti-iNOS antibodies. RT-PCR cloning, using avian osteoclast-like cell RNA and human iNOS primers, yielded a novel 900 bp cDNA with high sequence homology (76%) to human, rat, and mouse iNOS genes. In probing osteoclast-like cell RNA with the PCR-derived iNOS cDNA, a 4.8 kb mRNA species was detected whose levels were greatly increased by LPS. Induction of iNOS mRNA by LPS, or by proinflammatory cytokines, occurred prior to the rise of medium nitrite in time course studies and was diminished by dexamethasone. Moreover, osteoclast-like cells demonstrated an upregulation of NO production and iNOS mRNA by IL-8 and IL-10, regulatory mechanism's not previously described. It is concluded that osteoclast-like cells express a novel iNOS that is upregulated by inflammatory mediators, leading to NO production. Therefore, NO may serve as both a paracrine and autocrine signal for modulating osteoclast bone resorption. © 1996 Wiley-Liss, Inc.     

Polydactyly in the Strong's luxoid mouse is suppressed by limb deformity alleles

The study of limb development has provided insight into pattern formation during vertebrate embryogenesis. Genetic approaches offer powerful ways to identify the critical molecules and their pathways of action required to execute a complex morphogenetic program. We have applied genetic analysis to the process of limb development by studying two mouse mutants, limb deformity (Id) and Strong's luxoid (Ist). These mutations confer contrasting phenotypic alterations to the anteroposterior limb pattern. The six mutant Id alleles are fully recessive and result in oligosyndactyly of all four limbs. By contrast, the two mutant Ist alleles result in a mirror-image polydactylous limb phenotype inherited in a semidominant fashion. Morphological and molecular analysis of embryonic limbs has shown that the Id and Ist alleles affect the extent and distribution of two key signaling centers differentially: the apical ectodermal ridge and the zone of polarizing activity. Molecular characterization of the Id gene has defined a new family of evolutionarily conserved proteins termed the formins. The underlying molecular defect in the Ist mutation has not been identified; however, both loci are tightly linked on mouse chromosome 2, suggesting the possibility that they may be allelic. In this study, we have used genetic analysis to examine the epistatic and allelic relationships of Id and Ist. We observed that in + Id/Ist + double heterozygotes, a single mutant Id allele is able to suppress the semi-dominant polydactylous Ist limb phenotype. By segregating the Ist and Id loci in a backcross, we observed that these loci recombine and are separated by a genetic distance of approximately 6 cM. Therefore, while our observations demonstrate a genetic interaction between Id and Ist, it is probable that Id and Ist are not allelic. Instead, Ist and Id may be operating either in a linear or in a parallel (bypass) genetic pathway to affect the limb signaling centers. © 1996 Wiley-Liss, Inc.     

Current knowledge of vector-borne zoonotic pathogens in Zambia: A clarion call to scaling-up “One Health” research in the wake of emerging and re-emerging infectious diseases

BackgroundAlthough vector-borne zoonotic diseases are a major public health threat globally, they are usually neglected, especially among resource-constrained countries, including those in sub-Saharan Africa. This scoping review examined the current knowledge and identified research gaps of vector-borne zoonotic pathogens in Zambia.Methods and findingsMajor scientific databases (Web of Science, PubMed, Scopus, Google Scholar, CABI, Scientific Information Database (SID)) were searched for articles describing vector-borne (mosquitoes, ticks, fleas and tsetse flies) zoonotic pathogens in Zambia. Several mosquito-borne arboviruses have been reported including Yellow fever, Ntaya, Mayaro, Dengue, Zika, West Nile, Chikungunya, Sindbis, and Rift Valley fever viruses. Flea-borne zoonotic pathogens reported include Yersinia pestis and Rickettsia felis. Trypanosoma sp. was the only tsetse fly-borne pathogen identified. Further, tick-borne zoonotic pathogens reported included Crimean-Congo Haemorrhagic fever virus, Rickettsia sp., Anaplasma sp., Ehrlichia sp., Borrelia sp., and Coxiella burnetii.ConclusionsThis study revealed the presence of many vector-borne zoonotic pathogens circulating in vectors and animals in Zambia. Though reports of human clinical cases were limited, several serological studies provided considerable evidence of zoonotic transmission of vector-borne pathogens in humans. However, the disease burden in humans attributable to vector-borne zoonotic infections could not be ascertained from the available reports and this precludes the formulation of national policies that could help in the control and mitigation of the impact of these diseases in Zambia. Therefore, there is an urgent need to scale-up “One Health” research in emerging and re-emerging infectious diseases to enable the country to prepare for future epidemics, including pandemics.     

Comparative metabolism of isoleucine by corpora allata of nonlepidopteran insects versus lepidopteran insects,in relation to juvenile hormone biosynthesis

We studied the metabolism of [U-¹⁴C]isoleucine by intact and homogenized corpora allata (CA) from various insect species to determine how this substrate is converted to precursors of juvenile hormone (JH). CA homogenates of the lepidopterans Manduca sexta, Hyalophora cecropia, and Samia cynthia metabolize [U-¹⁴C]isoleucine to several products including 2-keto-3-methyl-valerate, 2-methylbutyrate, CO₂, propionate, and acetate. Intact CA of male H. cecropia produce particularly high levels of 2-keto-3-methylvalerate, indicating a highly active branched-chain-amino acid transaminase. In contrast, CA homogenates from the nonlepidopterans Periplaneta americana, Schistocerca nitens, Tenebrio molitor, and Diploptera punctata barely metabolize [U-¹⁴C]isoleucine. However, P. americana CA homogenate metabolizes [U-¹⁴C]2-keto-3-methylvalerate, the transamination product of [U-¹⁴C]isoleucine, more rapidly than does a homogenate of M. sexta CA. Furthermore, intact CA from P. americana incubated with [U-¹⁴C]2-keto-3-methylvalerate incorporate low levels of ¹⁴C into JH III, but do not metabolize this substrate to JH II or JH I. Intact CA from female Diploptera punctata produce very high levels of JH III, but are also unable to incorporate radiolabel from [U-¹⁴C]isoleucine into JH III, which substantiates our findings with other nonlepidopteran CA. The results suggest that CA of nonlepidopteran insects lack an active branched-chain amino acid transaminase and, consequently, are unable to utilize these substrates for JH biosynthesis.