Biology subjects

Beekman, M. M.

Publications and source records attributed to Beekman, M. M..

3 recordsLinked to original sources

bioRxiv2024

Insecticide resistance in Myzus persicae collected from sweet pepper

Populations of the green peach aphid, Myzus persicae, rapidly develop resistance to insecticides applied in agriculture, necessitating regular resistance monitoring of pest populations. Previous research identified two dominant multilocus genotypes (MLGs) in conventional (using insecticides + biological control agents) Dutch sweet pepper greenhouses: MLG-A under pymetrozine application and MLG-R under flonicamid application. This suggests positive selection for the genotypes by the application of these insecticides. However, no resistance of M. persicae to these insecticides has been reported yet. To investigate whether the insecticides were selectively driving the emergence of these specific MLGs, we compared the sensitivity of MLG-A and MLG-R to pymetrozine and flonicamid to that of six other genotypes from the same crop system. Additionally, we screened the M. persicae populations from Dutch sweet pepper greenhouses for known mutations conferring resistance to carbamates, pyrethroids, neonicotinoids, and tetronic and tetramic acid derivatives. Our results show that both MLG-A and MLG-R are less sensitive to pymetrozine compared to the other genotypes investigated. Furthermore, full mortality for MLG-R, the genotype least sensitive to flonicamid, was not achieved at the recommended field dose for this insecticide. Resistance mutations for carbamates and pyrethroids were prevalent among the MLGs, including MLG-A and MLG-R, while mutation A2226V, which is linked to resistance to tetronic and tetramic acid derivatives, was absent. Notably, the neonicotinoid resistance mutation R81T was found only in MLG-R, making this the northernmost detection of R81T in M. persicae to date. This study shows that various resistance mechanisms can accumulate in a single aphid genotype and that insecticides likely play a role in selecting for the dominant genotypes of M. persicae in conventional greenhouses.

genetics↗

bioRxiv2024

Population genetic structure of the aphid pest Myzus persicae in organic and conventional greenhouses

Aphids display remarkable adaptability to pest control strategies and their partheno-genetic reproduction results in rapid numerical increase of higher-fitness clones. Con-sequently, a high prevalence of only a few clonal lines could indicate positive selection for these genotypes, potentially reflecting adaptation to pest control methods. Here, we investigated the clonal diversity and population genetic structure of the green peach aphid Myzus persicae using microsatellite markers, in both organic and conventionally managed Dutch sweet pepper greenhouses over four consecutive years. In total, 26 distinct multilocus genotypes (MLG) were detected, with higher clonal diversity in organic than in conventional greenhouses. Strikingly, a single MLG dominated conventional greenhouses in 2019, only to be completely replaced by a new dominant MLG by 2022. Whole-genome sequencing of 15 sampled lines -- seven sharing the same MLG and eighth with unique MLGs -- revealed that all aphids with the dominant MLG of 2019, collected from various locations and over multiple years, originated from a single parthenogenetic ancestor. Our findings indicate that the population genetic structure of M. persicae differs between organically and conventionally managed sweet pepper greenhouses. The presence of dominant MLGs in conventional crop systems may suggest positive selection or evolutionary forces such as a founder effect. Understanding the forces driving these differences in population genetic structure and their impact on the efficacy of biocontrol agents will further help us improve control strategies for M. persicae in greenhouse crops.

genetics↗

bioRxiv2023

Genetic differentiation at extreme latitudes in the socially plastic sweat bee Halictus rubicundus

The sweat bee Halictus rubicundus is an important pollinator with a large latitudinal range and many potential barriers to gene flow. Alongside typical physical barriers, including mountain ranges and oceans, the climate may also impose restrictions on gene flow in this species. The climate influences voltinism and sociality in H. rubicundus, which is bivoltine and can nest socially at lower latitudes but can be univoltine and solitary in the north of its range and at higher altitudes where the climate is cooler. Variation in voltinism due to the climate may result in differences in phenology between populations across this species geographical range. Differences in phenology could limit gene flow, rendering populations at extreme latitudes genetically isolated and potentially more vulnerable to environmental stressors. A previous study found that the Irish Sea restricts gene flow in this species, but there was no evidence that differences in phenology had a similar effect as there was no genetic differentiation between H. rubicundus populations on mainland Britain. Here we extend the previous study to consider populations of H. rubicundus at extreme northern and southern latitudes in the UK. Using 12 microsatellite markers for genotyping, we found that bees from a population in the far north of Scotland were genetically differentiated from bees collected in Cornwall in the south-west of England. In contrast, bees collected across the Irish Sea in Northern Ireland showed genetic overlap with both the Scottish and Cornish bees. Our results suggest that when populations at extreme latitudes are considered, phenology and the climate may act alongside physical barriers such as the Scottish Highlands and the Irish Sea to restrict gene flow in H. rubicundus. We discuss the implications of our results for local adaptation in the face of rapidly changing selection pressures which are likely under climate change.

genetics↗