Population Genetics for Inferring Introduction Sources of the Oriental Fruit Fly, Bactrocera dorsalis: A Test for Quarantine Use in Korea

To infer the introduction sources of the oriental fruit fly, Bactrocera dorsalis, we used a mitochondrial marker to reconstruct the haplotype network and 15 microsatellite loci to reveal genetic structure and relationships between the geographically or temporally different collections from Asia. We performed Approximate Bayesian computations to infer a global origin and a source of the quarantine collections found in Korea. As a result, the 40 populations were divided into three groups, of which genetic similarity is not related to the geographic vicinity. Korean samples had a similar genetic structure to Taiwan and Thailand ones. Our results suggest that the place of origin of the B. dorsalis specimens found in Korea’s border quarantine is likely to be Taiwan or Thailand. As the global origin of B. dorsalis, we estimated that Taiwan and Thailand were most likely the global origins of Southeast Asian populations by testing hypothetical scenarios by the approximate Bayesian computation analyses. Our results will allow easier identification of the source region of the forthcoming invasion of quarantined B. dorsalis specimens.

Encapsulation of Basil Essential Oil by Paste Method and Combined Application with Mechanical Trap for Oriental Fruit Fly Control

In this work, the chemical compositions of basils oils, including those of lemon basil, white holy basil, Thai basil, tree basil and red holy basil, were analysed. Methyl eugenol was detected in all types of basils. The essential oils of red and white holy basils possessed a comparable ability (~25%) to attract male Oriental fruit fly to the synthesised fruit fly attractant in the laboratory experiment. To control the release of the active ingredients, the white holly basil oil (WBO) was encapsulated with maltodextrin (MD) and gum arabic (GA) by paste method. The essential oil is retained in the wall complex much longer with the addition of MD. The results also revealed that the combination of the MD:GA (25:75) had the highest loading efficiency of the oil (9.40%) as observed by the numerous porous structures by scanning electron microscopy. Fourier-transform infrared spectra of the encapsulated polymer confirmed traces of essential oil functional groups. The field test study advised that WBO-encapsulated products improved fruit fly attractive efficiency by maintaining the release rate of basil essential oil.

Insecticidal activity of crude extracts of three spices and commercial botanical pesticide on oriental fruit fly under laboratory conditions

Background The uses of botanical pesticides in pest management are currently on remarkable increase due to their efficacy, biodegradability, environment-friendly, and availability. Ethanol extracts of three spices (Piper guineense, Aframomum melegueta, Zingiber officinale) and commercial botanical pesticide AzaSol (6% azadirachtin) were assessed for contact toxicity, residual effects, and for their potential in soil application against pupariating larvae of oriental fruit fly (Bactrocera dorsalis) in the laboratory at ambient temperature of 27 ± 2 °C and relative humidity of 75–80%. The extracts and AzaSol were applied at 1:1.5 w/v concentration while cypermethrin was introduced as standard check and applied at 5 ml/liter of water. Results All the treatments were very effective against B. dorsalis in contact toxicity and residual affects recording 89.4–100% larval mortality at 24 h post-application. Z. officinale and cypermethrin had similar contact and residual effects on B. dorsalis, both recording 100% larval mortality at 24 h post-exposure. Piper guineense showed higher residual effects than contact effects, while A. melegueta and AzaSol showed better contact effects than residual effects against B. dorsalis larvae. AzaSol was the most effective among the botanicals in reducing the adult emergence and in enhancing larval mortality (96.7%) on treated soil followed by Piper guineense (83.3%). The efficacy of AzaSol on the treated soil was comparable to cypermethrin. All the extracts were significantly more effective than control in enhancing pupariating larvae mortality and in reducing adult emergence on treated soil. Conclusion Ethanol extracts of P. guineense and A. melegueta were highly promising against B. dorsalis on treated soil and could be adopted in soil application targeting puparia under the tree canopies as part of integrated pest management of B. dorsalis in orchards.

Bactrocera dorsalis (oriental fruit fly).

Bactrocera dorsalis is a highly invasive species. Native to Asia, Oriental fruit fly is now found in at least 65 countries, including parts of America and Oceania, and most of continental Africa (sub-Saharan countries). The potential risk of its introduction to a new area is facilitated by increasing international tourism and trade, and is influenced by changes in climate and land use. After introduction, it can easily disperse as it has a high reproductive potential, high biotic potential (short life cycle, up to 10 generations of offspring per year depending on temperature), a rapid dispersal ability and a broad host range. The economic impact would result primarily from the loss of the export markets and the costly requirement of quarantine restrictions and eradication measures. Furthermore, its establishment would have a serious impact on the environment, following the initiation of chemical and/or biological control programmes. Invasive B. dorsalis has been shown to be highly competitive with native fruit flies where it has established, quickly becoming the dominant fruit fly pest (Duyck et al., 2004; Vargas et al., 2007; Vayssières et al., 2015). Oriental fruit fly is of quarantine significance to EPPO (European Plant Protection Organization), APPPC (Asia and Pacific Plant Protection Commission), COSAV (Comité de Sanidad Vegetal del Cono Sur), CPPC (Caribbean Plant Protection Commission), IAPSC (Inter-African Phytosanitary Council) and OIRSA (Organismo Internacional Regional de Sanidad Agropecuaria) countries.

Molecular Characterization and Transcriptional Expression Analysis of ABC Transporter H Subfamily Genes in the Oriental Fruit Fly

The oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephretidae), is a serious pest of fruits and vegetables and has developed high levels of insecticide resistance. ATP-binding cassette transporter genes (ABC transporters) are involved in mediating the energy-driven transport of many substances across membranes and are closely associated with development and insecticide detoxification. In this study, three ABC transporters in the H subfamily were identified, and the possible roles of these genes in B. dorsalis are discussed. Bioinformatics analysis revealed that those genes are conserved, typical of half-transporters. The expression profiles of BdABCH genes (BdABCHs) in the developmental stages, tissues, and following insecticide exposure, extreme temperature, warm- and cold-acclimated strain, starvation, and desiccation stress were determined by quantitative real-time PCR. Expression of BdABCHs can be detected in various tissues and in different developmental stages. They were most highly expressed in the hindgut and in newly emerged adults. The mRNA levels of BdABCHs in males (including most tissues and body segments) were higher than in females. The expression of BdABCH1 was significantly upregulated 3.8-fold in the cold-acclimated strain, and was significantly upregulated by 1.9-, 3.8- and 4.1-fold in the 0°C, starvation, and desiccation treatments, respectively. Treatment with malathion and avermectin at LD20 and LD30 concentrations produced no obvious changes in the levels of BdABCHs. BdABCHs may be involved in the transport of related hormones during eclosion, as well as water and inorganic salts. BdABCH1 also demonstrated that it is related to the ability to cope with adverse environments.