Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) has shown remarkable range expansion over the past 10years and invaded several new continents including Africa. Here we report results of a detailed assessment of acute high and low temperature survival ability and the plasticity thereof, to test the hypothesis that traits of the thermal niche have contributed to the species' invasion ability. We also assess life-stage-related variation of thermal tolerances to determine potential stage-related environmental sensitivity. The temperatures at which c. 20% of the population survived of B. dorsalis were determined to be -6.5°C and 42.7°C, respectively, when using 2h exposures. Further, four life stages of B. dorsalis (egg, 3rd instar larvae, pupae and adults) were exposed to high and low discriminating temperatures to compare their thermal survival rates. The egg stage was found to be the most resistant life stage to both high and low temperatures, since 44±2.3% survived the low and 60±4.2% survived the high discriminating temperature treatments respectively. Finally, the potential for adult hardening responses to mediate tolerance of extremes was also considered using a diverse range of acute conditions (using 2h exposures to 15°C, 10°C and 5°C and 30°C, 35°C, 37°C and 39°C as hardening temperatures, and some treatments with and without recovery periods between hardening and discriminating temperature treatment). These showed that although some significant hardening responses could be detected in certain treatments (e.g. after exposure to 37°C and 39°C), the magnitude of this plasticity was generally low compared to two other wide-spread and more geographically-range-restricted con-familial species, Ceratitis capitata and C. rosa. In other words, Bactrocera dorsalis adults were unable to rapidly heat- or cold-harden to the same extent as the other Ceratitis species examined to date. These results suggest a narrower thermal niche in B. dorsalis compared to these Ceratitis species - in both basal and plastic terms - and suggests that its geographic distribution might be more restricted in consequence.
Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is an invasive and extremely damaging leaf-mining moth of South American origin. It is a serious pest of tomatoes. This species was first recorded outside of its native range in Spain (2006), and has subsequently spread into Asia and Africa. Here we report the first records of this species for the Republic of South Africa, where moths were first trapped in August and October 2016. The species was identified using both morphological and molecular approaches. Monitoring of the spread of tomato leaf miner in South Africa and the implementation of control measures are managed by the Department of Agriculture, Fisheries and Forestry (DAFF), South Africa.
Within South Africa, millions of rands in revenue are generated annually from the export of fruit produce. Citrus fruits are exported mostly to the U.S.A., South Korea and China. These countries have strict biosecurity laws in place which prohibit the import of specific problem insects, including several species of mealybug (Hemiptera: Pseudococcidae). Although the adult females for most species of mealybug are routinely identified through morphological keys, eggs and nymphs (crawlers) are more problematic. As such, export consignments are regularly refused based on the presence of unidentifiable mealybug nymphs or eggs. The aim of this paper is to report an easy, user-friendly molecular laboratory technique to accurately identify mealybug eggs and crawlers to species level. We amplified and sequenced a 749 bp portion of the mitochondrial DNA cytochrome oxidase subunit one (COI) gene. Phylogenetic trees indicated that the five species included here (Planococcus citri (Risso), Paracoccus burnerae (Brain), Pseudococcus longispinus (Targioni-Tozzetti), Ps. calceolariae (Maskell) and Ps. viburni (Signoret)) are reciprocally monophyletic and follow the 10× rule where sequence divergences separating species are an order of magnitude larger than divergences within species. As such, DNA can be extracted from eggs, crawlers or adults; analysed and compared with reference data, and unequivocally assigned to one of the five species.
South Africa imports plant budwood (dormant cuttings for propagation) from various countries. Phytosanitary measures, including inspections at points of entry, are implemented to minimize the chance of a pest being introduced on the budwood. This study presents the inspections and interceptions of mites and insects on budwood imported to South Africa from 2004 to 2011. The study presents crops and countries from which South Africa imports budwood, and gives data on the type of imports more often infested with arthropods. Interceptions of insects and mites are reported, including interceptions of phytosanitary, economically important and nonphytophagous mites. The arthropod taxa intercepted are listed, and it is noted that the majority of interceptions are of mites, particularly of Eriophyoidea. These data are discussed in the context of quarantine and research.
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