Weak Spatial and Temporal Population Genetic Structure in the Rosy Apple Aphid, Dysaphis plantaginea, in French Apple Orchards

We used eight microsatellite loci and a set of 20 aphid samples to investigate the spatial and temporal genetic structure of rosy apple aphid populations from 13 apple orchards situated in four different regions in France. Genetic variability was very similar between orchard populations and between winged populations collected before sexual reproduction in the fall and populations collected from colonies in the spring. A very small proportion of individuals (∼2%) had identical multilocus genotypes. Genetic differentiation between orchards was low (FST<0.026), with significant differentiation observed only between orchards from different regions, but no isolation by distance was detected. These results are consistent with high levels of genetic mixing in holocyclic Dysaphis plantaginae populations (host alternation through migration and sexual reproduction). These findings concerning the adaptation of the rosy apple aphid have potential consequences for pest management

Ban of a broad-spectrum insecticide in apple orchards: effects on tortricid populations, management strategies, and fruit damage

The objective of this study was to investigate the effects of the ban of Gusathion(A (R)) (azinphosmethyl) as insecticide in Swedish apple orchards on tortricid moth population density and tortricid-induced crop damage. In addition, the effects on growers' management strategies, such as choice of spraying dates and alternative insecticide combinations, were studied. Populations of Adoxophyes orana, Archips podana, Archips rosana, Cydia pomonella, Pandemis heparana, Hedya nubiferana, and Spilonota ocellana were monitored using sex-pheromone traps during the four consecutive seasons of 2008-2011, with annual crop damage estimates made prior to harvest. Azinphosmethyl was banned after 2008. Significantly increasing population densities were observed in A. orana, A. podana, C. pomonella, and H. nubiferana, whereas correspondingly increasing crop damage was observed only in the case of C. pomonella. The growers' management strategies, with respect to number and timing of spray applications, did not change during the study period although the insecticides available after the ban were less persistent and more specific, i.e., either with primarily ovicidal or larvicidal effect. Analysis of a broad range of factors showed that temperatures during winter and spring, number and timing of insecticide applications, and usage of azinphosmethyl in 2008 were important factors affecting population size and the damage caused by the tortricid species studied