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Introduction The oriental fruit fly Bactrocera dorsalis is one of the most destructive agricultural pests worldwide, with highly debated species delimitation, origin, and global spread routes.Our study intended to (i) resolve the taxonomic uncertainties between B. dorsalis and B. carambolae, (ii) reveal the population structure and global invasion routes of B. dorsalis across Asia, Africa, and Oceania, and (iii) identify genomic regions that are responsible for the thermal adaptation of B. dorsalis.Based on a high-quality chromosome-level reference genome assembly, we explored the population relationship using a genome-scale single nucleotide polymorphism dataset generated from the resequencing data of 203 B. dorsalis genomes and 25 B. carambolae genomes. Genome-wide association studies and silencing using RNA interference were used to identify and verify the candidate genes associated with extreme thermal stress.We showed that B. dorsalis originates from the Southern India region with three independent invasion and spread routes worldwide: (i) from Northern India to Northern Southeast Asia, then to Southern Southeast Asia; (ii) from Northern India to Northern Southeast Asian, then to China and Hawaii; and (iii) from Southern India toward the African mainland, then to Madagascar, which is mainly facilitated by human activities including trade and immigration. Twenty-seven genes were identified by a genome-wide association study to be associated with 11 temperature bioclimatic variables. The Cyp6a9 gene may enhance the thermal adaptation of B. dorsalis and thus boost its invasion, which tended to be upregulated at a hardening temperature of 38℃. Functional verification using RNA interference silencing against Cyp6a9, led to the specific decrease in Cyp6a9 expression, reducing the survival rate of dsRNA-feeding larvae exposed to extreme thermal stress of 45℃ after heat hardening treatments in B. dorsalis.This study provides insights into the evolutionary history and genetic basis of temperature adaptation in B. dorsalis.

Bactrocera carambolae is one of the approximately 100 sibling species of the Bactrocera dorsalis complex and considered to be very closely related to B. dorsalis. Due to their high morphological similarity and overlapping distribution, as well as to their economic impact and quarantine status, the development of reliable markers for species delimitation between the two taxa is of great importance. Here we present the complete mitochondrial genome of B. carambolae sourced from its native range in Malaysia and its invaded territory in Suriname. The mitogenome of B. carambolae presents the typical organization of an insect mitochondrion. Comparisons of the analyzed B. carambolae sequences to all available complete mitochondrial sequences of B. dorsalis revealed several species-specific polymorphic sites. Phylogenetic analysis based on Bactrocera mitogenomes supports that B. carambolae is a differentiated taxon though closely related to B. dorsalis. The present complete mitochondrial sequences of B. carambolae could be used, in the frame of Integrative Taxonomy, for species discrimination and resolution of the phylogenetic relationships within this taxonomically challenging complex, which would facilitate the application of species-specific population suppression strategies, such as the sterile insect technique.

Bactrocera carambolae is one of the approximately 100 sibling species of the Bactrocera dorsalis complex and considered to be very closely related to B. dorsalis. Due to their high morphological similarity and overlapping distribution, as well as to their economic impact and quarantine status, the development of reliable markers for species delimitation between the two taxa is of great importance. Here we present the complete mitochondrial genome of B. carambolae sourced from its native range in Malaysia and its invaded territory in Suriname. The mitogenome of B. carambolae presents the typical organization of an insect mitochondrion. Comparisons of the analyzed B. carambolae sequences to all available complete mitochondrial sequences of B. dorsalis revealed several species-specific polymorphic sites. Phylogenetic analysis based on Bactrocera mitogenomes supports that B. carambolae is a differentiated taxon though closely related to B. dorsalis. The present complete mitochondrial sequences of B. carambolae could be used, in the frame of Integrative Taxonomy, for species discrimination and resolution of the phylogenetic relationships within this taxonomically challenging complex, which would facilitate the application of species-specific population suppression strategies, such as the sterile insect technique.

In this study, 10 mosquito coils manufactured in China were obtained in Suriname, South America, where they are used extensively. The coils were analyzed for organics (allethrin, permethrin, and butylated hydroxytoluene) and heavy metals (Cr, Co, As, Cd, and Pb) by GC-MS and ICP-MS, respectively. Allethrin was the only target organic compound detected in all mosquito coils with concentrations ranging from ~1900 to ~4500 µg/g. The concentrations of heavy metals varied as follows (in µg/g): Cr: 2.9–9.4, Co: 0.1–1.2, Cu: 0.7–16.1, Se: 0.10–0.4, Ni: 2.1–5.8, As: 0.10–2.2, Cd: 0.10–0.2, and Pb: 1.1–3.6.

The carambola fruit fly (Bactrocera carambolae or CFF) was thought to be introduced in to Suriname in the 1960s or 1970s and first collected in 1975. An eradication programme based on the male annihilation technique (MAT) was developed and funded by IFAD (International Fund for Agricultural Development), the Netherlands, France and the United States and officially began in 1998. The programme worked in Guyana, Suriname, French Guiana and Brazil. By 2001, the distribution of B. carambolae was reduced to limited areas of Suriname and French Guiana. In 2002 funding was reduced and then halted. In the following years B. carambolae has expanded its distribution with detections as far southeast as Curralinho, in the Para state of Brazil, and as far north as Orlando, Florida, in the US. The closing of this programme before completion has resulted in increased cost to South American agriculture and increased risk to Central America, North America and the Caribbean. A coordinated programme amongst infested countries could still mitigate the risk of the spread of B. carambolae in the region.