RESUMEN
Wolbachia are intracellular bacteria in insects that can manipulate the sexual development and reproduction by male killing or other methods. We have recently identified a Wolbachia protein named Oscar that acts as a male-killing factor for lepidopteran insects. Oscar interacts with the Masculinizer (Masc) protein, which is required for both masculinization and dosage compensation (DC) in lepidopteran insects. Embryonic expression of Oscar inhibits masculinization and causes male killing in two lepidopteran species, Ostrinia furnacalis and Bombyx mori. However, it remains unknown whether Oscar-induced male killing is caused by a failure of DC. Here, we performed a transcriptome analysis of Oscar complementary RNA-injected O. furnacalis and B. mori embryos, and found that Oscar primarily targets the Masc protein, resulting in male killing by interfering with DC in lepidopteran insects.
Asunto(s)
Bombyx , Mariposas Nocturnas , Wolbachia , Animales , Masculino , Wolbachia/genética , Wolbachia/metabolismo , Mariposas Nocturnas/genética , Mariposas Nocturnas/metabolismo , Bombyx/genética , Bombyx/metabolismo , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Perfilación de la Expresión GénicaRESUMEN
Lepidoptera is one of the most speciose insect orders, causing enormous damage to agricultural and forest crops. Although genome editing has been achieved in a few Lepidoptera for insect controls, most techniques are still limited. Here, by injecting female pupae of the Lepidoptera model species, Bombyx mori, gene editing was established using the Receptor-Mediated Ovary Transduction of Cargo (ReMOT) control technique. We identified a B. mori oocytes-targeting peptide ligand (BmOTP, a 29 aa of vitellogenin N-terminal of silkworms) with a highly conserved sequence in lepidopteran insects that could efficiently deliver mCherry into oocytes. When BmOTP was fused to CRISPR-associated protein 9 (Cas9) and the BmOTP-Cas9 ribonucleoprotein complex was injected into female pupae, heritable editing of the offspring was achieved in the silkworms. Compared with embryo microinjection, individual injection is more convenient and eliminates the challenge of injecting extremely small embryos. Our results will significantly facilitate the genetic manipulation of other lepidopteran insects, which is essential for advancing lepidopteran pest control.
RESUMEN
Bacillus thuringiensis is widely used as an insecticide which is safe and environmentally friendly to humans and animals. One of the important insecticidal mechanisms is the binding of Bt toxins to specific toxin receptors in insect midgut and forming a toxin perforation which eventually leads to insect death. The resistance of target pests to Bt toxins is an important factor hampering the long-term effective cultivation of Bt crops and the continuous use of Bt toxins. This review summarizes the mechanism of insect resistance to Bt toxins from the perspective of important Bt toxin receptors in midgut cells of Lepidopteran insects, which may facilitate the in-depth study of Bt resistance mechanism and pest control.
Asunto(s)
Bacillus thuringiensis , Insecticidas , Animales , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Endotoxinas/genética , Endotoxinas/metabolismo , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Insectos/metabolismo , Resistencia a los Insecticidas/genética , Insecticidas/metabolismo , Insecticidas/farmacología , Control Biológico de VectoresRESUMEN
To investigate the species diversity of lepidopteran insects in Xinjiang wild fruit forests, establish insect community monitoring systems, and determine the local species pool, we test the applicability of DNA barcoding based on cytochrome c oxidase subunit I (COI) gene for accurate and rapid identification of insect species. From 2017 to 2019, a total of 212 samples with ambiguous morphological identification were selected for DNA barcoding analysis. Five sequence-based methods for species delimitation (ABGD, BINs, GMYC, jMOTU, and bPTP) were conducted for comparison to traditional morphology-based identification. In total, 2,422 samples were recorded, representing 143 species of 110 genera in 17 families in Lepidoptera. The diversity analysis showed that the richness indices for Noctuidae was the highest (54 species), and for Pterophoridae, Cossidae, Limacodidae, Lasiocampidae, Pieridae, and Lycaenidae were the lowest (all with 1 species). The Shannon-Wiener species diversity index (H') and Pielou's evenness (J') of lepidopteran insects first increased and then decreased across these 3 years, while the Simpson diversity index showed a trend of subtracted then added. For molecular-based identification, 67 lepidopteran species within 61 genera in 14 families were identified through DNA barcoding. Neighbor-joining (NJ) analysis showed that conspecific individuals were clustered together and formed monophyletic groups with a high support value, except for Lacanobia contigua (Denis & Schiffermüller, 1775) (Noctuidae: Hadeninae). Sixty-seven morphospecies were classified into various numbers of MOTUs based on ABGD, BINs, GMYC, jMOTU, and bPTP (70, 96, 2, 71, and 71, respectively). In Xinjiang wild fruit forests, the family with the largest number of species is Noctuidae, followed by Geometridae, Crambidae, and the remaining families. The highest Shannon diversity index is observed for the family Noctuidae. Our results indicate that the distance-based methods (ABGD and jMOTU) and character-based method (bPTP) outperform GMYC. BINs is inclined to overestimate species diversity compared to other methods.
RESUMEN
Bacillus thuringiensis is widely used as an insecticide which is safe and environmentally friendly to humans and animals. One of the important insecticidal mechanisms is the binding of Bt toxins to specific toxin receptors in insect midgut and forming a toxin perforation which eventually leads to insect death. The resistance of target pests to Bt toxins is an important factor hampering the long-term effective cultivation of Bt crops and the continuous use of Bt toxins. This review summarizes the mechanism of insect resistance to Bt toxins from the perspective of important Bt toxin receptors in midgut cells of Lepidopteran insects, which may facilitate the in-depth study of Bt resistance mechanism and pest control.
Asunto(s)
Animales , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Proteínas Bacterianas/metabolismo , Endotoxinas/metabolismo , Proteínas Hemolisinas/metabolismo , Insectos/metabolismo , Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Control Biológico de VectoresRESUMEN
Cry protein toxins produced by Bacillus thuringiensis (Bt) are now widely used in sprays and transgenic crops to control insect pests. Most recently, ATP-binding cassette transporter proteins (ABC transporter), including ABCC2, ABCC3, ABCG1, ABCA2 and ABCB1, were reported as putative receptors for different Cry toxins. However, little is known about the regulatory mechanism involved in the expression of these ABC transporter genes. In the present study, a conserved target site of miR-998-3p was identified from the coding sequence (CDS) of ABCC2 in diverse lepidopteran insects. Luciferase reporter assays demonstrated that miR-998-3p could bind to the CDS of ABCC2 and down-regulate its expression through a conserved site and several non-conserved sites in three representative lepidopteran pests, including Helicoverpa armigera, Spodoptera exigua and Plutella xylostella. Injection of miR-998-3p agomir significantly reduced the abundance of ABCC2, accompanied by increased tolerance to Cry1Ac toxin in H. armigera, S. exigua and P. xylostella (Cry-S) larvae, while injection of miR-998-3p antagomir increased the abundance of ABCC2 dramatically, and thereby reduced the Cry1Ac resistance in a Cry1Ac resistant population of P. xylostella (GX-R). These results give a better understanding of the mechanisms of post-transcriptional regulation of ABCC2, and will be helpful for further studies on the role of miRNAs in the regulation of Cry1Ac resistance in lepidopteran pests.
Asunto(s)
Proteínas Bacterianas/farmacología , Endotoxinas/farmacología , Proteínas Hemolisinas/farmacología , Proteínas de Insectos/genética , Resistencia a los Insecticidas/genética , Insecticidas/farmacología , MicroARNs/metabolismo , Mariposas Nocturnas/genética , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Animales , Toxinas de Bacillus thuringiensis , Proteínas de Insectos/metabolismo , Larva/efectos de los fármacos , Larva/genética , Larva/crecimiento & desarrollo , Larva/metabolismo , Mariposas Nocturnas/efectos de los fármacos , Mariposas Nocturnas/crecimiento & desarrollo , Mariposas Nocturnas/metabolismo , Proteína 2 Asociada a Resistencia a Múltiples Medicamentos , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/metabolismo , Spodoptera/efectos de los fármacos , Spodoptera/genética , Spodoptera/crecimiento & desarrollo , Spodoptera/metabolismoRESUMEN
Studies of the influence of biological parameters on the spatial distribution of lepidopteran insects can provide useful information for managing agricultural pests, since the larvae of many species cause serious impacts on crops. Computational models to simulate the spatial dynamics of insect populations are increasingly used, because of their efficiency in representing insect movement. In this study, we used a cellular automata model to explore different patterns of population distribution of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), when the values of two biological parameters that are able to influence the spatial pattern (larval viability and adult longevity) are varied. We mapped the spatial patterns observed as the parameters varied. Additionally, by using population data for S. frugiperda obtained in different hosts under laboratory conditions, we were able to describe the expected spatial patterns occurring in corn, cotton, millet, and soybean crops based on the parameters varied. The results are discussed from the perspective of insect ecology and pest management. We concluded that computational approaches can be important tools to study the relationship between the biological parameters and spatial distributions of lepidopteran insect pests.
Asunto(s)
Productos Agrícolas , Spodoptera , Distribución Animal , Animales , Larva , Longevidad , Glycine max , Zea maysRESUMEN
Isolation and identification of new strains with wide variety of target pests is an ever growing field. In this paper, a screening of 260 strains from Tunisian soil samples was conducted by dot-blot and PCR-sequencing analysis. The screening was done on the basis of the possession of cry1D-type genes and was followed by the evaluation of the insecticidal activity against Spodoptera littoralis. BLB250 strain showed an LC50 value (56.2 µg g(-1)) against S. littoralis lower than those of the two Bacillus thuringiensis reference strains HD1 and HD133. An interesting LC50 (167.6 µg g(-1)) was also recorded against Ephestia kuehniella larvae. The strain was, thus, selected because of its qualification to be highly toxic, at once, for both Lepidopteran insects. In vitro time course of proteolytic processing of BLB250 and HD133 protoxins by the gut juices from the two insect larvae revealed that the differences in toxicity against E. kuehniella are most likely attributed to differences in the efficiency of the activation of the corresponding protoxins into toxins. An activation comparative study using commercial proteases suggested that the intestinal proteases of E. kuehniella contain trypsin-like activities. With its high efficiency and toxicity against, at once, two Lepidopteran insects having different susceptibilities towards kurstaki and aizawai subspecies, BLB250 could be useful when developing more efficient and economical B. thuringiensis-based pesticides.