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The carambola fruit fly, Bactrocera carambolae Drew & Hancock, is native to Southeast Asia, infests about 150 plant species, and is considered a quarantine pest insect in several regions of the world. Bactrocera carambolae has invaded Suriname, French Guyana, and northern Brazil. In Brazil, it was first recorded in 1996 and has been restricted to the states of Amapá and Roraima due to official control efforts of the Ministry of Agriculture and Food Supply (Ministério da Agricultura e Pecuária—MAPA). This is the first study to estimate the genetic structure and diversity of South American populations of B. carambolae. A total of 116 individuals from 11 localities in Brazil and 7 localities in Suriname were analyzed. Additional sequences available at GenBank from Indonesia (Lampung) and Thailand (San Pa Tong and Muang District) were also used in the analysis. We sequenced a fragment of the mitochondrial gene cytochrome oxidase subunit I. A total of 35 haplotypes were found. Haplotypes from Indonesia were closest to the haplotypes from South America, separated only by a few mutational steps. This suggests that Indonesia is the likely source for the introduction of B. carambolae into South America. The Southeast Asian populations appeared as the most ancestral group in the phylogenetic trees. The high similarity and sharing of several haplotypes among populations within South America indicate a lack of genetic structure. The mismatch distribution and neutrality tests suggest that South American populations have undergone a rapid growth and expansion following a single founder event. The low genetic diversity and the population expansion evidenced by the neutrality tests lend support to the hypothesis of a recent introduction of a single lineage of the carambola fruit fly into South America.

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. Objectives: 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. Methods: 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 487 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. Results: 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 °C. 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 °C after heat hardening treatments in B. dorsalis. Conclusion: This study provides insights into the evolutionary history and genetic basis of temperature adaptation in B. dorsalis.

Specimens of Bactrocera carambolae Drew & Hancock, 1994 (Diptera: Tephritidae) were obtained from fruits of Averrhoa bilimbi L., Averrhoa carambola L. (Oxalidaceae), Malpighia emarginata DC. (Malpighiaceae), and Psidium guajava L. (Myrtaceae), from a survey carried out in Lethem, Republic of Guyana. This is the first record of B. carambolae in A. bilimbi, M. emarginata and P. guajava in the country.

Prenatal exposure to pesticides and the association with adverse health outcomes have been examined in several studies. However, the characterization of pesticide exposure among Surinamese women during pregnancy has not been assessed. As part of the Caribbean Consortium of Research in Environmental and Occupational Health research program, 214 urine samples were collected from pregnant women living in three regions in Suriname with different agricultural practices: capital Paramaribo, the rice producing district Nickerie, and the tropical rainforest, the Interior. We used isotope dilution tandem mass spectrometry to quantify urinary concentrations of biomarkers of three pesticide classes, including phenoxy acid herbicides and organophosphate and pyrethroid insecticides, all of which are commonly used in agricultural and residential settings in Suriname. We observed that participants residing in Nickerie had the highest urinary metabolite concentrations of 2,4-dichlorophenoxyacetic acid and pyrethroids compared to those from Paramaribo or the Interior. Paramaribo had the highest concentrations of organophosphate metabolites, specifically dialkyl phosphate metabolites. Para-nitrophenol was detected in samples from Paramaribo and the Interior. Samples from Nickerie had higher median urinary pesticide concentrations of 2,4-dichlorophenoxyacetic acid (1.06 μg/L), and the following metabolites, 3,5,6-trichloro-2-pyridinol (1.26 μg/L), 2-isopropyl-4-methyl-6-hydroxypyrimidine (0.60 μg/L), and 3-phenoxybenzoic acid (1.34 μg/L), possibly due to residential use and heavy rice production.