PCR-RFLP identification ofBemisia tabaci biotypes in the Mediterranean Basin

At least 20 genetic biotypes, with varying degrees of biological characterization, are currently recognized within theBemisia tabaci (Hemiptera: Aleyrodidae) species complex. Their identification relies on a set of different molecular techniques. However, none of the available markers is completely adequate, due to technical difficulties or lack of reproducibility. We therefore developed a method for rapid biotyping ofB. tabaci populations. The five biotypes (B, Q, M, S and T) reported until now in the Mediterranean Basin have been tested by PCR amplification of the cytochrome oxidase I mitochondrial gene followed by restriction with the enzymeTru9I. The digestion patterns produced by this enzyme were able to identify the five biotypes clearly. Digestion with another enzyme,TaqI, discriminated only between biotypes B and Q. The newly developed method enables rapid biotyping and can be applied in studies aimed at assessing biotype distribution and competition at least in the Mediterranean area. http://www.phytoparasitica.org May 14, 2006.     

Note: Current status ofBemisia tabaci in Coastal Croatia

Bemisia tabaci was first noted in Croatia in 2000, when it was identified in Split County, Dalmatia. Thirty-one plant species were identified as hosts of this pest in the central Adriatic region during 2001–2002. Four adult populations were analyzed at CIDA (Spain) by comparing a fragment of the COI gene of the mitochondrial DNA, and by examining a single microsatellitelocus. The results indicated a predominance of the Q biotype. The population dynamics ofB. tabaci was examined in outdoor conditions by observing populations fromIpomoea purpurea in 2002. The pest population appeared at the beginning of June and increased in number until its decline at the beginning of October. http://www.phytoparasitica.org posting Dec. 20, 2004.     

The overwintering ofExserohilum turcicum in Israel

Exserohilum turcicum (Pass.) Leonard and Suggs, the causal agent of northern leaf blight of corn, overwinters onSorghum halepense L. plants and on corn debris (dead leaves). Spqrulating lesions ofE. turcicum were observed on sorghum plants in the winter (February). Spores from these lesions were pathogenic to susceptible sweet corn plants cv. ‘Jubilee’. Infected sporulating leaves of corn were stored for 1 year at 20°C (40-60% relative humidity), at 5°C (60% relative humidity), or buried 5 cm underground. During the storage period, 32% and 22% of the spores formed chlamydospores, at 20° and 5°C, respectively. Leaves buried 5 cm underground were totally decomposed after 6 months. After 4 months, 25% of the spores in the buried leaves had formed chlamydospores. Spores with chlamydospores were pathogenic to corn plants. The viability of spores without chlamydospores stored at 20°, 5°C or buried underground was 0, 60 and 0%, respectively. In a parallel experiment infected leaves were stored under similar conditions and allowed to sporulate. No sporulation occurred on infected leaves buried in soil. Spores produced on infected leaves stored at 20° and 5°C were highly pathogenic to corn plants. In leaves treated with 0.1N glucose, chlamy dospore formation was significantly inhibited.     

Note: Biotype status ofBemisia tabaci from various crops in Cyprus

An extensive survey ofBemisia tabaci populations covering the southern half of the island of Cyprus was conducted in 2006 and 2007 in order to define the biotype status of the pest. Sampling was done both on protected and outdoor cultivations of vegetables and ornamental plants. Biotype identification was performed using molecular diagnostics based on the mitochondrial cytochrome oxydase I gene. Our results indicated the presence of only the biotype B in all 25 collections. http://www.phytoparasitica.org posting August 8, 2008.     

Characterization of biotype T ofBemisia tabaci associated withEuphorbia characias in Sicily

The T biotype ofBemisia tabaci (Gennadius, 1889), a population found colonizingEuphorbia characias L. plants on the Nebrodi-Peloritani mountains in Sicily, was biologically characterized. The minimum development time was 29.7 days at 28°C. Based on the regression of 1/dayvs T, the rate of development was calculated as 0.00206, the theoretical lower temperature threshold for development as 9.3°C, and the sum of effective temperatures as 485.1. At 25° C, egg-to-adult development was significantly shorter onDatura stramonium (30.1 days) than on eitherEuphorbia pulcherrima orEuphorbia characias (35.6 and 35.4 days, respectively). The fourth instar nymphs grown onD. stramonium had the typical oval outline and seven pairs of dorsal setae located on cone-like processes, often barely visible. The fourth instar nymphs and their pupal cases grown onE. characias had the outline deformed by the presence of hairs on the lower surface of the leaf. The pupae onD. stramonium were significantly larger (both longer and wider) than those reared onE. characias; on both host plants, female pupae were significantly larger than male ones. Analysis of variance showed that width of females onD. stramonium was significantly larger than the width of those reared onE. characias. Attempts at courtship between T- and Q-biotypes were observed, but adults from different biotypes were never seen mating. Only males were obtained from the seven heterologous crossing attempts, either way, whereas homologous, control breeding produced males and females. The T biotype was able to transmitTomato yellow leaf curl Sardinia begomovirus (TYLCSV) fromD. stramonium toD. stramonium, from tomato to tomato and from tomato toD. stramonium. Attempts to transmit TYLCSV fromD. stramonium to tomato were unsuccessful. The transmission efficiency was significantly lower when tomato was the test plant. The diverse biology and ecology of the T biotype confirm that it is genetically different from most Mediterranean biotypes. This paper is dedicated to the dear memory of our colleague Dr Claudio Arnò, who died on March 12, 2004, while this paper was being written.     

Natural occurrence of and inoculation experiments withConidiobolus coronatus andConidiobolus sp. in glasshouse populations ofBemisia tabaci

Bemisia tabaci (Gennadius), the sweetpotato whitefly, has only one known entomophthoralean pathogen,Erynia radicans (Entomophthoraceae). Two new pathogens have been isolated recently from a glasshouse population of this pest:Conidiobolus coronatus and another, undescribed species ofConidiobolus (Entomophthorales: Ancylistaceae). Artificial inoculation experiments revealed that eggs ofB. tabaci are practically immune to infection by either species. Second-instar larvae are highly resistant, only high doses of conidia causing between <1% and 4.6% mortality. Adults were found to be much more susceptible. Doses of 60 conidia/mm² ofC. coronatus caused average mortalities ofca 95%. The maximum mortality of adults caused byConidiobolus sp. was much lower,ca 30%, at a dose of 210 conidia/mm². The incubation period (inoculation to death) for both species, under our experimental conditions, is very short: 18–24 h forC. coronatus and 30 h forConidiobolus sp. Both fungi produced loricoconidia (conidia metamorphosed into resting spores) on cotton leaves and other dry surfaces. This ability allowedConidiobolus sp. to remain viable for 17–21 days on cotton leaves, in glasshouse conditions and in the absence of hosts, whileC. coronatus persisted for 10–14 days.     

烟粉虱的耐寒能力与自然越冬北界分析*

室内耐寒性测定结果表明,烟粉虱成虫在4 ℃和0 ℃暴露时的致死中时分别为13.86 h和12.07 h,在-2 ℃和-8 ℃分别为4.74 h和1.7 h,它们之间有明显差异。2009年2月14-22日野外调查显示,仙桃市、南昌市、金华市在露地和大棚均发现烟粉虱以伪蛹和卵在杂草上存在,九江市只在大棚发现烟粉虱;而孝感市大棚与露地均没有发现烟粉虱。根据已经调查到的越冬地点及其所在地的温度,给出了全国烟粉虱自然条件下可能的越冬北界模型图。首次探讨了烟粉虱在我国的自然越冬北界分布线为浙江省金华市,江西省南昌市,湖北省仙桃市,四川省和云南省。     

Effects of a primitive cotton accession on feeding ofspodoptera littoralis andhelicoverpa armigera and on oviposition ofBemisia tabaci

A primitive cotton(Gossypium hirsutum L.) accession, V-64, from the Caribbean Islands was bioassayed for antibiosis against pests of this crop in comparison with the commercial strains Acala SJ-2 and Pima S-5. V-64 reduced weight gain and leaf consumption ofSpodoptera littoralis andHelicoverpa armigera, and significantly reduced oviposition ofBemisia tabaci. The leaf pigment glands in V-64 were larger and more abundant than in the commercial strains, and the feeding ofH. armigera on these glands was avoided, indicating that the glands probably constituted the major resistance character in V-64. Contribution from the Agricultural Research Organization. No. 3187-E, 1991 series.     

Comparative spatial dispersal ofTomato yellow leaf curl virus vectored by B and Q biotypes ofBemisia tabaci in Tomato glasshouses

The spatial dispersal patterns ofTomato yellow leaf curl virus (TYLCV) disease vectored by the B and Q biotypes of the whiteflyBemisia tabaci in tomato glasshouses were compared. Tomato plants were arranged in glasshouses and TYLCV-infected plants were placed in the center of each plot. Adult whiteflies of each biotype were released onto TYLCV-infected plants and the insects were then freely dispersed in the glasshouses under high or moderate temperature conditions. The abundance and spatial distribution of dispersed whiteflies did not differ between the B and Q biotypes in tomato glasshouses. The disease incidence and dispersion of TYLCV as a result of short-distance movement of the whiteflies were also similar between the two biotypes, although on several investigation dates there was a tendency for the disease incidence caused by the B biotype to be slightly greater than that caused by the Q biotype. These results demonstrated that the aspects of spatial spread of TYLCV vectored by the B and Q biotypes ofB. tabaci in tomato glasshouses are similar. http://www.phytoparasitica.org posting Dec. 11, 2007.     

First report of the Q biotype ofBemisia tabaci in Japan by mitochondrial cytochrome oxidase I sequence analysis

The recent upsurgence ofBemisia tabaci (Genn.) as an important insect pest and vector ofTomato yellow leaf curl virus (TYLCV) is directly linked to serious damage to tomato crops grown throughout Japan. The molecular genetic identification and phylogenetic relationships of 12B. tabaci populations collected from representative locations in Japan were determined based on the mitochondrial cytochrome oxidase I (mtCOI) sequence. Phylogenetic analysis of the whitefly mtCOI sequence indicated that both the invasive B and Q biotypes now occur in Japan. The Q biotype was found at four locations: Mihara in Hiroshima, Nishigoshi in Kumamoto, Miyanojo and Okuchi in Kagoshima prefectures; the remaining eight collections were identified as the B biotype. This is the first report of the introduction of Q biotype in Japan. http://www.phytoparasitica.org posting July 21, 2006.     

Effect of foliar applications of some insecticides onBemisia tabaci, predators and parasitoids: Implications in its management in Pakistan

Three experiments were carried out during three consecutive years to evaluate 19 insecticides and 12 tank mixtures of different groups of insecticides against the whiteflyBemisia tabaci and its predators and parasitoids under field conditions in cotton. In the first experiment, the whitefly population was lower in treatments with thiacloprid and higher in those with black warrant (a.i. alcohol) and cypermethrin; the number of predators was higher with Agri-50 and spinosad and lowest with cypermethrin, whereas percent parasitism was higher with thiacloprid and lower with methamidophos. In the second experiment, the whitefly population was lower in treatments with buprofezin, pyriproxyfen and diafenthiuron and higher in those with endosulfan, imidacloprid and thiamethoxam; the number of predators was higher with pyriproxyfen and lower with thiamethoxam, whereas percent parasitism was higher with pyriproxyfen and lower with thiamethoxam. In the third experiment, the whitefly population was lower in a treatment mixture with buprofezin + fenpropathrin and higher in that with thiamethoxam + chlorpyrifos; the number of predators was higher with buprofezin + fenpropathrin and lower with deltamethrin + triazophos and deltamethrin + chlorpyrifos, whereas percent parasitism was higher with the mixture of pyriproxyfen + chlorpyrifos and lower in imidacloprid + chlorpyrifos, betacyfluthrin + triazophos, and deltamethrin + triazophos. Effective use of these insecticides to manage whitefly infestations and to save predators and parasitoids is discussed. http:www.phytoparasitica.org posting August 7, 2008.     

Effects of different cucurbit species and temperature on selected life history traits of the ‘B’ biotype ofBemisia tabaci

The development time and survival rate were determined at three constant temperatures for the ‘B’ biotype ofBemisia tabaci on cucumber (Beit Alpha F₁), cantaloupe (Anzer F₁), squash (Sakız F₁), and watermelon (Galactica F₁). The development time for immature stages at 20, 25 and 30±1°C was, respectively, 33.5, 19.3 and 16.8 days on cucumber; 36.5, 20.8 and 19.60 days on cantaloupe; 37.2, 20.1 and 19.8 days on squash; and 38.9, 23.8 and 21.9 days on watermelon. At 20, 25 and 30°C, the respective percentage survival of immature instars was 73.2, 83.2 and 72.9% on cucumber; 72.9, 84.9 and 75.6% on cantaloupe; 52.1, 76.1 and 57.5% on squash; and 37.6, 64.8 and 40.1% on watermelon. http://www.phytoparasitica.org posting May 14, 2006.     

The East-Mediterranean cereal leaf miner <Emphasis Type="Italic">Syringopais temperatella</Emphasis> Lederer and its larval parasitoids in Israel

Leaves of durum wheat infested with mines of the cereal leaf miner Syringopais temperatella Lederer (Lepidoptera: Scythridae) were collected from fields in Israel in spring 2016 and 2017. The parasitoids and moths reared from the leaf mines in the lab were identified and counted according to sex. The sex ratios of S. temperatella were 1:0.73 (♀ :♂) in 2016 and 1:0.41 in 2017. A cross-correlation analysis revealed that males appeared three days ahead of females (p<0.05). The following parasitoids were reared: Eulophidae (Cirrospilus vittatus Walker, Diglyphus chabrias (Walker), D. isaea (Walker), D. sensilis Yefremova, D. pusztensis (Erd?s & Novicky), Necremnus tidius (Walker), Neochrysocharis formosus (Westwood), Pnigalio gyamiensis Myartseva & Kurashev, P. pectinicornis Linnaeus), Pteromalidae (Norbanus sp.) and Braconidae (Habrobracon stabilis (Wesmail), Apanteles sp.); and Icheumonidae (Campoplex sp.). In all cases, the parasitoids emerged substantially prior to the mass appearance of the moths. The hatching dynamics of ecto- and endoparasitoids were also asynchronous. Most species of ectoparasitoids hatched three days ahead of the endoparasitoids (p<0.05). Syringopais temperatella recorded on clover revealed a similar dynamics of male appearance ahead of female, with a of female-to-male ratio of 1:0.25, and fewer parasitoid species.     

烟粉虱在山东滨州大发生原因及防治技术

对2001年滨州市烟粉虱大发生的危害进行了调查，分析了其暴发的原因，提出了综合防治技术措施。     

The Mediterranean vine mealybug and its natural enemies in southern Israel

The phenology of the Mediterranean vine mealybug population in the vineyards of southern Israel was found to be characterized by a peak, occurring between mid-May and mid-June, followed by a sharp drop during July. A second, smaller peak occurs between October and December. During winter the mealybugs remain beneath the bark of the trunk at a very low population level. The primary parasites, all of the anagyrine Encyrtidae, were (in descending order of abundance):Anagyrus pseudococci, Leptomastix flavus, Clausenia josefi, Pauridia peregrina, andLeptomastidea abnormis. The hyperparasites wereAchrysopophagus aegyptiacus (Encyrtidae) andPachyneuron siculum (Pteromalidae).Tetrastychus sp. (Eulophidae) andThysanus sp. (Signiphoridae), very rare parasites, remained unclassified.Hyperaspis spp. andScymnus spp. (Coccinellidae) are mealybug predators. They were sometimes parasitized byHomalotylus quaylei (Encyrtidae). The phenology of the entomophagous insects is described.     

Phyllocnistis citrella and its parasitoids in three citrus species in Greece

The relative abundance as well as the percentage of parasitism of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) and its parasitoids were studied in a citrus orchard with orange, mandarin and lemon trees in Greece. Infestation of P. citrella on each citrus host, as expressed by the number of mines per leaf, was significantly higher on lemon than on mandarin. The P. citrella parasitoid complex included the native species Neochrysocharis formosa and Pnigalio pectinicornis, as well as the introduced Citrostichus phyllocnistoides. The most abundant of those was N. formosa in all of the citrus species. The average percentage of parasitism was 13.1%, 13.8% and 11.7% on orange, mandarin and lemon, respectively. No significant differences in parasitism rate by each of the three parasitoid species separately were recorded among the three citrus species.     

The elm bark beetle Scolytus kirschi and its control in Israel1

Scolytus kirschi, a bark beetle new to Israel, was found in 1983 near Lake Kinneret affecting and killing young elm trees under stress. The main cause of the stress was water deficiency. Phytosanitation, seasonal irrigation and exposure of trap logs all slowed down the spread of the beetle and prevented further damage.     

Citrus leafminer Phyllocnistis citrella and its parasitoids in Sargodha region of Pakistan

In order to identify the parasitoids of Phyllocnistis citrella, an important pest of Citrus, the larvae and pupae of this pest were collected from Citrus reticulata Blanco orchards in the Sargodha region of Pakistan. The parasitoid species were identified, and their abundance was recorded. A total of two species were identified: Citrostichus phyllocnistoides (Narayan) (Hymenoptera: Eulophidae) and Cirrospilus ingenuus Gahan (Hymenoptera: Eulophidae). Out of a total of 409 P. citrella larvae and pupae collected, 73 C. phyllocnistoides and 39 C. ingenuus adults emerged. This paper documents the species and the abundance of the parasitoids associated with P. citrella in the Sargodha region of Pakistan.     

我国棉田烟粉虱的发生为害及控制

对我国棉田烟粉虱的发生为害特点及近几年种群上升的原因进行了概述和分析,并提出了棉田烟粉虱的控制措施。     

Seven invasive owlet moths (Lepidoptera: Noctuidae) in Israel and their potential parasitoids (Hymenoptera: Chalcidoidea)

Invasive tropical Noctuidae pest species collected in Israel included Spodoptera mauritia (Boisduval), Trichoplusia vittata (Wallengren), Anomis flava (Fabricius), Anomis sabulifera (Guenée), Earias vittella (Fabricius), Earias biplaga Walker, and Earias cupreoviridis (Walker). All seven noctuid species were rare and sporadically present only along the coastal plain. Possible reasons for this type of distribution are discussed. Abundance was greatest in May with smaller peaks present in February–March and September. Several common parasitoid species – Elasmus flabellatus (Fonscolombe), Elasmus nudus (Nees) and Elasmus viridiceps Thomson (Hymenoptera: Eulophidae), with potential as biological control agents for tropical noctuids, are detected in Israel.