Utilización de Microsatélites para la Determinación de la Polilla de la Manzana Cydia pomonella L. (Lepidoptera: Tortricidae) en Chile Central

Abstract

A B S T R A C TCodling moth (Cydia pomonella L.) is the main pest of pip fruits worldwide. Despite its economic importance, little is known about the genetic structure and patterns of movement at local and regional scale, important aspects for establishing a control strategy for this pest. An analysis of genetic variability on six populations of C. pomonella using microsatellite was performed in the two major apple (Malus domestica Borkh.) growing regions of Central Chile. In spite of geographic distances between some populations (aprox. 180 km), there was little genetic differentiation among populations (F ST = 0.0-0.00097 and G ST = 0.005-0.127), without isolation by distance, and high levels of gene flow (Nm ≈ 250). High frequencies of null alleles were found over all loci across populations (Na = 0.292) which seem to explain the significant heterozygote deficiencies found. Approximatelly 98% of the variance was found within individuals and very little at the other hierarchical levels. The high levels of genetic diversity and gene flow detected seem to indicate that the codling moth populations studied in both regions have an almost continuous distribution. R E S U M E NLa polilla de la manzana (Cydia pomonella L.) es la plaga más importante de los frutales pomáceos en el mundo. A pesar de su gran importancia económica, poco se sabe acerca de su estructura genética y patrones de movimiento a escala local y regional, aspectos importantes para establecer una estrategia de control de esta plaga. Mediante la utilización de microsatéli-tes se realizó un análisis de la variabilidad genética de seis poblaciones de la polilla de la manzana en las dos principales regiones productoras de manzanas (Malus domestica Borkh.) en Chile Central. A pesar de las distancias geográficas entre algunas poblaciones (aprox. 180 km), se encontraron bajos coeficientes de diferenciación genética entre poblaciones (F ST = 0,0-0,00097 y G ST = 0,005-0,127), sin presencia de aislamiento por distancia, y con altos niveles de flujo génico (Nm ≈ 250). Se encontraron altas frecuencias de alelos nulos (Na = 0,292) para todos los loci, a través de las poblaciones analizadas, lo que explicaría el significativo déficit de heterocigotos encontrado. Aproximadamente un 98% de la variabilidad genética encontrada corresponde a una variación intraindividual, atribuyéndose prácticamente nada a los demás niveles jerárquicos. La alta diversidad génica y los altos niveles de flujo génico parecen indicar que las poblaciones estudiadas de la polilla de la manzana en ambas regiones estudiadas están distribuidas formando casi un continuo.Palabras clave: flujo génico, estructura poblacional, biotecnología.

Population Genetic Structure of Codling Moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in Different Localities and Host Plants in Chile

“…We found significant but low levels of genetic differentiation between codling moth populations from different localities and regions. Interestingly, the genetic differentiation between localities found herein (FST = 0.03) was one to two orders of magnitude higher than in previous studies of codling moth in Chile (FST = 0.002 − 0.0001), covering a more restricted latitudinal range of approximately 180 km and using only apples as the host plant [14,31]. It is important to note that microsatellite markers used herein were different to those used in the previous studies from Chile.…”

Worldwide variability of insecticide resistance mechanisms in the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae)

“…More likely, insecticide resistance in C. pomonella is affected by local conditions influencing selection pressure, the spatial distribution of managed and unmanaged hosts, and population movement between habitats. Several recent genetic studies of C. pomonella populations have shown that these factors can create widely different geographical patterns within France (Franck et al , 2007), Chile (Espinoza et al , 2007) and South Africa (Timm et al , 2006). However, within all geographical regions, effective efforts to combat resistance will require continuous monitoring of resistance mechanisms and the implementation of resistance management practices by both growers and the insecticide industry.…”

“…In addition, a recent microsatellite DNA analysis on samples from different countries suggests that C. pomonella populations are structured according to geographical distance at supranational scale and that the intensity of insecticide applications is the main force structuring the populations at the national level (Franck et al, 2007). In the same way, Espinoza et al (2007) and Fuentes-Contreras et al (2008) did not detect differentiation by distance between Chilean C. pomonella populations, even when they were separated by more than 180 km. In contrast, Timm et al (2006) detected geographical differentiation in South-African populations.…”

A novel set of microsatellite markers for the European Grapevine MothLobesia botranaisolated using next-generation sequencing and their utility for genetic characterization of populations from Europe and the Middle East

“…Isolation of SSR markers in Lepidoptera has been shown to be particularly difficult due to similarities of regions flanking microsatellite loci or due to a multiplication of microsatellite loci as a consequence of the presence of mobile genetic elements (Meglécz et al, 2004(Meglécz et al, , 2007Zhang, 2004;Sinama et al, 2011). In addition, high null-allele frequencies and heterozygote deficits have been reported in many studies on SSR markers in Lepidoptera including L. botrana in the past (Amsellem et al, 2003;Ji et al, 2003;Franck et al, 2005;Van't Hof et al, 2005;Espinoza et al, 2007;Sinama et al, 2011). Presence of null-alleles may overestimate population differentiation and might hamper cross-species but also cross-population transferability and thus application of these markers in population genetic studies (Chapuis & Estoup, 2007).…”