Adult Whiteflies Research Articles

Elicitor-Induced Defense Response in Soybean Plants Challenged by Bemisia tabaci

The whitefly, Bemisia tabaci Biotype B (Hemiptera: Aleyrodidae), is considered one of the world’s major agricultural pest groups, attacking a wide range of crop hosts and causing considerable crop loss. Understanding the interactions between whiteflies and host plants promotes the development of novel strategies for controlling whiteflies. This study aimed to evaluate the biochemical alterations caused by induced resistance in soybean plants, challenged by B. tabaci. The experiment was performed at the Federal University of Technology, Parana. Soybean seeds (cv. BRS 284) were sown in polyethylene pots in the greenhouse. The elicitors sprayed on the soybean leaves were: acibenzolar-S-Methyl (ASM-0.005%); Salicylic Acid (SA-2Mm); foliar phosphite (ULTRA K®-0.004%); Chitosan (CH-1%); and silicon (SI-0.25%); whilst the control group was sprayed with distilled water. Plants were infested with 50 adult whiteflies in the cages that were released after applying the treatments. At 0, 24, 48 and 96 hours after the beginning of the experiment, biochemical analyses of total proteins and the activity of the phenylalanine ammonia-lyase (PAL), peroxidases (PO), phenolic compounds, chitinase, and β-1,3-glucanase were made. The results showed that the application of elicitors increased the route of the phenylpropanoids with the activation of PAL and formation of phenolic compounds. It was also verified the activation of pathogenicity-related enzymes such as peroxidases and chitinase.

Cassava Mosaic Disease and Associated Gemini Viruses in Bauchi State, Nigeria: Occurrence and Distribution

Cassava mosaic disease is one of the most important biotic constraint affecting Cassava limiting the production potential of the crop in Northern Nigeria. This study was carried out to evaluate the current status of Cassava mosaic disease incidence, severity, infection type, whitefly abundance in the farmers’ field as well as to determine the virus strains causing the disease in Bauchi State, North eastern Nigeria. A total of thirty three (33) farmers’ fields were surveyed and in each field, thirty plants were assessed along the two diagonals with respect to disease incidence, severity, infection type and whitefly abundance and leaf samples were collected from each field for the virus diagnosis. The results revealed that Cassava mosaic disease incidence was highest in Ganjuwa (88.66%) and lowest in Darazo (43.33%). The disease symptom severity was generally mild. It was also highest in Ganjuwa (2.85) and lowest in Darazo (1.34). Whitefly infection is most prevalent (59.73%) than cutting borne infection (2.67%) in the Districts. Adult whitefly (<i>Bemisia tabaci</i>) population was highest in Ganjuwa (56.33) followed by Kirfi (40.93) and lowest in Toro (27.63). Polymerase chain reaction (PCR) results using specific primers for African Cassava mosaic virus (ACMV) and East African Cassava mosaic virus (EACMV) detected single infections of ACMV and EACMV in 62.4% and 12.9% of the positive samples respectively. Co-infections of ACMV and EACMV were detected in 10.6% of the tested samples. Continuous monitoring of Cassava Mosaic Viruses and whiteflies population is required to provide appropriate management strategies of the disease in Nigeria.

Multiple Cassava Viruses’ Co-Infections and Resurgence of Pests Are Leading to Severe Symptoms and Yield Losses on Cassava in the South-Kivu Region, Democratic Republic of Congo

A survey was completed during the last five years (2014-2018) to update and assess changes in the cassava pests and diseases occurrence as well as to understand how these changes occur regarding the recent new viruses spread under a climate change context in the South-Kivu region, Democratic Republic of Congo. The eight territories of South-Kivu were surveyed during the rainy seasons from 2015 until 2017 except for Uvira and Fizi where data were recorded in 2018 regarding the prevalence of unstable agro ecological factors which may influence pest and diseases dynamic in these two territories. During the data collection, pests and disease incidence and severity were recorded as well as the sampling of cassava leaves for molecular viruses’ detection. The recorded data showed that Cassava mosaic disease (CMD) remains the most encountered disease (75% - 80%) and its vector (the whitefly Bemisia tabaci) the most important pest (10 - 18 adult whiteflies per leaf). The major changes were recorded for Cassava brown streak disease, recently reported in the region, for which a significant increase was recorded, with not reports before 2012 to 70% - 80% incidence in 2018 in the Ruzizi plain area (Uvira and Fizi). Molecular detection revealed a coexistence of both two viruses, the cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) in single and mixed infections. Co-infections cassava mosaic and cassava brown streak diseases were frequently recorded resulting in severe expression leaves’ symptoms and tuber yields’ losses. Common pests and diseases considered as minor have drastically become serious threat to cassava production by increasing both their incidence and severity values. The cassava bacterial blight (20%), cassava green mite (20% - 70%), cassava mealy bugs and cassava grasshoppers were recorded as a great challenge in relation with an occurrence of long dry season resulting in four consecutive dry months without rain. The high occurrence of CBSD on new CMD-resistant varieties has enforced farmers to recover local CMD-susceptible varieties which revealed a relative CBSD-tolerance and moderate yield losses. This need for virus control is really challenging cassava crop in a region where the diseases pressure is high and people consume cassava and its products seven days a week. Research gaps identified in the study are the need for breeding new varieties with tolerance/resistance to both CMD and CBSD viruses as well as the extensive use of rapid multiplex diagnostic tools to ensure early diagnostic and availability of good quality planting material at farmers’ level.

Incidence and severity of cassava mosaic disease in farmer’s fields in Ghana

A survey of cassava mosaic disease (CMD) was carried out in Ghana from 2007-2008 to assess CMD incidence, infection type, severity and adult whitefly population. A total of 136 farmers’ fields across major cassava producing areas in the Brong Ahafo, Western, Northern, Ashanti and Volta regions were assessed. CMD was prevalent in most of the 136 fields surveyed. Frequently encountered local landraces were susceptible to the disease. CMD incidence reached 100% in farmers’ fields. Mean disease incidence ranged from 46% in the Ashanti region to 90% in the Western region of the country. CMD incidence averaged 66.0%, with cutting-borne infection and Whitefly-borne infections being 54.0% and 12.0%, respectively. CMD shoot symptom severity ranged from 2.0 to 3.7 in the farmers’ fields, with a mean of 2.9. Mean adult whitefly population was 0.47. The high prevalence of CMD requires a concerted effort in the management of CMD in the country.

Methyl benzoate exhibits insecticidal and repellent activities against Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae).

Methyl benzoate (MB) is a plant-derived volatile organic compound with insecticidal properties, but such activity has not been evaluated against the sweetpotato whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), a major crop pest. In this study, we tested methyl benzoate control efficacy on B. tabaci infecting tomato plants in a greenhouse, specifically measuring contact and fumigant toxicity, as well as repellent activity. For direct spray applications of 0% (control), 0.1%, 0.25%, 0.5%, 1%, 2% MB onto tomato leaves infested with adults of B. tabaci (< 5-d-old), 2% MB showed the highest corrected mortality (100%) at 24 h post-treatment. For residual toxicity in which the same MB solutions were sprayed onto tomato leaves and allowed to dry for 2 h before < 5-d-old adults were released, the 2% MB also showed the highest corrected mortality (100%) at 48 h post-treatment. The lethal median concentration (LC50) for eggs, fourth-instar nymphs, and adults were 0.3%, 0.2%, and 0.2%, respectively. In pot culture experiments, 1% MB concentration was found more effective at killing nymphs and preventing adult eclosion than all other concentrations, and gave 100 percent population reduction compared with the control. MB repelled adult whiteflies and caused 96.5% fumigant toxicity within 10 h post-treatment. Repellency and anti-oviposition rates against B. tabaci had median effective doses of 0.24% and 0.16%, respectively. Our results suggest that MB has strong potential as an environmentally friendly biopesticide for control of B. tabaci but field trials and further greenhouse studies are required to establish efficacy under more natural conditions.

RNA interference mediated knockdown of juvenile hormone esterase gene in Bemisia tabaci (Gennadius): Effects on adults and their progeny

Abstract Juvenile hormone is responsible for regulating metamorphosis and reproduction in insects. Analysis of key elements of juvenile hormone regulation would enhance the understanding of this complex mechanism. Juvenile hormone esterase plays an important role in maintaining juvenile hormone titres in insects. In this study, effects of knockdown of juvenile hormone esterase gene (jhe) in Bemisia tabaci were studied using RNA interference (RNAi) technique. dsRNA corresponding to two conserved regions of jhe gene, substrate binding pocket site (jhe1), catalytic triad site (jhe2), green fluorescent protein gene (gfp) as control were synthesized. dsRNAs incorporated in artificial diet (20% sucrose solution) @ 2.5, 1.0, 0.5 and 0.1 μg/μl were fed to adult whiteflies for 48 h, followed by shifting whiteflies to live plants for next generation biology study. Based on qRT-PCR analyses, reduced jhe gene expression was observed in adult whiteflies after dsRNA feeding @ 2.5 and 1.0 μg/μl. jhe gene knockdown affects the survival and reproduction of whiteflies adversely in a dose-dependent manner. Moreover, oral feeding of dsRNA to adult whiteflies @ 2.5 and 1.0 μg/μl showed adverse effects on next generation of whitefly viz., lower egg hatchability and shortened egg incubation period. Minimum number of viable eggs (1.04 and 1.80 eggs/female) were observed when whiteflies were fed with highest concentration of dsjhe1 and dsjhe2 as compared to control (16.58 eggs/female). These data suggest that jhe gene acts as a major biological player in whitefly and its progeny and further indicate to be potential target for managing whitefly population.

Complete genome sequence and phylogenetic analysis of a novel dicistrovirus associated with the whitefly Bemisia tabaci

A novel single-stranded RNA virus was detected in a whitefly (Bemisia tabaci) sample subjected to high-throughput sequencing. The 8293 nt-long genome presents a polyadenylated 3’ end, and contains two ORFs encoding putative 1596 and 849 aa-long proteins. These putative proteins display significant similarity to replicase and capsid polyproteins, respectively, of discitroviruses. Its complete genome sequence shared the highest nucleotide identity (59.8%) with cricket paralysis virus (family Dicistroviridae, genus Cripavirus). Phylogenetic analyses showed that this new virus putative protein sequences clustered with those from members of Dicistroviridae. However, the replicase and capsid polyprotein sequences clustered with those of members of different genera, respectively to Aparavirus and Cripavirus. RT-PCR using newly collected adult and nymph whitefly samples confirmed the presence of this virus in field populations of B. tabaci. Genome sequence and organization, and polyproteins comparison indicate that this virus is a new species of the family Dicistroviridae. The name Bemisia-associated dicistrovirus 1 is proposed for this virus.

Insecticidal and inhibitory effects of dihydrobenzofuran neolignans on Bemisia tabaci

Bemisia tabaci (Gennadius) biotype B (Hemiptera: Aleyrodidae) has developed resistance to numerous conventional insecticides, which has led us to investigate the toxicity of ten dihydrobenzofuran- (DBN) and benzofuran-type (BN) neolignans structurally related to conocarpan against second instar B. tabaci nymphs. At concentrations higher than 5 mg/L, most of the tested compounds killed 100% of B. tabaci biotype B nymphs 6 days after spraying. The contact toxicity of compounds 2 ((±)-trans-dehydrodiferulate dimethyl ester), 3 ((±)-4-O-methyl-trans-dehydrodiferulate dimethyl ester), 5 ((±)-4-O-acetyl-trans-dehydrodiferulate dimethyl ester), 6 ((±)-7′,8′-dihydro-trans-dehydrodicoumarate dimethyl ester), 8 ((±)-4-O-methyl-7′,8′-dihydro-trans-dehydrodiferulate dimethyl ester), and 10 ((±)-7′,8′-dihydro-7,8-dehydro-trans-dehydrodicoumarate dimethyl ester) was higher than the contact toxicity of pyriproxyfen at a concentration of 75 mg/L, which was used as positive control. Repellent (compounds 2 and 7 ((±)-7′,8′-dihydro-trans-dehydrodiferulate dimethyl ester) and oviposition deterrent (compounds 2, 3, and 7) effects were observed for adult whiteflies exposed to leaves sprayed with DBNs for 24 and 48 h, respectively. These results suggest that DBNs have potential application in the development of effective pest management compounds.

Occurrence of Bondar's Nesting Whitefly, Paraleyrodes bondari (Hemiptera: Aleyrodidae), on cassava in Uganda

Cassava is a valued calorific source to millions of Africans who eat it daily and a vital staple for their food security. One of the key constraints to this crop is whiteflies which are both a vector of viral diseases and a direct pest. Although the African cassava whitefly is known to cause physical damage on cassava with considerable tuberous yield loss, a recent whitefly outbreak caused unusually severe damage, which prompted the current reported investigation. Molecular identification of whitefly adults sampled from the affected cassava field revealed the presence of a new whitefly species, Paraleyrodes bondari. This communication is the first report of the occurrence of P. bondari on cassava in Uganda.

Genotype by Environment Interaction Unravels Influence on Secondary Metabolite Quality in Cassava Infested by Bemisia tabaci

Cassava resistance to Bemisia tabaci is a result of many plant processes which involve plant biochemical constituents, shown to be affected by genotype and environment. The objective of this study was to assess the effect of genotype × environment interactions on concentrations of tannin, flavonoid, total phenolic content, antioxidative capacity and B. tabaci resistance. Fifteen cassava genotypes were evaluated monthly for tannin, flavonoid, total phenolic content and antioxidative capacity in three locations over two seasons with varying temperatures and rainfall. In addition, data were collected on B. tabaci population density and damage. The data collected was subjected to analysis of variance and additive main effects and multiplicative interactions (AMMI) analyses. Flavonoid, total phenolic content and antioxidative capacity varied significantly (P &lt; 0.001) across seasons with higher concentrations in season one than season two, attributed to different temperature and rainfall readings. Total phenolic content was significantly (P &lt; 0.001) associated to antioxidative capacity (r = 0.83) and temperature (r = 0.91). Leaf damage due to adult whitefly and nymphs was significantly (P &lt; 0.001) negatively correlated (r = -0.67) to antioxidative capacity. Genotypes UG 120257, UG 120291 and UG 120124 were shown to have high antioxidative capacity and more stable performance across environments. Temperature and B. tabaci feeding influenced concentrations of the phenolic content and antioxidative activity, as a result affected cassava resistance.

Identification and selection of resistance to Bemisia tabaci among 550 cotton genotypes in the field and greenhouse experiments

Plants have developed sophisticated systems to cope with herbivore challenge, including morphological barriers and secondary metabolites to reduce damage. In this study, 550 <i>Gossypium</i> genotypes were evaluated for whitefly (<i>Bemisia tabaci</i>) resistance in five experiments including two in the field and three in the greenhouse, with 23 resistant and 19 susceptible genotypes selected. Whitefly-resistance index determination showed that a leaf having a high density of hairs had resistance to whitfly egg/nymph production. Longer leaf hairs were also important for resistance. This study revealed that okra shaped leaves reduced adult whitefly oviposition preference, while glabrous leaves and high hair density helped not only in the reduction of the adults but also decreased oviposition preference. Gossypol was also observed to be involved in the reduction of adult whitefly development and/or survival.

Responses of the Whitefly &amp;lt;i&amp;gt;Bemisia tabaci&amp;lt;/i&amp;gt; (Hemiptera: Aleyrodidae) to Biologically Based Insecticides

The effects of three bio-insecticides Azatrol [neem: 1.2% azadirachtin A and B], Molt-X [neem: 3% azadirachtin], and Conserve SC [spinosad; 11.6% spinosyn A and spinosyn D], applied at different concentrations were evaluated on Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) under both laboratory and greenhouse conditions. Laboratory bioassays demonstrated that both neem-based insecticides were repellent to adult whiteflies in a dose-dependent manner. The amounts and frequency of honeydew excretion were significantly reduced up to 0.95 by foliar application of these insecticides at the labeled rate, as compared to untreated plants, with the neem products displaying greater effects on food uptake than spinosad. Reduced fecundity and egg hatch also were associated with these bio-insecticides. The bio-insecticides decreased significantly the survival of nymphs, egg hatch and adult emergence when applied systemically via the roots. However, the impacts of neem-based insecticides on all parameters tested were greater than that of spinosad. The results indicate that the biologically based formulations tested were effective in suppressing whitefly abundance and acting as an efficient repellent, though they were not able to completely inhibit food intake. The repellent and antifeedant activities of such natural products render plants unattractive to B. tabaci , thus potentially reducing the incidence of viral diseases transmitted by this pest. The systemic properties of these formulated biopesticides minimize their rapid degradation by strong ultraviolet light and their adverse effects on non-target organisms.

Comparision of Insecticide Bioassay Methods in Sweet Potato Whitefly Adults, 2017

Comparision of Insecticide Bioassay Methods in Sweet Potato Whitefly Adults, 2017

Features of the relationship between Tomato severe rugose begomovirus and Bemisa tabaci MEAM1 reveal that the virus is acquired during a probe lasting only one minute

Tomato severe rugose virus (ToSRV) is a begomovirus found only in Brazil and has been the prevalent species affecting tomato crops in southwest and midwest of the country. Although the virus is known to be transmitted by Bemisia tabaci MEAM1, this study was undertaken to better characterize the relationship between ToSRV and whiteflies on tomato plants. The minimum acquisition and inoculation access periods, latent period, and virus retention time in the vector were determined. The results of transmission experiments showed that the minimum acquisition and inoculation access periods (AAP and IAP) for transmission of ToSRV by MEAM1 were 1 min and 5 min, respectively. After monitoring 50 individual adult whiteflies during a one-minute AAP on ToSRV-infected tomato leaves, 21 insects (42%) were able to acquire the virus, as confirmed by PCR. In contrast, one hundred insects that were individually allowed one-minute AAP on Tomato chlorosis virus (ToCV)-infected tomato leaves, which is a phloem-limited crinivirus, were unable to acquire the virus. The latent period of ToSRV in MEAM1 was 12–15 h, with adult whiteflies retaining the virus for 25 days. Although the tissue distribution of ToSRV in tomato has not been determined, the short AAP suggests that the virus may be present in mesophyll cells, from where it may be acquired during a one-minute feeding probe.

Effectiveness of aromatic plant species for repelling and preventing oviposition of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

AbstractThis study assesses the effectiveness of essential oils for repelling whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), and deterring oviposition. We evaluated essential oils from four plants: Curcuma longa (Zingiberaceae), Litsea cubeba (Lauraceae), Piper nigrum (Piperaceae) and Zanthoxylum bungeanum (Rutaceae), under laboratory and glasshouse conditions. In the laboratory, ethanol‐extracted essential oils were applied uniformly on both sides of a tomato leaf in the treatment groups, and the same volume of liquid but without essential oil was used for the control. Results showed that essential oils from L. cubeba, P. nigrum, C. longa and Z. bungeanum provided some repellency of whiteflies and reduced oviposition. Oils from L. cubeba repelled adult females (69.14% and 62.49% repellency at 24 and 48 hr, respectively), and oils from C. longa deterred oviposition (68.46% and 65.94% at 24 and 48 hr exposures, respectively). In the glasshouse, potted tomato plants with eight leaves were sprayed with treatments and control material. Five‐day‐old adult female whiteflies were released in a cage between both pots. Essential oils from L. cubeba repelled females 54.77 at 24 hr and P. nigrum 44.37% at 48 hr whereas oils from P. nigrum reduced oviposition by 43.35 at 24 hr and Z. bungeanum 21.08% at 48 hr, under glasshouse conditions. Essential oils show potential to be used to reduce feeding and oviposition, and thus being important components of integrated pest management programs. However, future research is needed to investigate individual compounds of these oils against whitefly, and to enhance their effectiveness.

Diversity and Distribution of Cryptic Species of the Bemisia tabaci (Hemiptera: Aleyrodidae) complex in Pakistan.

Bemisia tabaci (Gennadius; Hempitera: Aleyrodidae) is considered to be a cryptic (sibling) species complex, the members of which exhibit morphological invariability while being genetically and behaviorally distinct. Members of the complex are agricultural pests that cause direct damage by feeding on plants, and indirectly by transmitting viruses that cause diseases leading to reduced crop yield and quality. In Pakistan, cotton leaf curl disease, caused by multiple begomovirus species, is the most economically important viral disease of cotton. In the study outlined here, the diversity and geographic distribution of B. tabaci cryptic species was investigated by analyzing a taxonomically informative fragment of the mitochondrial cytochrome c oxidase 1 gene (mtCOI-3'). The mtCOI-3' sequence was determined for 285 adult whiteflies and found to represent six cryptic species, the most numerous being Asia II-1 and Middle East Asia Minor 1 (MEAM-1), the later also referred to as the B-biotype, which was previously thought to be confined to Sindh province but herein, was also found to be present in the Punjab province. The endemic Asia I was restricted to Sindh province, while an individual in the Asia II-8 was identified in Pakistan for the first time. Also for the first time, samples were collected from northwestern Pakistan and Asia II-1 was identified. Results indicate that in Pakistan the overall diversity of B. tabaci cryptic species is high and, based on comparisons with findings from previous studies, the distribution is dynamic.

Fatal attraction of non‐vector impairs fitness of manipulating plant virus

Abstract Host manipulation refers to the expression of a host phenotype that is partly under the genetic control of a parasite. This phenomenon can enhance parasite transmission rates and is responsible for biological marvels such as “Zombie‐ants” and the “fatal attraction” of Toxoplasma‐infected rodents to their feline predators. Such host manipulation has evolved in all major phylogenetic lineages of parasites and is assumed to enhance the fitness of the parasite. However, the capacity to manipulate is not ubiquitous; that is, many clades of parasites comprise manipulating and non‐manipulating species. This pattern leads to the prediction of costs that select against the evolution of manipulation, but this has been difficult to show empirically. In the present study, we used a tripartitate system consisting of chili (Capsicum annuum) plants infected with Pepper golden mosaic virus and colonized by non‐vector whiteflies (Trialeurodes vaporariorum), to study the effects on viral load when a non‐vector herbivore feeds on the infected plants. We observed that virus‐infected plants emitted odours that attracted adult whiteflies, contained three times more amino acids in the phloem than mock‐inoculated controls and supported higher whitefly reproduction as compared to controls. However, viral load decreased almost 100‐fold in whitefly‐carrying plants, which was associated with a depletion of phloem amino acids. Synthesis. We show that a plant virus can suffer from a reduced within‐host reproduction rate when virus‐induced alterations of the plant cause a “fatal attraction” of a non‐vector insect that exploits the altered plant phenotype at its own benefits. The resulting fitness costs might represent a force that can select against the evolution of host manipulation by parasites.

Control of Tomato leaf curl New Delhi virus in zucchini using the predatory mite Amblyseius swirskii

The tobacco whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), is a serious pest of vegetables in many horticulture systems. It vectors the Tomato leaf curl New Delhi virus (ToLCNDV) which causes considerable damage in zucchini crops. Both pest and the disease are well established in field and greenhouse crops in the southeast of Spain, the largest vegetable growing area in Europe. The predatory mite Amblyseius swirskii Athias-Henriot (Arachnida: Phytoseiidae) is known to effectively manage B. tabaci populations in crops such as sweet pepper and cucumber, feeding on eggs and crawlers of this pest. However, there are no reports on the effectiveness of predatory mites against tobacco whitefly in zucchini crops. The potential to reduce whitefly populations as well as the spread of ToLCNDV in zucchini was evaluated by the pre-installation of A. swirskii in seedlings. Results showed that the number of adult whiteflies and deposited eggs on zucchini plants were significantly lower on plants with the phytoseiid predator, showing a significant negative impact of A. swirskii on B. tabaci colonization and reproduction but not on the primary infection with ToLCNDV. However, the pre-release of the predatory mites resulted in a strong decrease in eggs and subsequently emerging adults of whiteflies relative to plants without predators, and a significant reduction in secondary spread of the virus.

FIRST REPORT OF CUCURBIT CHLOROTIC YELLOWS VIRUS IN CUCUMBER IN TURKEY

In November 2015 and February 2016, yellowing symptoms were observed in three greenhouse-grown cucumber crops in Antalya recalling those induced by Beet pseudo-yellows virus (BPYV), Cucurbit yellow stunting disorder virus (CYSDV) and Cucurbit chlorotic yellows virus (CCYV). To investigate the etiology of the yellowing disease observed, leaves from 30 symptomatic plants were subjected to total RNA extraction and tested by RT-PCR for the presence of BPYV, CYSDV (Boubourakas et al., 2006), and CCYV (Orfanidou et al., 2014). Fifteen samples were found infected by CYSDV and 21 by CCYV, of which 6 plants were dually infected by CYSDV and CCYV. Since CYSDV was already known in Turkey, the partial RdRp region of 2 isolates of CCYV was sequenced (Orfanidou et al., 2014) and BLASTn analysis of the obtained sequences (accession Nos. LT577941, LT577942) showed 99% identity with a CCYV isolate from Japan (AB523788). Moreover, transmission experiments by Bemisia tabaci biotype Q (MED) were carried out. Five groups of 30 adult whiteflies were given an acquisition access time of 24 h on cucumber leaves naturally infected only with CCYV. Thereafter, each whitefly group was transferred onto a healthy cucumber plant (hybrid Galeon) for an inoculation access time of 72 h, and 3 weeks post inoculation CCYV was detected in 4 out of 5 inoculated plants by RT-PCR. To our knowledge, this is the first report of CCYV infecting cucumber in Turkey. CCYV has also been reported in Lebanon, Egypt and Greece thus indicating that it is an emerging pathogen of cucurbit crops in the Mediterranean region.

EFFECTIVITY OF THREE BOTANICAL CRUDE EXTRACTS ON IMMATURE OF WHITEFLY (BEMISIA TABACI GENN.) UNDER ENCLOSURE CONDITIONS

Pest management of habanero chili (Capsicum chinense Jacq., Solanaceae) the sweetpotato whitefly Bemisia tabaci Genn. (Hemyptera: Aleyrodidae) is a key plague insect as a virus-vector, capable of causing serious economic loss. Their control is broadly based on Imidacloprid, a neonicotinoids product. B. tabaci have resistance to imidacloprid now. Some plants extracts are suggest in the literature how insect repellent properties over whiteflies, including allspice [Pimenta dioca (L.) Merrill, (Myrtaceae)], sweet basil [Ocimun basilicum L. (Lamiaceae)] and wild feverfew [Parthenium hysterophorus L.(Asteraceae)]. The preliminary screening under controlled conditions for evaluating the repellent effect of crude aqueous extracts, in a 1:1 ratio based on mass weight foliage moisture; was evaluate for each one of above-mentioned plants, against nymphs and eggs of whitefly. Results show that basil and feverfew extracts was significantly effective in preventing oviposition by adult whiteflies on habanero chili foliage, with allspice showing the lowest effect. Fields studies have to be carried out in this regards.