Journal Of Crop Protection
Volume:4 Issue: 3, Sep 2015

Biological and demographic parameters of the mealybug ladybird, Cryptolaemus montrouzieri (Mulsant) were evaluated on citrus mealybug, Planococcus citri (Risso) and obscure mealybug, Pseudococcus viburni (Signoret) under 24 ± 2 ºC, 80 ± 5% relative humidity and a photoperiod of 16:8 (L: D) h. The mealybugs had a significant effect on developmental time and reproductive and demographic parameters of the ladybird. Life span (egg to adult death) was obtained 220.85 ± 5.78 and 119.44 ± 2.1 days when fed on Pl. citri and Ps. viburni, respectively. However, mean number of eggs per female (fecundity) and mean percent of egg hatching were significantly higher on Ps. viburni than on Pl. citri. In addition, values of intrinsic rate of increase (rm), finite rate of increase (λ) andnet reproductive rate (R0) were significantly higher on Ps. viburni than on Pl. citri.The values of intrinsic rate of increase were estimated 0.081and 0.094 day-1 on Pl. citri and Ps. viburni, respectively. Results of this study suggested that the obscure mealybug is a more suitable prey than the citrus mealybug as the ladybird displayed shorter developmental time, and higher fecundity and growth rate when fed with obscure mealybug.

New sources of maize resistance to the maize weevil, Sitophilus zeamais infestation are indispensable in successful breeding programs against post harvest grain damage. The study investigated the characters and mechanisms that confer resistance to weevil infestation using twenty elite maize genotypes. Detailed morphological and physical studies were conducted on whole-maize grain. The grain hull was separated from the whole-maize grain with a locally-fabricated machine and subjected to chemical analysis. Resistance was assessed at 33 days post infestation using weevil mortality, weevil survival, percent grain damage, weight of grain powder, percent weight loss and oviposition as indices rated on a scale developed by the present study. The resistant genotypes identified, particularly 2000SYNEE-WSTR and TZBRELD3C5 with very high degree of resistance should be used singly or best in an integrated pest management system for the control of S. zeamais infestation in stored maize. Though increases in the physical properties of grain hardness, weight, length and width increased varietal resistance, it was found that the bases of resistance were increased chemical attributes of phenolic acid, trypsin inhibitor and crude fiber while the bases of susceptibility were increased protein and starch. Characters that conferred resistance on the tested genotypes were found in the grain hull. The study identified antibiosis and antixenosis as the mechanisms of maize post harvest resistance to S. zeamais infestation.

In vitro antifungal activity of silver nanoparticles, at concentrations of 6, 8, 10, 12, 14 and 16 ppm, was studied on five phytopathogenic fungi, and a biocontrol agent. Then effect of silver nanoparticle at 6 ppm (optimum concentration) was evaluated on Macrophomina phaseolina in greenhouse. For in vitro experiment, the fungal isolates were grown on potato dextrose agar medium amended with silver nanoparticles. Radial fungal growth was recorded after 1, 2, 3, 5 and 10 days and mycelial growth inhibition rates were calculated. The most sensitive fungus to nanoparticles was Pythium aphanidermatum, since all tested concentrations showed 100% inhibition during the 10 days of observation.The second most sensitive fungus was Sclerotinia sclerotiorum, since it was able to grow only at concentration of 6 ppm and M. phaseolina was the third in sensitivity since its growth was inhibited in all concentrations after three days. In greenhouse experiments, five treatments including no nanosilver-no pathogen (Negative control), no nanosilver +pathogen (Positive control), 6 ppm nanosilver– no pathogen, 6 ppm nanosilver +pathogen, Carboxin-Thiram (0.15%) +pathogen were compared. Four characters viz shoot and root fresh and dry weights were measured. Based on the greenhouse experimental results, treatments with nanosilver and fungicide gave higher yields than the positive control. The chemical control treatment had the highest measured parameters, while 6 ppm nanosilver +pathogen treatment had the same parameters as negative control. It may therefore be suggested to use nanosilver as a safer alternative to chemical fungicides for control of M. phaseolina.

Five oppiid mite species (Oribatida: Oppiidae) belonging to three genera (Corynoppia, Ramusella and Rhinoppia) are reported as new records for the mite fauna of Iran. Some of their morphological features and distributions in the world are presented. A key to the subfamilies, genera and species of all Iranian oppiid mites is given.

Effects of three nutritional levels of beet root molasses, cheese permeate, wheat bran extract, rice bran extract and Sabouraud,s Dextrose Broth (SDB) were evaluated for blastospore production by two isolates of Beauveria bassiana sensu lato. at an interval of 24 h for seven days. Depending on the isolate, maximum blastospore production was obtained in 12% rice bran extract and 20% cheese permeates on the 7th day. Both isolates produced the fewest blastospores in 4% cheese permeate. Virulence of blastospores, produced in liquid media containing beet root molasses, permeate, wheat bran extract and SDB (as control), on third instar larvae of brown tail moth Euproctis chrysorrhoea indicated that there were no significant differences among these nutritional media for either one of the isolates. Considering blastospore quantity and quality in terms of virulence and local accessibility, cheese permeate was found to be the best medium for mass production of B. bassiana blastospores.

Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is one of the destructive diseases of wheat in the world. The fungal pathogen can infect 365 different grass and more than 70 Berberis species. DNA sequences for the ribosomal RNA internal transcribed spacer (ITS) have proven suitable to explore relationships at the species and subspecies levels. An isolate of Pgt which was collected from Iran and designated as TTSSK was used in this study. Three samples of the isolate were used. ITS region of the samples was amplified and sequenced. Consensus tree based on Maximum Parsimony clustering method was produced by Mega 6.0. Iranian isolate of TTSSK was placed in a clade with P. graminis which was isolated from Berberis sp. and Pgt isolate from Tajikistan. The results showed that more than one conserved genomic regions would be informative to identify phylogenetic relationship of Iranian Pgt isolates and samples from different parts of the world. Complementary studies with more sequence data from other genome loci are in progress.

The beet armyworm Spodoptera exigua (Hübner) is a serious and economically important pest of solanaceous crops worldwide. The nutritional indices of this pest on three host plants including pepper Capsicum frutescens, eggplant Solanum melongena and tomato Solanum lycopersicum were determined under laboratory conditions at 26 ± 1 °C, 60 ± 5% RH and 16: 8 (L: D) h. The highest relative consumption rate (9.40 mg/mg/day) and approximate digestibility (95.20%) were recorded on eggplant. The relative growth rate (RGR) (0.08 mg/mg/day) was the highest on tomato. The efficiency of the conversion of ingested food (ECI) (1.66%) and efficiency of conversion of digested food (ECD) (2.22%) were significantly highest on pepper. Results showed that pepper was the most nutritionally suitable food and even small amount of this food could successfully support maximum RGR as evidenced by high value of ECI and ECD.

The present study provides information about the Cryptinae and Ichneumoninae (Hymenoptera: Ichneumonidae) species collected from Kerman province, during 2013. A total of 12 species belonging to 10 genera of these two subfamilies were collected and identified. They were Cryptus inculcator (Linnaeus, 1758); Dichrogaster longicaudata (Thomson, 1884); Dichrogaster saharator (Aubert, 1964) and Mesostenus albinotatus Gravenhorst, 1829 (subfamily Cryptinae); Anisobas cingulatellus Horstmann, 1997; Apaeleticus bellicosus Wesmeal, 1845; Barichneumon derogator (Wesmeal, 1845); Ctenichneumon devylderi (Holmgren, 1871); Ctenichneumon edictorius (Linnaeus, 1758); Diadromus collaris (Gravenhorst, 1829); Heterischnus filiformis (Gravenhorst, 1829) and Lysibia nana (Gravenhorst, 1829) (subfamily Ichneumoninae) of which the genus Apaeleticus Wesmael and three species including M. albinotatus, A. bellicosus and B. derogator are new records for the fauna of Iran. All species are new for the fauna of Kerman province.

Some plant extracts have been reported to exhibit antimicrobial properties. Plant based pesticides appear to be an alternative for the synthetic pesticides because of their less dangerous impacts. The objective of this study was to assess the inhibitory activity of Brassica napus water extract on mycelial growth of six phytopathogenic fungi Rhizoctonia solani, Phythophtora drechseleri, Pythium aphanidermatum, Verticellium dahliae, Fusarium oxysporum, and Gaeumannomyces graminis. Antifungal activity test was performed by disc diffusion method. Concentrations of 100 and 50 ppm had the highest and the lowest inhibitory effects on all studied species respectively. The shoot extract (SE) was significantly exerted higher antifungal activity than root extract (RE). At 100 ppm, V. dahliae (17.02% inhibition by RE) and F. oxysporum (50% inhibition by SE) were the most sensitive species however, R. solani (1.8 and 15%) was the most resistant fungus to both extracts. Active compounds of B. napus extract were determined by high performance liquid chromatography (HPLC). Phenolic compounds had the highest concentrations in extracts and are probably the main cause of the mycelial growth inhibition. Application of canola aqueous extract or incorporation of canola in crop rotation program can be considered as a method for management of some soil-borne phytopathogenic fungi.

Nutritional indices of the willow leaf beetle, Plagiodera versicolora Laicharting, third instar larvae and adults were studied on four host plants including Salix alba L., Salix aegyptica L., Populus caspica Bornm.and Populus alba L.at 22 ± 2 ºC, 70 ± 10% R.H., and a photoperiod of 16:8 h (L: D). The results showed that the highest consumed food by the larvae and adults (148.5 ± 18.0 and 175.21 ± 4.51 mg dry weight, respectively) was on P. caspica. The larvae fed on S. alba and S. aegyptica had the highest efficiency of conversion of ingested food (ECI) (2.3 ± 0.33 and 2.23 ± 0.67%, respectively) and efficiency of conversion of digested food (ECD) (2.5 ± 0.35 and 2.41 ± 0.72%, respectively). Approximate digestibility (AD) of larvae was the highest on P. caspica and P. alba (98.51 ± 0.25 and 98.14 ± 0.1%, respectively). The lowest relative consumption rate (RCR) of the larvae and adults was on S. alba (0.14 ± 0.001 and 0.13 ± 0.006 mg/mg/day, respectively). ECI and ECD values of the adults fed on various host plants were not significantly different. Adults fed on P. caspica had the highest values of RCR (0.59 ± 0.01 mg/mg/day), relative growth rate (RGR) (0.02 ± 0.008 mg/mg/day) and AD (98.72 ± 0.24%). These results demonstrated the higher feeding performance of the willow leaf beetle on P. caspica and its poorer performance on P. alba.

Application of antagonistic agents in the rhizosphere of plants is an important approach in control of soil-borne pathogens. Establishment and persistence of biocontrol agents in the soil is a major concern in biological control. This study aimed to determine the effect of plant debris of oak forests on activity of Pseudomonas fluorescens and Trichoderma vierns against Meloidogyne javanica in tomato in green house conditions. In different treatments, both or one of the bioagents were applied to the soil inoculated with M. javanica and amended or unamended with oak plant debris. Based on the results, the growth–related factors of tomato improved in those treatments, in which plant debris were mixed with the soil. In case of nematode-related factors, the number of galls on roots decreased significantly in pots amended with plant debris. Maximum reduction in reproduction factor was observed in treatments with one or both of the biocontrol agents. In comparison to unamended treatments, the rate of reduction in root gall was 56.3% for treatments receiving T. virens and maximum increase in dry weight of root was observed in soils treated with P. fluorescens or T. virens, 68.2% and 56.1%, respectively.

Pauesia antennata Mukerji (Hymenoptera, Braconidae) as the unique parasitoid of the giant brown peach aphid, Pterochloroides persiace Cholodkovsky (Hemiptera, Aphididae) is considered to be the most effective biological control agent of this pest. In this study, the assessment of selected biological parameters of P. antennata demonstrated that the longevity of mature parasitoid was 3.90 ± 0.22, the developmental time was 14.48 ± 1.05 and the life span was 19.46 ± 0.68 days. The maximum flight activity and oviposition were observed at the second and third days of the parasitoid lifespan. The parasitism, emergence rates and the sex ratio were affected by the variations in the number of P. persicae relative to each population of the parasitoid.

Rust diseases continue to cause significant losses to wheat production around the world. Among them, yellow rust caused by Puccinia striiformis f. sp. tritici is an important disease that threatens wheat production in most cool environments. Host resistance, especially race- nonspecific resistance, is the most economical way to manage wheat stripe rust disease. In this study, the effectiveness of different types of resistance was compared in field plots at Ardabil Agricultural Research Station (Iran) during 2011-2013. Yield and yield components along with slow rusting parameters including final rust severity (FRS), apparent infection rate (r), relative area under disease progress curve (rAUDPC) and coefficient of infection (CI) were evaluated for 16 wheat cultivars/lines. In all, five wheat cultivars with race-specific resistance, 10 cultivars with different levels of slow rusting resistance and one susceptible cultivar were included in two treatments; with and without fungicide protection under high disease pressure. Results of combined variance analysis showed significant differences between cultivars/lines, also cultivar/line × year at 1% probability level. Wheat cultivars with slow rusting resistance displayed a range of responses indicating phenotypic diversity. Mean thousand kernels weight (TKW) losses of susceptible, race-specific and slow rusting genotypes were 41, 4.4 and 7.6%, respectively. Mean yield losses of susceptible, race-specific and slow rusting genotypes were 65.6, 7.3 and 15.9%, respectively. In this study cultivars having slow rusting resistance with low values of epidemiological parameters were identified. Also genotypes with low yield component losses, despite moderate disease levels, were characterized. Such genotypes can be used in breeding programs to get improved varieties with high levels of resistance and negligible yield losses. Kernels per spike (KPS) data of two experiments were not enough for comparing losses and need supplementary experiments.

A faunestic study on Stigmaeidae and Cryptognathidae families in Lorestan province was carried out during 2012-2013. In this study 18 species were collected and identified, of which Favognathus amygdalus and F. cordylus (Cryptognathidae) were new records for Iranian fauna, also all of the collected species in this study were new records for fauna of Lorestan province. Stigmaeidae with 14 species and Cryptognatidae with four species had the highest and lowest number of identified species, respectively.

Silicon (Si) is considered as one of the beneficial elements for plants that play important roles in plant resistance to stresses. In this experiment, the effects of three levels of silicon (0, 0.85 and 1.7 mM) on the growth and physiological processes of pumpkin were studied in plants inoculated with Sphaerotheca fuliginea (250000 conidia ml−1) and non-inoculated plants under hydroponic condition. Applying silicon increased the Si concentration in plant tissues. Application of Si in plants inoculated with S. fuliginea decreased significantly severity of disease symptom (30%) and also the shoot membrane permeability was decreased. Addition of Si significantly increased the reactive sulfhydryl group content whereas disease decreased sulfhydryl group which was significantly lower in Si-free medium. The infected plants that were treatedwith 1.7 mM Si levels grew and yielded similar to non -infected pumpkins. Using Si nutrition decreased Fe and Mn and increased Zn concentration in the roots and shoots of plants. Alleviation of disease severity in the silicon treatments may be due to enhancing of plant tolerance to disease by decreasing of shoot membrane permeability, increasing the reactive sulfhydryl group content, and also due to effect of silicon on the uptake and distribution of some ions. This study revealed that Silicon at 1.7 mM used in hydroponic system effectively reduced powdery mildew and improved pumpkin growth.