Soft Scale Insects Research Articles

Immune Gene Repertoire of Soft Scale Insects (Hemiptera: Coccidae).

Insects possess an effective immune system, which has been extensively characterized in several model species, revealing a plethora of conserved genes involved in recognition, signaling, and responses to pathogens and parasites. However, some taxonomic groups, characterized by peculiar trophic niches, such as plant-sap feeders, which are often important pests of crops and forestry ecosystems, have been largely overlooked regarding their immune gene repertoire. Here we annotated the immune genes of soft scale insects (Hemiptera: Coccidae) for which omics data are publicly available. By using immune genes of aphids and Drosophila to query the genome of Ericerus pela, as well as the transcriptomes of Ceroplastes cirripediformis and Coccus sp., we highlight the lack of peptidoglycan recognition proteins, galectins, thaumatins, and antimicrobial peptides in Coccidae. This work contributes to expanding our knowledge about the evolutionary trajectories of immune genes and offers a list of promising candidates for developing new control strategies based on the suppression of pests' immunity through RNAi technologies.

First record of the genus Marsipococcus Cockerell & Bueker (Hemiptera: Coccomorpha: Coccidae) from China, with description of a new species

The soft scale insect genus Marsipococcus Cockerell & Bueker, 1930 (Hemiptera: Coccomorpha: Coccidae) is reported for the first time from China; a new species, Marsipococcus brideliae sp. n., is described and illustrated from Guizhou Province on Bridelia retusa (Phyllanthaceae). A key is given to distinguish all four species in the genus. Type specimens of the new species are deposited at the Institute of Entomology, Guizhou University, Guiyang, China and the collection at the Department of Forestry Protection, Beijing Forestry University, Beijing.

Mixed insect pest populations of Diaspididae species under control of oligonucleotide insecticides: 3′-end nucleotide matters

Diaspididae are one of the most serious small herbivorous insects with piercing–sucking mouth parts and are major economic pests as they attack and destroy perennial ornamentals and food crops. Chemical control is the primary management approach for armored scale infestation. However, chemical insecticides do not possess selectivity in action and not always effective enough for the control of armored scale insects. Our previous work showed that green oligonucleotide insecticides (olinscides) are highly effective against armored and soft scale insects. Moreover, olinscides possess affordability, selectivity in action, fast biodegradability, and a low carbon footprint. Insect pest populations undergo microevolution and olinscides should take into account the problem of insecticide resistance. Using sequencing results, it was found that in the mixed populations of insect pests Dynaspidiotus britannicus Newstead and Aonidia lauri Bouche, predominates the population of A. lauri. Individuals of A. lauri comprised for 80% of individuals with the sequence 3′-ATC-GTT-GGC-AT-5′ in the 28S rRNA site, and 20% of the population comprised D. britannicus individuals with the sequence 3′-ATC-GTC-GGT-AT-5′. We created olinscides Diasp80–11 (5′-ATG-CCA-ACG-AT-3′) and Diasp20–11 (5′-ATA-CCG-ACG-AT-3′) with perfect complementarity to each of the sequences. Mortality of insects on the 14th day comprised 98.19 ± 3.12% in Diasp80–11 group, 64.66 ± 0.67% in Diasp20–11 group (p < 0.05), and 3.77 ± 0.94% in the control group. Results indicate that for maximum insecticidal effect it is necessary to use an oligonucleotide insecticide that corresponds to the dominant species. Mortality in Diasp80–11 group was accompanied with significant decrease in target 28S rRNA concentration and was 8.44 ± 0.14 and 1.72 ± 0.36 times lower in comparison with control (p < 0.05) on the 10th and 14th days, respectively. We decided to make single nucleotide substitutions in Diasp20–11 olinscide to understand which nucleotide will play the most important role in insecticidal effect. We created three sequences with single nucleotide transversion substitutions at the 5′-end – Diasp20(5′)-11 (A to T), 3′-end – Diasp20(3′)-11 (T to A), and in the middle of the sequence – Diasp20(6)-11 (6th nitrogenous base of the sequence; G to C), respectively. As a result, mortality of mixed population of the field experiment decreased and comprised 53.89 ± 7.25% in Diasp20(5′)-11 group, 40.68 ± 4.33% in Diasp20(6)-11 group, 35.74 ± 5.51% in Diasp20(3′)-11 group, and 3.77 ± 0.94% in the control group on the 14th day. Thus, complementarity of the 3′-end nucleotide to target 28S rRNA was the most important for pronounced insecticidal effect (significance of complementarity of nucleotides for insecticidal effect: 5′ nt < 6 nt < 3′ nt). As was found in our previous research works, the most important rule to obtain maximum insecticidal effect is complete complementarity to the target rRNA sequence and maximum coverage of target sequence in insect pest populations. However, in this article we also show that the complementarity of 3′-end is a second important factor for insecticidal potential of olinscides. Also in this article we propose 2-step DNA containment mechanism of action of olinscides, recruiting RNase H. The data obtained indicate the selectivity of olinscides and at the same time provide a simple and flexible platform for the creation of effective plant protection products, based on antisense DNA oligonucleotides.

Description of a new species of the genus Paralecanium Cockerell & Bueker (Hemiptera: Coccomorpha: Coccidae) from China.

A new species of soft scale insect (Hemiptera: Coccomorpha: Coccidae) belonging to the genus Paralecanium Cockerell & Bueker, P. sabia Tan, Meng & Xing sp. n., is described and illustrated. It was found on the leaves of Sabia swinhoei Hemsl (Sabiaceae) in Guizhou Maolan National Nature Reserve, Guizhou Province, China. Habitat photographs and illustrations are provided. The type material of P. sabia sp. n. is deposited at the Institute of Entomology, Guizhou University, Guiyang, China (GUGC) and in the insect collection at the Department of Forestry Protection, Beijing Forestry University, Beijing, China (NFUC). An identification key to separate the 28 species in Paralecanium, based on the morphology of adult females, is provided.

Investigations on the immature stages of some species of Eulecaniinae (Hemiptera: Coccomorpha: Coccidae).

The dependence on adult female morphology for the determination of soft scale insect species (Hemiptera: Coccomorpha: Coccidae) creates several problems. In this paper, various nymphal stages of soft scale insects from the Ankara district of Trkiye and Israel, belonging to Coccidae: subfamily Eulecaniinae, namely Eulecanium cerasorum (Cockerell), E. ciliatum (Douglas), E. tiliae (Linnaeus), Paleolecanium bituberculatum (Signoret), Physokermes piceae (Schrank) and Rhodoccus perornatus (Cockerell & Parrott) were studied. The morphology of all the nymphal stages of these species is described and illustrated, and identification keys are provided to each instar. The results show that nymphal stages can be used to accurately identify soft scale insect species.

Identification of Some Species of the Family Coccidae that Infest Fruit Orchards in Syria

Saleh, A.T. and A.M. Basheer. 2024. Identification of Some Species of the Family Coccidae that Infest Fruit Orchards in Syria. Arab Journal of Plant Protection, 42(2): 174-183. https://doi.org/10.22268/AJPP-001224 Soft scale insects are serious plant pests, are often small and highly cryptic. These pests are economically important in agriculture. Insect samples and infested plant parts were collected during the period April to June 2016 and 2017 from three locations (Al-Sanobar, Daba, and Jaba) and then brought to the Biological Control Studies and Research Center (BCSRC). The following soft scale insects of the order Coccomorpha and family Coccidae were identified: Coccus pseudomagnoliarum Kuwana, in Al-Sanobar and Dabba in Lattakia governorate in Java orange orchards, Saissetia oleae Olivier and C. pseudomagnoliarum Kuwana in Pomelo citrus tree in Daba locality, Sphaerolecanium prunastri Fonscolombe at the third site Jaba, Quneitra governorate, in almond orchards, and to our knowledge is the first record in Syria. Identification and characterization of the soft scale insects was based on microscopic characters of adult female using slide-mounted specimens. Identification of pests is essential for the implementation of biological control programs. Keywords: Coccidae, soft scale insects, Syria

New Host Plant Species of Grapevine Virus A Identified with Vector-Mediated Infections.

Grapevine virus A (GVA) is an economically important virus and a member of the genus Vitivirus (family Betaflexiviridae) that causes a range of symptoms with qualitative and quantitative effects on grape production. Wild and domesticated species of Vitis, including hybrids used as rootstocks, are considered important natural hosts of GVA. Mechanical transmission to some herbaceous plant species, graft transmission, and vector transmission from grape to grape by various mealybugs and soft scale insects have been reported. Under laboratory and greenhouse conditions, this study demonstrates the transmission of GVA from grapes to alternative hosts by the vine mealybug (Planococcus ficus). Results of ELISA, end-point one-step RT-PCR, and real-time RT-PCR, and in some cases electron microscopy and genome sequencing, confirmed successful transmission to three new plant species commonly found in Croatian vineyards: velvetleaf (Abutilon theophrasti), redroot pigweed (Amaranthus retroflexus), and field poppy (Papaver rhoeas), along with Chenopodium murale and the previously known host Nicotiana benthamiana, with variable infection rates. Depending on the host species, symptoms in the form of leaf reddening, yellow spots, reduced growth of lateral shoots, systemic vein clearing, foliar deformation and rugosity, and dwarfism were observed in GVA-infected plants, whereas no symptoms were observed in infected plants of A. theophrasti. Reverse transmission from these new hosts to grapevines by Pl. ficus was not successful. These results confirm four new GVA host species and open new research venues.

Identification of a receptor for the sex pheromone of the vine mealybug, Planococcus ficus

The vine mealybug, Planococcus ficus, is a significant pest of vineyards in all major grape growing regions of the world. This pest causes significant aesthetic damage to berry clusters through its feeding behavior and secretion of "honeydew", which leads to significant decreases in crop marketability. More importantly, the vine mealybug is a vector of several grapevine viruses which are the causal agent of grapevine leafroll disease, one of the most destructive and economically devastating diseases of the grape industry worldwide. As there is no cure for grapevine leafroll disease, the only control measures available to reduce its spread are to remove infected vines whilst simultaneously controlling mealybug populations. Using transcriptomic libraries prepared from male and female mealybugs and a draft genome, we identified and evaluated expression levels of members of the odorant receptor gene family. Interestingly, of the 50 odorant receptors identified from these P. ficus genetic resources, only 23 were found to be expressed in females, suggesting this flightless life stage has a decreased reliance on the olfactory system. In contrast, 46 odorant receptors were found to be expressed in the alate male life stage. Heterologous expression of eight of these receptors, along with the obligate co-receptor, Orco, in HEK293 cells allowed for the identification of two receptors that respond to lavandulyl senecioate, the sole constituent of the sex pheromone used by this species. Interestingly, one of these receptors, PficOR8, also responded to the sex pheromone used by the Japanese mealybug, Planococcus kraunhiae. The data presented here represent the first report of odorant receptor gene family expression levels, as well as the identification of the first sex pheromone receptor, in soft-scale insects. The identification of a receptor for the vine mealybug sex pheromone will allow for the development of novel, species-specific pest control tools and monitoring devices.

Metagenomic ecosystem monitoring of soft scale insects and mealybug communities

Soft scale insects and mealybugs are phloem-feeding Hemipterans that are considered major pests in agriculture and horticulture throughout the world. However, correct taxonomic identification in the field can be difficult, making it hard for growers to implement control strategies. In viticulture, soft scale insects are a major issue due to their ability to secrete honeydew, which facilitates the development of sooty mould, and their propensity for being transmission vectors of several viral diseases of grapevine. To facilitate the rapid identification and quantification of vineyard-associated insects a metagenomic-based bioinformatic pipeline (MitoMonitor) was developed for generalised ecosystem monitoring, which automated the assembly and classification of insect mitochondrial genomes from shotgun sequencing data using the Barcode of Life Database API. The proof-of-concept application of MitoMonitor on metagenomic data obtained from eight samples from South Australian vineyards led to the identification of Parthenolecanium corni (European fruit scale)—which was thought to be absent in Australian vineyards—as the dominant coccoid species across the samples, with less frequent, and also lower abundance of Pseudococcus viburni (obscure mealybug) and Pseudo. longispinus (long-tailed mealybug). In addition, parisitoidism by Coccophagus scutellaris (Aphelinidae) wasps was also detected. The discovery of Parth. corni as a member of scale communities in these samples has significant implications for the development of effective control strategies for this important group of pests in affected areas.

To bee or not to bee: creating DNA insecticides to replace non-selective organophosphate insecticides for use against the soft scale insect Ceroplastes japonicus Green

To bee or not to bee: creating DNA insecticides to replace non-selective organophosphate insecticides for use against the soft scale insect Ceroplastes japonicus Green

First complete mitochondrial genome of the tribe Coccini (Hemiptera, Coccomorpha, Coccidae) and its phylogenetic implications.

Soft scale insects (Hemiptera, Coccidae) are important pests of various agricultural and horticultural crops and ornamental plants. They have negative impacts on agriculture and forestry. The tribe Coccini represents one of the most ancient evolutionary lineages of soft scale insects. However, no complete Coccini mitochondrial genome (mitogenome) is available in public databases. Here, we described the complete mitogenome of Coccushesperidum L., 1758. The 15,566 bp mitogenome of C.hesperidum had a high A+T content (83.4%) and contained a typical set of 37 genes, with 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs) and two ribosomal RNA genes (rRNAs). Only seven tRNAs had the typical clover-leaf secondary structure and the remaining tRNAs lacked the DHU arm, TψC arm or both. Moreover, a comparative analysis of all reported scale insect mitogenomes from GenBank database was performed. The mitogenomes of scale insects showed high similarities in base composition and A+T content. Additionally, our phylogenetic analysis confirmed the monophyly of Coccomorpha and revealed that the archaeococcoids were the most basal lineage within Coccomorpha, while Ericeruspela and Didesmococcuskoreanus, belonging to Coccidae, were often mixed with Aclerdidae, making Coccidae a paraphyletic group. These findings expand the mitogenome database of scale insects and provide new insights on mitogenome evolution for future studies across different insect groups.

Parasitoid and predator species of Coccidae (Hemiptera: Coccoidea) species in fruit orchards of Diyarbakır and Elazığ Provinces, Türkiye

This study was carried out in order to determine the predator and parasitoid species that feed on soft scale insect (Hemiptera: Coccidae) species in orchards of Diyarbakır and Elazığ Provinces in Turkiye in 2017 and 2018. Visual identification and rearing methods were used. Eight predatorory species belonging to the families Coccinellidae (4) and Cybocephalidae (1) (Coleoptera), Forficulidae (2) (Dermaptera), and Chrysopidae (1) (Neuroptera), were detected. In addition, 14 parasitoid and 2 hyperparasitoid species from the families Encyrtidae (14), Aphelenidae (1) and 2 Pteromalidae (1) (Hymenoptera) were collected. Among the parasitoid species, Metaphycus ater, M. luteolus, M. chermis and M. unicolor (Hymenoptera: Encyrtidae) are first records for the insect fauna of Türkiye.

Diyarbakır ve Elazığ illeri meyve bahçelerindeki Koşnil (Hemiptera:Coccomorpha: Coccidae) türleri

This study was carried out in order to determine the soft scale insects (Hemiptera: Coccomorpha: Coccidae) species, their host plants, distribution areas, densities and infestation rates on fruit production areas of Diyarbakır and Elazığ Provinces in 2017-2018. As a result of the study, 7 soft scale species were determined on 12 fruit plants. The most common species and the widest host plant range was Parthenolecanium corni (Bouché, 1844) in the study areas. Sphaerolecanium prunastri (Boyer de Fonscolombe, 1834) and Didesmococcus unifasciatus (Archangelskaya, 1923) were determined to be the most important species in the region. Didesmococcus unifasciatus caused heavy infestation on almond, Prunus dulcis (Mill.) (Rosales: Rosaceae) trees (Scale 4) at rates of 3.1% and 0,9% in Çınar district of Diyarbakır and Sivrice district of Elazığ, respectively. Sphaerolecanium prunastri caused heavy infestation on apricots, Prunus armeniaca L. (Rosales: Rosaceae) at rates of 3.8% and 4.6% in Elazığ's Central and Baskil districts, which have significant apricot production areas.

Taxonomic relationship among four European Physokermes species (Hemiptera: Coccomorpha) based on nuclear and mitochondrial DNA

IntroductionScale insects (Hemiptera: Coccomorpha) feed on a wide variety of agricultural crops and forest and ornamental trees worldwide. These pest insects damage plants not only by causing sap loss but also by reducing the plant's photosynthetic activity. This is because the honeydew they produce acts as a substrate for mold, which covers leaf surfaces. In the last decades, several outbreaks of Physokermes spp. (soft-scale insects) have occurred throughout Europe and have partly been attributed to unusual weather conditions or climate change, as some species seem to be expanding their distribution range. However, the small size of these insects and their large intraspecific morphological variation have hindered the identification of the species responsible for outbreaks.MethodsIn this study, mitochondrial DNA (cytochrome c oxidase subunit I, COI), ribosomal RNA (28S), and nuclear (elongation factor 1α, EF1α) DNA markers were used to reconstruct the phylogenetic relationships of four Physokermes species sampled throughout Europe in 2013–2015.Results and discussionThe results allowed us to clearly distinguish P. hellenicus and P. inopinatus from each other, as these appeared in well-supported clades in the phylogenetic trees and from P. piceae and P. hemicryphys. However, P. hemicryphus appeared in a single clade in trees based on 28S and EF1α but among P. piceae in the COI tree. Further investigations are therefore required to determine the taxonomic status of P. piceae and P. hemicryphys, which seem to comprise a species complex.

Toumeyella parvicornis versus endotherapic abamectin: three techniques, 1 year after.

Toumeyella parvicornis is an invasive soft scale insect native to North America that is rapidly spreading in Italy and France, provoking severe infestations on Pinus pinea L. To date, the control of this pest is entrusted to three endotherapic techniques whose short-term efficacy is partially known. No information on long-term efficacy is currently available, although fundamental. This work aims to report on the long-term effect that abamectin-based insecticides, injected with the three different techniques, have on adult female populations. The study was carried out in an infested P. pinea forest in the area of Rome, Italy. Results showed that the tested methods had a similar long-term effect, and only in one case there were differences with the untreated control. Multiresidue analysis reported a zero level of abamectin in plant tissues 14 months apart from injection, except for one treatment where pesticide concentration was just above the limit of quantification. This study represents the first long-term evaluation about endotherapic control strategy against T. parvicornis. In fact, the pest may quickly bring the death and fall of the stone pines, representing a concerning risk for citizens, however, control actions to manage it are still partially known and deserve more in-depth investigations. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A new genus and species of soft scale insect (Hemiptera: Coccomorpha: Coccidae) on Ficus sp. from Côte d’Ivoire

During a brief visit to the West African Rice Development Association (WARDA) in Bouaké, Côte d'Ivoire, several samples of scale insects (Hemiptera: Coccomorpha) were collected. Amongst these was an undescribed genus and species of soft scale (Coccidae: Coccinae), Bandamacoccus labiosus Hodgson (gen. nov. and sp. nov.). The adult female and second-instar male nymph are described below. A striking feature of both stages is the large size of the labium, which is wider than the clypeolabral shield, whilst the second-instar male also has a prominent inner submarginal band of ventral microducts.

Response of the soft scale insect Parthenolecanium corni and its natural enemies on honeylocust trees to urban conditions

Urban habitats can alter tree physiology in ways that make trees more susceptible to insect pests. We examined how urban conditions (e.g., impervious surfaces and warming) affected the soft scale insect, European fruit lecanium, Parthenolecanium corni Bouché (Hemiptera: Coccidae) and the health of thornless honeylocust trees (Gleditsia tricanthos L. var. inermis) in Indianapolis, Indiana, USA. Hot and cool study sites were selected based on surface air temperatures obtained from thermal LANDSAT-8 images overlaid against a map of honeylocust tree locations. Based on temperature probe data, study trees located in hot sites had mean average daily temperatures up to 1.56 °C and 1.79 °C warmer than cool sites in 2019 and 2020, respectively. We hypothesized that abundance and fecundity of scale insects would be higher on trees in hot sites and those surrounded by more impervious surface cover within a 20 m radius. Although our data supported these hypotheses, impervious surface cover predicted more of the variation in abundance and fecundity of scale insects in hot sites compared to cool sites. Rates of parasitism were not affected by impervious surface cover or whether the site was from a hot or cool location. However, we found strong density dependence in parasitism of scale insects in both hot and cool sites when scale densities were at or below the levels present in cool sites. This suggests that lower densities of scale insects were associated with a positive numerical response of parasitoids, a necessary prerequisite for population regulation by top-down effects. In contrast, this numerical response was lacking at the higher densities of scales found on trees located in hot sites where, presumably bottom-up factors like water-stress increased the fecundity of scale insects. These findings add to a growing body of evidence linking rising global temperatures with increased pest abundance in ways that cannot be mitigated by local populations of natural enemies.

Redescriptions of five of Takahashi’s soft scale species (Hemiptera: Coccomorpha: Coccidae) with comments on their status and relationships

This paper redescribes and illustrates five currently poorly known species of soft scale insect (Hemiptera: Coccomorpha: Coccidae) originally described by Ryoichi Takahashi, namely Coccus lumpurensis Takahashi, Maacoccus scolopiae (Takahashi), Membranaria sacchari (Takahashi), Platylecanium cyperi Takahashi and P. mesuae Takahashi. Lectotypes are designated for C. lumpurensis, P. cyperi and P. mesuae. Two of these species are known only from Taiwan, and three from Malaysia. Their status and relationships are discussed. A key to the species of Maacoccus is included.

Toxicity assessment of certain insecticides on the red soft scale insect, Pulvinaria tenuivalvata (Newstead) infesting sugarcane plants

Pulvinaria tenuivalvata (Newstead) (Hemiptera: Coccidae) red soft scale insect is one of the most prevalent insect pests that attacks sugarcane plants. Insecticidal efficiency of six selected insecticides (Malatox, Sulfar, Admiral, Nomolt, Tafaban and Biover) was evaluated for their impact against nymphs and adult females of P. tenuivalvata on sugarcane leaves using leave dipping methods. This investigation was carried out for two successive seasons (July 2021-2022) at the laboratory of the Plant Protection Research Department at the El-Mattana Agricultural Research Station, Luxor Governorate, Egypt. Obtained results showed that the tested insecticides varied in efficacy on the different stages of pest (nymphs and adult females). Moreover, the nymphal stage of P.tenuivalvata was more susceptible to the tested pesticides compared to the adult stage. Admiral and nomolt were the most toxic against the nymphal and adult female stages of P. tenuivalvata on sugarcane leaves, sulfar, however, was the least successful in controlling this pest.

Recent adventive soft scale insects (Hemiptera: Coccomorpha: Coccidae) and mealybugs (Hemiptera: Coccomorpha: Pseudococcidae) in India

Four species of soft scale insect [Hemiptera: Coccidae: Fistulococcus pokfulamensis Hodgson & Martin, Kilifia deltoides De Lotto, Maacoccus piperis (Green) and Paralecanium machili Takahashi] and two species of mealybug [Hemiptera: Pseudococcidae: Antonina thaiensis Takahashi and Formicococcus simplicior (Green)] are recorded in India for the first time. Each of the six species is comprehensively diagnosed based on Indian material, and compared with earlier descriptions. Keys to the Indian species in their respective genera are provided to facilitate identification. Ecological information on host plants, associated ants and natural enemies is also given.