Low prevalence of secondary endosymbionts in Myzus persicae (Hemiptera: Aphididae) and Brevicoryne brassicae (Hemiptera: Aphididae) sampled from rapeseed crops.

Abstract

Abstract Peach-potato aphids, Myzus persicae Sulzer (Hemiptera: Aphididae), and cabbage aphids, Brevicoryne brassicae Linnaeus (Hemiptera:Aphididae), are significant herbivorous insects. Insecticides are routinely used to manage aphid populations; however, widespread use of insecticides has resulted in an increase in insecticide resistant aphid populations, increasing the need for biological control. Aphids can harbour a range of non-essential endosymbiotic bacteria and these endosymbionts are drivers of phenotypic diversity in aphids. A key endosymbiont-derived phenotype is protection against parasitism from parasitoid wasps, which can have consequences on the effectiveness of biological control. Endosymbiont prevalence has been reported to vary in M. persicae : Some M. persicae populations contain low endosymbiont frequencies (0-2%), while others can contain high endosymbiont frequencies (above 50%), and the underlying drivers behind this variability are unclear; no endosymbionts have yet been reported for B. brassicae . For the success of aphid control strategies to be estimated the presence of defensive endosymbionts that can disrupt the success of biocontrol agents needs to be determined in natural aphid populations. Here, we sampled aphids and mummies (parasitised aphids) from an important rapeseed production region in Germany and used multiplex PCR assays to characterise the endosymbiont communities. We found that aphids rarely harboured facultative endosymbionts, with 3.6% of M. persicae and 0% of B. brassicae populations forming facultative endosymbiont associations. This is comparable with endosymbiont prevalence described for M. persicae populations surveyed in Australia, Europe, Chile, and USA, but is in contrast with observations from China where M. persicae populations have more abundant and diverse endosymbiotic communities.