Alessio De Biase

Effects of the Diet on the Microbiota of the Red Palm Weevil (Coleoptera: Dryophthoridae)

Rhynchophorus ferrugineus, also known as the red palm weevil, is regarded as the major pest of palm trees. Although studies of the microbiota associated with this species have been performed in recent years, little attention has been dedicated to the influence of the diet in shaping the host bacterial community. Here, we investigated the influence of food sources (i.e. palm tissues vs apple based substrate) on the microbial diversity associated with RPW, which was compared with the microbiota associated with wild individuals of the sister species Rhynchophorus vulneratus. The bacterial characterization was performed using a culture independent approach, i.e. the 16S rRNA pyrotag, and a culture dependent approach for a subset of the samples, in order to obtain bacterial isolates from RPW tissues. The bacterial community appeared significantly influenced by diet. Proteobacteria resulted to be the most abundant clade and was present in all the specimens of the three examined weevil groups. Within Proteobacteria, Enterobacteriaceae were identified in all the organs analysed, including hemolymph and reproductive organs. The apple-fed RPWs and the wild R. vulneratus showed a second dominant taxon within Firmicutes that was scarcely present in the microbiota associated with palm-fed RPWs. A comparative analysis on the bacteria associated with the palm tissues highlighted that 12 bacterial genera out of the 13 identified in the plant tissues were also present in weevils, thus indicating that palm tissues may present a source for bacterial acquisition.

Molecular re-examination of the taxonomy of the Meligethes viridescens species complex (Coleoptera: Nitidulidae)

Abstract Allozyme and RAPD analysis were performed to clarify taxonomic relationships within the Meligethes viridescens complex (Coleoptera, Nitidulidae, Meligethinae). Five populations from Central Italy belonging to three species: M. viridescens , M. czwalinai , and a new undescribed species ( M . sp. cfr. viridescens ), and one population of the morphologically well-differentiated M. aeneus were analysed. The degree of observed genetic differentiation supports separation at the specific rank of M. viridescens , M. czwalinai , and M . sp. cfr. viridescens . The species’ ecology and morphological observations based on scanning electron microscopy also supports such a taxonomic separation. The M13 RAPD primer is a diagnostic marker for distinguishing the four species. Estimates of divergence times calculated from allozymic genetic distance data suggest that the pattern of differentiation observed may be related to the palaeoclimatic changes during the Plio/Pleistocene ice cycles in southern Europe.

DNA Fingerprinting to Improve Data Collection Efficiency and Yield in an Open-Field Host-Specificity Test of a Weed Biological Control Candidate

Abstract An open-field test was conducted in southern France to assess the host-specificity of Ceratapion basicorne (Illiger), a candidate for biological control of yellow starthistle. Test plants were infested by naturally occurring populations of C. basicorne but were also exposed to sympatric herbivore species, including other Ceratapion spp. Insects from the test plants were collected directly into tubes of ethanol and were subsequently identified to species according to DNA sequence similarity with morphologically identified reference specimens. This integrated, morphological and molecular identification method was used in an effort to maximize the amount of data gained in the field bioassay and to minimize the number of taxonomist–hours necessary to complete the study. The results obtained showed that the French C. basicorne population only attacked yellow starthistle and cornflower, another known host of C. basicorne. Molecular phylogenetic analysis of the insects collected from all other nonhost plants rejected the possibility that any were C. basicorne. Nomenclature: Cornflower, Centaurea cyanus L. CENCY; yellow starthistle, Centaurea solstitialis L. CENSO; Ceratapion basicorne (Illiger)

Redescription and natural history of Meligethes longulus Schilsky, 1894, and provisional revision of the M. coracinus species‐complex (Coleoptera, Nitidulidae, Meligethinae)

Abstract The taxonomic identification and a re‐description of the problematic Meligethes longulus Schilsky, 1894 from eastern Turkey are presented. This species, belonging to the M. coracinus complex and known so far on the basis of a single immature holo‐type, was repeatedly confused in the past with other closely related taxa, thus introducing considerable instability in the nomenclature and taxonomy of the whole group, involving several distinct biological species throughout southern Europe and western Asia. The recent re‐discovery of this species in eastern Turkey allowed M. longulus to be definitely identified as being an extremely rare and localized species, with larval stages strictly associated with the host‐plant Matthiola odoratissima (Bieb.) R.Br. (Brassicaceae), in dry exposed terrigenous and sandy hill slopes of eastern Turkey. An updated key to the identification of both described and un‐described members of the M. coracinus complex is also presented, and a rather isolated species of the M. coracinus complex from southern Turkey, M. cristofaroi n. sp., is described as new. A preliminary evolutionary scenario of the whole species‐complex, based also on results from a companion molecular research, is finally discussed.

Specific distinction by allozymic data of sympatric sibling species of the pollen-beetle genus Meligethes (Coleoptera, Nitidulidae)

Abstract An allozyme analysis was performed, combined with field data on insect/host‐plant associations, in order to clarify taxonomic relationships within the W‐Palaearctic Meligethes coracinus complex (Coleoptera, Nitidulidae, Meligethinae). The analysis was focused on the specific distinction of M. coracinus, M. matronalis and M. subaeneus, with special regard to the last two species occurring in sympatry. Alternative fixed and unique alleles were scored at several loci. The genetic distances between M. matronalis, M. subaeneus and M. coracinus (0.198–0.572) were in the range of values usually scored between closely related insect species. Genetic data and ecological evidence clearly show that M. matronalis and M. subaeneus, erroneously synonymized in a recent paper, are distinct biological species that frequently occur in syntopy in central and southern Europe, on different larval host plants, although they rarely show synchronous phenology. Their specific differentiation likely occurred during the palaeoclimatic changes of the Plio‐Pleistocene ice cycles in southern Europe.

A new genus of pollen-beetle from South Africa (Coleoptera: Nitidulidae), with discussion of the generic classification of the subfamily Meligethinae

The pollen-beetle Sebastiangethes anthystrixoides, n.gen., n.sp. from northern South Africa is described. The taxonomic position of Sebastiangethes, the related genus Anthystrix Kirejtshuk, 1981, as well as a relatively large assemblage of partially undescribed allied African taxa is discussed in the context of the Oriental genus Cyclogethes Kirejtshuk, 1979. An informal taxonomic assemblage named “Anthystrix-complex of genera” is here introduced. The previously unknown larval host-plants of African members of this “Anthystrix-complex of genera” are identified as dioecious trees belonging to Asteraceae within the tribe Tarchonantheae (genera Tarchonanthus and Brachylaena). Concepts of the generic and subgeneric classification of the subfamily Meligethinae also are discussed.

The importance of cryptic species and subspecific populations in classic biological control of weeds: a North American perspective

Classical biological control of weeds depends on finding agents that are highly host-specific. This requires not only correctly understanding the identity of the target plant, sometimes to subspecific levels, in order to find suitable agents, but also identifying agents that are sufficiently specific to be safe and effective. Behavioral experiments and molecular genetic tools have revealed that some arthropod species previously thought to be polyphagous really consist of multiple cryptic species, host races or biotypes, some of which are more host-specific than others. Whereas true species are reproductively isolated, individuals from subspecific populations may potentially interbreed with those of other populations if they should encounter them. Furthermore, biotypes may consist of individuals sharing a genotype that is not fixed within a monophyletic group, and thus may not be evolutionarily stable. This raises the question of how such populations should be classified, and how to confirm the identity of live arthropods before releasing them as classical biological control agents. The existence of host races or cryptic species may greatly increase the number of prospective biological control agents available. However, it may also create new challenges for governmental regulation. These issues are discussed using pertinent examples, mainly from North America.

Environmental heterogeneity effects on predator and parasitoid insects vary across spatial scales and seasons: a multi-taxon approach

As predator and parasitoid insects depend on multiple resources for adult feeding and reproduction, environmental heterogeneity (EH) is expected to be a key driver of their species diversity. In temperate regions, the benefits of EH are expected to vary across spatial scales and seasons, depending on species life‐history traits and temporal fluctuations in resources. We tested the importance of EH at multiple spatial scales on diversity and abundance of predator and parasitoid insects, and whether its effects changed across seasons. Insect sampling was carried out in highly fragmented landscapes in a Mediterranean region (Tuscany, Central Italy). We selected 18 semi‐natural patches, embedded in an intensive agricultural matrix. For each patch, EH was measured at three spatial scales (micro, patch, and landscape). Five groups of predator and parasitoid insects were sampled 16 times with pan traps between March and November, 2012. EH at the landscape scale positively influenced the diversity of predator and parasitoid insects, while the effects at smaller spatial scales were less evident. The strength and the direction of EH˗diversity relationship changed between groups and across seasons, indicating that the mechanisms by which EH affects predators and parasitoids are various and complex. Conservation strategies aimed at maximising the diversity of predators and parasitoids should focus more on increasing EH at the landscape scale than at the local scale.

Morphological, genetic and host-plant diversification in pollen-beetles of the Brassicogethes coracinus group (Coleoptera: Nitidulidae: Meligethinae)

The 17 known members of the mostly Western Palaearctic Brassicogethes coracinus species group (highly specialized pollen beetles associated with flowers of Brassicaceae) were re-analyzed, with the aim to reconstruct their phylogenetic relationships and the pattern of evolution of their larval/host-plant associations. Evidence from mtDNA data (COI marker), combined with an estimation of divergence times, placed the main differentiation of the clade around 5 My with most species likely differentiated in the last 1–2 My. Combined evidence from mtDNA, morphology and ancestral state parsimony reconstruction of larval/host-plant associations, suggested that Brassicaceae of the tribe Brassiceae likely represented the ancestral host plants for the group, with a subsequent series of independent host shifts during the evolution and radiation of the clade (in association first with Cardamineae, and later with Arabideae, Sisymbrieae, Erysimeae, Hesperideae and Anchonieae). Molecular and ecological evidence also suggests the need to formally separate European populations of the widespread Brassicogethes subaeneus (Sturm, 1845) into two distinct and widely sympatric cryptic taxa, one of them described herein as new (Brassicogethes cardaminicola sp. nov.). The neotype of the true B. subaeneus is also herein designated.

In silico mining of microsatellite markers for the Red Palm Weevil as contribution to its invasion management

The Red Palm Weevil is an invasive pest causing huge damages by attacking several palm species of the family Arecaeae. One of the most important challenges of conservation biology for the near future is the management of biological invasions and their effects. In this study we used 454 pyrosequencing and in silico mining to identify novel microsatellite markers for investigating the reproductive biology and the invasion dynamics, crucial to plan the control strategies against the pest. We report 14 variable microsatellites out of 37 screened for levels of polymorphism. Allele number per locus ranged between 2 and 15 and Ho from 0.04 to 0.86.