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Bacterial communities of Aphis gossypii and Myzus persicae (Hemiptera: Aphididae) from pepper crops (Capsicum sp.).

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.

SUBMITTER: Gallo-Franco JJ

PROVIDER: S-EPMC6453963 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND: Among herbivorous insects that have exploited agro-ecosystems, the peach-potato aphid, Myzus persicae, is recognized as one of the most important agricultural pests worldwide. Uses over 400 plant species and has evolved different insecticides resistance mechanisms. As M. persicae feeds upon a huge diversity of hosts, it has been exposed to a wide variety of plant allelochemicals, which probably have promoted a wide range of detoxification systems. METHODOLOGY/PRINCIPAL FINDINGS: In this work we (i) evaluated whether insecticide resistance mutations (IRM) in M. persicae can give an advantage in terms of reproductive fitness when aphids face two hosts, pepper (Capsicum annuum) a suitable host and radish (Raphanus sativus) the unfavorable host and (ii) examined the transcriptional expression of six genes that are known to be up-regulated in response to insecticides. Our results show a significant interaction between host and IRM on the intrinsic rate of increase (r(m)). Susceptible genotypes (not carrying insensitivity mutations) had a higher r(m) on pepper, and the transcriptional levels of five genes increased on radish. The r(m) relationship was reversed on the unfavorable host; genotypes with multiple IRM exhibited higher r(m), without altering the transcriptional levels of the studied genes. Genotypes with one IRM kept a similar r(m) on both hosts, but they increased the transcriptional levels of two genes. CONCLUSIONS/SIGNIFICANCE: Although we have studied only nine genotypes, overall our results are in agreement with the general idea that allelochemical detoxification systems could constitute a pre-adaptation for the development of insecticide resistance. Genotypes carrying IRM exhibited a higher r(m) than susceptible genotypes on radish, the more unfavorable host. Susceptible genotypes should be able to tolerate the defended host by up-regulating some metabolic genes that are also responding to insecticides. Hence, our results suggest that the trade-off among resistance mechanisms might be quite complex, with a multiplicity of costs and benefits depending on the environment.

Project description:BACKGROUND: Insecticide resistance is one of the best examples of rapid micro-evolution found in nature. Since the development of the first synthetic insecticide in 1939, humans have invested considerable effort to stay ahead of resistance phenotypes that repeatedly develop in insects. Aphids are a group of insects that have become global pests in agriculture and frequently exhibit insecticide resistance. The green peach aphid, Myzus persicae, has developed resistance to at least seventy different synthetic compounds, and different insecticide resistance mechanisms have been reported worldwide. METHODOLOGY/PRINCIPAL FINDINGS: To further characterize this resistance, we analyzed genome-wide transcriptional responses in three genotypes of M. persicae, each exhibiting different resistance mechanisms, in response to an anti-cholinesterase insecticide. The sensitive genotype (exhibiting no resistance mechanism) responded to the insecticide by up-regulating 183 genes primarily ones related to energy metabolism, detoxifying enzymes, proteins of extracellular transport, peptidases and cuticular proteins. The second genotype (resistant through a kdr sodium channel mutation), up-regulated 17 genes coding for detoxifying enzymes, peptidase and cuticular proteins. Finally, a multiply resistant genotype (carrying kdr and a modified acetylcholinesterase), up-regulated only 7 genes, appears not to require induced insecticide detoxification, and instead down-regulated many genes. CONCLUSIONS/SIGNIFICANCE: This study suggests strongly that insecticide resistance in M. persicae is more complex that has been described, with the participation of a broad array of resistance mechanisms. The sensitive genotype exhibited the highest transcriptional plasticity, accounting for the wide range of potential adaptations to insecticides that this species can evolve. In contrast, the multiply resistant genotype exhibited a low transcriptional plasticity, even for the expression of genes encoding enzymes involved in insecticide detoxification. Our results emphasize the value of microarray studies to search for regulated genes in insects, but also highlights the many ways those different genotypes can assemble resistant phenotypes depending on the environmental pressure.

Dataset Information

Bacterial communities of Aphis gossypii and Myzus persicae (Hemiptera: Aphididae) from pepper crops (Capsicum sp.).

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