The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith, 1797), known as an important agricultural pest around the world, is indigenous to the tropical–subtropical regions in the Western Hemisphere, although its distribution has expanded over large parts of America, Africa, Asia and Oceania in the last few years. The pest causes considerable costs annually coupled with its strong invasion propensity. Temperature is identified as the dominant abiotic factor affecting herbivorous insects. Several efforts have reported that temperature directly or indirectly influences the geographic distribution, phenology and natural enemies of the poikilothermal FAW, and thus may affect the damage to crops, e.g., the increased developmental rate accelerates the intake of crops at higher temperatures. Under some extreme temperatures, the FAW is likely to regulate various genes expression in response to environmental changes, which causes a wider viability and possibility of invasion threat. Therefore, this paper seeks to review and critically consider the variations of developmental indicators, the relationships between the FAW and its natural enemies and the temperature tolerance throughout its developmental stage at varying levels of heat/cold stress. Based on this, we discuss more environmentally friendly and economical control measures, we put forward future challenges facing climate change, we further offer statistical basics and instrumental guidance significance for informing FAW pest forecasting, risk analyses and a comprehensive management program for effective control globally.
1 October 2018 in International Journal of Biological Macromolecules
The booklouse, Liposcelis bostrychophila is an important storage pest worldwide. The mt genome of an asexual strain (Beibei, China) of the booklouse, L. bostrychophila, comprises two chromosomes; each chromosome contains approximate half of the 37 genes typically found in animals. The mt genomes of two sexual strains of L. bostrychophila, however, comprise five and seven chromosomes respectively; each chromosome contains one to six genes. To understand mt genome evolution in L. bostrychophila and whether L. bostrychophila is a cryptic species, we sequenced the mt genomes of six strains of asexual L. bostrychophila collected from different locations in China, Croatia and USA. The mt genomes of all of the six asexual strains of L. bostrychophila collected in China, Croatia and USA have two chromosomes. Phylogenetic analysis of mt genome sequences divided nine strains of L. bostrychophila into four groups. Each group has a distinct mt genome organization and substantial sequence divergence (48.7-87.4%) from other groups. Furthermore, the seven asexual strains of L. bostrychophila including the published Beibei strain are more closely related to two other species of booklice, L. paeta and L. sculptilis, than to the sexual strains of L. bostrychophila. Our results revealed highly divergent mt genomes in the booklouse, L. bostrychophila, and indicated that L. bostrychophila is a cryptic species.
1 August 2021 in Molecular Phylogenetics and Evolution
The Ceratitis FARQ complex (formerly FAR complex) includes four frugivorous tephritids, Ceratitis fasciventris, C. anonae, C. rosa and C. quilicii, the latter two causing important agricultural losses in Africa. Although FARQ species can be identified on the basis of subtle morphological differences, they cannot be resolved as monophyletic when trying phylogenetic tree reconstructions based on mitochondrial or nuclear gene fragments except for microsatellites. In this study, we used mitogenome and genome-wide SNPs to investigate the phylogenetic relationship within the complex as well as between all four Ceratitis subgenera. The analysis of 13 species supported the monophyly of the Ceratitis subgenera Ceratitis, Ceratalaspis, Pardalaspis, and recovered Pterandrus as paraphyletic but could not properly resolve species within the FARQ complex. Conversely, gene and species tree reconstructions based on 785,484 genome-wide SNPs could consistently resolve the FARQ taxa and provide insights into their phylogenetic relationships. Gene flow was detected by TreeMix analysis from C. quilicii to C. fasciventris, suggesting the existence of introgression events in the FARQ complex. Our results suggest that genome-wide SNPs represent a suitable tool for the molecular diagnosis of FARQ species and could possibly be used to develop rapid diagnostic methods or to trace the origins of intercepted samples.
1 September 2018 in International Journal of Biological Macromolecules