[Show abstract][Hide abstract] ABSTRACT: Species in the stem borer noctuid subtribe Sesamiina are notoriously difficult to distinguish because most related species have homogeneous wing patterns and almost indistinguishable genitalia. The latter is potentially problematic because this group include several important pest species that are usually hardly distinguishable from non-pest species. In this study we focus on the Mediterranean corn stalk borer Sesamia nonagrioides (Lefèbvre), an important pest of maize with a wide area of distribution that covers most of Africa and extends to the south of Europe and Western Asia. According to a recent study, this pest consists of three allopatric populations which were formerly considered as distinct species or subspecies. Here we rely on recent collections of 5,470 specimens (sampled in 17 countries and 175 localities) that putatively belong to S. nonagrioides. Integrative taxonomy studies allowed us to unravel the existence of six new species that are closely related to S. nonagrioides and described in this paper. In contrast with S. nonagrioides these new species have more specific ecological preferences, as they are associated with a limited number of plant species and habitats. Dating and population genetic analyses carried out on 100 S. nonagrioides specimens also indicate a more complex than previously thought population structuration for S. nonagrioides, which can be likely accounted for by late Cenozoic environmental changes.
Zoological Journal of the Linnean Society 09/2015; 175:244-270. DOI:10.1111/zoj.12275 · 2.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Species in the stem borer noctuid subtribe Sesamiina are notoriously difficult to distinguish because most related species have homogeneous wing patterns and almost indistinguishable genitalia. The latter is potentially prob- lematic because this group includes several important pest species that are usually baregly distinguishable from non-pest species. In this study we focus on the Mediterranean corn stalk borer Sesamia nonagrioides (Lefèbvre), an important pest of maize with a wide area of distribution that covers most of Africa and extends to the south of Europe and western Asia. According to a recent study, this pest consists of three allopatric populations that were formerly considered as distinct species or subspecies. Here we rely on recent collections of 5470 specimens (sampled in 17 countries and 175 localities) that putatively belong to S. nonagrioides. Integrative taxonomy studies allowed us to unravel the existence of six new species that are closely related to S. nonagrioides and described in this paper. In contrast to S. nonagrioides these new species have more specific ecological preferences, as they are associated with a limited number of plant species and habitats. Dating and population genetic analyses carried out on 100 S. nonagrioides specimens also indicate a more complex population structure than previously thought for S. nonagrioides, which can probably be accounted for by late Cenozoic environmental changes.
Zoological Journal of the Linnean Society 06/2015; 175:244-270. · 2.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The yellow-legged hornet, Vespa velutina, was accidentally introduced from Southeast Asia and then invaded France and Korea over the last 10 years. Since its introduction, its predation on honeybee colonies has rapidly become an economic problem in invaded countries. Using mitochondrial cytochrome C oxidase and 22 nuclear microsatellite loci, we showed that native hornet populations were well differentiated and highly diverse. In contrast, introduced populations from France and Korea suffered a genetic bottleneck, which did not prevent their rapid geographic expansion. Analysis of the genetic data indicates that French and Korean populations likely arose from two independent introduction events. The most probable source population is from an area between the Chinese provinces of Zhejiang and Jiangsu. This invasion route is in agreement with knowledge on trade and historical records. By studying colonies of V. velutina, we demonstrated its polyandry, which is very rare among Vespidae. This mating behavior could have favored the success of this Asian hornet in Europe and Korea. Combined, the population and colony results suggest that very few or possibly only one single multi-mated female gave rise to the invasion.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to review the species of Conicofrontia Hampson, a small genus of noctuid stem-borers (Noctuidae, Apameini) that is distributed in East and Southeastern Africa. We review the morphology of species in this group and provide new diagnoses and ecological data for five species. The following taxonomic changes are proposed: Hygrostola dallolmoi (Berio, 1973) (= Conicofrontia dallolmoi Berio, 1973) comb. nov. and Conicofrontia bipartita (Hampson, 1910) (= Phragmatiphila bipartita Hampson, 1910) comb. nov., stat. rev. One new species is also described: C. lilomwa, sp. nov. from Tanzania. Wing patterns and male and female genitalia of the five species are described and illustrated. Finally we carried out molecular phylogenetic and molecular species delimitation analyses on a multi-marker dataset of 31 specimens and 15 species, including the five species of interest. The results of molecular analyses provide a clear support for the proposed taxonomical changes.
[Show abstract][Hide abstract] ABSTRACT: The extent of damage to crop plants from pest insects depends on
the foraging behaviour of the insect’s feeding stage. Little is known,
however, about the genetic and molecular bases of foraging
behaviour in phytophagous pest insects. The
candidate gene encoding a PKG-I, has an evolutionarily conserved
function in feeding strategies. Until now,
had never been studied
in Lepidoptera, which includes major pest species. The cereal stem
is therefore a relevant species within this
order with which to study conservation of and polymorphism in the
gene, and its role in foraging – a behavioural trait that is directly
associated with plant injuries. Full sequencing of
revealed a high degree of conservation with other insect
taxa. Activation of PKG by a cGMP analogue increased larval
foraging activity, measured by how frequently larvae moved between
food patches in an actimeter. We found one non-synonymous allelic
variation in a natural population that defined two allelic variants.
These variants presented significantly different levels of foraging
activity, and the behaviour was positively correlated to gene
expression levels. Our results show that
gene function is
conserved in this species of Lepidoptera, and describe an original
case of a single nucleotide polymorphism associated with foraging
behaviour variation in a pest insect. By illustrating how variation in
this single gene can predict phenotype, this work opens new
perspectives into the evolutionary context of insect adaptation to
plants, as well as pest management.
[Show abstract][Hide abstract] ABSTRACT: Pheromone-binding proteins (PBPs) are thought to contribute to the specificity of the pheromone detection system through an initial selective binding with pheromone molecules. Here, we report different expression levels of PBP transcripts in the antennae of two populations of the stemborer Sesamia nonagrioides (Lepidoptera: Noctuidae), one collected in Europe and one in sub-Saharan Africa. The three PBP transcripts previously identified in this species were found to be expressed in both male and female antennae. Whereas PBP3 did not show any differential expression, PBP1 and PBP2 appeared to be expressed differently according to the population origin and sex. Simultaneously, we measured and compared the ratio of the three components of the S. nonagrioides pheromone blend (Z11-16:Ac; Z11-16:OH; Z11-16:Ald) in females of the two populations. The ratio of Z11-16:OH and Z11-16:Ald varied significantly according to the population origin of this species. Cluster analyses revealed similar differentiation patterns between PBP1 and PBP2 expression levels and the ratios of Z11-16:OH and Z11-16:Ald. Different female sexual signals may thus correspond to different male reception systems, which are adjusted by the PBP expression levels, thereby ensuring optimal communication within populations.
Journal of Chemical Ecology 08/2014; 40:923-927. DOI:10.1007/s10886-014-0485-2 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ten morphologically similar species of Acrapex from Eastern and Southeastern Africa belonging to the A. stygiata and A. albivena groups are reviewed. Six species are described as new: A. brunneella, A. mitiwa, A. mpika, A. salmona, A. sporobola and A. yakoba. The Poaceae host plants of eight species are recorded; four species, A. mitiwa. A. subalbissima, A. syscia and A. yakoba, were found developing exclusively on Imperata cylindrica (L.) Beauv., (Andropogoneae), two species, A. sporobola and A. salmona, on I. cylindrica and Sporobolus macranthelus Chiov. (Zoysieae), and A. albivena on I. cylindrica, Miscanthus capensis (Nees) Andersson (Andropogoneae) and Cymbopogon sp. (Andropogoneae). Acrapex stygiata larvae developed on M. capensis and Cymbopogon sp. The host plants of A. brunneella and A. mpika remain unknown. We also conducted molecular phylogenetics and molecular species delimitation analyses on a comprehensive sample of 49 specimens belonging to nine of the studied species. Molecular phylogenetics and molecular species delimitation analyses provided additional evidence of the validity of the six newly described species but also suggested a level of hidden biodiversity for one of them.
[Show abstract][Hide abstract] ABSTRACT: Phylogenetic analysis combined with chemical ecology can contribute to the delimitation of closely related insect species, particularly in Lepidoptera. In this study, the taxonomic status of a species in the genus Busseola (Lepidoptera: Noctuidae) was discussed using morphological data, cross-mating experiments, sex pheromone chemistry, field-trapping, and molecular classification. The results of the chemical ecology experiments corroborated those from the phylogeny studies. It was concluded that several reproductive isolation components, namely host plants, geography, pheromone emission time, pheromone blend, and post-zygotic isolation factors, led to the separation of Busseola n. sp. from its closely related species B. segeta. Molecular data showed a strong difference between these two species, regardless of the marker used. The new species named Busseola nairobica was morphologically described and a hypothesis about the evolutionary history of the studied species was put forward.
Annales- Societe Entomologique de France 12/2013; 49(3):345-354. DOI:10.1080/00379271.2013.863040 · 0.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Habitat modification and fragmentation are considered as some of the factors that drive organism distribution and host use diversification. Indigenous African stem borer pests are thought to have diversified their host ranges to include maize [Zea mays L.] and sorghum [Sorghum bicolor (L.) Moench] in response to their increased availability through extensive cultivation. However, management efforts have been geared towards reducing pest populations in the cultivated fields with few attempts to understand possible evolution of new pest species. Recovery and growing persistence of Busseola segeta Bowden on maize (Zea mays L.) in Kakamega called for studies on the role of wild host plants on the invasion of crops by wild borer species. A two-year survey was carried out in a small agricultural landscape along the edge of Kakamega forest (Kenya) to assess host range and population genetic structure of B. segeta. The larvae of B. segeta were found on nine different plant species with the majority occurring on maize and sorghum. Of forty cytochrome b haplotypes identified, twenty-three occurred in both wild and cultivated habitats. The moths appear to fly long distances across the habitats with genetic analyses revealing weak differentiation between hosts in different habitats (FST = 0.016; p = 0.015). However, there was strong evidence of variation in genetic composition between growing seasons in the wild habitat (FST = 0.060; p < 0.001) with emergence or disappearance of haplotypes between habitats. Busseola segeta is an example of a phytophagous insect that utilizes plants with a human induced distribution range, maize, but does not show evidence of host race formation or reduction of gene flow among populations using different hosts. However, B. segeta is capable of becoming an important pest in the area and the current low densities may be attributed to the general low infestation levels and presence of a wide range of alternative hosts in the area.
[Show abstract][Hide abstract] ABSTRACT: Between the late Oligocene and the early Miocene, climatic changes have shattered the faunal and floral communities and drove the apparition of new ecological niches. Grassland biomes began to supplant forestlands, thus favouring a large-scale ecosystem turnover. The independent adaptive radiations of several mammal lineages through the evolution of key innovations are classic examples of these changes. However, little is known concerning the evolutionary history of other herbivorous groups in relation with this modified environment. It is especially the case in phytophagous insect communities, which have been rarely studied in this context despite their ecological importance. Here, we investigate the phylogenetic and evolutionary patterns of grass-specialist moths from the species-rich tribe Apameini (Lepidoptera, Noctuidae). The molecular dating analyses carried out over the corresponding phylogenetic framework reveal an origin around 29 million years ago for the Apameini. Ancestral state reconstructions indicate (i) a potential Palaearctic origin of the tribe Apameini associated with a major dispersal event in Afrotropics for the subtribe Sesamiina; (ii) a recent colonization from Palaearctic of the New World and Oriental regions by several independent lineages; and (iii) an ancestral association of the tribe Apameini over grasses (Poaceae). Diversification analyses indicate that diversification rates have not remained constant during the evolution of the group, as underlined by a significant shift in diversification rates during the early Miocene. Interestingly, this age estimate is congruent with the development of grasslands at this time. Rather than clade ages, variations in diversification rates among genera better explain the current differences in species diversity. Our results underpin a potential adaptive radiation of these phytophagous moths with the family Poaceae in relation with the major environmental shifts that have occurred in the Miocene.
PLoS ONE 07/2012; 7(7):e41377. DOI:10.1371/journal.pone.0041377 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This article documents the addition of 299 microsatellite marker loci and nine pairs of single-nucleotide polymorphism (SNP) EPIC primers to the Molecular Ecology Resources (MER) Database. Loci were developed for the following species: Alosa pseudoharengus, Alosa aestivalis, Aphis spiraecola, Argopecten purpuratus, Coreoleuciscus splendidus, Garra gotyla, Hippodamia convergens, Linnaea borealis, Menippe mercenaria, Menippe adina, Parus major, Pinus densiflora, Portunus trituberculatus, Procontarinia mangiferae, Rhynchophorus ferrugineus, Schizothorax richardsonii, Scophthalmus rhombus, Tetraponera aethiops, Thaumetopoea pityocampa, Tuta absoluta and Ugni molinae. These loci were cross-tested on the following species: Barilius bendelisis, Chiromantes haematocheir, Eriocheir sinensis, Eucalyptus camaldulensis, Eucalyptus cladocalix, Eucalyptus globulus, Garra litaninsis vishwanath, Garra para lissorhynchus, Guindilla trinervis, Hemigrapsus sanguineus, Luma chequen. Guayaba, Myrceugenia colchagüensis, Myrceugenia correifolia, Myrceugenia exsucca, Parasesarma plicatum, Parus major, Portunus pelagicus, Psidium guayaba, Schizothorax richardsonii, Scophthalmus maximus, Tetraponera latifrons, Thaumetopoea bonjeani, Thaumetopoea ispartensis, Thaumetopoea libanotica, Thaumetopoea pinivora, Thaumetopoea pityocampa ena clade, Thaumetopoea solitaria, Thaumetopoea wilkinsoni and Tor putitora. This article also documents the addition of nine EPIC primer pairs for Euphaea decorata, Euphaea formosa, Euphaea ornata and Euphaea yayeyamana.
[Show abstract][Hide abstract] ABSTRACT: Tecia solanivora (Lepidoptera: Gelechiidae) is an invasive species that attacks the tubers of the potato Solanum tuberosum. It is considered a serious pest of potato crops and stocks in all countries where it occurs. In the present study, we sequenced
541 individuals sampled across the T. solanivora distribution range, using the mitochondrial DNA marker Cytochrome b (Cytb) to delimit the area of species origin. We also
analyzed the genetic structure of T. solanivora in its putative area of origin and described differences in haplotype diversity between samples from different geographic
origins affected by the invasion. We observed a gap in the level of genetic diversity between Guatemalan samples (h between 0.77 and 0.97) and those from Costa-Rica, Venezuela, Colombia, Ecuador and the Canary Islands (h between 0 and 0.56). The number of haplotypes has decreased over the colonization process, ending with the observation of
a single haplotype in Colombia, Ecuador and the Canary Islands. Consequently, the invasion of South American countries by
T. solanivora is likely to have had a front-like step-wise progression, where the most recently invaded country becomes the source of subsequent
–Invasive species–Mitochondrial DNA–Genetic diversity–Invasion scenario
[Show abstract][Hide abstract] ABSTRACT: We report the characterization of fifteen microsatellite markers in Vespa velutina, an invasive hornet from Asia that has been unintentionally introduced in France before 2005. It is expanding rapidly, covering one third of the French territory and northern Spain, and causes severe losses to honeybee colonies. An enrichment protocol was used to isolate microsatellite loci, and polymorphism was explored in an invasive population from France and in a population from the native mainland location in China. These markers showed a number of alleles per locus and per population ranging from 1 to 11, and expected heterozygosities ranging from 0.151 to 0.891. These polymorphic markers will be useful to identify the source of the invading population and to discover the invasion pathways.
[Show abstract][Hide abstract] ABSTRACT: Nine polymorphic microsatellite markers were isolated from Tecia solanivora, one of the most serious pests of potato tubers in Central and South America. As found in other studies of Lepidoptera, development of microsatellites is a difficult task: in our case, despite the large number of clones sequenced (796), of which 70 were unique, only nine loci were found to be both variable, and in Hardy-Weinberg equilibrium, No null alleles were detected. The loci were tested in three other co-occurring Gelechiidae species, one of which was variable. These loci will be used to provide a greater understanding of the genetic changes occurring during the invasive process in this species.
[Show abstract][Hide abstract] ABSTRACT: Sesamia calamistis Hampson (Lepidoptera: Noctuidae) is one of the indigenous stem borer pests associated with maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] (both Poaceae) in Africa. Its pest status varies across the continent and this has been attributed to variation in diet breadth and ecological preferences among populations. Its larvae were found on 12 plant species during a study initiated at four sites (Muhaka, Mtito Andei, Kakamega, and Suam) in Kenya to estimate its diet breadth and genetic population structure. Ten of the infested plant species belonged to the family Poaceae [Echinochloa haploclada (Stapf) Stapf, Eleusine corocana L., Eleusine jaegeri Pilg., Panicum deustum Thunb, Panicum maximum Jacquin, Pennisetum purpureum Schumacher, Setaria verticillata (L.) P. Beauv., Sorghum arundinaceum (Desvaux) Stapf, S. bicolor, and Z. mays]; the other two were Cyperaceae: Cyperus distans L. and Cyperus dives Delile. Combined with collections from other African countries (Uganda, South Africa, Benin, Ghana, Nigeria, and Togo), comparisons of partial cytochrome b sequences revealed the presence of 68 haplotypes that differentiated into clades I and II. In Kenya, the two clades colonized different regions, except in Mtito Andei where they co-existed. Individuals from Mtito Andei could be separated based on their host plants: clade I with 14 haplotypes was found mainly on maize (78.6%), whereas clade II with 10 haplotypes was found mainly among wild host plants (63.6%). Detection of divergence among these clades with cytochrome b suggests that their evolutionary separation may have taken place about one million years ago. This article discusses the potential implication of this differentiation for the management of S. calamistis as a pest of maize and sorghum in Africa.
[Show abstract][Hide abstract] ABSTRACT: The level of genetic diversity within populations of introduced species has received increasing attention as an important
factor influencing their survival and adaptive potential. We examined this issue with the Guatemalan potato tuber moth Tecia solanivora, an agricultural pest which has successfully invaded South America and the Canary Islands within the last 20years. To analyse
changes in T.solanivora genetic diversity, the mitochondrial marker cytochrome b was sequenced from individuals collected across its known distribution area. High haplotypic diversity was observed in Guatemala,
whereas only three haplotypes have been found in Venezuela and a single one in the remaining invaded South American countries
and the Canary Islands. Invasive haplotypes were not observed in our samples from Guatemala but are closely related to Guatemalan
haplotypes. These results are consistent with the hypotheses that (i) either a few individuals were introduced into Venezuela leading to a strong initial genetic bottleneck, or selection pressure
may have lead to the disparition of all but a reduced number of introduced haplotypes, (ii) a second bottleneck occured between Venezuela and Colombia, and (iii) the invasion of the Canary Islands originated from South America. We further reviewed the recent literature to compare this
change in genetic diversity with those reported for other invasive species. We quantified the changes in genetic diversity
between native and introduced ranges for 57 biological invasions. We found that the genetic homogenization in T.solanivora was among the strongest reported and discuss factors that can explain the success of invasive populations with low genetic