Tabaci Populations Research Articles

Comparative evolutionary analyses of eight whitefly Bemisia tabaci sensu lato genomes: cryptic species, agricultural pests and plant-virus vectors

BackgroundThe group of > 40 cryptic whitefly species called Bemisia tabaci sensu lato are amongst the world’s worst agricultural pests and plant-virus vectors. Outbreaks of B. tabaci s.l. and the associated plant-virus diseases continue to contribute to global food insecurity and social instability, particularly in sub-Saharan Africa and Asia. Published B. tabaci s.l. genomes have limited use for studying African cassava B. tabaci SSA1 species, due to the high genetic divergences between them. Genomic annotations presented here were performed using the ‘Ensembl gene annotation system’, to ensure that comparative analyses and conclusions reflect biological differences, as opposed to arising from different methodologies underpinning transcript model identification.ResultsWe present here six new B. tabaci s.l. genomes from Africa and Asia, and two re-annotated previously published genomes, to provide evolutionary insights into these globally distributed pests. Genome sizes ranged between 616—658 Mb and exhibited some of the highest coverage of transposable elements reported within Arthropoda. Many fewer total protein coding genes (PCG) were recovered compared to the previously published B. tabaci s.l. genomes and structural annotations generated via the uniform methodology strongly supported a repertoire of between 12.8—13.2 × 103 PCG. An integrative systematics approach incorporating phylogenomic analysis of nuclear and mitochondrial markers supported a monophyletic Aleyrodidae and the basal positioning of B. tabaci Uganda-1 to the sub-Saharan group of species. Reciprocal cross-mating data and the co-cladogenesis pattern of the primary obligate endosymbiont ‘Candidatus Portiera aleyrodidarum’ from 11 Bemisia genomes further supported the phylogenetic reconstruction to show that African cassava B. tabaci populations consist of just three biological species. We include comparative analyses of gene families related to detoxification, sugar metabolism, vector competency and evaluate the presence and function of horizontally transferred genes, essential for understanding the evolution and unique biology of constituent B. tabaci. s.l species.ConclusionsThese genomic resources have provided new and critical insights into the genetics underlying B. tabaci s.l. biology. They also provide a rich foundation for post-genomic research, including the selection of candidate gene-targets for innovative whitefly and virus-control strategies.

Efficacy of Different Neonicotinoids and Bio Pesticides on Okra Against Bemisia Tabaci

The current study was investigated at the Agricultural Research Institute Tarnab, Peshawar during 2020 in a Randomized Complete Block Design (RCBD) with three replications. The study aimed was determining the efficacy of different neonicotinoids insecticides and bio- pesticides against Bemisia tabaci on okra crop. Results revealed that significantly maximum number of whitefly (Bemisia tabaci) population reduction was recorded in imidacloprid (7.55plant-1) treated plot followed by acetamiprid (8.88plant-1) and bio-pesticides (11.99 plant-1) while minimum population reduction was recorded in clothianidin (14.66 plant-1) treated plot over checked plot after 1st application while similar observation was recorded after the 2nd application. In terms of CB ratio, highest CB ratio was recorded by imidacloprid treated plot followed by bio pesticide, acetamiprid and clothianidin while lowest CB ratio was recorded by acetamiprid. Similarly, the research work concluded that overall best performed by imidacloprid after 1st and 2nd application while minimum control was observed by clothianidin treated plot over the control treatment. 
 

Relationship Between whitefly (Bemisia tabaci) Population and Pepper Yellow Leaf Curl Disease on Chili Plant Yield in The Field

Relationship Between whitefly (Bemisia tabaci) Population and Pepper Yellow Leaf Curl Disease on Chili Plant Yield in The Field

Effect of several reduced-risk insecticides on the population of Bemisia tabaci Genn. and incidence of pepper yellow leaf curl Indonesia virus (PepYLCIV) on chili plants

Tobacco whitefly, Bemisia tabaci Genn. can directly, and indirectly damage chili plants by sucking the plant sap and transmitting Pepper yellow leaf curl Indonesia virus (PepYLCIV), respectively. Farmers control PepYLCIV by using synthetic insecticides with 2-3 applications a week to suppress the vector population. The intensive use of insecticide raises concern about potential detrimental effects on the environment and non-target organisms. An alternative control measure for B. tabaci is the use of reduced-risk insecticides that are effective but safer. Thus, the study aimed to determine the effectiveness of various reduced-risk insecticides in reducing the whitefly population and PepYLCIV incidence. This experiment consisted of 12 treatments using insecticides of abamectin, azadiractin, imidacloprid, deltamethrin, spinosad, and water (control), applied once and twice a week. The results showed that the low-risk insecticides had no significant effect on the numbers of adults and nymphs of B. tabaci and the PepYLCIV incidence. Imidacloprid had significantly lower egg number and PepYLCIV incidence than the control and the other insecticide treatments. Our results also showed that B. tabaci populations were low throughout the season but the incidences of PepYLCIV were relatively high. This indicated a possibility that PepYLCIV is seed-borne.

New Biocompatible Technique Based on the Use of a Laser to Control the Whitefly Bemisia tabaci

The whitefly Bemisia tabaci is among the most important agricultural pests in the world and one of the world’s top 10 most invasive insect pests. Bemisia tabaci is associated with severe yield and quality losses, mainly due to the transmission of plant viruses, as in the case of common beans (Phaseolus vulgaris L.). Reducing insecticide applications is a research priority, e.g., developing innovative and clean tools such as electromagnetic waves. The present work aims to determine the effective parameters of laser to reduce the Bemisia tabaci population in common beans. Preliminary assays were conducted by manually irradiating continuous-wave laser beams with different wavelengths (444 nm, 527 nm, and 640 nm) and optical intensities directly on the insects. Among these, the most effective wavelength was 444 nm. Later, we repeated the experiments using a homemade automated system to control the exposure time (t1 = 1 s, t2 = 2 s, t3 = 3 s and t4 = 4 s) of whiteflies to the incident beam at different optical intensities (I1 ≈ 10 Wcm−2, I2 ≈ 4 Wcm−2, I3 ≈ 2 Wcm−2). We have achieved 100% insect mortality by irradiating 454 nm laser wavelength on the 3rd instar nymphs of Bemisia tabaci, with the following parameters: I1(t1), I2(t3) and I3(t4). Moreover, the laser irradiation test did not affect plant yield and development, revealing that our preliminary results present a photonic technique that could control whiteflies without harming the plants’ development.

Genetic diversity, distribution, and structure of Bemisia tabaci whitefly species in potential invasion and hybridization regions of East Africa.

Outbreaks of whitefly, Bemisia tabaci species in East and Central Africa, have become increasingly prevalent during the previous 25 years and are responsible for driving the spread of plant-virus diseases, such as cassava mosaic disease and cassava brown steak disease. Epidemics of these diseases have expanded their ranges over the same period, spreading from Uganda into other sub-Saharan African countries. It was hypothesised that a highly abundant 'invader' population of B. tabaci was responsible for spreading these diseases from Uganda to neighbouring countries and potentially hybridising with the resident cassava B. tabaci populations. Here, we test this hypothesis by investigating the molecular identities of the highly abundant cassava B. tabaci populations from their supposed origin in Uganda, to the northern, central, eastern and coastal regions of Tanzania. Partial mitochondrial cytochrome oxidase I (mtCOI) barcoding sequences and nuclear microsatellite markers were used to analyse the population genetic diversity and structure of 2734 B. tabaci collected from both countries and in different agroecological zones. The results revealed that: (i) the putative SSA1 species is structured according to countries, so differ between them. (ii) Restricted gene flow occurred between SSA1-SG3 and both other SSA1 subgroups (SG1 and SG2), even in sympatry, demonstrating strong barriers to hybridization between those genotypes. (iii) Not only B. tabaci SSA1-(SG1 and SG2) was found in highly abundant (outbreak) numbers, but B. tabaci SSA1-SG3 and the Indian Ocean (IO) species were also recorded in high numbers in several sites in Tanzania. (iv) The SSA1-(SG1 and SG2) species was distributed in both countries, but in Tanzania, the B. tabaci IO and SSA1-SG3 species predominated. These data confirm that multiple, local Tanzanian B. tabaci species produce highly abundant populations, independent of the spread of the putative invasive B. tabaci SSA1-(SG1 and SG2) populations.

Gene Expression Analysis Reveals Potential Regulatory Factors Response to Temperature Stress in Bemisia tabaci Mediterranean.

Exposure to extreme temperatures can hinder the development of insects and even reduce their survival rate. However, the invasive species Bemisia tabaci exhibits an impressive response to different temperatures. This study aims to identify important transcriptional changes of B. tabaci occupying different temperature habitats by performing RNA sequencing on populations originating from three regions of China. The results showed that the gene expression of B. tabaci populations inhabiting regions with different temperatures was altered and identified 23 potential candidate genes that respond to temperature stress. Furthermore, three potential regulatory factors' (the glucuronidation pathway, alternative splicing, and changes in the chromatin structure) response to different environmental temperatures were identified. Among these, the glucuronidation pathway is a notable regulatory pathway. A total of 12 UDP-glucuronosyltransferase genes were found in the transcriptome database of B. tabaci obtained in this study. The results of DEGs analysis suggest that UDP-glucuronosyltransferases with a signal peptide may help B. tabaci resist temperature stress by sensing external signals, such as BtUGT2C1 and BtUGT2B13, which are particularly important in responding to temperature changes. These results will provide a valuable baseline for further research on the thermoregulatory mechanisms of B. tabaci that contributes to its ability to effectively colonize regions with considerable temperature differences.

Mitochondrial genetic diversity of Thrips tabaci (Thysanoptera: Thripidae) in onion growing regions of the United States.

Onion thrips (Thrips tabaci Lindeman, Thysanoptera: Thripidae) causes severe damage to many horticultural and agronomic crops worldwide. It also acts as a vector of several plant viruses. T. tabaci is a key pest of Allium cepa in the United States. However, there is limited information available on the genetic variation within and between T. tabaci populations in the United States and its key evolutionary parameters. In the current study, 83 T. tabaci specimens were collected from A. cepa from 15 different locations comprising four states of the United States. A total of 92 mtCOI gene sequences of T. tabaci from A. cepa were analyzed to understand the genetic diversity and structure of T. tabaci collected from onion host. Seven distinct haplotypes of T. tabaci infesting A. cepa were identified from the current collection, while nine T. tabaci sequences retrieved from GenBank comprised 5 haplotypes. Overall, 15 haplotypes of T. tabaci infesting A. cepa were identified in the world that includes the ten haplotypes in the United States. In the phylogenetic analysis, all the populations collected during the study clustered with thelytokous lineage, while T. tabaci sequences retrieved from GenBank corresponded to leek-associated arrhenotokous lineage. The highest genetic variation was found in Elba and Malheur populations with 3 haplotypes identified in each. The results suggest that haplotypes 1 and 7 are more frequently prevailing haplotypes in the north-western United States, with haplotype 1 being the predominant all over the country. The eastern United States appears to have a more diverse group of haplotypes. The populations from Hungary constituted distinct haplotypes and a haplotype from Kingston linked it with the predominant haplotype.

Insecticide Resistance and Its Management in Two Invasive Cryptic Species of Bemisia tabaci in China.

The sweet potato whitefly Bemisia tabaci is a major agricultural pest with a wide host range throughout the world. The species designation for B. tabaci includes numerous distinct cryptic species or biotypes. Two invasive B. tabaci biotypes, MEAM1 (B) and MED (Q), were found in China at the end of the 20th century and at the beginning of the 21st century. MEAM1 (B) and MED (Q) show higher pesticide resistance levels than native strains, and the levels of resistance vary with changes in insecticide selection pressure. Recent studies have revealed metabolic resistance mechanisms and target site mutations in invasive B. tabaci strains that render them resistant to a range of insecticides and have uncovered the frequency of these resistance-related mutations in B. tabaci populations in China. Novel pest control agents, such as RNA-based pesticides and nano-pesticides, have achieved effective control effects in the laboratory and are expected to be applied for field control of B. tabaci in the future. In this review, we discuss the mechanisms of resistance developed by these invasive B. tabaci populations since their invasion into China. We also provide suggestions for ecologically sound and efficient B. tabaci control.

Native and Non-Native Bemisia tabaci NAFME Haplotypes Can Be Implicated in Dispersal of Endemic and Introduced Begomoviruses in Oman.

Irrigated agriculture and global trade expansion have facilitated diversification and spread of begomoviruses (Geminiviridae), transmitted by the Bemisia tabaci (Gennadius) cryptic species. Oman is situated on major crossroads between Africa and South Asia, where endemic/native and introduced/exotic begomoviruses occur in agroecosystems. The B. tabaci 'B mitotype' belongs to the North Africa-Middle East (NAFME) cryptic species, comprising at least eight endemic haplotypes, of which haplotypes 6 and/or 8 are recognized invasives. Prevalence and associations among native and exotic begomoviruses and NAFME haplotypes in Oman were investigated. Nine begomoviral species were identified from B. tabaci infesting crop or wild plant species, with 67% and 33% representing native and exotic species, respectively. Haplotypes 2, 3, and 5 represented 31%, 3%, and 66% of the B. tabaci population, respectively. Logistic regression and correspondence analyses predicted 'strong'- and 'close' virus-vector associations involving haplotypes 5 and 2 and the exotic chili leaf curl virus (ChiLCV) and endemic tomato yellow leaf curl virus-OM, respectively. Patterns favor a hypothesis of relaxed virus-vector specificity between an endemic haplotype and the introduced ChiLCV, whereas the endemic co-evolved TYLCV-OM and haplotype 2 virus-vector relationship was reinforced. Thus, in Oman, at least one native haplotype can facilitate the spread of endemic and introduced begomoviruses.

Population Dynamics of Insect Pests and Beneficials on Different Snap Bean Cultivars

Snap bean is an important crop in the United States. Insecticides are commonly used against pests on snap bean, but many pests have developed resistance to the insecticides and beneficials are threatened by the insecticides. Therefore, host plant resistance is a sustainable alternative. Population dynamics of insect pests and beneficials were assessed on 24 snap bean cultivars every week for six weeks. The lowest number of sweetpotato whitefly (Bemisia tabaci) eggs was observed on cultivar 'Jade', and the fewest nymphs were found on cultivars 'Gold Mine', 'Golden Rod', 'Long Tendergreen', and 'Royal Burgundy'. The numbers of potato leafhopper (Empoasca fabae) and tarnished plant bug (Lygus lineolaris) adults were the lowest on cultivars 'Greencrop' and 'PV-857'. The highest numbers of adults were found in Week 1 (25 days following plant emergence) for B. tabaci and Mexican bean beetle (Epilachna varivestis); Week 3 for cucumber beetle, kudzu bug (Megacopta cribraria), and E. fabae; Weeks 3 and 4 for thrips; Week 4 for L. lineolaris; and Weeks 5 and 6 for bees. Temperature and relative humidity correlated with B. tabaci, E. varivestis, bee, and predator ladybird beetle populations. These results provide valuable information on the integrated pest management of snap beans.

Insecticide resistance management of Bemisia tabaci (Hemiptera: Aleyrodidae) in Australian cotton - pyriproxyfen, spirotetramat and buprofezin.

Bemisia tabaci is a globally significant agricultural pest including in Australia, where it exhibits resistance to numerous insecticides. With a recent label change, buprofezin (group 16), is now used for whitefly management in Australia. This study investigated resistance to pyriproxyfen (group 7C), spirotetramat (group 23) and buprofezin using bioassays and available molecular markers. Bioassay and selection testing of B.tabaci populations detected resistance to pyriproxyfen with resistance ratios ranging from 4.1 to 56. Resistance to spirotetramat was detected using bioassay, selection testing and sequencing techniques. In populations collected from cotton, the A2083V mutation was detected in three populations of 85 tested, at frequencies ≤4.1%, whereas in limited surveillance of populations from an intensive horticultural region the frequency was ≥75.8%. The baseline susceptibility of B.tabaci to buprofezin was determined from populations tested from 2019 to 2020, in which LC50 values ranged from 0.61 to 10.75 mg L-1 . From the bioassay data, a discriminating dose of 200 mg L-1 was developed. Recent surveillance of 16 populations detected no evidence of resistance with 100% mortality recorded at doses ≤32 mg L-1 . A cross-resistance study found no conclusive evidence of resistance to buprofezin in populations with high resistance to pyriproxyfen or spirotetramat. In Australian cotton, B.tabaci pest management is challenged by ongoing resistance to pyriproxyfen, while resistance to spirotetramat is an emerging issue. The addition of buprofezin provides a new mode-of-action for whitefly pest management, which will strengthen the existing insecticide resistance management strategy. © 2023 Commonwealth of Australia. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Distribution of Bemisia tabaci in different agro-ecological regions in Uganda and the threat of vector-borne pandemics into new cassava growing areas

Previous studies in sub-Saharan Africa have showed the spread of cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) pandemics into different cassava growing regions by high Bemisia tabaci populations. Studies did indicate that there were stark differences in some whitefly species, yet they have not looked extensively across agroecologies. Members of B. tabaci species complex termed sub-Saharan Africa 1 (SSA1) and SSA2 have been linked to the spread of CMD and CBSD viruses. During the period of a severe CMD pandemic in the 1990s, SSA2 was the most predominant until the resurgence of SSA1, particularly SSA1-subgroup1 (SSA1-SG1) from the early 2000s to date. Cassava being a drought resilient crop has become an important food security crop and has been introduced into new areas and regions. Considering the role B. tabaci in the spread of cassava virus pandemics into neighboring regions, we investigated the genetic diversity and distribution of B. tabaci in nine different agro-ecological regions of Uganda in 2017. Adult whiteflies were collected from cassava and 33 other host plants from cassava-growing areas, those with limited cassava and areas with no cassava, where it is being introduced as a food security crop. The partial sequences of the mitochondrial cytochrome oxidase 1 (mtCO1) gene (657 bp) were used to determine the phylogenetic relationships between the sampled B. tabaci. Cassava B. tabaci SSA1 (-SG1, -SG2, -Hoslundia (previously called SSA1-SG1/2), -SG3), SSA2 and SSA3; non-cassava B. tabaci SSA6, SSA10, SSA11, SSA12, SSA13, MED-ASL, MED-Q1, MEAM1, Indian Ocean; and other Bemisia species, Bemisia afer and Bemisia Uganda1 were identified in the study. SSA3, one of the key B. tabaci species that occurs on cassava in West Africa, was identified for the first time in Uganda. The SSA1-SG1 was widely distributed, predominated on cassava and was found on 17 other host-plants. The ability of SSA1-SG1 to exist in environments with limited or no cassava growing poses the risk of continued spread of virus pandemics. Therefore, measures must be put in place to prevent the introduction of diseased materials into new areas, since the vectors exist.

Bemisia tabaci (Hemiptera: Aleyrodidae): Evaluation of Leaf Trichome Density based Resistance on Several Soybean Varieties

The whitefly Bemisia tabaci (Gennadius) is one of the important soybean pests which can reduce production up to 80 %. Soybean defense mechanism against B. tabaci is affected by the physical characteristics of the leaf surface, e.g. leaf thickness, density of trichomes, and sticky glandular trichomes. The objective of this research was to investigate B. tabaci population – trichome density relationship on ten soybean varieties. The experiment was carried out in Ngale Station, Ngawi District, East Java. The tested soybean varieties were Anjasmoro, Demas 1, Dena 1, Dering 1, Devon, Detam 3, Dewah, Gema, Grayak 1, and Wilis. The experiment was done by completely randomized design with three replications. Observation on the whitefly population was conducted weekly from 2 until 10 weeks after planting on 23 sample plants in each plot. The result showed that Devon was the variety with the highest population levels of B. tabaci, 10.89 (eggs), 14.48 (nymphs) individuals per leaf, respectively. The population of B. tabaci was affected by trichomes density. Devon was the highest density of trichomes (613.7 hairs per cm2). The density of trichomes and the number of whitefly eggs and nymphs relationship were significant (R2= 0,78 (egg) and 0.84 (nymph), n= 10, ?= 1 %, F Value= 0.00157, respectively).

LABORATORY EVALUATION OF THE ADULTICIDAL AND NYMPHICIDAL ACTIVITY OF Aspergillus niger In Bemisia tabaci (HEMIPTERA: ALEYRODIDAE)

Whitefly, Bemisia tabaci (Gennadius), is a widespread polyphagous insect pest and a dangerous vector for many viruses that cause plant diseases. Farmers urgently need safe pesticides to protect their crops and plants, making biopesticide a good alternative to chemicals. Biopesticides are part of an integrated pest management program and offer a safer, more natural alternative to chemical pesticides. Since biocides were introduced, several pest management products have been released, some of which dominate the market. The current laboratory study tested the biological agent Aspergillus niger at three concentrations (0.25, 0.50, and 1.00 con/ml) to manage and reduce Bemisia tabaci population density in greenhouses and field crops. Laboratory tests showed that the two isolates were highly virulent against Bemisia tabaci nymphs and adults. Mortality was significantly different from controls in relation to isolate concentrations and time. Culture filtrate concentration and duration affected nymph and adult mortality. The 100% concentrations of both An1 and An2 were superior to the remaining concentrations, giving mortality in nymphs of B.tabaci 48.88 and 45.55 for isolates (An1 and An2) respectively, 42.21 and 36.66 for isolates (An1 and An2) respectively in adults stage. Effect of duration on post treatment mortality, highest mortality in nymphs and adults occurred 9 days after treatment, 74.44 , 56.66% in nymph and 53.33, 45.55 in adults for isolates (An1and An2) respectively. Concerning the interaction between concentration and duration, as is clear from Tables (1) and (2), the mortality was highest at 1.00% concentration. After 9 days of treatment, the isolates (An1, An2) achieved mortality 86.66, 80.0 in nymphs and 73.33%, 63.33% in adults, respectively. These findings demonstrate A. niger's biopesticide potential.

Molecular Analysis of Cytochrome Oxidase I in Bemisia tabaci (Gennadius) Populations Collected from Four Districts in the Special Region of Yogyakarta

Bemisia tabaci is an agricultural pest that interferes plant growth, as well as being an insect vector of various types of viruses, one of which is the geminivirus group. B. tabaci is called Cryptic Species Complex due to their similar morphology but has different genetic profiles. Climate change and increased global trading of agricultural products could increase B. tabaci population and lead to the emergence of genetic disparity. This study aims to obtain the latest information on the population homogeneity of B. tabaci in four districts of the Yogyakarta and potential differences on their nucleotide arrangements. Molecular identification was performed using PCR and primers C1-J-2198/L2-N-3914 on B. tabaci. B. tabaci COI gene sequences were then compared using a phylogenetic analysis and similarities of nucleotide bases were determined. Results showed that the populations of B. tabaci in Yogyakarta were still homogeneous showed by biotypes similarity, namely the non-B biotype. B. tabaci from Yogyakarta have nucleotide base similarity of 100% with B. tabaci from Singapore (AY686095) and Thailand (AY686092) and 99.56% with species from Bangladesh (AJ748388). Results also showed no differences in the composition of both nucleotide bases and amino acids from the four districts of B. tabaci sampling location. The homogeneous population of B. tabaci and the high incidence of yellowing disease caused by Begomovirus in chili pepper plants in the Special Region of Yogyakarta prove that it is necessary to review the current methods of controlling B. tabaci pests.

A meta-analysis of climatic conditions and whitefly Bemisia tabaci population: implications for tomato yellow leaf curl disease

BackgroundTomato yellow leaf curl disease (TYLCD), which is caused by the genus Begomovirus, is basically transmitted by the vector whitefly, Bemisia tabaci (B. tabaci). It remains a destructive disease of tomato across the world. The disease is present in many tomato growing countries, and it has a broad geographical distribution. The population and distribution of the vector are therefore an important factor in disease spread. This study assesses the determinants of the relationship between climatic factors and whitefly population. A thorough search of relevant papers was first initiated, and eventually 16 articles with 142 estimates were selected. A meta-regression analysis, especially the random-effects model with a restricted maximum likelihood (REML) estimator, was applied.ResultsSummarization of effect sizes revealed a mean effect size for the study of r = 0.15. The forest plot suggested a significant amount of study heterogeneity. No evidence of significant publication bias was uncovered. The meta-analysis revealed that the population of whiteflies was significantly related to climatic independent variables such as maximum and minimum temperature and rainfall. Other factors such as altitude, number of symptoms, pesticide policy, type of soil, number of references, impact factor and publication status were found to significantly influence the effect sizes.ConclusionsWhiteflies are playing a major role in spreading the TYLCD. Several factors were identified to have a significant impact on the climatic conditions-whitefly population nexus. Since climatic factors, altitude, existing pesticide laws and type of soil were found to have a significant impact on the effect sizes, agricultural management policies could be enacted by specifically considering those factors in a view to minimize the impact of whiteflies. In general, all the above factors could be considered in strategy to manage TYLCD.

Resistance to dinotefuran in Bemisia tabaci in China: status and characteristics.

Bemisia tabaci (Gennadius) is a serious agricultural pest worldwide. Neonicotinoids are the most important new class of synthetic insecticides used in the management of B. tabaci. However, B. tabaci populations have developed resistance to various active ingredients in neonicotinoids following long-term and widespread application. Dinotefuran exhibited high toxicity against most B. tabaci field populations. One population (Din-R) with a high level of resistance to dinotefuran (255.6-fold) was first identified in the field. The Din-R population exhibited medium to high levels of resistance to all the tested neonicotinoid insecticides and a high level of resistance to spinetoram. Genetic inheritance analysis revealed that resistance to dinotefuran was incompletely recessive and polygenic. The synergist piperonyl butoxide significantly increased the toxicity of dinotefuran to Din-R. P450 activity in the Din-R population was 2.19-fold higher than in the susceptible population. RNA-sequencing analysis showed that 12 P450 genes were significantly upregulated in the Din-R population, of which CYP6DW5, CYP6JM1 and CYP306A1 were found to exhibit more than 3.00-fold higher expression in Din-R when using a reverse transcription quantitative real-time polymerase chain reaction. Expression of eight P450 genes was obviously induced by dinotefuran, and CYP6DW5 showed the highest expression level. After knockdown of CYP6DW5 in Din-R, the toxicity of dinotefuran increased significantly. P450 had a crucial role in dinotefuran resistance in B. tabaci, and CYP6DW5 was involved in the resistance. These results provide important information for the management of resistance in B. tabaci and improve our understanding of the resistance mechanism of dinotefuran. © 2022 Society of Chemical Industry.

Relationship between viruliferous Bemisia tabaci population and disease incidence of Pepper yellow leaf curl Indonesia virus in chili pepper

Abstract. Temaja IGRM, Selangga DGW, Phabiola TA, Khalimi K, Listihani L. 2022. Relationship between viruliferous Bemisia tabaci population and disease incidence of Pepper yellow leaf curl Indonesia virus in chili pepper. Biodiversitas 23: 5360-5366. Bemisia tabaci Genn is an important pest in horticulture crops. Until today, B. tabaci has always been found in chili pepper and causes damage. In addition to a direct injury to the chili pepper, it is also the vector of Begomovirus. There is no research till date regarding the relationship between B. tabaci with Begomovirus which caused damage to chili pepper crops. Thus, the aim of this research was to analyze the interaction between B. tabaci population with the disease incidence of Begomovirus on chili peppers crops, as well as the percentage of viruliferous B. tabaci. This research noted B. tabaci population dynamics, disease incidence of pepper yellow leaf curl disease, and the percentage of viruliferous B. tabaci via PCR by using Begomovirus universal primer and DNA analysis confirmation. The highest imago population occurred at 6 WAP with the average density 27.21 imago/yellow sticky card, while the highest nymph population occurred at 8 WAP with the average density of 4.26 nymph/leaf. The high population of B. tabaci nymph and imago caused the incidence of Begomovirus disease to reach 83.07% at 12 WAP. Result showed that high population of B. tabaci accelerated the speed of virus in the field. The confirmation result of Begomovirus in B. tabaci body showed that the virus was Pepper yellow leaf curl Indonesia virus (PYLCIV). The highest homology obtained was between PYLCIV isolates from Sekaan, Bangli with isolates from Bayung Gede, Bangli which ranged from 99.6 to 99.8%. Further phylogenetic analysis showed that PYLCIV isolates from Sekaan, Bali formed a group with the isolate from Bayung Gede, Bangli, which was from a different group with other isolates. This proved that B. tabaci carries and transmits PYLCIV to chili peppers in Bali.

The Toxicity, Sublethal Effects, and Biochemical Mechanism of β-Asarone, a Potential Plant-Derived Insecticide, against Bemisia tabaci.

Bemisia tabaci is a threat to agriculture worldwide because of its potential to cause devastating damage to various crops. β-asarone is a bioactive pesticidal chemical originating from Acorus calamus (or “Sweet Flag”) plants, and it displays significant lethal effects against insect pests. In this study, we established a baseline of susceptibility to β-asarone from China and patterns of cross-resistance to other popular insecticides. We found that all the 12 field-collected B. tabaci populations exhibited high susceptibility to β-asarone, and there was no cross-resistance detected for other tested insecticides. We subsequently evaluated the sublethal effects of β-asarone on physiology and biochemistry via LC25 treatment (4.7 mg/L). LC25 of β-asarone resulted in prolonged developmental duration and decreased survival rates in B. tabaci nymphs, pseudopupae, and adults. Significant reductions in oviposition duration, fecundity, and hatchability were also observed. Additionally, the metabolic enzyme activity and expression profiles of selected cytochrome P450 monooxygenase (P450) genes following the LC25 treatment of β-asarone suggest that enhanced detoxification via P450s could be involved in the observed sublethal effects. These findings demonstrate the strong toxicity and significant sublethal effects of β-asarone on B. tabaci and suggest that the induced overexpression of P450 genes could be associated with the response to β-asarone.