Uncovering the tracks of a recent and rapid invasion: the case of the fruit fly pest Bactrocera invadens (Diptera: Tephritidae) in Africa

Abstract

Phytophagous insects of the genus Bactrocera are among the most economically important invasive fruit fly pests. In 2003, an unknown Bactrocera species was found in Kenya. First identified as an ‘aberrant form’ of the Asian B. dorsalis complex, it was later recognized as a new species, Bactrocera invadens. Within 2 years of its discovery, the species was recorded in several African countries, becoming an important quarantine pest. As this invasive fly was discovered only recently, no data are available on its invasion pattern in Africa. This pilot study attempts to infer from genetic data the dynamic aspects of the African invasion of this pest. Using microsatellite markers, we evaluated the level of genetic diversity and the extent of common ancestry among several African populations collected across the invaded areas. A sample from the Asian Sri Lankan population was analysed to confirm the Asian origin of this pest. Genetic data cast no doubt that Sri Lanka belongs to the native range, but only a small percentage of its genotypes can be found in Africa. African populations display relatively high levels of genetic diversity associated with limited geographical structure and no genetic footprints of bottlenecks. These features are indicative of processes of rapid population growth and expansion with possible multiple introductions. In the span of relatively few years, the African invasion registered the presence of at least two uncorrelated outbreaks, both starting from the East. The results of the analyses support that invasion started in East Africa, where B. invadens was initially isolated.

Invasion Genetics of the Western Flower Thrips in China: Evidence for Genetic Bottleneck, Hybridization and Bridgehead Effect

“…Consistent with the mtDNA data, the microsatellite genetic diversity indices ( uH E  = 0.723 and H S  = 0.726) in the 14 invasive populations were lower than those in the United States ( uH E  = 0.855 and H S  = 0.853) [19]. Moreover, the genetic diversity estimates ( N h and uH E ) for F. occidentalis in China was comparable to those reported for populations of fire ant Solenopsis invicta in newly invaded areas in China, Australia, New Zealand and the Caribbean ( N h  = 3; [61]) and Bactrocera invadens in Africa ( H E  = 0.56, computed over 11 microsatellites; [62]). As expected, the bottleneck signature in China is more pronounced in the mitochondrial genome, which is subject to stronger genetic drift than the nuclear genome because of its maternal and haploid mode of inheritance and reduced effective population sizes [32], [63], [64].…”

Parameter Identification in Population Models for Insects Using Trap Data

“…In 2010, B. invadens was detected in the northern part of the Limpopo province in South Africa [21]. Its capacity for rapid population growth, high invasive potential [16], and wide range of fruit hosts [26] represents a major threat for all fruit industries in South Africa.…”

Genetic and cytogenetic analysis of the American cherry fruit fly, Rhagoletis cingulata (Diptera: Tephritidae)

“…In the case of agricultural pests, they can be used to address a variety of important biological questions and can help to improve planning of environmental control methods, such as the Sterile Insect Technique (SIT). Especially in Tephritidae, microsatellites have been used to study recent invasion phenomena (Bonizzoni et al 2001;Khamis et al 2009;Zygouridis et al 2009), species expansion routes (Augustinos et al 2005;Nardi et al 2005;Aketarawong et al 2007), adaptation and ongoing speciation (Michel et al 2007;Cameron et al 2010), mating patterns in nature (Kraaijeveld et al 2005;Song et al 2007) and the structure of populations of cosmopolitan and invading species (Gilchrist and Meats 2010;Virgilio et al 2010). One major problem is the difficulty and cost of developing de novo microsatellite markers, but cross-amplification of microsatellite markers from closely related species may provide an alternative.…”