Nonadaptive host-use specificity in tropical armored scale insects

Pest categorisation of Morganella longispina

Following the commodity risk assessment of Acer palmatum plants grafted on Acer davidii from China, in which Morganella longispina (Hemiptera: Diaspididae) was identified as a pest of possible concern, the European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of M. longispina for the territory of the European Union (EU). The origin of the scale insect M. longispina is uncertain, with either South America or eastern Asia suggested as the native range. The geographic distribution of the species includes many countries of the continents of Africa, North and South America, Asia and Oceania. M. longispina is polyphagous, feeding on plants assigned to 86 genera in 42 families. Important crops of the EU that may be affected by this insect are avocado, citrus, fig, peach, plum, olive and walnut. It is a viviparous insect with several generations per year in Algeria. Host availability and climate suitability indicate that the southern EU countries would support the establishment of M. longispina. The introduction of this pest would likely have an economic impact on several crops in the EU as it can cause significant damage to host plants. Uncertainty exists, however, about the magnitude of yield and quality losses due to the insect, and this is a key uncertainty. M. longispina is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. Phytosanitary measures are available to reduce the likelihood of entry, establishment and spread of the pest into the EU. All criteria assessed by EFSA for consideration as a potential quarantine pest are met.

Taxon-specific ultraconserved element probe design for phylogenetic analyses of scale insects (Hemiptera: Sternorrhyncha: Coccoidea)

Scale insects (Coccoidea) are morphologically specialized members of the order Hemiptera, with 56 families recognized to date. However, the phylogenetic relationships within and among families are poorly resolved. In this study, to further characterize the phylogenetic relationships among scale insects, an ultraconserved element (UCE) probe set was designed specifically for Coccoidea based on three low-coverage whole genome sequences along with three publicly available genomes. An in silico test including eight additional genomes was performed to evaluate the effectiveness of the probe set. Most scale insect lineages were recovered by the phylogenetic analysis. This study recovered the monophyly of neococcoids. The newly developed UCE probe set has the potential to reshape and improve our understanding of the phylogenetic relationships within and among families of scale insects at the genome level.

Jack-of-all-trades paradigm meets long-term data: Generalist herbivores are more widespread and locally less abundant

Insect herbivores are relatively specialized. Why this is so is not clear. We examine assumptions about associations between local abundance and dietary specialization using an 18-year data set of caterpillar-plant interactions in Ecuador. Our data consist of caterpillar-plant associations and include standardized plot-based samples and general collections of caterpillars, allowing for diet breadth and abundance estimates across spatial scales for 1917 morphospecies. We find that more specialized caterpillars are locally more abundant than generalists, consistent with a key component of the 'jack of all trades, master of none' hypothesis. As the diet breadth of species increased, generalists were not as abundant in any one location, but they had broader occupancy across the landscape, which is a pattern that could reflect high plant beta diversity and is consistent with an alternative neutral hypothesis. Our finding that more specialized species can be both rare and common highlights the ecological complexity of specialization.

Diversity, distribution and host plants of armored scale insects (Hemiptera: Diaspididae) in Espírito Santo, Brazil

Abstract: Armored scale insects (Hemiptera: Diaspididae), are phytophagous species that occur in major biogeographic regions of the world. Because of the importance of diaspidids as pests, there is widespread interest in countries that export and import unprocessed agricultural products in increased knowledge of this group which includes invasive and quarantine pests of great economic concern. The diversity, geographic distribution, and host of diaspidids were studied from November 2002 to December 2018 in 34 municipalities in the state of Espírito Santo, Brazil. Forty species of Diaspididae from 27 genera were collected and identified. The species Acutaspis perseae (Comstock), A. umbonifera (Newstead), Aonidiella aurantii (Maskell), Comstockaspis perniciosa (Comstock), Lepidosaphes beckii (Newman), Lepidosaphes gloverii (Packard), Morganella longispina (Morgan), Mycetaspis apicata (Newstead), and Thysanofiorinia nephelii (Maskel) were found for the first time in Espírito Santo. The plant families Myrtaceae, Moraceae, Arecaceae, Asparagaceae, and Rutaceae had the greatest number of host plant species of armored scale. Fifty-seven new host associations were observed for 25 species of diaspidids and 11 diaspidid species were recorded for the first time from nine families of plants. Selenaspidus articulatus (Morgan) was the most polyphagous species observed with 17 host plant species from 12 families, followed by Pseudaonidia trilobitiformis (Green), and Parlatoria proteus (Curtis). With these new records, 41 species and 28 genera of Diaspididae have been recorded in Espírito Santo.

Four new species of Aspidiotini (Hemiptera, Diaspididae, Aspidiotinae) from Panama, with a key to Panamanian species

Four new species of armored scale insect, Clavaspisselvaticasp. nov., Clavaspisvirolaesp. nov., Davidsonaspistovomitaesp. nov., and Rungaspisneotropicalissp. nov., are described and illustrated from Panama. We also transfer two previously described species of Panamanian Aspidiotini to new genera, Hemiberlesiacrescentiae (Ferris) comb. nov. and Rungaspisrigida (Ferris) comb. nov., and report the first record of Selenaspidopsisbrowni Nakahara in Panama. A key to the species of Aspidiotini occurring in Panama is provided.

What We Don't Know About Diet-Breadth Evolution in Herbivorous Insects

Half a million species of herbivorous insects have been described. Most of them are diet specialists, using only a few plant species as hosts. Biologists suspect that their specificity is key to their diversity. But why do herbivorous insects tend to be diet specialists? In this review, we catalog a broad range of explanations. We review the evidence for each and suggest lines of research to obtain the evidence we lack. We then draw attention to a second major question, namely how changes in diet breadth affect the rest of a species’ biology. In particular, we know little about how changes in diet breadth feed back on genetic architecture, the population genetic environment, and other aspects of a species’ ecology. Knowing more about how generalists and specialists differ should go a long way toward sorting out potential explanations of specificity, and yield a deeper understanding of herbivorous insect diversity.