Psyllid Species Research Articles

Insect phylogeny structures the bacterial communities in the microbiome of psyllids (Hemiptera: Psylloidea) in Aotearoa New Zealand.

The bacterial microbiome of psyllids has been studied for decades, with a strong focus on the primary and secondary endosymbionts capable of providing essential amino acids for the insects' diet and therefore playing a key role in the insects' ability to radiate on novel plant hosts. Here, we combine metabarcoding analysis of the bacterial communities hosted by psyllids with a multi-gene phylogenetic analysis of the insect hosts to determine what factors influence the bacterial diversity of the psyllids' microbiomes, especially in the context of the dispersal and evolutionary radiation of these insects in Aotearoa New Zealand. Using multi-gene phylogenetics with COI, 18S and EF-1α sequences from 102 psyllid species, we confirmed for the first time monophyly for all the six genera of native/endemic Aotearoa New Zealand psyllids, with indications that they derive from at least six dispersal events to the country. This also revealed that, after its ancestral arrival, the genus Powellia has radiated onto a larger and more diverse range of plants than either Psylla or Ctenarytaina, which is uncommon amongst monophyletic psyllids globally. DNA metabarcoding of the bacterial 16S gene here represents the largest dataset analysed to date from psyllids, including 246 individuals from 73 species. This provides novel evidence that bacterial diversity across psyllid species is strongly associated with psyllid phylogenetic structure, and to a lesser degree to their host plant association and geographic distribution. Furthermore, while the strongest co-phylogenetic signals were derived from the primary and secondary symbionts, a signal of phylosymbiosis was still retained among the remaining taxa of the bacterial microbiome, suggesting potential vertical transmission of bacterial lineages previously unknown to have symbiotic roles.

Cacopsylla fuscicella Sp. Nov. (Hemiptera, Psyllidae), a New Loquat Pest in China

Psylloidea, commonly known as jumping plant-lice, have a phloem-sucking habit and strong specificity to their host plants. Within the Psyllidae family, the genus Cacopsylla Ossiannilsson, 1970 stands out as being the most diverse, with three species feeding on the genus Eriobotrya Lindl. In this study, a new psyllid species, Cacopsylla fuscicella sp. nov., was described from China. It is a pest of Eriobotrya japonica (Thunb.) Lindl. and has been cultivated as a commercial fruit tree for years. Illustrations of habitus, morphological structures, and its damage to loquat were also provided. The complete mitochondrial genome of C. fuscicella sp. nov. was sequenced and annotated. The phylogenetic tree inferred from the maximum likelihood analyses confirmed C. fuscicella sp. nov. as a member of the genus Cacopsylla. Genetic distances were generated to assess comparative genetic distances within Psyllinae.

Association of endoplasmic reticulum associated degradation (ERAD) with the transmission of Liberibacter solanacearum by its psyllid vector.

Candidatus Liberibacter solanacearum (CLso) is a complex of gram negative plant pathogenic and fastidious bacterial haplotypes restricted to the phloem and transmitted by several psyllid species. In Israel, the carrot psyllid Bactericera trigonica transmits CLso haplotype D in a persistent and propagative manner and causes the carrot yellows disease, inflicting significant economic losses in many countries. Understanding the transmission of CLso is fundamental to devising sustainable management strategies. Persistent transmission of vector-borne pathogens involves the critical steps of adhesion, cell invasion and replication inside the insect gut cells before passage to the hemolymph. Using microscopy and expression analyses, we have previously confirmed a role for the endoplasmic reticulum (ER) in inducing immune responses and subsequent molecular pathways resulting in programmed cell death (apoptosis) upon CLso-infection in the midgut. In the current study, we confirm that the ER-associated degradation (ERAD) machinery and its associated marker genes were upregulated in CLso infected insects, including Derlin-1, Selenoprotein-1 and Ubiquitin Ligase RNF-185. Silencing Derlin-1, which acts on the ER membrane by regulating the degradation of unfolded proteins upon ER stress, revealed its role in CLso persistence and transmission. Molecular pathways initiated in the ER membrane upon bacterial infection are well documented in human, animal and insect systems, and this study confirms the role of the ER in CLso-psyllid interactions.

The phylogeny and distribution of Wolbachia in two pathogen vector insects, Asian citrus psyllid and Longan psyllid.

Wolbachia is the most abundant bacterial endosymbiont among insects. It can play a prominent role in the development, reproduction and immunity of its given insect host. To date, Wolbachia presence is well studied within aphids, whiteflies and planthoppers, but relatively few studies have investigated its presence in psyllids. Here, the infection status of Wolbachia in five species of psyllid, including Asian citrus psyllid Diaphorina citri and longan psyllid Cornegenapsylla sinica was investigated. The phylogenetic relationships of different Wolbachia lines and their infection density and patterns in D. citri and C. sinica from different countries was also examined. The infection rates of Wolbachia in D. citri and C. sinica were both 100%, and their sequencing types are ST173 and ST532 respectively. Phylogenetic analysis revealed that the Wolbachia lines in D. citri and C. sinica both belong to the Con subgroup of Wolbachia supergroup B. In addition, Wolbachia displayed a scattered localization pattern in the 5th instar nymphs and in the reproductive organs of both D. citri and C. sinica but differed in other tissues; it was highest in the midgut, lowest in the salivary glands and medium in both the testes and ovaries. Our findings assist in further understanding the coevolution of Wolbachia and its psyllid hosts. Given that Wolbachia could play an important role in insect pest control and pathogen transmission inhibition, our findings may also provide new insights for development of control strategies for D. citri and C. sinica.

<i>Paurocephala famendongoeis </i>sp. n. (Hemiptera: Psyllidae), Insect Pest of <i>Psorospermum febrifugum</i> (Hypericaceae) from Adamawa-Cameroon

A new psyllid species collected on <i>Psorospermum febrifugum</i> (Hypericaceae) is described from Adamawa Region of Cameroon, <i>Paurocephala</i> <i>famendongoeis</i> sp. n. It’s different morphologically with the previous described species of the same genus by the following characters: paramere with 11 stout setae in basal half posterior; male proctiger very enlarged in the basal third and bearing in its apical internal part located toward rear a large and very long seta; forewing without surface spinules in all cells. Antenna of fifth instar larvae without sectasetae, rather presence only of long simple setae; first flagellum very long with 9 long simple setae grouped in 3, 2, 1 and 1; dorsal sclerites covered by truncated setae grouped in pairs at the level of lateral margins of abdomen; caudal plate without process. Previously, <i>Paurocephala nkomekui</i> was described from Cameroon on <i>Agelaea hirsuta</i> (Coronnaceae). Root, leaves and barks of <i>Psorospermum febrifugum</i> are used in African traditional medicine to fight again fever, malaria, sore, eczema, cutaneous eruption and insect bite. Damages on host plant are rolling of leaves and leaves discolouration.

Detection of ‘Candidatus Phythoplasma prunorum’ in Apricot Trees and its Associated Psyllid Samples

‘Candidatus Phytoplasma prunorum’ is causing ever increasing economic losses through the decline of apricot trees in European countries, e.g., Hungary. In this study, the pathogen was identified from plant tissues and insects by nested-PCR. The insect species were identified via morphology and molecular methods. The incidence of the pathogen was 29.6% in randomly selected apricot trees. Most of the infected trees with symptoms died within a year. These results show that phytoplasma is significantly present and causes damage in the investigated plantations. The only known insect vector of this phytoplasma is the plum psyllid, Cacopsylla pruni, which was regularly encountered in the sampled apricot orchards and in their surroundings. In a two-year study, several adults among the sampled specimens were observed to be infected by the pathogen. This observation further confirms the role of the plum psyllid in vectoring the phytoplasma. All the sampled plum psyllid adults belonged to the ‘B’ biotype. Besides C. pruni, Cacopsylla crataegi was abundant in the samples. Several adults of the latter species were also infected by the pathogen ‘Ca. Phytoplasma prunorum’. The rates of occurrence of this phytoplasma in male and female adults of the two psyllid species appeared to be similar. The examined C. crataegi individuals showed genetic differences from each other and from specimens included in a previous investigation.

16S rRNA Gene Sequencing of Six Psyllid Species of the Family Carsidaridae Identified Various Bacteria Including Symbiopectobacterium.

Psyllids (Hemiptera: Sternorrhyncha: Psylloidea) are plant sap-sucking insects that are closely associated with various microbes. To obtain a more detailed understanding of the ecological and evolutionary behaviors of microbes in Psylloidea, the bacterial populations of six psyllid species, belonging to the family Carsidaridae, were analyzed using high-throughput amplicon sequencing of the 16S rRNA gene. The majority of the secondary symbionts identified in the present study were gammaproteobacteria, particularly those of the order Enterobacterales, including Arsenophonus and Sodalis, which are lineages found in a wide variety of insect hosts. Additionally, Symbiopectobacterium, another Enterobacterales lineage, which has recently been recognized and increasingly shown to be vertically transmitted and mutualistic in various invertebrates, was identified for the first time in Psylloidea. This lineage is closely related to Pectobacterium spp., which are plant pathogens, but forms a distinct clade exhibiting no pathogenicity to plants. Non-Enterobacterales gammaproteobacteria found in the present study were Acinetobacter, Pseudomonas (both Pseudomonadales), Delftia, Comamonas (both Burkholderiales), and Xanthomonas (Xanthomonadales), a putative plant pathogen. Regarding alphaproteobacteria, three Wolbachia (Rickettsiales) lineages belonging to supergroup B, the major group in insect lineages, were detected in four psyllid species. In addition, a Wolbachia lineage of supergroup O, a minor group recently found for the first time in Psylloidea, was detected in one psyllid species. These results suggest the pervasive transfer of bacterial symbionts among animals and plants, providing deeper insights into the evolution of the interactions among these organisms.

The psyllid fauna (Hemiptera: Psylloidea) of vegetable fields in Brazil

Some psyllids transmit 'Candidatus Liberibacter solanacearum' (Lso), the causal agent of devastating plant diseases of cultivated Solanaceae and Apiaceae. The recent detection of Bactericera cockerelli and Lso in Ecuador seriously threatens these crops in South America. There, neither the role of native psyllids in the Lso epidemiology nor the psyllid fauna of vegetables are known. With the aim to identify potential vectors and risk scenarios for the spread of Lso in South America, a survey of the psyllid fauna of Solanaceae and Apiaceae crops and associated weeds was conducted in Brazil. Samples were taken at 29 localities in four states. A total of 2857 specimens were sampled, representing at least 37 species of 23 genera and seven families. The most frequent species on carrot, chilli pepper and potato were Russelliana solanicola, R. capsici and Isogonoceraia divergipennis, respectively. Immatures of R. capsici were found on chilli pepper and of R. solanicola on carrot and potato, confirming these plants as hosts. The two psyllid species have been suspected previously to transmit plant pathogens of unknown identity. Russelliana solanicola is one of the few polyphagous species. Here the species is reported for the first time from carrot. Recent collections in Rio Grande do Sul suggest that Solanum laxum represents the original host of R. capsici, which subsequently shifted to chilli pepper. Both, adaptation to agricultural crops and the possibility of ability to transmit pathogens, make the two Russelliana species dangerous potential vectors of Lso and other plant pathogens in South America.

Lisne buve štetočine kruške (Hemiptera: Psyllidae) u Srbiji

Pear psyllids or pear jumping plant-lice, are the most important pests of this fruit. In Serbia, four species of pear psyllids are harmful to pear. Ali four belong to the genus Cacopsylla: C. pyri (common pear psyllid), C. bidens, C. pyricola (small pear psyllid) and C. pvrisuga (large pear psyllid). The first three belong to the subgenus Hepatopsvlla, have a larger number of generations per year and usually overwinters on the host plant, and C. pvrisuga belongs to the subgenus Thamnopsvlla, has one generation per year and overwinters outside the host plant pear. They can damage the pear directly, through nutrition by sucking out the juices, leading to chlorosis, necrosis and defoliation, and indirectly, by secreting "honeydew". Added to this damage is the role of C. pyri and C. pyricola as vectors of the phytoplasma "Candidatus Phytoplasma pyri", the cause of the disease called "pear decline".

Infection Patterns of a Liberibacter Associated with Macrohomotoma gladiata, a Psyllid Feeding on Ficus microcarpa.

Almost all known Liberibacters can be transmitted by psyllids. This suggests that there is a coevolutionary relationship between these two groups of organisms. However, detailed investigation of Liberibacters and psyllids have often focused on only a few species, thus potentially limiting knowledge on Liberibacter-psyllid associations. This study investigated the infection patterns of a Liberibacter inhabiting Macrohomotoma gladiata, a psyllid species feeding on Ficus microcarpa. Comparison of the Liberibacter's near-full-length 16S rDNA sequence with those of other known Liberibacters revealed that it is closely related to Candidatus Liberibacter asiaticus. A survey of different M. gladiata populations in Taiwan using conventional and quantitative PCR (qPCR) indicated that the Liberibacter could be detected with variable frequencies in all the tested populations; the proportions of individuals carrying large Liberibacter populations also differed depending on the population. Additional analysis of a larger set of samples collected from one specific population revealed that the psyllid's gender and abdominal color were associated with Liberibacter infection density. Significantly greater proportions of individuals with a blue/green abdomen carried high Liberibacter titers. Analysis of the psyllids' body lengths revealed that body size was not affected by Liberibacter infection status and that females, particularly those with an orange abdomen, tended to be larger. The infection patterns of Liberibacter in nymph-infested and nymph-free twigs of F. microcarpa were also determined, and Liberibacter distribution was found to be associated with the presence of nymphs. These findings broaden the understanding of Liberibacter ecology in general and have implications for managing Liberibacter-associated diseases. IMPORTANCE Despite the ever-increasing interest in Liberibacter-psyllid interactions, most of the current knowledge on the subject has been established from studies focusing on species associated with crop diseases. To obtain a more holistic understanding of Liberibacter ecology, we investigated the infection patterns of a Liberibacter recently detected in Macrohomotoma gladiata, a psyllid pest of Ficus microcarpa. We showed that a Liberibacter closely related to Candidatus Liberibacter asiaticus is widely distributed across M. gladiata populations in Taiwan. The study also identified factors associated with the Liberibacter infection patterns, both in M. gladiata and in F. microcarpa. The effects of Liberibacter infection status on psyllid body sizes were also examined. Some of the patterns detected in this work were similar those found in well-known Liberibacters, while some were the opposite. The findings in this work broaden our understanding of Liberibacter ecology in general and may facilitate development of strategies for managing plant diseases.

Identification of three new ‘Candidatus Liberibacter solanacearum’ haplotypes in four psyllid species (Hemiptera: Psylloidea)

Eleven haplotypes of the bacterium, ‘Candidatus Liberibacter solanacearum’, have been identified worldwide, several of which infect important agricultural crops. In the United States, haplotypes A and B are associated with yield and quality losses in potato, tomato, and other crops of the Solanaceae. Both haplotypes are vectored by potato psyllid, Bactericera cockerelli. Recently, a third haplotype, designated F, was identified in southern Oregon potato fields. To identify the vector of this haplotype, psyllids of multiple species were collected from yellow sticky cards placed near potato fields during two growing seasons. Over 2700 specimens were tested for ‘Ca. L. solanacearum’ by polymerase chain reaction. Forty-seven psyllids harbored the bacterium. The infected specimens comprised four psyllid species in two families, Aphalaridae and Triozidae (Hemiptera: Psylloidea). Nucleic acid and/or amino acid sequence analysis of the ‘Ca. L. solanacearum’ 16S ribosomal RNA, 50S ribosomal proteins L10/L12, and outer membrane protein identified three new haplotypes of the bacterium, designated as Aph1, Aph2 and Aph3, including two variants of Aph2 (Aph2a and Aph2b). The impact of these new haplotypes on solanaceous or other crops is not known. The vector of ‘Ca. L. solanacearum’ haplotype F was not detected in this study.

Survey of Candidatus Liberibacter Solanacearum and Its Associated Vectors in Potato Crop in Spain.

Simple SummaryZebra chip disease (ZC) in potato is an economically important disorder, documented in North and Central America and New Zealand. It is associated with the bacterium ‘Candidatus Liberibacter solanacearum’ (CaLsol), which is transmitted by the psyllid Bactericera cockerelli. The characteristic symptom of ZC is a dark and light striped pattern in chips, making them commercially unacceptable. Naturally CaLsol-infected potato tubers were reported in Europe, where the threat of ZC for European potato crops is a major concern. This work studied the presence and abundance of ZC symptoms and CaLsol in potato plants, as well as those psyllid species that eventually could transmit the bacterium, in the main producing areas in Spain. Very few symptomatic and CaLsol-positive plants were detected in Mainland Spain, and any positive plant was detected in the Canary Islands. Most of the adult psyllids captured were identified as Bactericera nigricornis, and some of them as Bactericera trigonica, but no B. cockerelli was detected. B. nigricornis was found widely distributed in the northern half of the Iberian Peninsula, and it was the only one able to feed and reproduce on potato plants. However, this psyllid does not seem sufficient to pose a threat to potato production, due to the scarce number of specimens and because the frequency of B. nigricornis specimens that were CaLsol+ was very low.‘Candidatus Liberibacter solanacearum’ (CaLsol), the etiological agent of potato zebra chip (ZC), is transmitted to potato plants by the psyllid Bactericera cockerelli (Šulc, 1909) in North and Central America and New Zealand. The risk of the dispersion of ZC in Spain depends on the presence of an efficient vector. This work studies the presence and abundance of ZC symptoms and CaLsol in potato plants, as well as the presence and abundance of psyllid species associated with potato crops in the main producing areas in Spain. Eighty-eight plots were surveyed punctually to detect ZC symptoms and psyllid species in the main potato-producing areas. Furthermore, fourteen potato plots were surveyed by different sampling methods during the cropping season to detect psyllid species from 2016 to 2018. Very few symptomatic and CaLsol-positive plants were detected in Mainland Spain, and any positive plant was detected in the Canary Islands. Most of the adult psyllids captured were identified as Bactericera nigricornis (Foerster, 1848), and some of them as Bactericera trigonica, but no B. cockerelli was detected. B. nigricornis was found widely distributed in the northern half of the Iberian Peninsula; however, this psyllid does not seem sufficient to pose a threat to potato production, due to the scarce number of specimens and because the frequency of B. nigricornis specimens that were CaLsol+ was very low.

Determination of potential insect vectors and subgroups of aster yellows phytoplasma in the carrot (Daucus carota L.) (Apiaceae) cultivation areas of Ankara and Konya Provinces, Türkiye

Aster yellows phytoplasma (16Sr-I, AYp) is a widespread plant pathogen affecting a wide range of economically important crops. AYp can be distributed widely via insect vectors and is associated with severe redness and yellowing in carrot leaves. The presence of potential insect vectors of aster yellows phytoplasma was investigated in the Ankara and Konya Provinces, the largest carrot production areas in Türkiye. Forty-five insect samples were collected during the field studies between March and September 2020. Morphological and molecular studies have shown that Neophilaenus campestris (Fallén, 1805) (Hemiptera: Aphrophoridae), Empoasca decipiens Paoli, 1930 (Hemiptera: Cicadellidae) and Psammotettix striatus (L., 1758) (Hemiptera: Cicadellidae) carried 16SrI-F phytoplasma. Psammotettix striatus collected from different locations contained subgroup 16SrI-R, as well. In addition, subgroup 16SrI-B was determined in Cicadula divaricata Ribaut, 1952 (Hemiptera: Cicadellidae) and in a psyllid (Psylloidea: Psyllidae) species. Empoasca sp., Anaceratagallia sp. (Hemiptera: Cicadellidae) and Psammotettix confinis (Dahlbom, 1850) (Hemiptera: Cicadellidae) were determined as potential phytoplasma vectors. Phytoplasma 16Sr rRNA and insect cytochrome oxidase gene nucleotide sequences were used for phylogenetic analysis. The results will contribute to vector-based control of aster yellows phytoplasmas in carrot cultivation areas.

Value‐adding in biosecurity surveillance and monitoring: Testing colour and non‐target semiochemical lures on Psylloidea and Pentatomoidea

AbstractCost efficiency in biosecurity surveillance is vital, and the ability to survey multiple pest species using just one trap is, therefore, highly appealing. The Psylloidea, or plantlice, contain significant horticultural pest species that act as vectors for a number of deleterious plant bacteria. We examine the efficacy of using two different coloured sticky traps, and two semiochemical lures on the general Psylloidea and Pentatomoidea fauna, and a target extant pest psyllid; tomato potato psyllid (TPP) Bactericera cockerelli (Šulc) in Western Australia. Specifically, we test the effect of semiochemical lure (no lure, Asian citrus psyllid ACP lure, brown marmorated stink bug BMSB lure, combined lures), sticky trap colour (yellow‐green vs yellow) and sentinel plant (tomato vs citrus) on psyllid and pentatomid species in 104 urban backyards across Perth, Australia. We found that tomato sentinel host plants and yellow‐green traps significantly increased the capture rate of TPP, but that lures decreased the capture of TPP constraining their use. Yellow‐green traps also increased the capture rate of all other Psylloidea. Although BMSB lures reduced TPP capture, these lures increased the abundances of other Psylloidea and the pest stinkbug Plautia affinis (Dallas) on traps. Thus, our experiment demonstrates that increased efficiencies can be gained with multi‐species traps and semiochemical lures for particular groups, provided that they have been tested on focal organisms in the first instance, as reactions to non‐target lures are unpredictable and species specific.

Microbiome of pear psyllids: A tale about closely related species sharing their endosymbionts.

Psyllids are phloem-feeding insects that can transmit plant pathogens such as phytoplasmas, intracellular bacteria causing numerous plant diseases worldwide. Their microbiomes are essential for insect physiology and may also influence the capacity of vectors to transmit pathogens. Using 16S rRNA gene metabarcoding, we compared the microbiomes of three sympatric psyllid species associated with pear trees in Central Europe. All three species are able to transmit 'Candidatus Phytoplasma pyri', albeit with different efficiencies. Our results revealed potential relationships between insect biology and microbiome composition that varied during psyllid ontogeny and between generations in Cacopsylla pyri and C. pyricola, as well as between localities in C. pyri. In contrast, no variations related to psyllid life cycle and geography were detected in C. pyrisuga. In addition to the primary endosymbiont Carsonella ruddii, we detected another highly abundant endosymbiont (unclassified Enterobacteriaceae). C. pyri and C. pyricola shared the same taxon of Enterobacteriaceae which is related to endosymbionts harboured by other psyllid species from various families. In contrast, C. pyrisuga carried a different Enterobacteriaceae taxon related to the genus Sodalis. Our study provides new insights into host-symbiont interactions in psyllids and highlights the importance of host biology and geography in shaping microbiome structure.

Repellent Activity of Clove Essential Oil Volatiles and Development of Nanofiber-Based Dispensers against Pear Psyllids (Hemiptera: Psyllidae).

Simple SummaryPear psyllids are responsible for transmitting the pathogen ‘Candidatus Phytoplasma pyri’, causing the pear decline disease. Specific repellents are a potential method for controlling this pest and reducing the spreading of phytoplasma pear in orchards. Little is known about the chemical ecology of these insects. Based on recent literature, we tested the behavioral reactions of Cacopsylla pyri and Cacopsylla pyricola to the major synthetic compounds of clove essential oil in olfactometer experiments. In addition, we developed new nanofiber-based repellents dispensers and evaluated their repellent and host-odor masking activity in the laboratory and later in the field. Results demonstrate that only the synthetic mixture of the three major compounds of the clove essential was repellent to both psyllids species. When volatiles were formulated in nanofibers, they were not only repellent but could mask the odors of pear plants, disrupting the insects from finding the host. In the field, no differences in psyllids captures were observed in color-attractive sticky traps with repellent-loaded nanofibers or nanofibers without repellent. Our study also evaluated the release rates of volatiles from the nanoformulation. We discussed using nanofibers as volatile dispensers and the improvements necessary to use repellents as a management tool for pear psyllids in the field.Pear psyllids are the main vectors of the pathogen ‘Candidatus Phytoplasma pyri’ causing pear decline. Based on earlier reports, we tested the behavioral activity of the major synthetic compounds of clove essential oil (eugenol, eugenyl acetate, and β-caryophyllene) against Cacopsylla pyri and C. pyricola. Of six mixtures tested in olfactometer assays, a formulation consisting of three specific compounds (M6 mixture) demonstrated a repellent effect on both psyllid species. In addition, this formulation masked the odor of the host Pyrus communis cv. Williams Christ, disturbing the host finding ability of C. pyri. Electrospun fibers were produced with biocompatible polymers poly(ε-caprolactone), cellulose acetate, and solvents formic acid and acetic acid, loaded with the repellent mixture to test their efficacy as dispensers of repellents in laboratory and field. The fibers produced were repellent to C. pyri and effectively masked the odors of pear plants in olfactometer tests. In a pear orchard, we compared the captures of pear psyllids in green-colored attractive traps treated with nanofibers loaded with M6 mixture or unloaded nanofibers (blank). The result showed no differences in the captures of C. pyri between treatments. The release rates of volatiles from the fibers were evaluated weekly over 56 days. The fibers were able to entrap the major compound of the M6 mixture, eugenol, but the release rates were significantly reduced after 21 days. Our results suggest that biodegradable dispensers could be produced with electrospinning, but further improvements are necessary to use repellents as a management tool for pear psyllids in the field.

Chromosomal-level assembly of Bactericera cockerelli reveals rampant gene family expansions impacting genome structure, function and insect-microbe-plant-interactions.

Lineage specific expansions and gene duplications are some of the most important sources of evolutionary novelty in eukaryotes. Although not as prevalent in eukaryotes compared to bacteria, horizontal gene transfer events can also result in key adaptations for insects, especially for those involved in insect-microbe interactions. In this study we assemble the first chromosomal assembly of the psyllid Bactericera cockerelli and reveal that the B.cockerelli genome has experienced significantly more gene expansion events compared to other Hemipteran representatives with fully sequenced genomes. We also reveal that B.cockerelli's genome is the largest psyllid genome (567 Mb) sequenced to date and is ~15% larger than the other two psyllid species genomes sequenced (Pachypsylla venusta and Diaphorina citri). Structurally, B.cockerelli appears to have an additional chromosome compared to the distantly related psyllid species P.venusta due to a previous chromosomal fission or fusion event. The increase in genome size and dynamic nature of the B.cockerelli genome may largely be contributed to the widespread expansion of type I and II repeat elements that are rampant across all of B.cockerelli's. chromosomes. These repeat elements are distributed near equally in both euchromatic and heterochromatic regions. Furthermore, significant gene family expansions and gene duplications were uncovered for genes that are expected to be important in its adaptation to insect-plant and microbe interactions, which include transcription factors, proteases, odorant receptors, and horizontally transferred genes that are involved in the nutritional symbioses with their long-term nutritional endosymbiont Carsonella.

First systematic inventory of the jumping plant lice of Luxembourg (Hemiptera, Sternorrhyncha, Psylloidea).

Psyllids (superfamily Psylloidea), also known as jumping plant lice, are a group of plant-sap sucking Hemiptera having significant pest status for crops, forest trees and ornamental plants. Only seven species of psyllids have been recorded in Luxembourg so far. An additional group of seven species has been recorded exclusively, based on the findings of their galls or specific plant deformations; but no mention exists in literature on the actual collection of the inducing insect in Luxembourg. To fill this knowledge gap, field collections were carried out during the years 2019-2020. In addition, samples from 1999-2000 stored in the wet collection of the Musée National d'Histoire Naturelle de Luxembourg were studied. This research, in combination with information coming from literature, allowed us to list 48 species of the families Aphalaridae (5 species), Liviidae (5), Psyllidae (24) and Triozidae (14), though the presence of one species within the last family (Triozarhamni) needs to be confirmed. Brief information on geographical distribution, biology and (if available) illustrations of diagnostic characters are provided on the psyllid species detected in Luxembourg so far.

The complete mitochondrial genome of Cacopsyllaburckhardti (Hemiptera, Psylloidea, Psyllidae).

Cacopsyllaburckhardti Luo, Li, Ma & Cai, 2012 (Hemiptera, Psylloidea, Psyllidae) is a pear psyllid species, distributed in the East Asia. The complete mitogenome of C.burckhardti is obtained in this study for the first time. The mitogenome of C.burckhardti is circular form and 14,798 bp long, which consists of 13 protein-coding genes, 22 tRNAs and two rRNAs. The base composition is 38.80% for A, 34.89% for T, 9.99% for G and 16.33% for C, with the higher A + T contents (73.69%). The phylogenetic analysis, using 13 protein-coding genes, shows that C.burckhardti is clustered with other Cacopsylla species and nested in the Psyllidae clade within the superfamily Psylloidea.

Taxonomy of Two Psyllid Species of Cacopsylla genus (Hemiptera: Psyllidae) Associated with Prunus africana (Rosaceae) from Cameroon

Psyllids (Hemiptera: Psylloidea) are sap-sucking insects inducing serious damages to their host plants. Among the plants attacked by the psyllids in Cameroon, there is Prunus africana (Rosaceae), an important medicinal plant which is associated with two non-described psyllid species belonging to Cacopsylla genus. The two species induce necrosis of the leaves and stunt the growth of shoots of the host plant principally when it is in nursery. The aim of this survey is to describe and identify the two species of psyllids associated to P. africana. The specimens were captured with a sweep net of 0.5 mm mesh size and mouth aspirator. The fifth instar immatures and adults were described from the illustrated diagrams made with the aid of microscope as well as the morphological comparison with previously described species. The morphological examination shows that the two species share the nymph circumanal shape, but the abdomen distal margin bears different types of setae. In adult, the two species also share the head, forewing, and distal portion of aedeagus shape. They differ morphologically from the structure of paramere and female genitalia. When the two species of Cacopsylla described in this survey are compared to other species described elsewhere, they are morphologically different, notably the structure of paramere and female genitalia, the host plant species are also different. Then they are new species named Cacopsylla bamendae sp. nov. and C. messii sp. nov.