Journal of Phytopathology and Pest Management (Al-Azhar University)
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Evaluation of different chemicals to control Erysiphe betae the causal pathogen of sugar beet powdery mildew
Get PDFSurvey on sugar beet plantations at Minia and Assiut governorates, Egypt revealed that powdery mildew disease was the most epidemic threat on sugar beet plantations. It was noticed that the highest Area Under Powdery Mildew Progress Curve (AUPMPC) value was detected in Abnob locality, Assiut governorate while the lowest one was found in Maghagha locality, Minia governorate. Data revealed that five months’ post collection conidia of Erysiphe betae failed to infect sugar beet leaves cultivar FD.0807. Results of conidial germination showed that the percent germination in darkness was lower than in light. Also a high percentage of germinating conidia formed appressorium on dry glass slides. The examination of powdery mildew infected sugar beet leaves using scanning electron microscopy showed that the fungus penetrates the epidermis of the leaves by the haustoria which are folded in many patches forming a complex web almost completely covers the leaf. Field experiment was conducted to evaluate three chemical compounds containing plant macronutrients, along with five fungicides against powdery mildew disease. Results showed that sodium bicarbonate achieved the best disease control among the macronutrient-containing compounds followed by calcium chloride and potassium silicate, respectively. Sodium bicarbonate achieved the highest total soluble solids (TSS) percentage and root weight at all rates of application followed by calcium chloride, while potassium silicate achieved the least TSS % and root weight. Concerning fungicides, Bellis 38%WG gave noticeable result in disease reduction followed by Collis 30% SC and Tilt 25% EC, respectively. The results showed that the highest TSS % and root weight were detected in the roots of sugar beet plants treated with Bellis 38% fungicide followed by Collis 30%. Meanwhile, the lowest significant of TSS % and root weight was detected after treatment with Permatrol 99%
Genetic diversity of Fusarium oxysporum f.sp. niveum responsible of watermelon Fusarium wilt in Tunisia and Spain
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Fusarium wilt is a serious disease, caused by Fusarium oxysporum f. sp. niveum (FON) and responsible of significant yield losses in watermelon crop in Tunisia. Thirty-nine FON isolates were collected from different infected watermelon fields in Tunisia and were identified on the basis of morphological features and by using one pair of species-specific primers Fn-1/Fn-2. Genetic diversity of the twenty-six FON isolates, originated from Spain and Tunisia, was studied by applying Inter simple sequence repeat genotyping. PCR amplification appears to be efficient to identify FON isolates amplifying only a single PCR band of approximately 800 bp. The RAMS study using two, bi and four trinucleotide microsatellites primers, showed a different genetic similarity degree among FON isolates. Seventy-one bands were amplified by four ISSR primer combinations. Diversity in the banding patterns obtained by DNA fingerprinting was always >50% and allowed us to distinguish all the isolates tested, according to number and size of the fragments, which ranged from 300 to 2800 bp. The genetic similarity values are comprised between 8 and 97%. UPGMA grouped the 45 genotypes into six main clusters at a similarity index value above 0.5, showing a relative genetic homogeneity and no correlation has been found among FON isolates and their origins. The most abundant Cluster VI comprising thirty-nine FON isolates
Comparison between the toxicity of nano and bulk formulations of imidacloprid against wheat aphid, bird cherry-oat aphid, Rhopalosiphum padi L
Get PDFRecently, nano-insecticide formulations and new insecticide application methods are promised in pest control improvement. Wheat crop is infested by many sucking pests, such as cereal aphids in Upper Egypt. The toxicity of the recommended dose of imidacloprid (70% WS GAUCHO®) as positive control, the full and half recommended dose of nano and bulk imidacloprid 25% WP (BEST®) formulations were investigated under laboratory and field conditions against bird cherry-oat aphid, Rhopalosiphum padi L. The leaf-dip bioassay results indicated that the nano-imidacloprid formulations had higher potency ratio than the bulk formulations by 2.53 to 7.17 folds. Significant reduction percentage of aphids was recorded in seed treatments of field wheat crops, the aphid reductions reached 95% after 60 days. All insecticide treatments showed significant increasing in grain yield ranging from 10.55% to 22.02% higher than the control. The results concluded that the nano-imidacloprid formulation is promising formulation in cereal aphid control. Moreover, the seed-treatment is better than foliar treatment as a pest control tool for protecting the wheat seedling against sucking insect pests
Population fluctuations of oystershell scale insect, Lepidosaphes ulmi (L.) (Homoptera: Diaspididae) on certain olive varieties and the factors affecting its population
Get PDFOystershell scale, Lepidosaphes ulmi (L.) (Homoptera: Diaspididae) is one of the most common scale insects that attacks olive trees in Egypt. Therefore, the population density fluctuation of L. ulmi and its parasitoids, and their relations to some weather factors were investigated on three olive varieties (Picual, Coratina and Chemlali) at Faculty of Agriculture, Assiut University, Egypt, during 2017/2018 and 2018/2019 seasons. The results indicated that the pest population was concentrated during the period from April to September. The highest average of L. ulmi population was recorded on picual variety (7.81 and 8.96 insect/ 10 leaves) during 2017-2018 and 2018-2019 seasons, respectively. While the lowest population average was recorded on coratina (4.72 and 5.01 insect/ 10 leaves) during 2017-2018 and 2018-2019 seasons, respectively. During both seasons, there were significant differences in the average numbers of L. ulmi among the olive varieties, picual, coratina and chemlali. Theresults also showed that picual variety was more infested than other two varieties. Survey of L. ulmi parasitoids resulted in two species of parasitoids, Aphytis chrysomphali (Mercet) and Aphytis disppidis (Howared). The average percentage of parasitism was relatively high during, May, June, July and August on picual and chemlali varieties. While on coratina variety the average percentage of parasitism was relatively high during, April, May, September, December, and January during 2018-2019 season. Statistical analysis of the data indicates that, no significant differences among the percentage of the average annual parasitism on the three varieties (4.86 % on chemlali, 4.22 % on picual and 3.89 % on coratina variety). The effects of weather factors on the population of L. ulmi and its parasitoids and the effects of these parasitoids on the population of the pest were also studied. The results might be helpful in an IPM program to control the oystershell scale insect, L. ulmi and to settle the best time for pesticide application on olive varieties
Insecticidal effect of lemongrass oil on behavioural responses and biochemical changes in cowpea weevil, Callosobruchus maculatus (Fabricius)
Get PDFThe cowpea weevil, Callosobruchus maculatus (Fabricius), is the most important postharvest insect pest of cowpeas throughout the tropics causing about 70% infestation within 6 months of storage. Control interventions have often been by way of synthetic chemical application but the negative impact of these chemicals on biotic and abiotic elements of the environment continues to motivate search for alternative control measures. The present study was conducted to evaluate insecticidal effect of essential oil (EO) from lemongrass, Cymbopogon citratus (DC.) Stapf, against the weevil. Air-dried lemongrass leaves were milled into powder, the EO was extracted by hydro-distillation using a Clevenger-type apparatus and the extract was dried over anhydrous sodium sulphate. Acute toxicity was determined by inhalation over a period of 24 h using five serial concentrations (0.62, 1.28, 2.50, 5.00 and 10.00 mg/ml) of the EO on filter papers. The median lethal concentration (LC50) was determined from mortality data using probit analysis and three sublethal concentrations (1.41, 2.83 and 5.66 mg/ml) were used in subsequent antioviposition test and biochemical assays. Repellency against the weevils was tested using 2 ml 10 mg/ml EO concentration applied evenly on ½ disc of filter paper. Weevil homogenates were assayed for acetylcholinesterase (AChE), glutathione-S-transferase (GST), reduced glutathione (GSH), superoxide dismutase (SOD), lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. Changes in the concentrations of total protein (TPR) and glycogen (GLY) as influenced by dosage and exposure time to the EO were also determined. The results showed that the EO had effective insecticidal properties against the pest. Weevil mortality was concentration- and time-dependent and 80% death rate was attained within 24 h of inhaling 10 mg/ml EO with a LC50 value of 7.07 mg/ml. The EO repelled a significantly higher number of weevils (66%) and fewer eggs were laid on cowpea seeds treated with the EO. The values of AChE (P ≤ 0.01), GLY (P ≤ 0.001), SOD (P ≤ 0.001) and TPR (P ≤ 0.001) reduced significantly with increasing EO concentrations giving an evidence of induced physiological stress in exposed weevils. Kinetics of the assayed enzymes and physiological implications for the storage pest were highlighted. In addition, potential of lemongrass EO as an alternative to synthetic chemicals was discussed
Seasonal incidence and efficacy of nano-thiamethoxam on tomato leaf miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae)
Get PDFSeasonal incidence of tomato leaf miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae), and evaluation of the new nano-formulation of thiamethoxam insecticide under climatic factors that supplying the vital knowledge for successful integrated pest management (IPM) programs. This study was conducted in two successive seasons 2017-18/ 2018-19 on variety (no. 765) of tomato that cultivated at the plant protection experimental Farm, Faculty of Agriculture, Assiut University, Assiut, Egypt. The numbers of mines on the tomato leaf were recorded from the first of November to the first of the February in the two seasons. The highest peak of mines was 28.34 mines/ plant in the 13th of December, 2018, while, it was 41.8/ plant in the January1st, 2019. Further, the climatic factor analysis during the two studied seasons demonstrated that the relative humidity was the most efficient factor (52.49 % out of 91.46 %), while the temperature was the least effective one (8.67% out of 91.46%). The nano thiamethoxam at the recommended dose (1x) of neonicotinoid insecticide significantly reduced the mines compared to traditional thiamethoxam. Furthermore, the half recommended dose of nano thiamethoxam in the two tested seasons was equal in the efficacy to the traditional thiamethoxam (1x). The reduction percentages were 86.87, 75.81 and 68.67 for nano-thiamethoxam (1x), thiamethoxam (1x), and nano- thiamethoxam (½ x), respectively, in 2017-18 for the first spray. In the same corresponding treatments, the values recorded were 78.94, 65.61and 62.75% in the second spray. Results of the second season (2018-19) were in the same line, where, the reduction percentages were 84.23, 76.43 and 62.43% at first spray, while the second spray were 72.95, 65.40 and 59.31% for nano-thiamethoxam (1x), thiamethoxam (1x) and nano- thiamethoxam (½ x), respectively. These results suggested that, the relative humidity was the main climatic factor effect on the mines population of Lirimyza trifolii. The nano-thiamethoxam was significantly reduced the pest population. Results of this study highly recommend using nano formulation in applying of IPM leaf miner programs
Evaluation of certain Egyptian wheat cultivars against rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) using biochemical and biophysical traits
Get PDFSitophilus oryzae (L.) is the most destructive pest of stored wheat, and is widely distributed in tropical regions. In the present study, the susceptibility of 11 Egyptian wheat cultivars, including seven durum wheat and four bread wheat cultivars were evaluated against S. oryzae were on the basis of percentage of weight loss, and damaged grain. The comparison between tested wheat cultivars in respect to wheat biophysical traits (kernel weight, kernel hardness and moisture), and biochemical variants (starch, wet gluten and protein content) was assayed. The correlation between these biophysical and biochemical traits and the percentage of weight loss and damaged grain was estimated. The results revealed that bread wheat cultivars (Misr-1, Misr-2, Giza-171, and Gimmiza-10) were highly susceptible to S. oryzae infestation than durum wheat (Beni Sweaf-1, Beni Sweaf-3, Beni Sweaf-4, Beni Sweaf-5, Beni Sweaf-6, Sohag-3, and Sohag-5). The most susceptible cultivar was the bread wheat cultivar Gemmieza-10, and the most resistant was durum wheat cultivar Beni Sweaf-3. The tested cultivars significantly varied in there biophysical and biochemical traits. A significant positive correlation was observed between percentage of damaged grain and grains content of starch, and wet gluten. However, negative correlations were found in grain hardness index and percentage of damaged grain. Protein content, grain diameter, kernel weight, %moisture (a) and (b) did not show a significant correlation to damaged grain
Diversity of pollen species in commercial honey samples collected from different governorates of Egypt
Get PDFAnalysis of pollen species in bee honey reflects the nectar sources of specific honey. It is a very important method to evaluate honey quality situation and frequency of adulteration. To determine dominant sources of Egyptian honeys, 16 commercial honey samples were collected from supermarkets during season of 2017. Using mellissopalynology technique, a total of 27 pollen species belonging to 18 families were identified in tested honey samples. The predominant pollen sources were clover, alfalfa, date palm, faba bean, coriander, eucalyptus, sunflower and citrus, while the other pollen species were present in honey samples as secondary pollen sources. Most of pollen types identified in honey samples were from necteriferous plants. The date palm was the only main polleneferous plant in the pollen spectrum of studied honeys. Pollen diversity was higher in summer honey samples in comparison with spring honey samples. The present results showed that all sixteen trademark tested honey samples had a natural source and unadulterated
Molecular characterization and biological control of some rice seed-borne fungal pathogens
Get PDFSeed-borne fungi cause enormous losses in rice production in Egypt. Ten different fungal species were isolated from four rice seed cultivars (Giza 177, Giza 179, Sakha 101 and Sakha 106) showing grain discoloration symptoms. Ten fungal species were initially identified as Fusarium spp. and Bipolaris spp. based on conidial morphology, colony appearance, pigmentation and growth rate. Molecular identification of these fungal isolates via PCR utilizing Internal transcribed spacer (ITS) region universal primers was carried out. ITS region was amplified to confirm the species identification. DNA sequence of PCR products and analysis via BLAST and data of the Genbank showed that four isolates belonging to F. graminearum, four isolates belonging to F. verticilliodies and two isolates identified as Bipolaris oryzae. The phylogenetic tree revealed different levels of molecular variation among the fungal species isolates compared to the international isolates deposited in the Genbank. Two biological control isolates of T. harzianum (Tr1 and Tr2) were used against F. graminearum, F. verticilliodies and B. oryzae isolates. The highest growth inhibition was exhibited by both T. harzianum isolates against F. graminearum (76.77% and 76.74% respectively), followed by F. verticilliodies. The least growth inhibition was observed on Bipolaris oryzae using Tr2 and Tr1 isolates (53.33% and 50.0% respectively). Moreover the naturally infected rice grains treated with both isolates Tr1 and Tr2 showed 100% inhibition of fungal pathogens associated with rice grains compared to untraded naturally infected grains
Bioactivity of some plant extracts against the lesser grain borer, Rhyzopertha dominica (Fabr.) (Coleoptera: Bostrichidae)
Get PDFThe lesser grain borer, Rhyzopertha dominica (Fabr.) is an important insect pest of stored cereals in the world. Plant extracts from Acacia nilotica, Artemisia annua L. and Thuja orientalis were tested for their insecticidal activities against this pest. Contact on surface of a Petri dish and ingestion with wheat grains methods as well as, combinations of mixture of these extracts were used against R. dominica adult. Plant extract of A. annua had higher mortality of R. dominica adult than other tested extracts. The mixtures of A. annua with A. nilotica or T. orientalis are converted to more toxic metabolites against R. dominica adult than each plant extracts alone. Understanding the mechanism of mixture of plant extract to enhance activity of them can facilitate the creation of artificial blends that optimize their efficacy against insect pests