The Membrane-Anchoring Region of the AcMNPV P74 Protein Is Expendable or Interchangeable with Homologs from Other Species

Baculoviruses are insect pathogens that are characterized by assembling the viral dsDNA into two different enveloped virions during an infective cycle: occluded virions (ODVs; immersed in a protein matrix known as occlusion body) and budded virions (BVs). ODVs are responsible for the primary infection in midgut cells of susceptible larvae thanks to the per os infectivity factor (PIF) complex, composed of at least nine essential viral proteins. Among them, P74 is a crucial factor whose activity has been identified as virus-specific. In this work, the p74 gene from AcMNPV was pseudogenized using CRISPR/Cas9 technology and then complemented with wild-type alleles from SeMNPV and HearSNPV species, as well as chimeras combining the P74 amino and carboxyl domains. The results on Spodoptera exigua and Rachiplusia nu larvae showed that an amino terminal sector of P74 (lacking two potential transmembrane regions but possessing a putative nuclear export signal) is sufficient to restore the virus infectivity whether alone or fused to the P74 transmembrane regions of the other evaluated viral species. These results provide novel information about the functional role of P74 and delimit the region on which mutagenesis could be applied to enhance viral activity and, thus, produce better biopesticides.

Isolation of Bacillus thuringiensis strains from Saudi Arabia soil and study of their potential efficiency against the lepidopteran pest Ephestia kuehniella

Insect pests represent a major threat to food crops and human health, and therefore have to be combated in several ways, including chemical methods. However, researchers demonstrated that these molecules are dangerous for the farmers, consumers and the environment in general. For this reason, scientists permanently searched environment friendly alternatives such as the use of the bacterium Bacillus thuringiensis classified as one of the best insect pathogens. This microorganism is known by its ability to produce two types of insecticidal proteins, Vegetative insecticidal proteins (Vip) and delta-endotoxins produced during vegetative and sporulation stages of growth, respectively. In the present study, 15 B. thuringiensis strains were isolated from soil collected from different regions in Saudi Arabia (Al Baha, Jeddah, Khulis and Yanbu). B. thuringiensis isolates were then classified according to the shape of their parasporal crystals identified under microscope and proteins content of these crystals. Delta-endotoxins efficiency of the different isolates was investigated and promising strains were identified as very active. After 5 days-treatment, B. thuringiensis isolates 14 and 7 killed Ephestia kuehniella larvae with low LC50 of about 59.18 and 65.67 mg/cm2, respectively. The results described in the present study proved that the new B. thuringiensis isolates could be of a great interest in the control of lepidopteran pests by using their delta-endotoxins in bioinsecticide formulations.

Conserved and Noncanonical Activities of Two Histone H3K36 Methyltransferases Required for Insect-Pathogenic Lifestyle of Beauveria bassiana

Set2 and Ash1 are histone methyltransferases (KMTs) in the KMT3 family normally used to catalyze methylation of histone H3K36 (H3K36me) but remain unexplored in fungal insect pathogens. Here, we report broader/greater roles of Set2 and Ash1 in mono-/di-/trimethylation (me1/me2/me3) of H3K4 than of H3K36 in Beauveria bassiana and function similarly to Set1/KMT2, which has been reported to catalyze H3K4me3 as an epigenetic mark of cre1 (carbon catabolite repressor) to upregulate the classes I and II hydrophobin genes hyd1 and hyd2 required for conidial hydrophobicity and adherence to insect cuticle. H3K4me3 was more attenuated than H3K36me3 in the absence of set2 (72% versus 67%) or ash1 (92% versus 12%), leading to sharply repressed or nearly abolished expression of cre1, hyd1 and hyd2, as well as reduced hydrophobicity. Consequently, the delta-set2 and delta-ash1 mutants were differentially compromised in radial growth on various media or under different stresses, aerial conidiation under normal culture conditions, virulence, and cellular events crucial for normal cuticle infection and hemocoel colonization, accompanied by transcriptional repression of subsets of genes involved in or required for asexual development and multiple stress responses. These findings unravel novel roles of Set2 and Ash1 in the co-catalysis of usually Set1-reliant H3K4me3 required for fungal insect-pathogenic lifestyle.

insectDisease: programmatic access to the Ecological Database of the World's Insect Pathogens

Curated databases of species interactions are instrumental to exploring and understanding the spatial distribution of species and their biotic interactions. In the process of conducting such projects, data development and curation efforts may give rise to a data product with utility beyond the scope of the original work, but which becomes inaccessible over time. Data describing insect host-pathogen interactions are fairly rare, and should thus be preserved and curated with appropriate metadata. Here, we introduce the insectDisease R package, a mechanism for curating, updating, and distributing data from the Ecological Database of the World's Insect Pathogens, a database of insect host-pathogen associations, including attempted inoculations and infection outcomes for insect hosts and pathogens (bacteria, fungi, nematodes, protozoans, and viruses). This dataset has been utilized for several projects since its inception, but without a well defined, curated and permanent repository, its existence and access have been limited to word-of-mouth connections. The current effort presented here aims to provide a means to preserve, augment, and disseminate the database in a documented and versioned format. This project is an example of the type of effort that will be necessary to maintain valuable databases after the original funding disappears.

Diseases in edible insect rearing systems

Due to a swift and continuous growth of the insect rearing industry during the last two decades, there is a need for a better understanding of insect diseases (caused by insect pathogens). In the insect production sector, insect diseases are a bottleneck for every type and scale of rearing system with different degrees of technology investment (i.e. semi-open rearing, closed rearing, industrial production, small-scale farming). In this paper, we provide an overview of insect pathogens that are causing disease in the most common insect species reared or collected for use in food and feed. We also include a few examples of diseases of insect species, which are not (yet) reported to be used as food or feed; those examples may increase our understanding of insect diseases in general and for the development of disease prevention and control measures. We pay special attention to the effect of selected biotic and abiotic factors as potential triggers of insect diseases. We discuss the effect of such factors in combination with other production variables on disease development and insect immunocompetence. Additionally, we touch upon prevention and control measures that have been carried out and suggested up to now for insect production systems. Finally, we point towards possible future research directions with possibilities to enhance the resilience of insect production to insect disease outbreaks.

Dysbacteriosis of the Intestinal Flora Is an Important Reason for the Death of Adult House Flies Caused by Beauveria bassiana

Beauveria bassiana is one of the most widespread insect pathogens and can be used in the biological control of agricultural, forestry and medical pests. The mechanisms by which B. bassiana leads to mortality in different host insects are also different. For house flies, B. bassiana has strong virulence, but its microecological mechanism is not clear. In this paper, the virulence of three strains of B. bassiana (TB, CB and BB) isolated from different hosts to house flies was studied. The results showed that the three strains of B. bassiana had strong pathogenicity to house fly adults. Specifically, TB was the strongest, CB was the second strongest, and BB was the weakest, with maximum lethal effects on house fly populations 5, 6, and 7 days after infection, respectively. Further study showed that the intestinal flora of house flies was disordered 3, 4, and 5 days after B. bassiana TB, CB and BB strain infection, respectively. Intestinal flora dysbacteriosis may be an important reason for the death of house flies caused by B. bassiana. After infection, the negative interaction ratio of bacteria in the house fly intestine decreased, and the stronger the virulence was, the lower the negative interaction ratio was. The time from B. bassiana infection to intestinal flora dysbacteriosis was not fixed. We named this period the “spring stage”. The stronger the virulence of the B. bassiana strain was, the shorter the “spring stage” was. Therefore, the “spring stage” can be used as a virulence marker for evaluating the pathogenicity of different B. bassiana strains.

Evaluation of the nucleopolyhedrovirus of Anticarsia gemmatalis as a vector for gene therapy in mammals

Background: Baculoviruses are insect pathogens with important biotechnological applications that transcend their use as biological controllers of agricultural pests. One species, Autographa californica multiple nucleopolhyedrovirus (AcMNPV) has been extensively exploited as a molecular platform to produce recombinant proteins and as a delivery vector for genes in mammals, because it can transduce a wide range of mammalian cells and tissues without replicating or producing progeny. Objective/Method: To investigate if the budded virions of Anticarsia gemmatalis multiple nucleopolhyedrovirus (AgMNPV) species has the same ability, the viral genome was modified by homologous recombination into susceptible insect cells to integrate reporter genes and then it was evaluated on mammalian cell lines in comparative form with respect to equivalent viruses derived from AcMNPV. Besides, the replicative capacity of AgMNPV´s virions in mammals was determined. Results: The experiments carried out showed that the recombinant variant of AgMNPV transduces and support the expression of delivered genes but not replicates in mammalian cells. Conclusion: Consequently, this insect pathogen is proposed as an alternative of non-infectious viruses in humans to explore new approaches in gene therapy and other applications based on the use of mammalian cells.

PERAN DAN POTENSI MUSUH ALAMI DALAM PENGENDALIAN HeUcoverpa armigera (HUBNER) PADA KAPAS

<p><strong>The role and potency of natural enemies in controlling HeUcoverpa armigera Hubner in cotton</strong></p><p><strong></strong>HeUcoverpa armigera. known as the cotton bollworm, is one of cotton productivity limiting factors. Efforts in controlling this pesl have been directed lo (he use of its natural enemies, viz. parasiloids. predator and insect pathogens in conservation techniques The study was conducted in two activities. The irst activity was the inventory of parasiloids and predators of// armigera. which was conducted from 1986 to 1999 in the cotton development area in Central Java (Rembang, Pati, and Grobogan). East Java (Situbondo, Banyuwangi, Tuban. and Lanongan), NIB (Menangabaris. Lokopriya, and Sandubaya), and NTF (Maumere, Wailiti. and Larantuka). The second activity was to sludy the potency of dominant parasiloids and predators in cotton, which was conducted in 1999/2000 in the Research Instalaiion for Tobacco and Fibre Crops, Asembagus. The objectives of the study were to evaluate Ihe diversity of natural enemies, particularly parasiloids and predators, and their role in controlling Ihe population of // armigera in cotton. The inventory of parasiloids and predators was conducted to 15 and 21 species, respectively. The predominant parasiloids were Trichogramma-loidea armigera Nagaraja (egg parasitoid) and Eriborus argenteopilosus Camreon (larval parasitoid). The predominant predators were Deraeocoris indianus Carvalho, Campylomma diversicornis Rcuter (Hemiptera Miridae). Paederus fasciatus Curtis (Coleoptera Staphylinidac) and Coccinellid beetles (Coleoptera Coccincllidac). These predators feed on eggs and small larvae of //. armigera. The potency of these parasiloids and predator, as mortality factors of the pesl, was quantitatively studied in insecticide sprayed and unsprayed cotton ields. The egg and larval parasiloids caused mortality of //. armigera eggs and larvae as high as 65% and 21%, respectively. The predators suppressed // armigera population by 82%, so that its population was lower than that of the plots treated with insecticide. These suppressions resulted in a significantly lower damage of cotton fruiting bodies (4.3-8.0% on sprayed plots vs.1.7-3.4% on unsprayed plots) and hence, a signiicantly higher production of seed cotton ( I 838 kg/ha on sprayed plots vs. 2 170 kg/ha on unsprayed plots). Thereore, // armigera population on collon basically could be managed by its natural enemies below its action threshold, when Hie natural enemies were allowed to build up their population.</p>

Rapid molecular evolution of Spiroplasma symbionts of Drosophila

Spiroplasma are a group of Mollicutes whose members include plant pathogens, insect pathogens, and endosymbionts of animals. Spiroplasma phenotypes have been repeatedly observed to be spontaneously lost in Drosophila cultures, and several studies have documented a high genomic turnover in Spiroplasma symbionts and plant pathogens. These observations suggest that Spiroplasma evolves quickly in comparison to other insect symbionts. Here, we systematically assess evolutionary rates and patterns of Spiroplasma poulsonii, a natural symbiont of Drosophila. We analysed genomic evolution of sHy within flies, and sMel within in vitro culture over several years. We observed that S. poulsonii substitution rates are among the highest reported for any bacteria, and around two orders of magnitude higher compared with other inherited arthropod endosymbionts. The absence of mismatch repair loci mutS and mutL is conserved across Spiroplasma and likely contributes to elevated substitution rates. Further, the closely related strains sMel and sHy (>99.5% sequence identity in shared loci) show extensive structural genomic differences, which potentially indicates a higher degree of host adaptation in sHy, a protective symbiont of Drosophila hydei. Finally, comparison across diverse Spiroplasma lineages confirms previous reports of dynamic evolution of toxins, and identifies loci similar to the male-killing toxin Spaid in several Spiroplasma lineages and other endosymbionts. Overall, our results highlight the peculiar nature of Spiroplasma genome evolution, which may explain unusual features of its evolutionary ecology.