JOURNAL OF CROP PROTECTION
Year:2018 | Volume:7 | Issue:2 |Papers Count:11

The sugarcane stem borer, Sesamia cretica Lederer, is one of the most economically important pests of sugarcane in Khuzestan province, southwest Iran. The egg parasitoidTelenomus busseolae Gahan significantly affect S. cretica population in the field. Host age is an important factor of host acceptance and suitability for egg parasitoids. We examined the ability of T. busseolaeto parasitize and develop in S. cretica eggs of different ages. In a no choice laboratory experiment, we measured the effect of host age (12, 36, or 60 h old) on parasitism rate and offspring fitness characteristics such as survival, development time, sex ratio, size, and progeny longevity and fecundity. Results revealed that the suitability of host eggs decreased as host age increased. Exposure of parasitoids to 12h old eggs resulted in higher percentage parasitism, higher acceptance, higher survival and larger body size of parasitoid progeny. Progeny that emerged from 12h old eggs had also higher longevity and fecundity than those emerged from other host ages tested.

Essential oils of four aromatic plants, Artemisia monosperma Del., Callistemon viminals(Sol.ex Gaertn.) G. Don, Citrus aurantifolia (Christm.) Swingle and Cupressus macrocarpaHartw. ex Gordon, were evaluated for their anti-nutritional, antifeedant, growth inhibitory and insecticidal activities againstSopdoptera littoralis (Boisduval) (Lepidoptera: Noctuidae). The essential oils of A. monosperma and C. aurantifolia caused the highest reduction in relative growth rate (RGR) at the tested concentrations (125, 250, 500, 1000 and 2000mg/l). The RGR values ranged between 8.63 and 3.05 mg/day for A. monosperma, and between 10.74 and 2.89 mg/day for C. aurantifolia compared with 14.89 mg/day for control after 72 h of treatment. In general, the results showed that the values of relative growth rate (RGR) decreased with increasing the concentration of the tested oils. In addition, the tested oils significantly reduced efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) values, particularly at the higher concentrations of 500, 1000 and 2000mg/l. On the other hand, the tested oils showed antifeedant activity against the larvae ofS. littoralis with A. monosperma and C. aurantifolia oils being more active than C. viminalsand C. macrocarpa oils. The tested oils showed remarkable growth inhibition effect as the growth inhibition index values were increased from 37.63 to 79.80% forA. monosperma, from 21.69 to 52.12% for C. viminals, from 16.55 to 28.59% for C. aurantifoliaand from 37.64 to 52.32% for C. macrocarpa when the concentration increased from 125 to 2000mg/l. Based on chitin formation ratio values, the tested essential oils induced reduction in chitin formation.A. monosperma and C. macrocarpa essential oils revealed the highest insecticidal activity on 4th instar larvae of S. littoralis. Examination of reproductive tracts of adult females emerged from treated larvae indicated that the tested oils caused undifferentiated ovarioles.

Habrobracon hebetorSay is an idiobiont and gregarious larval ectoparasitoid of many moths.In this study, lethal and sublethal effects of Eucalyptus camaldulensis, Carum carviand Heracleum persicum essential oils on the demographic parameters of H. hebetor were assessed at 26 ± 2oC, 60 ± 5% RH, and a photoperiod of 16: 8 (L: D) h. Essential oils were obtained from these plants by hydro-distillation method using a Clevenger apparatus.The chemical constituents of essential oils were detected by Gas Chromatography-Mass spectrometry (GC-MS).250ml Glass vials were used for the fumigant toxicity experiments. In order to assess the sublethal effects, adult wasps were exposed to an LC25 of each essential oil and then the demographic parameters of live parasitoid wasps were studied. Fumigant toxicitywith adults indicated that the lethal concentration (LC50) values of the above essential oils against H. hebetor femaleswere 1.116, 0.34 and 3.416ml/l air, respectively. Chemical analysis by GCMS displayed o-Cymene (15.11%), Carvone (55.8%) and Hexyl butyrate (41.78%) were main constituents of the essential oils of E. camaldulensis, C. carvi and H. persicum, respectively. The results showed that the intrinsic rate of increase (r), finite rate of increase (l), net reproductive rate (R0) and gross reproductive rate (GRR) were significantly affected by the essential oils. The highest and the lowest rvalues were 0.226 and 0.130 day-1 in control and C. carvi -treated insects, respectively. According to these results, essential oils have suitable potential for the integrated management of stored product pests.

Fusarium solani f. sp. cucurbitae races cause crown, fruit and root rots of cucurbits and economic problem for farmers. The aim of this study is identification of Fusarium solani f. sp. cucurbitae races which collected in Shahrood, Jiroft and Varamin, provinces of Iran using morphological characteristics and fungal-specific primers. Symptomatic cucurbit plants were collected from different fields in three provinces. After isolation and purification of the causal agents, pathogenicity test and DNA extraction were performed. Specific primers for TEF-1α gene were used to distinguish among different species of Fusarium and Fusarium solani. The isolates that showed a specific 658 bp amplicon on agarose gel were selected for subsequent PCR assay in order to detection of F. solani f. sp. cucurbitae race 1 and 2. PCR assays were performed with taxon-specific primers race 1 (505bp PCR product) and race 2 (425bp PCR product). Some samples amplified a 505bp amplicon which is specific for race 1 and was in accordance with morphological characteristics. In these isolates, 5 septate macroconidia were dominant that is specific to Fusarium solani f. sp. cucurbitae race 1 macroconidia. None of the isolates were amplified by race 2 taxon-specific primers. Our study showed that, race 1 of F.solani is the dominant race of the pathogen in Shahrood, Jiroft and Varamin provinces which can help to implement effective disease management strategies.

In recent years, different formulations such as nanoemulsions have been widely used for the target delivery, and enhanced biological functions of pesticides combinations. In this study, contact toxicity ofMentha longifolia L.essential oil compared with its nanoemulsion onEphestia kuehniella Zeller has been investigated. The experiments were conducted and executed at 27 ± 1oC, and 75 ± 5% relative humidity under dark conditions. Chemical composition of this plant extract was also studied. The main constituents were pulegone (28.84%), 1, 8-cineol (19.6%), p-menthan-3-one-cis (8.2%), b-pinene (6.46%) and p-menthan-3-one-trans (5.86%). Results indicated that the mortality rate of 5th instar larva of E. kuehniella increased with rising concentrations (10000-40000ppm) for oil and (8000-20000 ppm) for nanoemulsion, respectively. The essential oil LC50 was 21352ppm, while this value for nanoemulsion was 14068ppm. According to the results, nanoemulsion was more effective than essential oil.M. longifolia oil had lower durability and the 50% persistent time (PT50) was 2.39 day compared to the nanoemulsion (PT50=17.13 day) in the highest concentration of essential oil. The nanoparticle size was 14-36 nanometers (nm) when the transmission electron microscope (TEM) was applied. The surface morphology of nanoemulsion was also studied by TEM.The average size of the particles was estimated 234nm by using laser light scattering apparatus. The overall results of this study show that by using nanoemulsion formulation, the effect of essential oil contact toxicity and its durability increases. Hence, the nanoemulsion slow-release formulation may represent a new category of biopesticides and this should be considered in the integrated pest management program.

The effect of methanolic extracts ofAchillea millefolium and Teucrium poliumon third instar larvae of Egyptian cotton leafworm, Spodoptera littoraliswere investigated. Methanolic plant extracts were mixed with artificial diet and then nutritional indices, glutathione-S transferase, esterase, a-amylase and protease, activity were measured 72h later.Approximate digestibility was increased significantly in larvae fed on the food containing methanolic extract of T. polium but there was not any significant change in insects treated with A. millefolium. T. polium significantly decreased relative growth rate (RGR), relative consumption rate (RCR), efficiency of digested food (ECD) and efficiency of conversion of ingested food (ECI) whereasA. millefolium only decreased RGR and RCR. Feeding on artificial diet containing plant extract decreased α-amylase and protease activities in the midgut of the insect. Furthermore, the effect of methanolic extract of plants on detoxifying enzymes showed that they have no effect on glutathione Stransferase and esterase activities.

We provide keys and new distributional data for the Iranian cuckoo wasps of four Elampini genera: Chrysellampus Semenov, 1932, Omalus Panzer, 1801, Philoctetes Abeille de Perrin, 1879 and Pseudomalus Ashmead, 1902. Two species are newly recorded for Iran: Chrysellampus pici (du Buysson, 1900) andPhiloctetes kuznetzovi (Semenov, 1932). One new synonymy is proposed: Pseudomalus masalskii (Semenov, 1932) syn. nov. of Pseudomalus turkestanicus(Mocsáry, 1889). The lectotype of Ellampus hypocritadu Buysson, 1893 is designated

Cercospora leaf spot caused byCercospora beticola has a great negative impact on yield and quality of sugar beet. In the present study, pathogenic and genotypic variation of 24C. beticola isolates collected from different regions of Iran were studied using RFLP of the Internal Transcribed Spacer (ITS-RFLP), and Random Amplified Polymorphic DNA (RAPDPCR).Pathogenic variability and genotype × isolate interaction were evaluated in greenhouse experiments on five sugar beet cultivars (FD0018, HM1836, Puma, Eudora and Monatuna). All of the 24 isolates tested were found to be pathogenic on the cultivars with significant variation in disease severity. Results of RAPD analysis showed wide DNA polymorphism among the IranianC. beticola isolates. Restriction pattern of the internal transcribed spacer of rDNA (ITS1-5.8-ITS4) was studied using three restriction endonucleases: EcoR1, Taq1, and Busr1. The length of undigested DNA fragment of all isolates was estimated to be 500bp without rDNA polymorphism after digestion withEcoR 1 (280, 270 bp), Taq 1 (330 bp) and Busr1 (240, 220, 90 bp). RAPD and ITS-RFLP markers showed the highest level of genetic diversity which confirms the variation inC. beticola detection.

In this study, the roles of proximate composition, mineral profile and heavy metal contamination were investigated on selected biological activities of Callosobruchus maculatus (F.) that were maintained on six cowpea cultivars. The levels of heavy metals; cadmium, lead and arsenic in six cowpea cultivars; Ife Brown, Ife BPC, Oloyin, Drum, Sokoto Local, and Niger White were determined by atomic absorption spectrophotometry while those of nutrient elements; zinc, sodium, calcium and potassium were determined using flame photometry. The proximate analyses and physico-chemical characterization of the cowpea cultivars were also performed.Callosobruchus maculatuswas maintained on the cowpea cultivars and biological activities such as oviposition, adult emergence, percentage seed damage, and weight loss were monitored. The levels of heavy metals, mineral elements and proximate composition differed significantly among the cultivars investigated, and the values were comparable to those reported for cowpea cultivars in other studies.Of the cowpea cultivars, the Ife Brown was the most susceptible to the bruchid C. maculatusinfestation while the Drum cultivar was the least susceptible. In conclusion, the results from this study show that the cowpea cultivars differed in the levels of toxic and mineral elements. While there were significant relationships between physical parameters (e. g. seed hardness), proximate composition (moisture contents and crude fibre) and adult emergence and oviposition, there was no strong evidence that the levels of heavy metals and mineral elements play significant role on the biology of C. maculatus.

The combined effect of gamma radiation and Carum copticum C. B. Clarke essential oil were determined for the management of Tribolium confusumDu Val larvae and adults. Experiments were carried out at 27 ± 1oC and 65 ± 5% R. H. under dark condition and three steps were designed: (A) Application of gamma radiation and essential oil at the same time. (B) Irradiation followed by essential oil. (C) Essential oil followed by irradiation. Radiation doses of 100 to 500 Gy were applied in combination with 5.97, 7.52 and 10.47ml/l air of essential oil for the adults and 1.91, 4.08 and 12.02ml/l for the larvae. The result showed that the combination of gamma radiation with C. copticum oil increased larval and adult mortality compared with the control, so that, the interaction of 500 Gy with 10.47ml/l air for adults and 12.02ml/l air for larvae caused 100% mortality in 13 and 8 days, respectively; although 100% of the larvae and adults mortality at 500 Gy alone caused within 22 days. It was revealed that the combination of irradiation and essential oils could be used as an effective control method and a good alternative to fumigants.

The water fern weevil, Stenopelmus rufinasus Gyllenhal (Coleoptera: Curculionidae), is considered as the most important biological control agent of Azolla spp. in the world. Azolla spp. was introduced in Iran in 1986. In August 2017, two specimens of S. rufinasus were collected on Azolla spp. in waterways near Anzali lagoon and Rice Research Institute of Iran (RRII) in Guilan province for the first time. Identification was based on molecular sequencing. This is the first record of S. rufinasus from Iran.