Sap-sucking Pests Research Articles

Diversity and temporal variations of the leafhopper fauna (Cicadellidae, Auchenorrhyncha, Hemiptera) in two ecological zones of Egypt

ABSTRACT Leafhoppers constitute one of the largest and most common groups of plant sap-sucking pests found in wild and agricultural habitats. They cause damage to plants directly through feeding and oviposition or indirectly through transmission of dangerous plant pathogens. The present study aims to list, assess and compare the diversity and temporal fluctuations of the cicadellid species associated with different cultivated agronomic crops in two governorates (Qena and Alexandria), representing two different Egyptian ecological zones. By light trapping, 33 species (four species identified only to the genus level) belonging to 22 genera, 12 tribes and 4 subfamilies were collected from six field sites throughout the year 2018. The most common leafhopper species was Empoasca decipiens, composing 51.3% of the total individuals collected, while the other 32 species encompassed 48.7%. Although a significant difference was found in the species richness of leafhoppers between the two governorates, none was found for abundance, species diversity or evenness. A cluster analysis derived from similarity of species composition of cicadellid communities showed a clear grouping of the study sites in each ecological zone. Furthermore, significant differences were found between the community structures in Qena and Alexandria governorates (analysis of similarities [ANOSIM], R = 0.722). A similar population pattern was observed for both governorates. Generally, the density of nearly all cicadellids showed unimodal seasonal patterns with one peak in midsummer (July or August). Spearman’s rank correlation analysis showed significant positive relationships between abundance of cicadellids and temperatures in both governorates; however, no correlation with humidity was found. This is the first faunal and systematic study conducted on a diverse range of leafhopper species collected from different cultivated agronomic crops in two Egyptian governorates.

Host Specificity Tests Reveals New Host of a Global Biological Control Agent Psyllaephagus bliteus (Hymenoptera: Encyrtidae)

Glycaspis brimblecombei (Hemiptera: Aphalaridae) is an invasive, sap-sucking eucalypt pest in various parts of the world. Psyllaephagus bliteus (Hymenoptera: Encyrtidae) was first released as a biological control agent against this pest in California in 2000. Since then, P. bliteus has been found with its insect pest host, with no intentional introduction, in various South American, European and North African countries, and recently South Africa. Here we report on host specificity studies of P. bliteus in South Africa in order to determine potential risks to non-target hosts. Non-target test insects included the only native lerp-forming psyllid in South Africa, Retroacizzia mopani (Hemiptera: Psyllidae), as well as two free-living and one lerp-forming psyllid that are not native but also feed on Eucalyptus species. Psyllaephagus bliteus was monitored during no-choice tests for antennation, probing and oviposition behaviours towards the test insects. In addition, P. bliteus was enclosed on live plants infested with the test insects which were then monitored for offspring of P. bliteus. Retroacizzia mopani and the non-native free-living psyllids were not attacked, but P. bliteus did attack and develop on the non-native lerp psyllid, Spondyliaspis cf. plicatuloides (Hemiptera: Aphalaridae). Choice tests were then undertaken with G. brimblecombei and S. cf. plicatuloides, and G. brimblecombei was found to be the preferred host. The results indicate that the risk of P. bliteus to native insects is low, but that the host range of P. bliteus is not restricted to Glycaspis spp. and Creiis costatus (Hemiptera: Aphalaridae) as previously thought. The host range of P. bliteus may thus include other lerp-forming insects on eucalypts, especially those within the Spondyliaspidinae.

Comparative bioefficacy of Bacillus and Pseudomonas chitinase against Helopeltis theivora in tea (Camellia sinensis (L.) O.Kuntze.

Tea (Camellia sinensis (L.) O.Kuntze) is an industry-oriented economical crop in India. Among the sap sucking pests, tea mosquito bug (Helopeltis theivora) is one of the most serious pests causing heavy crop loss in tea plantation. Continuous use of chemical pesticides causes environmental pollution and health hazards besides developing pesticide residues in tea powder. The control of pests by bacterial metabolite is an alternative that may contribute to reduce or eliminate the chemical pesticide use. The use of chitinase as a biological control is an emerging field of research. In the present study, Chitinase(~ 25kDa) was purified from Bacillus cereus C-13 strain using gel-filtration chromatography and further characterized for its optimum pH, temperature and substrate specificity. Bioefficacy of chitinase from B. cereus C-13 was compared with our previously reportedPseudomonas fluorescens MP-13 chitinase against H. theivora. Result concluded that, 100% and 78% mortality was observed by using P. fluorescens MP-13 chitinase and B. cereus C-13 chitinase, respectively. In future, bacterial chitinase can be utilized in eco-friendly pest management strategies.

Fitness costs in clothianidin-resistant population of the melon aphid, Aphis gossypii.

Clothianidin is a second-generation neonicotinoid insecticide, widely used against sap-sucking insect pest including melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae). This pest causes severe economic damage to Cucurbitaceae plants worldwide. In this study, we investigated clothianidin resistance development under continuous selection pressure. Moreover, the age-stage, two-sex life table approach was used to evaluate the impact of clothianidin resistance on the fitness of A. gossypii. A clothianidin resistant strain (CT-R) with a 23.17-fold resistance level was developed from a susceptible strain (CT-S) after continuous selection for 24 generations. Life table results showed a significant reduction in the relative fitness (0.847) of CT-R strain compared to the CT-S strain of A. gossypii. The developmental duration, oviposition days, total pre-oviposition period (TPOP), longevity, and fecundity of CT-R strain were found to be significantly lower when compared to CT-S strain. The demographic parameters, including the intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and mean generation time (T) were also significantly decreased in CT-R strain compared to the CT-S strain. Both the reproductive and survival rates were affected by clothianidin resistance in CT-R strain compared with the CT-S strain of A. gossypii. Overall, our results demonstrate that in-depth knowledge about the trade-off at play between resistance degree and fitness cost might be useful to design resistance management strategies against A. gossypii.

Effects of a novel mesoionic insecticide, triflumezopyrim, on the feeding behavior of rice planthoppers, Nilaparvata lugens and Sogatella furcifera (Hemiptera: Delphacidae)

The rice planthoppers, Nilaparvata lugens and Sogatella furcifera, are important sap-sucking pests of rice in Asia. The mesoionic insecticide triflumezopyrim was previously shown to be highly effective in controlling both N. lugens and S. furcifera. In this study, electropenetrography (EPG) was used to evaluate the effect of three triflumezopyrim concentrations (LC10, LC50 and LC90) on the feeding behavior of N. lugens and S. furcifera. EPG signals of planthoppes indicated that there were six different waveforms NP, N1, N2, N3, N4, and N5, which corresponded to non-penetration, stylet penetration into epidermis, salivation, extracellular movement of stylet, sap ingestion in phloem, and water ingestion in xylem during feeding. Compared to untreated controls, triflumezopyrim at LC50 and LC90 prolonged the duration of the non-penetration period by 105.3 to 333.7%. The probing frequencies of N. lugens exposed to triflumezopyrim at LC10 and LC50 were significantly increased; however, the probing frequencies of S. furcifera showed a significant decrease when exposed to triflumezopyrim at all concentrations. Triflumezopyrim exposure prolonged the duration of salivation and shortened the duration of extracellular movement. The duration of phloem sap ingestion decreased from 37.2 to 77.7% in the LC50 and LC90 treatments, respectively. Differences in feeding behavior in response to triflumezopyrim and pymetrozine were minimal. In summary, the results show that the LC50 and LC90 concentrations of triflumezopyrim inhibit the feeding activities of N. lugens and S. furcifera mainly by prolonging the duration of non-penetration and by shortening the duration of phloem sap ingestion, which may foster more efficient use of triflumezopyrim in Asia.

Sub-Lethal Effects of Partially Purified Protein Extracted from Beauveria bassiana (Balsamo) and Its Presumptive Role in Tomato (Lycopersicon esculentum L.) Defense against Whitefly (Bemisia tabaci Genn.).

Simple SummaryApart from their direct entomopathogenicity, many entomopathogenic fungi synthesize protein molecules that can trigger plant defense mechanisms against herbivore insect pests. This laboratory study determined the sub-lethal effects of a partially purified protein derived from Beauveria bassiana against whitefly Bemisia tabaci on tomato plants along with the subsequent gene expression analyses of key gens potentially linked to jasmonic acid (JA) and salicylic acid (SA) associated plant defense pathways. The exogenous foliar application of B. bassiana-derived protein significantly reduced the whitefly survival and fecundity parameters concomitantly with an up-regulation of all the plant defense associated genes, particularly of SA pathway genes. These findings demonstrate the putative role of this partially purified entomopathogenic fungal protein and suggest its further purification and characterization for using in future microbial pest control strategies against whiteflies and other sap-feeding insect pests.Plants rely on various physiological and molecular defense mechanisms against biotic stresses such as herbivore insects. Many entomopathogenic fungi synthesize protein molecules that can trigger these plant defenses. This laboratory study characterized the bioactivity of a partially purified protein derived from Beauveria bassiana (ARSEF 2860) against whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), which is an economically important pest of agricultural and horticultural crops worldwide. Different concentrations (i.e., 0.021, 0.042 and 0.063 μM) of fungal protein were bioassayed to determine their sub-lethal effect on the survival percentage and fecundity rate of B. tabaci on tomato (Lycopersicon esculentum) plants. In addition, the putative role of this partially purified B. bassiana protein in the defense mechanisms of plant was assessed through the expression analyses of important genes related to salicylic acid (SA)—and jasmonic acid (JA)—associated pathways using RT-qPCR. Results revealed a significant suppression of the survival percentage and fecundity rate of B. tabaci by the fungal protein. Lowest survival (41%) was recorded for the highest concentration of protein (0.063 μM), whereas mean survival for the other two protein concentrations (0.042 and 0.021 μM) were 62 and 71%, respectively. Likewise, the highest and lowest mean fecundity rates were observed for the control and the highest protein concentration (i.e., 3.3 and 1.8 eggs day−1 female−1, respectively). Furthermore, the exogenous application of B. bassiana-derived protein on tomato plants strongly up-regulated the SA-related genes (PAL, PR1, BGL2 and EDS1) and slightly up-regulated the JA-related genes (AOC, AOS, OPR3 and LOX) as compared to the control plants. These findings demonstrate the putative role of this partially purified B. bassiana protein fraction in inducing systemic resistance in the tomato plants against B. tabaci, suggesting its further purification and characterization to be used as novel biological pest control tool against B. tabaci and other sap-sucking insect pests.

Generalized population dynamics model of aphids in wheat based on catastrophe theory

Wheat aphids are major wheat sap sucking pests found throughout the world. The analysis of wheat aphid population dynamics to develop aphid control strategies is therefore important. Even if all factors that control the size of aphid populations are known, several mathematical tools are needed to help us understand their combined effect. Based on the knowledge of population ecology and catastrophe theory, we proposed a generalized population dynamics model to describe variation of wheat aphid populations and obtained a dynamic threshold function for aphid control. Field survey data from 1997 to 2002 were used to validate this model. The results indicated the model could predict the results of practical measures against a pest if the factors of their immediate effects are known or could be estimated. By explaining and forecasting the size of an aphid outbreak and its probability of occurrence, this catastrophe model can provide a scientific basis for wheat aphid control.

RNAi‐mediated silencing of ferritin genes in the brown planthopper Nilaparvata lugens affects survival, growth and female fecundity

The brown planthopper (BPH), Nilaparvata lugens, is the most destructive rice insect pest. To exploit potential target genes for applications in transgenic rice to control this sap-sucking insect pest, three ferritin genes were functionally characterized in this study. In this study, three ferritin genes, that is, ferritin 1 Heavy Chain (NlFer1), ferritin 2 Light Chain (NlFer2) and soma ferritin (Nlsoma-Fer), were identified from BPH. Tissue-specific analyses showed that all three genes were highly expressed in the gut. Although double-stranded RNA injection-mediated RNA inference (RNAi) of Nlsoma-Fer expression resulted in only < 14% mortality in BPH, knockdown of NlFer1 or NlFer2 led to retarded growth and 100% mortality in young nymphs, and downregulation of NlFer1 and NlFer2 in newly emerged female adults caused undeveloped ovaries and severely inhibited oocyte growth, resulting in extremely low fecundity and a zero hatching rate. Knockdown of NlFer1 and NlFer2 caused similar phenotypes in BPH, indicating that they function together, as in many other animals. The results demonstrated that NlFer1 and NlFer2 were essential for BPH development and reproduction. BPHs showed high sensitivity to both dsNlFer1 and dsNlFer2, and injection of only 0.625 ng dsNlFer1 per BPH resulted in 100% mortality. Additionally, the effectiveness of feeding dsNlFer1 and dsNlFer2 to BPH nymphs was further proven. NlFer1 and NlFer2 are essential for BPH development and reproduction, and the insect is highly sensitive to their depletion, suggesting that the two gut-highly-expressed genes are promising candidates for application in RNAi-based control of this destructive pest.

Characteristics of biochemical resistance mechanism of novel insecticides in Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

Phenacoccus solenopsis Tinsley is a major sap-sucking insect pest of many ornamental and agricultural crops in Pakistan. Insecticides are recommended to manage P. solenopsis but due to inappropriate use of insecticides, the resistance become the major concern. The study was conducted to investigate resistance against insecticides with different action modes (carbosulfan, clothianidin and chlorfenapyr) by selecting P. solenopsis populations successively for twelve generations with mentioned insecticides. Along with, possible biochemical mechanisms (acetylcholinesterase (AChE), acid and alkaline phosphatases (ACP and ALP), esterase (EST) and glutathione S-transferases (GST)) were assessed. The results described very high resistance (235-fold) to carbosulfan selected pop. (Carbo-SEL G12) and clothianidin selected pop. (Cloth-SEL G12) (112-fold) and high resistance to chlorfenapyr selected pop. (Chlor-SEL G12) (86-fold), relative to the unselected population. The activities of AChE, ACP, ALP, EST and GST enzymes gradually increased upon selection from G1 to G10. The enzymes contribute in resistance of tested insecticides were following: EST (15.61 μmol/min/mg of protein) in Carbo-SEL G12. Whereas, AChE activity (21.5 μmol/min/mg of protein) in Cloth-SEL G12 and the highest ALP enzymes activity 16.57 μmol/min/mg of protein in Chlor-SEL G12, as compared to the unselected population. Current research suggests that the detoxifying enzymes may contribute to resistance evolvement in P. solenopsis and this information may be used for the efficient management of insecticide resistance.

Expression of Pinellia ternata leaf agglutinin under rolC promoter confers resistance against a phytophagous sap sucking aphid, Myzus persicae

Background: Piercing/sucking insect pests in the order Hemiptera causes substantial crop losses by removing photoassimilates and transmitting viruses to their host plants. Cloning and heterologous expression of plant-derived insect resistance genes is a promising approach to control aphids and other sap-sucking insect pests. While expression from the constitutive 35S promoter provides broad protection, the phloem-specific rolC promoter provides better defense against sap sucking insects. The selection of plant-derived insect resistance genes for expression in crop species will minimize bio-safety concerns. Results: Pinellia ternata leaf agglutinin gene ( pta ), encodes an insecticidal lectin, was isolated and cloned under the 35S and rolC promoters in the pGA482 plant transformation vector for Agrobacterium -mediated tobacco transformation. Integration and expression of the transgene was validated by Southern blotting and qRT-PCR, respectively. Insect bioassays data of transgenic tobacco plants showed that expression of pta under rolC promoter caused 100% aphid mortality and reduced aphid fecundity up to 70% in transgenic tobacco line LRP-9. These results highlight the better effectivity of pta under rolC promoter to control phloem feeders, aphids. Conclusions: These findings suggested the potential of PTA against aphids and other sap sucking insect pests. Evaluation of gene in tobacco under two different promoters; 35S constitutive promoter and rolC phloem-specific promoter could be successfully use for other crop plants particularly in cotton. Development of transgenic cotton plants using plant-derived insecticidal, PTA, would be key step towards commercialization of environmentally safe insect-resistant crops. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Times New Roman; mso-bidi-theme-font:minor-bidi;}

Suitable reference genes for RT-qPCR analysis in Dichelops melacanthus (Hemiptera: Pentatomidae).

The relative quantification of gene expression is mainly realized through reverse transcription-quantitative PCR (RT-qPCR). However, the accuracy of this technique is deeply influenced by the expression stability of the reference genes used for data normalization. Therefore, the selection of suitable reference genes for a given experimental condition is a prerequisite in gene expression studies. Dichelops melacanthus (Hemiptera: Pentatomidae) is an important phloem sap-sucking insect pest of soybean, wheat, and maize in Brazil. Most of the genetic and molecular biology studies require gene expression analysis. Nevertheless, there are no reports about reference genes for RT-qPCR data normalization in D. melacanthus. In this study, we evaluated the expression stability of nine candidate reference genes (nadh, sdhb, gapdh, fau, ef1a, rpl9, ube4a, gus and rps23) in different developmental stages, body parts, sex, starvation-induced stress and dsRNA exposure by RefFinder software that integrates the statistical algorithms geNorm, NormFinder, BestKeeper, and ΔCt method. Our results showed that ef1a and nadh are the most stable reference genes for developmental stages, fau and rps23 for sex, ube4a and rps23 for body parts, rpl9 and fau for starvation stress, and nadh and sdhb for dsRNA exposure treatment. The reference genes selected in this work will be useful for further RT-qPCR analyses on D. melacanthus, facilitating future gene expression studies that can provide a better understanding of the developmental, physiological, and molecular processes of this important insect pest. Moreover, the knowledge gained from these studies can be helpful to design effective and sustainable pest management strategies.

Chromosome-level assembly of the melon thrips genome yields insights into evolution of a sap-sucking lifestyle and pesticide resistance.

Thrips are tiny insects from the order Thysanoptera (Hexapoda: Condylognatha), including many sap-sucking pests that are causing increasing damage to crops worldwide. In contrast to their closest relatives of Hemiptera (Hexapoda: Condylognatha), including numerous sap-sucking species, there are few genomic resources available for thrips. In this study, we assembled the first thrips genome at the chromosomal level from the melon thrips, Thrips palmi, a notorious pest in agriculture, using PacBio long-read and Illumina short-read sequences. The assembled genome was 237.85Mb in size, with 1,324 contigs and a contig N50 of 567kb. All contigs were assembled into 16 linkage groups assisted by the Hi-C technique. In total, 16,333 protein-coding genes were predicted, of which 88.13% were functionally annotated. Among sap-sucking insects, polyphagous species (e.g., T. palmi and Bemisia tabaci) usually possess more detoxification genes than oligophagous species (e.g., Diaphorina citri). The polyphagous thrips genomes characterized so far have relatively more detoxification genes in the GST and CCE families than polyphagous aphids, but they have fewer UGTs. HSP genes, especially from the Hsp70s group, have expanded in thrips compared to other hemipterans. These differences point to different genetic mechanisms associated with detoxification and stress responses in these two groups of sap-sucking insects. The expansion of these gene families may contribute to the rapid development of pesticide resistance in thrips, as supported by a transcriptome comparison of resistant and sensitive populations of T. palmi. The high-quality genome developed here provides an invaluable resource for understanding the ecology, genetics, and evolution of thrips as well as their relatives more generally.

Population dynamics of Cacopsylla sp. (Hemiptera: Psylloidea: Psyllidae), pest insect of Prunus africana (Rosaceae), medicinal plant species in Cameroon

Prunus africana is threatened in Cameroon by xylophagous and sap-sucking pest as Cacopsylla sp. This last causes deformations of the young leaves and buds and the plant end up losing all its leaves. Effective control of phytophagous pests requires a thorough understanding of their seasonal population dynamics. The objective of this work carried out on 150 young plants of P. africana in the nursery in Dschang, was to study the population dynamics of Cacopsylla sp. and the impact of climatic factors on the population. From January 2006 to December 2007, monthly collections of larvae, males and females of Cacopsylla sp. were carried out. The results showed, in 2006, three peaks (March, August and December) and two peaks in 2007 (March and August) with larvae. The fluctuation of males' population showed five peaks with two peaks in 2006 (March and December) and three peaks in 2007 (March, June and December) while in females' population, four peaks with two peaks in 2006 (March and December) and two peaks in 2007 (March and November). The annual numerical variation of Cacopsylla sp. individual is statistically correlated with variation of precipitations and the insolation. The precipitations have a negative effect on the numerical variation of males (r=-0.430, p&lt;0.0360) and females (r=-0,434, p&lt;0.0336) of Cacopsylla sp. The insolation has a positive effect on the numerical variation of males (r=0.732, p&lt;0.0000002), females (r=0.653, p&lt;0.000523) and the total individuals (r=0.601, p&lt;0.00197) of Cacopsylla sp. With the larvae, the correlation was negative and non-significant. This work showed that March and December were better indicated to engage the fight against Cacopsylla sp. in Dschang.

The potential and efficacy of Allium sativum leaf lectin (ASAL) against sap-sucking insect pests of transgenic maize

The gene sequence encoding the mannose-binding homodimeric protein Allium sativum leaf agglutinin (ASAL) was introduced into maize inbred lines to achieve resistance against sap-sucking corn leaf aphids in transgenic lines. Maize transformants were generated after the co-cultivation of immature maize embryos with the Agrobacterium strain LB4404 harbouring a recombinant Ti-binary ASAL construct driven by the polyubiquitin promoter. The preliminary screening of maize transformants was performed via GUS histochemical analysis, and PCR and Southern blotting confirmed the insertion of the transgene and its stable integration in five transgenic maize lines. Transcript abundance was quantified by a quantitative real-time PCR assay, which revealed variable expression of the ASAL transgene among five transgenic maize lines. The highest mRNA expression of the ASAL gene was found in the A23 transgenic maize line, while the lowest expression was found in the AU1 transgenic maize line. In planta bioassays in the T1 progeny of the transgenic maize lines revealed high resistance against corn leaf aphids compared to the control non-transgenic line. The mortality of the infesting aphids (Rhopalosiphum maidi) was found to vary from 40 to 71% compared to that of the non-transgenic control maize line.

Impact of Sowing Dates and The Control on Sap-Sucking Pests in Pepper Plant (Capsicum annuam L) Under Field Conditions at Qalubiya Governorate, Egypt.

Impact of Sowing Dates and The Control on Sap-Sucking Pests in Pepper Plant (Capsicum annuam L) Under Field Conditions at Qalubiya Governorate, Egypt.

Inaccessibility to double-stranded RNAs in plastids restricts RNA interference in Bemisia tabaci (whitefly).

RNA interference (RNAi) has emerged as a promising technology for insect pest control. Because of the accumulation of high levels of long double-stranded RNAs (dsRNAs) in plastids, it was previously shown that expression of dsRNAs from plastid genome led to higher mortality of some insect pests with chewing mouthparts than dsRNAs expression from nuclear genome. However, whether plastid-expressed dsRNAs have effects on phloem sap-sucking pests is unknown. In this study, we compared the RNAi effects of nuclear transgenic and transplastomic plants on the whitefly Bemisia tabaci, a serious sap-sucking pest. Nuclear transgenic and transplastomic tobacco plants were developed for the expression of dsRNA against BtACTB gene of Bemisia tabaci, respectively. Feeding nuclear transgenic plants to Bemisia tabaci resulted in reduced gene expression of BtACTB and survival rate, and impaired fecundity of Bemisia tabaci. We did not observe any effects of transplastomic plants on Bemisia tabaci fitness. Furthermore, we found that the inability of B. tabaci to obtain dsRNAs from plastids might restrict its RNAi responses. Our study indicated that the expression of dsRNAs in nuclear transgenic plants was more effective than that in transplastomic plants for the control of Bemisia tabaci. The inaccessibility of Bemisia tabaci to plastids contributes to the inefficiency of plastid-mediated RNAi. Our findings are of great significance to future optimization of transgenically delivered RNAi approaches for efficient controlling of sap-sucking pests. © 2020 Society of Chemical Industry.

Reconstructing early routes of invasion of the bronze bug Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae): cities as bridgeheads for global pest invasions

Insect pest invasions pose a major threat to agriculture, forestry and many natural ecosystems. Thaumastocoris peregrinus is an invasive sap-sucking pest of significant economic importance to Eucalyptus forestry that has recently invaded several countries worldwide. In this study we identify the origin and retrace the invasion history of T. peregrinus. We analysed samples from six locations in Africa, South America and Australia using microsatellites markers and a combination of clustering methods and scenario testing using Approximate Bayesian Clustering. We detected clear genetic substructure differentiating African and South American samples, with representatives of both present in Australia. The Australian population from New South Wales showed substantially higher genetic diversity than the Queensland source, which could indicate that this region could be part of the core range and evolutionary origin of the species. Africa and South America were colonised by independent introductions that occurred more or less concurrently. The study illustrates the impact of the bridgehead effect on global invasions following an outbreak or ‘invasion’ within a city in the native range of the insect.

High Diversity and Functional Complementation of Alimentary Canal Microbiota Ensure Small Brown Planthopper to Adapt Different Biogeographic Environments.

Almost all insects harbor commensal bacteria in the alimentary canal lumen or within cells and often play a pivotal role in their host’s development, evolution, and environmental adaptation. However, little is known about the alimentary canal microbiota and their functions in sap-sucking insect pests of crops, which can damage plants by removing plant sap and by transmitting various plant viruses, especially in the small brown planthopper, Laodelphax striatellus. In this study, we characterized the alimentary canal microbiota of L. striatellus collected from seven regions in China by sequencing 16S rDNA. The insects harbored a rich diversity of microbes, mainly consisted of bacteria from phyla Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Tenericutes. The composition and abundance of microbiota were more similar as the geographic distance decreased between the populations and clustered by geographic location into three groups: temperate, subtropical, and tropical populations. Although the abundance and species of microbes differed among the populations, the various major microbes for each population performed similar functions based on a clusters of orthologous group analysis. Greater diversity in ecological factors in different regions might lead to higher microbial diversity, thus enabling L. striatellus to adapt or tolerate various extreme environments to avoid the cost of long-distance migration. Moreover, the abundance of various metabolic functions in the Kaifeng populations might contribute to higher fecundity in L. striatellus.

Reducing sap-sucking pests infesting Eggplant using biological control agent and colored plastic soil mulches under green house

Reducing sap-sucking pests infesting Eggplant using biological control agent and colored plastic soil mulches under green house

Influence of Crapemyrtle aphid, Tinocallis kahawaluokalani (Hemiptera: Aphididae) on population characteristics of three aphidophagous ladybird beetles

The crapemyrtle aphid, Tinocallis kahawaluokalani is a common sap-sucking insect pest of crapemyrtle plant, Lagerstroemia indica L. (Pers.) (Myrtales: Lythraceae). The life history and population characteristics of three aphidophagous ladybird beetles (Coccinella septempunctata, Menochilus sexmaculatus and Oenopia sauzeti) were studied on T. kahawaluokalani based on two sex life table theories. Results reveal that immature survival, total longevity of adult and reproductive parameters was higher for C. septempunctata than to M. sexmaculatus and O. sauzeti. The population dynamic parameters including net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (λ) were higher for C. septempunctata and M. sexmaculatus than those for O. sauzeti. The intrinsic rate of increase ‘r’ as a key fitness parameter for three aphidophagous predators on T. kahawaluokalani in increasing order was C. septempunctata > M. sexmaculatus > O. sauzeti. These results suggested that C. septempunctata and M. sexmaculatus have more potential to control T. kahawaluokalani. The information obtained from current study may also be useful in using T. kahawaluokalani for mass rearing of these beetles in the laboratory.