RESUMO
BACKGROUND: A first step in any pest management initiative is recognizing the existing problem - identifying the pest species and its abundance and dispersal capacities. This is not simple and even more challenging when insidious (invasive) species are involved constituting a pest complex. Understanding a species' population diversity and structure can provide a better understanding of its adaptation and relative pest potential. Such is the need for the native rice stink bug Oebalus poecilus and the invasive O. ypsilongriseus in low and high flatlands of South America. RESULTS: The genetic structure differed between both rice stink bug species (FST = 0.157, P = 0.001), where 84% of the overall genetic variability takes place within species and three genetic groups were recognized through Bayesian approach (K = 3). Oebalus poecilus exhibited slightly higher genetic diversity (HE = 0.253) and structuring (FST = 0.050, P = 0.001) than the invasive O. ypsilongriseus (HE = 0.211; FST = 0.038, P = 0.013). Nonetheless, only the former exhibited significant correlation between genetic and geographic distances (r = 0.48, P = 0.013). CONCLUSION: Despite the pointed peculiarities, the obtained results indicate overlap in both species' occurrence and similar genetic structure allowing for a compound problem to be dealt with as the complex requires managing without, as yet, a prevailing species or a niche specialization. © 2022 Society of Chemical Industry.
Assuntos
Heterópteros , Oryza , Animais , Teorema de Bayes , Heterópteros/genética , Variação GenéticaRESUMO
Bumblebees are essential insects for the preservation of biodiversity in many ecosystems, as they can pollinate a wide variety of wild and cultivated plants. Knowledge of the genetic diversity of bumblebees can be used to understand and predict the health status of bee populations, enabling the development of strategies for crop management and conservation of this important group of pollinators. Here, we characterized the genetic diversity of B. morio populations from the Rio Grande do Sul state, Brazil, by amplification of the partial mitochondrial cytochrome oxidase I gene. The resulting data were then compared with genetic parameters of Bombus morio (Swederus 1787) obtained in populations from this species' full geographic range in South America. Our results revealed the presence of nine mitochondrial haplotypes in Rio Grande do Sul, three of which were novel haplotypes, and of significant genetic divergence among bumblebee populations from Brazil and South America. The mitochondrial haplotype BM01 was the most common and is probably the ancestral haplotype from which the others originated. There is also evidence that strong gene flow has taken place among Brazilian B. morio populations, explaining the sharing of haplotypes between distant populations. The populations of B. morio from Rio Grande do Sul present significant genetic diversity as the species is native to Southern/Southeastern Brazil and adapted to the ecological conditions in this wide range. Having well-connected populations with a large genetic potential will help this species to remain well adapted to the different environmental conditions within its native range.
Assuntos
Ecossistema , Fluxo Gênico , Abelhas/genética , Animais , Brasil , Haplótipos , Variação GenéticaRESUMO
This study provides the first genetic characterization of the soybean looper, Chrysodeixis includens (Walker, 1857), an important defoliating pest species of soybean crops in Brazil. Population genetic variability and the genetic structure of C. includens populations were evaluated by using ISSR markers with samples from the major soybean producing regions in Brazil in the growing seasons 2011/2012. Seven different primers were applied for population characterization of the molecular variability and genetic structure of 8 soybean looper populations from 8 states of Brazil. The seven ISSR loci generated 247 bands in 246 individuals of C. includens sampled. The expected heterozygosity (HE) in the populations varied between 0.093 and 0.106, while the overall HE was 0.099, indicating low genetic diversity. The analysis of molecular variance indicated that 98% of the variability was expressed among individuals within populations (FST = 0.021, p = 0.001). The low level of polymorphism over all populations, the high levels of gene flow, and the low genetic structure are indicatives of the exchange of genetic information between the different sampled regions. Population structuring suggests the presence of two major groups which do not correlate with their geographic sampling location in Brazil. These results may indicate recent recolonization of C. includens in Brazil or migration patterns following source-sink dynamics. Furthermore, the presence of two groups within C. includens suggests that a study on development of resistance or any other genetic-based trait needs to be evaluated on both groups, and pest management in soybean fields should be aware that differences may come to the control strategies they use.
Assuntos
Genoma de Inseto , Lepidópteros/genética , Animais , Brasil , Evolução Molecular , Variação Genética , Repetições de Microssatélites , Dinâmica Populacional , Glycine max/parasitologiaRESUMO
The worldwide spread of diseases is considered a major threat to biodiversity and a possible driver of the decline of pollinator populations, particularly when novel species or strains of parasites emerge. Previous studies have suggested that populations of introduced European honeybee (Apis mellifera) and bumblebee species (Bombus terrestris and Bombus ruderatus) in Argentina share the neogregarine parasite Apicystis bombi with the native bumblebee (Bombus dahlbomii). In this study we investigated whether A. bombi is acting as an emergent parasite in the non-native populations. Specifically, we asked whether A. bombi, recently identified in Argentina, was introduced by European, non-native bees. Using ITS1 and ITS2 to assess the parasite's intraspecific genetic variation in bees from Argentina and Europe, we found a largely unstructured parasite population, with only 15% of the genetic variation being explained by geographic location. The most abundant haplotype in Argentina (found in all 9 specimens of non-native species) was identical to the most abundant haplotype in Europe (found in 6 out of 8 specimens). Similarly, there was no evidence of structuring by host species, with this factor explaining only 17% of the genetic variation. Interestingly, parasites in native Bombus ephippiatus from Mexico were genetically distant from the Argentine and European samples, suggesting that sufficient variability does exist in the ITS region to identify continent-level genetic structure in the parasite. Thus, the data suggest that A. bombi from Argentina and Europe share a common, relatively recent origin. Although our data did not provide information on the direction of transfer, the absence of genetic structure across space and host species suggests that A. bombi may be acting as an emergent infectious disease across bee taxa and continents.