Anastrepha striata is widely distributed across the Americas and is a pest of economically important crops, especially crops of the Myrtaceae family. Insect population structures can be influenced by the presence of physical barriers or characteristics associated with habitat differences. This study evaluated the effect of the Western Andes on the population structure of A. striata. Individuals were collected from Psidium guajava fruits from three natural regions of southwestern Colombia (Pacific Coast, mountainous region and the inter-Andean valley of the Cauca River). Based on a 1318 bp concatenated of the genes Cytochrome Oxidase subunit I (COI) and NADH dehydrogenase subunit 6 (ND6), 14 haplotypes with few changes among them (between 1 and 3) were found. There was only one dominant haplotype in all three regions. No genetic structure associated with the three eco-geographical regions of the study was found. Moreover, the Western Andes are not an effective barrier for the genetic isolation of the populations from the Pacific Coast compared with the inter-Andean valley populations. This genetic homogeneity could be partially due to anthropogenic intervention, which acts as a dispersal agent of infested fruits. Another hypothesis to explain the lack of structure would be the relatively recent arrival of A. striata to the region, as indicated by an analysis of the demographic history, which reveals a process of population expansion. This study represents the first attempt to understand the population genetics of A. striata in Colombia and could contribute to the integral management of this pest.

The West Indian fruit fly, Anastrepha obliqua (Macquart) (Diptera: Tephritidae), is a quarantine pest in Colombia that infests economically important plants, although little is known about its population dynamics. In this study, cytochrome oxidase subunit I (COI) and NADH dehydrogenase subunit 6 (ND6) mitochondrial genes were concatenated to characterise the genetic diversity and population structure of A. obliqua, associated with two factors: (1) ecosystem differences in two geographical regions of southwestern Colombia (the inter-Andean valley of the Cauca River and the mountain region), and (2) the host plants present in the area. Additionally, a first approach was made at understanding the species demographic history. Seven haplotypes were found with Kimura 2-parameter (K2P) genetic distances between 0.1 and 4%. Haplotype genealogies and demographic analyses suggest that the population of A. obliqua in southwestern Colombia is the result of introductory events of multiple populations of A. obliqua. However, the data indicate that the population genetic structure could be related to the ecological differences of the two regions being studied. Significant differences were also found among the distribution of haplotype frequencies of A. obliqua with regard to the diversity of host plants. This study is the first to provide an understanding of the population dynamics of A. obliqua in Colombia, which may ultimately contribute to strategies, such as sterile insect technique (SIT), for the management of the pest.

Phytophagous insects are organisms that use a part of a plant as a food resource.Within this group, we focused on the pest insect Anastrepha obliqua, a fly that feeds on fruits of plants of different species and causes economic losses on the American continent. The ability of the larvae of this species to feed on various fruits (polyphagia) has been studied from different perspectives but never at the level of microRNAs.These interfering RNAs can regulate gene expression in tissues and organs of an organism. The objective of this work was to obtain the first micro-transcriptome and to determine its expression levels and possible target mRNAs when the third instar larvae of the species A. obliqua feed on fruits of plants of three different species:Spondias purpurea, Mangifera indica and Averrhoa star fruit. A total of 116 microRNAs were identified in the study, of which 37 were completely new. Fifty-four microRNAs were expressed in all larvae, regardless of the fruit, while 44 were detected in larvae that fed on a specific fruit. Twenty-one microRNAs showed differential expression, and the annotation of the targets showed that these interfering RNAs have important genes that play roles in the development, feeding and detoxification of the larvae as possible targets. The construction of the first micro-transcriptome and the identification of possible targets for A. obliqua provide new information for understanding the mechanisms that control gene expression in this species of dipteran.

Graphical abstract

Anastrepha obliqua (Macquart) (Diptera: Tephritidae) is an important pest in the neotropical region. It is considered a polyphagous insect, meaning it infests plants of different taxonomic families and readily colonizes new host plants. The change to new hosts can lead to diversification and the formation of host races. Previous studies investigating the effect of host plants on population structure and selection in Anastrepha obliqua have focused on the use of data from the mitochondrial DNA sequence and microsatellite markers of nuclear DNA, and there are no analyses at the genomic level. To better understand this issue, we used a pooled restriction site-associated DNA sequencing (pooled RAD-seq) approach to assess genomic differentiation and population structure across sympatric populations of Anastrepha obliqua that infest three host plants—Spondias purpurea (red mombin), Mangifera indica (mango) of the family Anacardiaceae and Averrhoa carambola (carambola) of the family Oxalidaceae—in sympatric populations of the species Anastrepha obliqua of Inter-Andean Valley of the Cauca River in southwestern Colombia. Our results show genomic differentiation of populations from carambola compared to mango and red mombin populations, but the genetic structure was mainly established by geography rather than by the host plant. On the other hand, we identified 54 SNPs in 23 sequences significantly associated with the use of the host plant. Of these 23 sequences, we identified 17 candidate genes and nine protein families, of which four protein families are involved in the nutrition of these flies. Future studies should investigate the adaptive processes undergone by phytophagous insects in the Neotropics, using fruit flies as a model and state-of-the-art molecular tools.