Abstract
Insects harbor a wide variety of microorganisms that form complex and changing communities and play an important role in the biology and evolution of their hosts. Aphids have been used as model organisms to study microorganism-insect interactions. Almost all aphids are infected with the obligate endosymbiont Buchnera aphidicola and can host different bacteria that allow them to acquire traits of agronomic importance, such as resistance to high temperatures and/or defense against natural enemies. However, the bacterial communities of most aphid species remain poorly characterized. In this study, we used high-throughput DNA sequencing to characterize the bacterial communities of Aphis gossypii and Myzus persicae from two cultivable pepper species, Capsicum frutescens (Tabasco variety) and C. annuum (Cayenne variety), in four localities of southwestern Colombia. In addition, we evaluated the dynamics of A. gossypii-associated microorganisms on a seasonal basis. Our results show that the bacterial communities of A. gossypii and M. persicae are dominated by the primary endosymbiont B. aphidicola, while the presence of the facultative symbiont Arsenophonus sp. was only detected in one A. gossypii population from cayenne pepper. In addition to these two known symbionts, eight bacterial OTUs were identified that presented a frequency of 1% or more in at least one of the analyzed populations. The results show that the bacterial communities of aphids associated with pepper crops appears to be structured according to the host aphid species and the geographical location, while no differences were observed in the diversity of bacteria between host plants. Finally, the diversity and abundance of the A. gossypii bacterial community was variable among the four sampling points evaluated over the year and showed a relation with the aphid’s population dynamics. This study represents the first approach to the knowledge of the bacterial community present in chili pepper aphids from Colombia. Nevertheless, more in-depth studies, including replicates, are required to confirm the patterns observed in the microbial communities of aphids from pepper crops.
Highlights
Insects are associated with various microorganisms, many of which are capable of significantly affecting different aspects of their biology[1]
Eight samples of A. gossypii and M. persicae were used to compare diversity among localities, aphid species and host plants, and four samples collected in the Yotoco locality were used to evaluate seasonal dynamics of the A. gossypii bacterial community
The rarefaction curves tended toward saturation (Fig. S1), and the coverage value of the sequencing data, with a dissimilarity value of 0.03, was greater than 99% in all the samples (Table 2). These results suggest that the depth of sequencing used was adequate to detect most of the bacterial diversity of A. gossypii and M. persicae from pepper crops
Summary
Insects are associated with various microorganisms, many of which are capable of significantly affecting different aspects of their biology[1]. The presence of certain species of bacteria seems to confer resistance to high temperatures, which could affect the range and variability of climates that a host organism tolerates and determine its range of geographical distribution[7] These microorganisms can be involved in determining the host plant that is attacked by aphids[8] and can facilitate the transmission of viruses[9,10,11], an effect of the symbiont-insect interaction that is of great relevance for agronomic management due to the role that aphids can play as virus vectors for different host plants[12,13]. Capsicum frutescens (Tabasco var.), C. annuum (Cayenne var.) and C. chinense (Habanero var.), are the most cultivated for domestic consumption and for export purposes
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