Journal Of Crop Protection
Volume:4 Issue: 1, Mar 2015

Nutritional indices of Helicoverpa armigera (Hübner) larvae, an economic insect pest of agricultural crops in the world, were studied on five corn hybrids (SC700, SC704, SC500, DC370 and SC260) when incorporated into artificial diets under laboratory conditions at 25 ± 1 °C, relative humidity of 65 ± 5% and a photoperiod of 16:8 (L: D) h. The highest values of consumption index (CI) and relative growth rate (RGR) of the fourth instars were on SC500 (37.21 ± 3.34 and 0.43 ± 0.07 mg/mg/day, respectively) and lowest values of these indices were on SC704 (21.44 ± 2.83 and 0.18 ± 0.04, respectively). Among five corn hybrids tested, efficiency of conversion of ingested food (ECI) of fifth instars was the highest on SC260 (6.92 ± 0.5%) and the highest value of efficiency of conversion of digested food (ECD) was on SC704 (10.71 ± 3%). However, the larvae fed on SC700 had the lowest values of ECI and ECD (3.57 ± 0.3 and 4.39 ± 0.4%, respectively). For the sixth instar larvae, although the lowest CI and approximate digestibility (AD) values were observed on SC260 (3.49 ± 0.17 and 53.89 ± 3.70%, respectively) the highest value of ECI and ECD was on SC260 (9.11 ± 0.6 and 16.54 ± 1.5%, respectively). For the whole instars larvae (fourth to sixth instars), ECD value of H. armigera was the highest on SC260 (10.15 ± 1.08%) and lowest on SC700 (6.32 ± 0.47%). The results of this study pointed out higher nutritional performance of the larvae H. armigera reared on SC704 and SC260 and lower on SC700 and SC500.

The prey suitability for generalist predators is an important feature for efficient mass rearing and IPM. The green lacewing, Chrysoperla carnea (Stephens) is a polyphagous predator attacking several pests on various crops. This experiment was conducted under laboratory conditions at 25 ± 2 ºC, 60 ± 5% R. H. and a photoperiod of 16L: 8D, at Kerman Shahid Bahonar University. The effects of different prey species were investigated on the pre-imaginal development, survival, adult longevity and fecundity of the green lacewing. The results indicated that duration of each pre-imaginal stage development and total development time in C. carnea were significantly affected by species of prey tested. The total developmental period was 19.63 ± 0.125, 20.63 ± 0.180, 22.06 ± 0.183, 22.35 ± 0.120, and 23.81 ± 0.356 days on Aphis gossypii(Glover), Myzus persicae(Sulzer), Aphis punicae(Passerini), Aphis fabae(Scopoli) and Aphis craccivora(Koch),respectively. The maximum mean fecundity per female of C. carnea was 478.50 ± 8.38 eggs recorded when fed as larvae on M. persicae followed by 409.33 ± 8.16 eggs on A. gossypii, whereas, the minimum of 242.78 ± 7.37 eggs was recorded when fed on A. craccivora nymphs. The longest female longevity was recorded for C. carnea fed on M. persicae. There was significant difference in adult longevity due to feeding on different preys. However, nymphs of M. persicae and A. gossypii were the best of the prey species tested, in that when fed on these species the pre-imaginal developmental period of C. carnea was shorter and its adult longevity, fecundity and percentage survival was greater than those fed on the other preys. These findings could be useful in defining more optimum conditions for the mass rearing of C. carnea in IPM programs.

A survey was carried out on citrus nurseries in Mazandaran and Kerman provinces as the major citrus growing regions of Iran. Different varieties of orange and tangerine with abnormal symptoms were examined for the occurrence of Candidatus Liberobacter asiaticus, Spiroplasma citri and phytoplasma as the most important vascular limited pathogens in citrus. By visual inspection and molecular examination of 360 samples for the presence of fastidious prokaryotes only an occasional occurrence of phytoplasma and Spiroplasma citri were detected, using phytoplasma universal primer pairs P1/P7 and fU5/rU3 (in single tube nested PCR assay) and Spiroplasma specific primers P89-r/f and P58-6f/4r. PCR products of phytoplasmas were digested with MseI, AluI, BamHI and TaqI restriction enzymes and the digestion results showed phytoplasma related to aster yellows phytoplasma group. No amplicon was obtained for Candidatus Liberobacter asiaticus. The findings suggest when pathogen’s titre is low; symptoms of vascular limited disease are almost confused with disorder and deficiencies signs. So for sanitary selection and certification program, using sensitive detection method is recommended. Multiplex PCR assay used in this study successfully detected Candidatus Liberibacter asiaticus, Spiroplasma citri and phytoplasma in one reaction and suggests for health certification programs.

In this study, Trichoderma harzianum BI was evaluated for its capability to reduce the incidence and severity of the root-knot nematode, Meloidogyne javanica, and Fusarium wilt, F. oxysporum f. sp. lycopersici, as causal agents of a complex disease of tomato in the laboratory and greenhouse conditions. Initial in vitro studies revealed that the parasitism of M. javanica eggs by T. harzianum BI was up to 49.6%. In dual culture tests, maximum growth inhibition of F. oxysporum f. sp. lycopersici by T. harzianum BI (55%) was observed on the fifth day in laboratory. In greenhouse studies, the efficiency of treatments was appraised by using nematode-related factors such as diameter of galls, number of galls per plant, number of egg masses per plant and also incidence of Fusarium wilt. The antagonistic fungus was further tested for its ability to induce production of defense related enzymes in tomato. The activity of phenylalanine ammonia lyase (PAL) was increased significantly in the seedlings treated with the antagonistic fungus in comparison with control and its maximum amount was reached on the fourth day after inoculation with T. harzianum BI. Thus, the present study shows that in addition to direct antagonism, induction of defense-related enzymes, by T. harzianum BI that are involved in PAL pathway contributed to enhanced resistance against invasion of M. javanica and F. oxysporum f. sp. lycopersici in tomato.

During spring and summer of 2012, a disease characterized by panicle blight was observed on some pistachio (Pistacia vera L.) trees grown in Kerman province.Eighteen isolates of a Botryosphaeriaceae sp. were obtained from affected panicles. Based on morphological and molecular characteristics, isolates were identified as Botrysphaeria dothidea. To our knowledge, this is the first report of B. dothidea associated with pistachio panicles in Iran.

On the basis of preliminary in vitro screening tests, a competent strain of Pantoea agglomerans ENA1 (P. agg. ENA1) recovered from soybean nodule was evaluated for its antagonistic activity against Macrophomina phaseolina caused charcoal rot of soybean. The results of various in vitro assays showed that P. agg. ENA1 is capable of exerting strong antagonistic effect against M. phaseolina inhibiting its mycelial growth up to 89% as compared to control. The results showed a significant reduction of the disease as measured in host-plant weight increase, reduced microsclerotial coverage of the host tissues and decreased population of the pathogen in soil. Soils treated with the antagonist in presence of the pathogen resulted in 40% increase in aerial fresh weight and 63% decrease in root and stem surface covered by microsclerotia as compared with control. Furthermore, a significant decrease in the pathogen population ranging from 73 to 76% was observed in sterile and non-sterile soils, respectively. Providing excellent rhizosphere colonization and control against M. phaseolina by P. agg. ENA1 was proved it as a potent biocontrol agent.

In Iran, common bunt of wheat is one of the most important diseases of wheat and using resistant varieties is the best strategy against it. In order to find resistance sources against the disease for effective breeding programs, determining races of the pathogen is critical. In this study, spikes infected with common bunt of wheat were collected from different farms of Khuzestan province in 2005-2006. Tilletia laevis and T. caries were identified as the causal agents of the disease. Twenty selected isolates were inoculated on differential genotypes and planted in farm condition. Fifteen different pathogenic races were identified in this study; L-19, L-21, and L-1 (for T. laevis) T-11, T-1, T-2 and T-31 (for T. caries). Except L-21 and L-1, other races were reported for the first time in Iran until 2008. Also eight pathogenic races were identified based on virulence/avirulence patterns in this study. Results showed that host resistance genes Bt6 and Bt14 were effective against races of T. laevis, and host resistance genes Bt5, Bt6, Bt10 and Bt14 were effective against races of T. caries in Khuzestan province.

Taeniothrips inconsequens (Uzel) of the subfamily Thripinae (Thysanoptera: Thripidae) collected on flowers from Doha is reported in this paper, which represents the first record of both the genus and the species from Qatar. Morphological characters and geographical distribution of the newly recorded thrips are given.

It has been hypothesized that the survival, development, fecundity and even population expansion of insects are all affected significantly by extremely high temperature. The diamondback moth, Plutella xylostell (L.) (Lepidoptera: Plutellidae), is a serious and economically important pest of cruciferous crops throughout the word. In this research, the adult longevity and fecundity of P. xylostella were studied. After effect of heat shock stress, (30, 35 and 40 °C) for 2, 4, 6 and 8h, the experiments were conducted at 25±1 °C, 65±5% RH, and a photoperiod of 16:8 (L:D)h on Brassica napus. The developmental time of immature stages were significantly affected after heat shock temperatures (30 to 40 °C) when compared to the 25 °C control, but the developmental time of larvae did not differ significantly at 40 °C. The pupal development time differed significantly at heat shock temperatures, which the longest (6.13±0.05 days) at 30 °C for 2h. Heat shock temperature also had significant impact on adult longevity and fecundity of diamondback moth. The longest adult longevity for females and males was determined to be 14.47±1.04 and 11.04±0.95 respectively at 35 °C for 2h. The fecundity of females fluctuated significantly with increasing temperature stress. Our findings can be used to develop a more profound understanding on the potential for this insect to evolve in response to environmental temperature changes.

Brazilian peppertree (Schinus terebinthifolius) leaf extract was applied against two strains of the crown gall disease (Agrobacterium tumefaciens); strains C58 and AR125. In vitro, we used the agar well diffusion method and the extract was tested in different solvents selected according to their polarity indices, at different concentrations and different incubation temperatures. In vivo, we tested the extract prepared in different solvents on the stems of young tomato plants (cv. Firenze) which were inoculated with the strain C58.The best results were obtained with the extract prepared in hot sterile distilled water and in methanol (0.3 g.ml-1) incubated at 25 °C and 30 °C. The minimum inhibitory concentration (MIC) was evaluated to 10-4 g.ml-1. In another aspect, to identify the nature of certain substances from S. terebinthifolius leaf extracts, we made a test of fractionation using the Thin Layer Chromatography (TLC) method and phytochemical screening of the crude methanol leaf extract. We noticed the presence of alkaloids and flavonoid compounds which may be responsible for the antibacterial activity. These tests indicated that false pepper leaf extract has an antibiotic effect against Agrobacterium tumefaciens both in vitro and in vivo, which represents a conceptual approach with great promise for future biological control.

Chromatomyia horticola (Goureau) (Diptera: Agromyzidae) is a highly polyphagous leaf miner that cause severe damage to different crops. Sampling on the Alysiinae (Braconidae) parasitoids of C. horticola was performed at various locations of Kermanshah province during 2009–2010. Infested leaves of host plants bearing the larvae and puparia of C. horticola were collected and placed inside the plastic rearing boxes and transferred to laboratory. The samples were preserved for 2–4 weeks, until the emergence of parasitoids. Three species of Alysiinae parasitoids were reared and identified in the association with C. horticola in Kermanshah including, Chorebus (Stiphrocera) aphantus (Marshall, 1986), Chorebus (Stiphrocera) uliginosus (Haliday, 1839) and Dacnusa (Aphantus) hospita (Foerster, 1862). All three species have been recorded for the first time as parasitoids of C. horticola. In addition, C. aphantus is newly recorded for the fauna of Iran. An identification key to the parasitoid species is given.

Cercosporoid fungi including the genus Cercospora and other morphologically similar genera are associated with leaf spot symptoms on various host plants. In this research three taxa including Passalora cucurbiticola (on Cucurbita sp.), P. bolleana (on Ficus carica), and Pseudocercosporella capsellae (on Capsella bursa-pastoris, Sinapis arvensis) were identified. Among these, P. cucurbiticola and P. capsellae are new records for mycobiota of Iran.

Insecticidal efficacy of three diatomaceous earth (DE) formulations, DEBBM, DEA and F2 was evaluated on three different wheat cultivars, Chamran, Verinak and Behrang, against Tribolium confusum Jacqueline du Val. DEs were applied at the rates of 100, 200 and 300 mg/kg. Bioassays were carried out on wheat at 27 ± 1 °Cand 55 ± 5% RH in continuous darkness. Mortality of adults was counted after 2, 7 and 14 days of exposure. Adults of T. confusum were the most susceptible to DEBBM in Behrang. So that DEBBM concentration of 100 mg/kg after 7 days of exposure caused 98% mortality which reached 100 after 14 days. Therefore, Behrang was the most tolerant cultivarto T. confusum infestations. Furthermore, DEBBM was more effective than the other two testedformulations.

Applying a precise forecasting method is necessary to achieve acceptable results in IPM programs. Performances of the wing and delta pheromone traps for forecasting the codling moth phenology were compared with physiological time data based on Degree-Hours. Six pheromone traps (three wing and three delta style) were applied for the monitoring of the codling moth population. Traps were placed in an apple orchard in Tehran Province, Damavand region by the start of bloom. All traps were checked every week and the number of moths caught was recorded. Physiological time was estimated by using hourly recoded temperature, considering temperature thresholds for codling moth development. The results showed that the delta style traps statistically caught more male moth than wing traps. It was also shown that the results of the pheromone traps data were affected severely by weather conditions. Moreover, false fluctuations in recorded data from pheromone traps made some false population peaks, the interpretation of which was very hard. On the other hand, forecasting model based on the physiological time data, was not affected by the mentioned conditions and its results was easy to use for determination of the pest phenology without further interpretations.

Symptoms of the leaf scorch disease on the leaves of oleander infected by Xylella fastidiosa appearing for the first time in Lebanon were confirmed by ELISA tests and anatomical observations of sections of petioles by a scanning electron microscope. Xylella fastidiosa was detected in the xylem forming bacterial aggregates in the lumen of tracheary elements. The bacterium colonizes and invades the conducting tissues degrading pit membranes (PMs) of tracheary elements. Dense networks of fibrillar material and tyloses, originating from the plant, as a defense mechanism form around the bacterial aggregates to limit the movement of the pathogen. The bacterial aggregates that plug the tracheary elements and the tyloses produced by the infected oleander plants cause water stress and consequently leaf scorch symptoms. To the best of our knowledge, this is the first report of Xylella fastidiosa in Lebanon.