Pest categorisation of Eulecanium giganteum

The EFSA Panel on Plant Health performed a pest categorisation of Eulecanium giganteum (Hemiptera: Coccidae), the giant eulecanium scale, for the territory of the European Union, following the commodity risk assessment of Acer palmatum plants from China, in which E. giganteum came to attention as a pest of possible concern. The pest is only known to be present in Asia, where it has been reported from China, India, Iran, Japan and eastern Russia (Primorsky Krai). The pest has not been reported within the EU. It is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is polyphagous, feeding on broad-leaf trees and shrubs assigned to 41 genera in 22 plant families. Host plant species commonly found in the EU include apricot (Prunus armeniaca), elm (Ulmus spp.), grapevine (Vitis vinifera), maple (Acer spp.), oak (Quercus spp.), oriental plane (Platanus orientalis), pomegranate (Punica granatum), quince (Cydonia oblonga), silkworm mulberry (Morus alba), walnut (Juglans regia), and several ornamentals. Climatic conditions and availability of host plants in southern EU countries would most probably allow this species to successfully establish and spread. However, EU native natural enemies are anticipated to provide biological control and therefore reduce potential impacts. Phytosanitary measures are available to reduce the likelihood of entry and spread. E. giganteum satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest, other than the criterion on impact which is a key uncertainty.

Pest categorisation of Didesmococcus unifasciatus

The EFSA Panel on Plant Health performed a pest categorisation of Didesmococcus unifasciatus (Hemiptera: Sternorrhyncha: Coccidae) for the EU following commodity risk assessments of Malus domestica (apple), Prunus dulcis (almond) and P. persica (peach) plants for planting from Türkiye in which D. unifasciatus was identified as a pest that could potentially enter the EU. It was first described in Uzbekistan and is widely distributed in Central and Western Asia, including Türkiye (where it was recently reported as limited to the Hakkari and Diyarbakir regions in the Asian part of the country). It has not been reported within the EU. It is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It completes one generation per year; a female lays between 1,500 and 2,400 eggs. It feeds on several important fruit trees of the family Rosaceae (e.g. P. dulcis, M. domestica), as well as Ficus carica and Ulmus sp. Most of its hosts are widely cultivated in the EU. Woody plants for planting and cut branches are the main potential pathways for entry of D. unifasciatus into the EU. Climatic conditions and availability of host plants would likely allow this species to establish and spread in southern parts of the EU. Just as in other invaded areas, the presence of many of its natural enemies in the EU is likely to prevent the scale from becoming an economic or environmental pest. Nevertheless, phytosanitary measures are available to reduce the likelihood of entry and spread. Considering the weight of evidence, D. unifasciatus does not meet all the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Pest categorisation of Takahashia japonica

The EFSA Panel on Plant Health performed a pest categorisation of Takahashia japonica (Hemiptera: Sternorrhyncha: Coccidae), the Asian string cottony scale, for the EU. This insect is native to Japan, and it is now established in many countries in Asia. It was first recorded in the EU (Italy) in 2017 and has also been found in Croatia. It is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is polyphagous, feeding on broad-leafed trees and shrubs assigned to 25 genera belonging to 17 families. Host plant species commonly found in EU include maple (Acer spp.), alder (Alnus japonica), silkworm mulberry (Morus alba), black mulberry (Morus nigra), quince (Cydonia oblonga), walnut (Juglans regia), cherry plum (Prunus cerasifera), apple (Malus domestica) and citrus (Citrus sp.). Climatic conditions and availability of host plants in southern and central EU countries have allowed this species to establish and spread. Impact in cultivated hosts including citrus, mulberries, quinces, apples, plums, forest trees, as well as ornamental plants, is anticipated. Phytosanitary measures are available to reduce the likelihood of entry and further spread. T. japonica meets the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Pest categorisation of Milviscutulus mangiferae

The EFSA Panel on Plant Health performed a pest categorisation of Milviscutulus mangiferae (Hemiptera: Sternorrhyncha: Coccidae), the mango shield scale, for the EU. The native range of M. mangiferae is uncertain. This species occurs widely in tropical and warmer subtropical regions throughout the world. Within the EU, the pest has been recorded in Italy in a greenhouse at the Botanical Garden of Padua on mango trees imported from Florida (USA); however, its establishment remains uncertain. It is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is polyphagous, feeding on plant species belonging to more than 86 genera in more than 43 families including many crop and ornamental plants. It can be a serious pest of mango (Mangifera indica) and an occasional pest of a range of ornamental plants. Economically important crops in the EU such as citrus (Citrus spp.), avocado (Persea americana) and ornamentals such as hibiscus (Hibiscus spp.) and myrtle (Myrtus communis), are included in the host list of M. mangiferae. Reproduction of M. mangiferae is generally parthenogenetic and it completes two to three generations annually. Plants for planting, cut flowers and fruits provide potential pathways for entry into the EU. Climatic conditions in southern EU countries and host plant availability in those areas are conducive for establishment and spread. Establishment could also occur in heated greenhouses in cooler areas of the EU. The introduction of the mango shield scale is expected to have an economic impact in the EU through the reduction in yield, quality and commercial value of fruits and ornamental plants. Phytosanitary measures are available to reduce the likelihood of entry and further spread. M. mangiferae meets the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Mitochondrial genomes of soft scales (Hemiptera: Coccidae): features, structures and significance

BACKGROUND

Soft scales (Hemiptera: Coccidae), including important agricultural and forestry pests, are difficult to identify directly by morphological characters. Mitochondrial genomes (mitogenomes) have been widely used in species identification and phylogenetic research. However, only three complete mitogenomes, and very few mitochondrial genes of scale insects (Hemiptera: Coccoidea) can be searched in GenBank. Mitogenome comparisons between scale insects or between scale insects and other hemipteran species have not yet been reported.

RESULTS

In this study, detailed annotation of three new mitogenomes and comparative analysis of scale insects were completed, as well as comparative analysis of the gene composition, gene arrangement, codon usage and evolutionary forces between scale insects and 488 other hemipteran species for the first time. We found that high A + T content, gene rearrangement and truncated tRNAs are common phenomena in soft scales. The average A + T content and codon usage bias of scale insects are higher and stronger than those of other hemipteran insects, respectively. The atp8 gene of Hemiptera and nine other protein-coding genes of scale insects are under positive selection with higher evolutionary rates.

CONCLUSIONS

The study revealed the particularity of the scale insect mitogenomes, which will provide a good reference for future research on insect phylogenetic relationships, insect pest control, biogeography and identification.

Pest categorisation of Pulvinaria psidii

The EFSA Panel on Plant Health performed a pest categorisation of Pulvinaria psidii (Hemiptera: Coccidae), the green shield scale, for the EU. P. psidii was originally described from Hawaii on Psidium sp. and it is now established in many countries in tropical and subtropical regions of the world. Within the EU, the pest has been reported from mainland Spain and the Canary Islands. P. psidii is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is highly polyphagous, feeding on 230 plant species belonging to more than 70 botanical families with preference for avocado (Persea americana), citrus (Citrus spp.), coffee (Coffea sp.), guava (Psidium guajava), litchi (Litchi chinensis), mango (Mangifera indica), mulberry (Morus sp.) and pomegranate (Punica granatum). It has also been recorded feeding on some solanaceous plants: tomato (Solanum lycopersicum) and pepper (Capsicum annuum), as well as on ornamental plants. Climatic conditions and availability of host plants in southern EU countries would most probably allow this species to successfully establish and spread. Economic impact in cultivated hosts including citrus, mangoes, mulberries, as well as vegetable and ornamental crops is anticipated if establishment occurs. Indeed, P. psidii has already been reported causing damage to Melia azedarach, a widely used ornamental tree that lines streets in Valencia. There is contradictory information regarding impact in mangoes in Spain. This could be due to the relatively recent establishment of the pest. Phytosanitary measures are available to reduce the likelihood of entry and further spread. P. psidii meets the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Transmission of Grapevine leafroll-associated virus-1 (Ampelovirus) and Grapevine virus A (Vitivirus) by the Cottony Grape Scale, Pulvinaria vitis (Hemiptera: Coccidae)

The cottony grape scale Pulvinaria vitis is a scale insect colonizing grapevine; however, its capacity as a vector of grapevine viruses is poorly known in comparison to other scale species that are vectors of viral species in the genera Ampelovirus and Vitivirus. The ability of P. vitis to transmit the ampeloviruses Grapevine leafroll-associated viruses [GLRaV]−1, −3, and −4, and the vitivirus Grapevine virus A (GVA), to healthy vine cuttings was assessed. The scale insects used originated from commercial vine plots located in Alsace, Eastern France. When nymphs sampled from leafroll-infected vineyard plants were transferred onto healthy cuttings, only one event of transmission was obtained. However, when laboratory-reared, non-viruliferous nymphs were allowed to acquire viruses under controlled conditions, both first and second instar nymphs derived from two vineyards were able to transmit GLRaV−1 and GVA. This is the first report of GLRaV−1 and GVA transmission from grapevine to grapevine by this species.

Rediscovering digitules in Aphidomorpha and the question of homology among Sternorrhyncha (Insecta, Hemiptera)

We explore and expand on the morphological term digitule. The term was originally proposed for toe-like setae on a species of Phylloxera Boyer de Fonscolombe, 1834 (Hemiptera, Sternorrhyncha, Aphidomorpha) by Henry Shimer, an American naturalist. While it is standard terminology in scale systematics (Hemiptera, Sternorrhyncha, Coccidomorpha), the term digitule was ignored by aphid specialists despite being the original taxon for which the term was described. Similar setae occur on many arthropod groups, so the homology is poorly understood even within any superfamily of Hemiptera. We provide the etymology of the term, a proposed explanation for why it was used among scale taxonomists and not aphid taxonomists, and discuss briefly options to progress beyond the confusion between terminology for morphology and homology in Sternorrhyncha.

Redescription of the red-striped soft scale, Pulvinaria tenuivalvata (Newstead), with a new synonymy (Hemiptera, Coccomorpha, Coccidae)

The soft scale, Pulvinariatenuivalvata (Newstead, 1911), is a major pest of sugarcane in Egypt. This paper provides a redescription and illustration of the adult female based on a microscopic study of the morphology of several adult female specimens and of the type series illustrated by De Lotto (1965) on citronella grass from Uganda. Two paratypes of Pulvinariasaccharia De Lotto, 1964 are also studied and the name is placed here as a junior synonym of Pulvinariatenuivalvata.

Scale insect larvae preserved in vertebrate coprolites (Le Quesnoy, France, Lower Eocene): paleoecological insights

Coprolites of terrestrial vertebrates from the Sparnacian Le Quesnoy locality (Ypresian, Eocene, MP7, 53 Ma; Oise, France) were examined for possible parasitic helminth eggs. The extraction of the coprolite components was performed by a weak acetolyse and a slide mounting in glycerin. This long examination did not reveal paleoparasite remains, which may be explained through several arguments. However, some pollen grains, some enigmatic components, and two well-preserved first-instar cochineal nymphs (Hemiptera: Sternorrhyncha: Coccoidea) were evidenced in coprolites. Identified as Coccidae, these larvae are the earliest stage of the scale insect development ever reported as fossil, revealing the specific environment of preservation that fossilized scats may provide. These observations, combined to the coprolites morphotype, enable to ascribe the fossil scats producer to a small herbivorous mammal present in the deposit (early perissodactyls or Plesiadapidae). Regarding the ecology of extant representatives of Coccidae, this mammal was a likely foliage consumer, and the abundant Juglandaceae and/or Tiliaceae from Le Quesnoy might have lived parasitized by scale insects. These Early Eocene parasites had an already well-established dissemination strategy, with prevalent minute first-instar larvae. The herein performed extraction technique appears well-suited for the study of carbonate coprolites and could certainly be useful for evidencing other kind of microorganisms (including internal parasites).

Encyrtid parasitoids of soft scale insects: biology, behavior, and their use in biological control

Parasitoids of the hymenopterous family Encyrtidae are one of the most important groups of natural enemies of soft scale insects and have been used extensively in biological control. We summarize existing knowledge of the biology, ecology, and behavior of these parasitoids and how it relates to biological control. Soft scale stage/size and phenology are important determinants of host range and host utilization, which are key aspects in understanding how control by these parasitoids is exerted. Furthermore, the nutritional ecology of encyrtids and their physiological interactions with their hosts affect soft scale insect population dynamics. Lastly, the interactions among encyrtids, heteronomous parasitoids, and ants shape parasitoid species complexes and consequently have a direct impact on the biological control of soft scale insects.

Preliminary study of wing interference patterns (WIPs) in some species of soft scale (Hemiptera, Sternorrhyncha, Coccoidea, Coccidae)

The fore wings of scale insect males possess reduced venation compared with other insects and the homologies of remaining veins are controversial. The hind wings are reduced to hamulohalterae. When adult males are prepared using the standard methods adopted to females and nymphs, i.e. using KOH to clear the specimens, the wings become damaged or deformed, an so these structures are not usually described or illustrated in publications. The present study used dry males belonging to seven species of the family Coccidae to check the presence of stable, structural colour patterns of the wings. The visibility of the wing interference patterns (WIP), discovered in Hymenoptera and Diptera species, is affected by the way the insects display their wings against various backgrounds with different light properties. This frequently occurring taxonomically specific pattern is caused by uneven membrane thickness and hair placement, and also is stabilized and reinforced by microstructures of the wing, such as membrane corrugations and the shape of cells. The semitransparent scale insect’s fore wings possess WIPs and they are taxonomically specific. It is very possible that WIPs will be an additional and helpful trait for the identification of species, which in case of males specimens is quite difficult, because recent coccidology is based almost entirely on the morphology of adult females.