Geographic distribution and abundance of the Afrotropical subterranean scale insect Stictococcus vayssierei (Hemiptera: Stictococcidae), a pest of root and tuber crops in the Congo basin

Open Access Article; Published online: 01 Oct 2019Stictococcus vayssierei is a major pest of root and tuber crops in central Africa. However, data on its ecology are lacking. Here we provide an updated estimate of its distribution with the aim of facilitating the sustainable control of its populations. Surveys conducted in nine countries encompassing 13 ecological regions around the Congo basin showed that African root and tuber scale was present in Cameroon, Central African Republic, Congo, Democratic Republic of Congo, Equatorial Guinea, Gabon and Uganda. It was not found on the sites surveyed in Chad and Nigeria. The pest occurred in the forest and the forest-savannah mosaic as well as in the savannah where it was never recorded before. However, prevalence was higher in the forest (43.1%) where cassava was the most infested crop, compared to the savannah (9.2%) where aroids (cocoyam and taro) were the most infested crops. In the forest habitat, the pest was prevalent in all but two ecological regions: the Congolian swamp forests and the Southern Congolian forest-savanna mosaic. In the savannah habitat, it was restricted to the moist savannah highlands and absent from dry savannahs. The scale was not observed below 277 m asl. Where present, the scale was frequently (87.1% of the sites) attended by the ant Anoplolepis tenella. High densities (>1000 scales per plant) were recorded along the Cameroon–Gabon border. Good regulatory measures within and between countries are required to control the exchange of plant materials and limit its spread. The study provides information for niche modeling and risk mapping

Mutualism between armoured scale insects and ants: new species and observations on a unique trophobiosis (Hemiptera: Diaspididae; Hymenoptera: Formicidae: Melissotarsus Emery)

The association between African armoured scale insects (Hemiptera: Coccoidea: Diaspididae) and ants belonging to Melissotarsus Emery (Hymenoptera: Formicidae: Myrmicinae) is the only trophobiosis known in which ants do not receive honeydew or nectar in exchange for protection and other services. Food reward for the ants in this mutualism remains unknown, despite repeated suggestions that diaspidids are consumed by the associated ants, thus serving as ‘domestic cattle’. We describe new observations on interactions between Melissotarsus emeryi Santschi and the diaspidid Morganella conspicua (Brain) from South Africa. Worker ants exhibited previously undescribed tending behaviours, most notably a ‘squeezing and licking’ performed on an adult female diaspidid and ‘culling’, in which a worker removed an adult female armoured scale from the host plant. These could represent the gathering of secretory products and the cultivation of an individual for consumption, respectively. An ant exclusion study over 12 days of isolation showed that adult female diaspidids and second-instar nymphs secreted no wax or exudates that attending ants would ordinarily collect. Workers of M. emeryi did not defend their nest against invading colonies of Crematogaster and other unidentified ants: we hypothesize that the primary mode of defence is maintenance of isolation within galleries. We describe three new ant-associated diaspidid species: Affirmaspis cederbergensis Schneider sp.n. from South Africa, Diaspis doumtsopi Schneider sp.n. from Cameroon, and Melissoaspis incola Schneider sp.n. from Madagascar. Melissoaspis formicaria (Ben-Dov) comb.n. is transferred from Morganella (Brain). Diagnostic characteristics for Melissoaspis Ben-Dov are revised, and additional taxonomic information defining this genus allows ease of identification. An updated identification key to the species of ant-associated diaspidids is provided

Nuclear and mitochondrial sequences confirm complex colonization patterns and clear species boundaries for flightless weevils in the Galápagos archipelago

Nuclear sequence data were collected from endemic Galápagos species and an introduced close relative, and contrasted with mitochondrial DNA sequences, continuing investigation into the colonization history and modes of diversification in the weevil genus Galapaganus. The current combined phylogeny together with previously published penalized likelihood age estimates builds a complex picture of the archipelago's colonization history. The present reconstruction relies on submerged platforms to explain the early divergence of the young southern Isabela endemics or the Española or San Cristobal populations. Diversity is later built through inter-island divergence starting on older islands and continuing on two simultaneous tracks towards younger islands. The amount of diversity generated through intra-island processes is skewed towards older islands, suggesting that island age significantly influences diversity. Phylogenetic concordance between nuclear and mitochondrial datasets and well-supported monophyletic species in mitochondrial derived topologies appear to reject the possibility of inter-species hybridization. These clear species boundaries might be related to the tight host associations of adult weevils in discrete ecological zones. If shared hosts facilitate hybridization, then host- or habitat-promoted divergences could prevent it, even in the case of species that share islands, since the altitudinal partitioning of habitats minimizes range overlap

Fungal genus Hypocrea/Trichoderma: from barcodes to biodiversity* §

Hypocrea/Trichoderma is a genus of soil-borne or wood-decaying fungi containing members important to mankind as producers of industrial enzymes and biocontrol agents against plant pathogens, but also as opportunistic pathogens of immunocompromised humans and animals, while others can cause damage to cultivated mushroom. With the recent advent of a reliable, BarCode-aided identification system for all known taxa of Trichoderma and Hypocrea, it became now possible to study some of the biological fundamentals of the diversity in this fungal genus in more detail. In this article, we will therefore review recent progress in (1) the understanding of the geographic distribution of individual taxa; (2) mechanisms of speciation leading to development of mushroom diseases and facultative human mycoses; and (3) the possible correlation of specific traits of secondary metabolism and molecular phylogeny