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Background: Spodoptera frugiperda (FAW) is a pest that poses a significant threat to corn production worldwide, causing millions of dollars in losses. The species has evolved into two strains (corn and rice) that differ in their genetics, reproductive isolation, and resistance to insecticides and Bacillus thuringiensis endotoxins. The microbiota plays an important role in insects' physiology, nutrient acquisition, and response to chemical and biological controls. Several studies have been carried out on FAW microbiota from larvae guts using laboratory or field samples and a couple of studies have analyzed the corn strain microbiota across its life cycle. This investigation reveals the first comparison between corn strain (CS) and rice strain (RS) of FAW during different developmental insect stages and, more importantly, endosymbiont detection in both strains, highlighting the importance of studying both FAW populations and samples from different stages., Methods: The composition of microbiota during the life cycle of the FAW corn and rice strains was analyzed through high-throughput sequencing of the bacterial 16S rRNA gene using the MiSeq system. Additionally, culture-dependent techniques were used to isolate gut bacteria and the Transcribed Internal Spacer-ITS, 16S rRNA, and gyr B genes were examined to enhance bacterial identification., Results: Richness, diversity, and bacterial composition changed significantly across the life cycle of FAW. Most diversity was observed in eggs and males. Differences in gut microbiota diversity between CS and RS were minor. However, Leuconostoc , A2, Klebsiella , Lachnoclostridium , Spiroplasma , and Mucispirilum were mainly associated with RS and Colidextribacter , Pelomonas , Weissella , and Arsenophonus to CS, suggesting that FAW strains differ in several genera according to the host plant. Firmicutes and Proteobacteria were the dominant phyla during FAW metamorphosis. Illeobacterium, Ralstonia , and Burkholderia exhibited similar abundancies in both strains. Enterococcus was identified as a conserved taxon across the entire FAW life cycle. Microbiota core communities mainly consisted of Enterococcus and Illeobacterium . A positive correlation was found between Spiroplasma with RS (sampled from eggs, larvae, pupae, and adults) and Arsenophonus (sampled from eggs, larvae, and adults) with CS. Enterococcus mundtii was predominant in all developmental stages. Previous studies have suggested its importance in FAW response to B. thuringensis . Our results are relevant for the characterization of FAW corn and rice strains microbiota to develop new strategies for their control. Detection of Arsenophonus in CS and Spiroplasma in RS are promising for the improvement of this pest management, as these bacteria induce male killing and larvae fitness reduction in other Lepidoptera species., Competing Interests: The authors declare that they have no competing interests., (© 2024 Marulanda-Moreno et al.)

The fall armyworm (Spodoptera frugiperda) is one of the major pest insects damaging diverse crops including cotton, corn, rice, and sorghum. Fall armyworms have been identified as two morphologically indistinguishable strains, the corn strain, and the rice strain, named after their preferred host-plants. Although initially recognized as host-plant strains, there has been an ongoing debate regarding whether the corn and rice strains should be considered as such. In this article, we present arguments based on recent population genomics studies supporting that these two strains should be considered to be host-plant strains. Furthermore, host-plant adaptation appears to be a driving evolutionary force responsible for incipient speciation in the fall armyworm., (© 2024 The Authors. Insect Science published by John Wiley & Sons Australia, Ltd on behalf of Institute of Zoology, Chinese Academy of Sciences.)

Wolbachia is an obligate intracellular bacterium with a high frequency of infection and a continental distribution in arthropods and nematodes. This endosymbiont can induce various reproductive phenotypes in their hosts and has been previously found naturally in several pests including thrips (Thripidae). These insects cause physical fruit damage and economic losses in avocado. The presence of Wolbachia was evaluated for the first time in avocado thrips populations of Frankliniella sp. and Scirtothrips hansoni sp.n. from eastern Antioquia. DNA from adult thrips individuals was used to assess the detection of Wolbachia by amplifying a fragment (600 bp) of the Wolbachia major surface protein ( wsp ) gene. Results confirmed the presence of two new Wolbachia strains in these two thrips species, with a higher percentage of natural infection in S. hansoni sp.n. The first Wolbachia species was found in Frankliniella sp. and belongs to supergroup A and the second was detected in S. hansoni sp.n. and is part of supergroup B. Wolbachia was more frequently found in females (32.73%), and only found in one male. Analysis of phylogenetic relationships, suggests that the two new Wolbachia sequences ( wFran : Frankliniella and wShan : Scirtothrips hansoni ) detected here represent two new groups for this endosymbiont. The haplotype network shows the presence of two possible haplotypes for each strain. Future studies to evaluate the possible use of Wolbachia as a control agent in avocado thrips are necessary., Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-021-00951-5., Competing Interests: Conflict of interestThe authors declare that no conflict of interest exists in the study., (© Association of Microbiologists of India 2021.)

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) represents a pest of economic importance in all Western Hemisphere. This polyphagous species has diverged into two populations that have been mainly recognized with various mitochondrial and nuclear molecular markers and named "the rice" and "the corn" strains. In Colombia, both strains have evolved prezygotic and postzygotic isolation. They differ in tolerance to Bacillus thuringiensis (Cry1Ac and Cry1Ab endotoxins) and the insecticides lambda-cyhalothrin and methomyl. In 2014, a wing morphometric analysis made in 159 individuals from a colony showed that both strains significantly differ in wing shape. The species also exhibits sexual dimorphism in the rice strain as in females wing size is larger than in males. Here, we continued this work with another wing morphometric approach in laboratory-reared strains to calculate wing size and shape heritabilities using a full-sib design and in wild populations to determine if this method distinguishes these strains. Our results show that male heritabilities of both traits were higher than female ones. Wild populations were significantly different in wing shape and size. These results suggest that wing morphometrics can be used as an alternative method to molecular markers to differentiate adults from laboratory-reared populations and wild populations of this pest, particularly in males of this species. Finally, Q ST values obtained for wing size and shape further demonstrated that both strains are genetically differentiated in nature.

The complete mitogenome of the potato tuber moth Tecia solanivora (Lepidoptera: Gelechiidae) was sequenced, annotated, characterized and compared with 140 species of the order Lepidoptera. The circular genome is 15,251 bp, containing 37 genes (13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and an A+T-rich region). The gene arrangement was identical to other lepidopteran mitogenomes but different from the ancestral arrangement found in most insects for the tRNA-Met gene (A+T-region, tRNA-I, tRNA-Q, tRNA-M). The mitogenome of T. solanivora is highly A+T-biased (78.2%) and exhibits negative AT- and GC-skews. All PCGs are initiated by canonical ATN start codons, except for Cytochrome Oxidase subunit 1 (COI), which is initiated by CGA. Most PCGs have a complete typical stop codon (TAA). Only NAD1 has a TAG stop codon and the COII and NAD5 genes have an incomplete stop codon consisting of just a T. The A+T-rich region is 332 bp long and contains common features found in lepidopteran mitogenomes, including the 'ATAGA' motif, a 17 bp poly (T) stretch and a (AT)8 element preceded by the 'ATTTA' motif. Other tandem repeats like (TAA)4 and (TAT)7 were found, as well as (T)6 and (A)10 mononucleotide repeat elements. Finally, this mitogenome has 20 intergenic spacer regions. The phylogenetic relationship of T. solanivora with 28 other lepidopteran families (12 superfamilies) showed that taxonomic classification by morphological features coincides with the inferred phylogeny. Thus, the Gelechiidae family represents a monophyletic group, suggesting that T. solanivora and Pectinophora gossypiella have a recent common ancestor., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Understanding why some hybrid zones are bimodal and others unimodal can aid in identifying barriers to gene exchange following secondary contact. The hybrid zone between the grasshoppers Chorthippus brunneus and C. jacobsi contains a mix of allopatric parental populations and inter-mingled bimodal and unimodal sympatric populations, and provides an ideal system to examine the roles of local selection and gene flow between populations in maintaining bimodality. However, it is first necessary to confirm, over a larger spatial scale, previously identified associations between population composition and season and habitat. Here we use cline-fitting of one morphological and one song trait along two valley transects, and intervening mountains, to confirm previously identified habitat associations (mountain versus valley) and seasonal changes in population composition. As expected from previous findings of studies on a smaller spatial scale, C. jacobsi dominated mountain habitats and mixed populations dominated valleys, and C. brunneus became more prevalent in August. Controlling for habitat and incorporating into the analysis seasonal changes in cline parameters and the standard errors of parental trait values revealed wider clines than previous studies (best estimates of 6.4 to 24.5 km in our study versus 2.8 to 4.7 km in previous studies) and increased percentage of trait variance explained (52.7% and 61.5% for transects 1 and 2 respectively, versus 17.6%). Revealing such strong and consistent patterns within a complex hybrid zone will allow more focused examination of the causes of variation in bimodality in mixed populations, in particular the roles of local selection versus habitat heterogeneity and gene flow between differentiated populations.

Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is an important pest of several crops in the western hemisphere. This insect has genetically differentiated into two host-associated populations: the corn (Zea mays L.) and the rice (Oryza sativa L.) strains. The corn strain also is found in cotton (Gossypium hirsutum L.) and sorghum and the rice strain in Bermuda grass [Cynodon dactylon (L.) Pers.] and millet. In the United States and Brazil, lines from corn, rice, Bermuda grass, and millet were used to evaluate the resistance of both strains to various insecticides, and found that the corn strain is more resistant than the rice strain. However, in these studies the larvae were not genotyped. In Colombia, genotyping of fall armyworm is necessary because the rice strain also can be found in corn fields. In this work, collected larvae from corn and rice fields from Tolima (central Colombia) were genotyped and evaluated for the resistance to methomyl and lambda-cyhalothrin. We found that the rice strain does not significantly differ in resistance to methomyl compared with the corn strain but it develops tolerance more rapidly to lambda-cyhalothrin. The eggs viability of treated females also was significantly affected by methomyl on each generation. The realized heritability of resistance was higher for lambda-cyhalothrin (0.23-0.42) than for methomyl (0.04-0.14). The number of generations needed for 10-fold increase in resistance is approximately 11.5 generations for methomyl and 6.5 for lambda-cyhalothrin. Finally, the genetic basis of resistance to both insecticides involves few recessive autosomal genes. The results obtained here suggest that methomyl is a better option than lambda-cyalothin to control fall armyworm.

The fall army worm Spodoptera frugiperda (Smith) is a migratory important pest of corn, sorghum, rice, grass and bermudagrass in North and South America. This species has diverged into two genetically differentiated but morphologically identical strains, "the rice" and "the corn". They have been analyzed by sequencing the genes cytochrome oxydase I, II and ITS1 from populations from the United States and Brazil. However, no such studies were performed in Colombia. In here, we identified 43 haplotypes by sequencing a fragment of the COI gene from 102 individuals, of which 40 had already been identified as the "corn" and "rice" strains or to their hybrids from Tolima, and the rest were collected from corn, cotton, sorghum, grass and rice fields in other regions of Colombia. The corn strain haplotype H1 was the most frequently found in this country, representing the main target for FAW monitoring programs. AMOVA analysis confirmed the population structure between Colombian and North American S. frugiperda haplotypes (F(ST) = 0.76812, P < 0.001), but not within the different Colombian regions, suggesting high gene flow within the country. The ML trees obtained for Tolima and for Colombia as a whole did not generate clustering amongst S. frugiperda sequences, neither via host-plant association nor by geographical areas. The minimum spanning network for Colombia corroborated our finding that the haplotype H1 has the highest frequency in the country. Our data suggest that haplotype frequency determination will be useful in the establishment of a monitoring system for this species.

Brycon henni is a native species in Magdalena's River basin, and because of its cultural and economic importance, is strongly overexploited. This study aimed to describe the genetic variability and population structure of this species from Nare and Guatapé rivers basins. A total of 195 individuals were collected and DNA extractions were obtained from muscle and blood tissue. Fourteen primers were evaluated with the RAPD technique, being four of them polymorphic, and produced 66 different fragments (63% polymorphism). Besides, using the molecular variance (AMOVA) analysis, the population structure was described for all sites (phi(ST) = 0.297, phi(ST) = 0.163; Nare and Guatapé river basins, respectively), and suggested the importance of the migratory behaviour of the species in the genetic differentiation. Genetic distances among sampled sites showed that most of the genetic differentiation occurred between sites Guatapé and El Cardal with respect to the others. A Mantel Test demonstrated a correlation between genetic and geographic distances (r = 0.431 both of the basins evaluated; r = 0.377, Nare river middle basin), and suggested isolation by distance. The outcomes obtained in this study have valuable implications in species conservation and the genetic variability of natural populations of B. henni, and should be complemented with morphological analyses.