JOURNAL OF CROP PROTECTION
Year:2015 | Volume:4 | Issue:4|Papers Count:16

Rigidoporus microporusis a major threat to Hevea brasiliensis in the rubber growing regions of the world.In vitro synthetic fungicide sensitivity assays of Tridemorph, Benomyl and Bayfidan at seven different concentrations, andin vivo effectiveness of the three fungicides on R. microporus inoculated on rubber seedlings were evaluated. The three chemical fungicides used in this study were effective on R. microporus, with Tridemorph being the most effective. The minimum inhibitory concentration value for Bayfidan was between fungicide concentrations of 0.001mg/ml and 0.005mg/ml. Percentage of plant death and presence of rhizomorph recorded at two months after inoculation were higher than that recorded at the termination of five months experimental period after inoculation. Tridemorph treatment had the highest plant health both at two months and at five months after inoculation. Decline in plant death from the third months onward suggested a reduction in fungal activity of R. microporus. Tridemorph was most effective among the three fungicides tested as it exhibited higher mycelial percentage inhibition in the management of R. microporus in vitroand higher plant health of rubber seedlings in vivo.

The significant reduction of bollworm infestation by the implementation of Integrated Pest Management (IPM) inBt Cotton as a component of IPM led to reduction in bollworm infestation and increase in yield.However, these alterations have brought in many new biotic problems hitherto unknown or of little economic importance. Field survey of rainfedBt cotton fields in Perambalur district of Tamil Nadu, India during 2008-2014 revealed that the incidence of various insect pests and plant diseases is on the rise in differentBt cotton hybrids. In 2008-2009, it was observed that the Bt cotton was damaged by cotton mealybug (Phenacoccus solenopsis Tinsley), green mirid bug (Creontiades biseratance Distant) and root rot (Rhizoctonia solani Kuhn) which caused severe yield losses. In addition to that, other pests like papaya mealybug (Paracoccus marginatus Williams & Granara de Willink) and Alternarialeaf spot caused more damage in Bt cotton during 2009-10. Besides these pests, the mirid bug (Campyloma livida Reuter), stripped mealybug (Ferrissia virgata Ckll), tobacco streak virus, grey mildew Ramularia areola and boll rot incidence inBt cotton were noticed in 2010-12. Apart from this pest and disease problems, theAlterrnaria leaf blight, root rot (Macrophomina phaseolinaMaubl) and Myrothecium leaf spot caused severe yield losses in Bt cotton during 2012-2014. The survey revealed that, the pests and disease problems are increasing year by year inBt cotton which caused yield reduction and also increased the cost of cultivation. If left unchecked these pests and disease problems are capable of undoing all benefits gained due toBt cotton in terms of increased yield and reduction in use of chemical pesticides.

Genetic diversity relationships of 50 isolates of Cytospora schulzeri on apple from different parts of the Semirom region were analyzed using 15 polymerase chain reaction (PCR) based markers, 7 random amplified polymorphic DNAs (RAPDs) and 8 Microsatellite primed polymerase chain reaction (MPPCR).Using 7 selected RAPD primers 113 bands were generated, of which 81 bands were polymorphic (71.7%), with an average of 11.57 polymorphic fragments per primer, and with 8 selected MP-PCR primers 107 amplified bands were observed with 78 polymorphic bands (72.3%), with an average of 9.75 polymorphic fragments per primer. In RAPD marker, number of polymorphic bands varied from 8 (241) to 15 (230, 238, OPA13) with an average of 11.57 per primer and which varied in size from 200 to 3750 bp. Percentage of polymorphism ranged from 64% (203 and 232) to a maximum of 83% (238). In MP-PCR marker, number of polymorphic bands varied from 6 (CAG) to 12 (GTG and ATG) with an average of 9.75 per primer and which varied in size from 200 to 3500 bp.Percentage of polymorphism ranged from 54% (CAG) to a maximum of 81% (ACTG). By combining markers, a total of 220 bands were detected, of which 159 bands (72%) were polymorphic and produced on an average 10.6 polymorphic bands per primer. The results showed that both markers were suitable for the detection of genetic polymorphism among appleC. schulzeri isolates. Estimated genetic relationship using similarity co-efficient (Jaccard’s) values between different pair of accessions varied from 0.54 to 0.89 in RAPD, 0.62 to 0.89 in MPPCR and 0.62 to 0.87 with combined markers based similarities. High cophenetic correlation between the similarity matrix and corresponding dendrogram was obtained by RAPD+MP-PCR marker (r=0.81). Cluster analysis of the data using UPGMA based on Jaccard´s similarity coefficient, divided the isolates into six groups, showing a high genetic diversity among populations ofC. schulzeri.

Maize genotypes were screened for host resistance and seed treatment chemicals were evaluated in field to manage Fusarium ear rot complex of maize at high- and mid-hill environments in Nepal during 2003 and 2004. Seven popular maize genotypes along with a susceptible check were used in the host resistance study. The maize genotypes adopted from exotic sources, Manakamana-3 and Deuti, performed superior for ear rot resistance.Three seed treatment chemicals, VitavaxÒ 200B, Captan 75 WP, and BavistinÒ were tested in Fusarium susceptible cultivar. Seed treatment chemicals, VitavaxÒ 200B, Captan 75 WP and BavistinÒ, significantly (P< 0.05) reduced ear rot incidences of maize. This study suggests that cultivation of resistant varieties and applications of seed treatment chemicals can be integrated to prevent crop loss from ear rot complex and reduce potential health hazards due to mycotoxins contamination in maize grains.

Control of stored-product insect by gamma radiation could be enhanced by other possible techniques such as essential oils as effective alternatives to chemical insecticides. In this study, the efficiency of gamma radiation combined with Perovskia atriplicifolia (Benth) was verified to assess their enhanced antifeedant effect against the Tribolium castaneum (Herbst).Flour disc bioassay was employed to assess the nutritional indices, such as relative growth rate (RGR), relative consumption rate (RCR), efficiency of conversion ingested food (ECI) and feeding deterrence index (FDI). The results showed that irradiation, essential oil and combination of both of them significantly reduced RGR, RCR and ECI in treated larvae and adults. As irradiation at 100 Gy reduced RGR of the larvae and adults from 0.0884 and 0.0366 to 0.0596 and 0.0332 mg/mg/day respectively, when combined with doses of P. atriplicifolia essential oil, the reduction reached to 0.051 - 0.388 and 0.01- 0.224 mg/mg/day respectively. The reduction rates in larvae were even greater when combination of irradiation and EO treatments were used. The results showed a significant increase in the feeding deterrence due to irradiation, essential oil and specially their combination. Therefore, findings led to a conclusion that irradiation can enhance antifeedant activity of essential oils.

The bioactivity of chemical extracts from silverleaf nightshade Solanum elaeagnifoliumCav. seeds and leaves were tested for herbicidal activities, through water and ethanol extracts, againstPortulaca oleracea L., Corchorus olitoriusL., Convolvulus arvensis L. and Echinochloa crus-galli (L.) found in mostZea mays L. fields. Characterization of the isolated constituents from ethanol extract was conducted by various spectroscopic techniques. Purification of chloroform (100%) column fraction carried out by TLC plate using developing system; chloroform: ethanol: acetic acid (92: 4: 4) and hexane: chloroform: ethyl acetate (16: 16: 1) resulted chlorogenic acid, kaempferol and mangiferin. The second active column fraction eluted by chloroform: ethyl acetate was purified on TLC by chloroform: methanol: water (13: 7: 1) and butanol: water: formic acid (4: 5: 1) resulted in (coumaroyl glucoside, coumaroyl quince acid) and (kaempferol b-D- (6”-O-cis-cinnamoyl glucoside), dicaffeoyl quinic acids) respectively. The most active isolated component fromS. elaeagnifolium seeds was chlorogenic acid which decreasedP.oleracea total biomass fresh weight by (86.5%) followed by kaempferol b -D- (6”-O-cis-cinnamoyl glucoside) (84.4%), while a moderate effect was achieved from coumaroyl glucoside (79.37%), mangiferin (76.98), kaempferol (72.48%) and coumaroyl quince acid (66.47%); finally the lowest activity (63.6%) was achieved by dicaffeoyl quinic acids compared with the controls. Thus, the herbicidal activity of these constituents suggests their potential for development as natural herbicides.

Ninety one monoconidialBipolaris isolates were obtained from lesions on different parts of rice in different locations of Mazandaran province during the summer of 2009.Bipolaris species were identified using morphological features such as color and shape of colony and color and size of conidia and conidiophores. The isolates were separated into two species; 85 (93.4%) isolates belonged toBipolaris oryzae and the remaining 6 (6.6%) isolates toBipolaris cynodontis. Therefore B. oryzae is regarded as the major cause of rice brown spot disease in Mazandaran province. In order to analyze genetic diversity amongB. oryzae isolates, 71 isolates were subjected to fingerprinting analysis by rep-PCR using BOX and REP primers. In cluster analysis, 15 clonal lineages and 54 haplotypes were identified. The largest clonal lineage contained with 36 haplotypes was the most common lineage.These results also indicate a relatively high level of genetic diversity amongB.oryzaeisolates. Also, pathogenicity test of a few B. oryzae isolates (12 isolates) was conducted under greenhouse condition and showed that those isolates were pathogenic to rice seedlings of cv. Tarom. All isolates produced some leaf spots 24 h after inoculation.

The objective was to study the population development of Tuta absoluta (Meyrick, 1917) on tomato in greenhouse conditions at Droh. The trial assessed the occurrence of T. absoluta adults from the month of October to May in traps; a low numbers is noted. The high numbers recorded (170 adults/greenhouse) are caught at the end of crop cycle. The mean number of capture is 22 adults/ week/ trap. Regarding the other developmental stages, immatures of T. absoluta are also very low mainly at the beginning of the crop season. The highest numbers of immature stages recorded is: 36 eggs per 30 leaves on 19 April 2012, 14 larvae 19 April and 3 May 2012. One pupa is recorded on 17 November 2011 and 26 January 2012. During the survey, no natural enemies are detected on the different developmental stages ofT. absoluta.

The subfamily Metopiinae was taxonomically studied in Fars and Hormozgan provinces during 2011–2013. The specimens were collected by using Malaise traps and sweep net. Five species were collected and identified, of which three species are recorded for the first time from Iran: Colpotrochia cincta (Scopoli, 1763), Exochus suborbitalis Schmiedeknecht, 1924, and Metopius (Peltocarus) turcestanicusClement, 1930. An identification key to the species and an updating checklist of Metopiinae of Iran, as well as zoogeographical notes are provided.

Bean yellow mosaic virus(BYMV, Potyvirus, Potyviridae) causes serious disease inGladiolus spp. In this work, the possibility of obtaining BYMV free plant material from virus infected gladiolus corms was studied. Thermotherapy, meristemtip culture and combination of both techniques on infected corms/meristem-tip explants (0.5–1 mm in length) resulted in BYMV elimination up to 15.38, 78.04 and 86.66%, respectively, as determined by double antibody sandwich-enzyme-linked immunosorbent assay (DAS-ELISA) and reverse transcription-polymerase chain reaction (IC-RT-PCR). Individual virus-free shoots readily rooted in vitro and were transferred to corm formation medium. The results showed that thermotherapy promotes the survival rate of explants during meristem-tip culture steps (except regeneration step) and also plantlet acclimatization. Statistical analysis showed that the BYMV elimination in gladiolus corms was significantly (P≤ 0.01) affected by thermotherapy treatment of infected corms. Thermotherapy combined with meristem culture can greatly improve BYMV elimination efficiency from infected gladiolus corms, resulting in the production of BYMV free gladiolus plants.

The strawberry spider mite (SSM), Tetranychus turkestani Ugarov& Nikolski, is an important pest of greenhouse cucumber in tropical and temperate regions of the world. The use of the host plant resistance is a basic method to reduce pesticide application in greenhouses. In this study, the biological responses of SSM to six greenhouse cucumber cultivars (Puia, Hedieh, Milad Ghadim, Milad Jadid, Khasib and Negin) were investigated.Non-choice tests were performed to evaluate the interaction between the host plant-mite. All tests of this study were carried out under laboratory conditions at 28 ± 1oC, 60 ± 5% RH and 16: 8 h (L: D) in a walk-in growth chamber. The results indicated that immature development time and adult longevity of SSM was significantly influenced by cucumber cultivars. The highestr,  l, and R 0 were 0.275 (day-1), 1.316 (day-1) and 36.180 (offspring/generation) all of which were recorded for the mites reared on the Hedieh cultivar. No significant difference was observed for these parameters among the other cultivars. Mean generation times of T. turkestani reared on Negin (14.020 day) and Milad Ghadim (13.57 day) cultivars were significantly longer than for the other cultivars. This mite had the shortest generation time on Puia cultivar (11.43 day). In conclusion, it seems that Hedieh and Milad Jadid cultivars are the more susceptible and resistant cultivars to the SSM than the other tested cultivars, respectively.

To determine the effectivebio-control agents of water fern, Azolla filiculoides, adults and nymphs of water lily aphid, Rhopalosiphum nymphaeae (L.), were collected on A. filiculoides in Guilan Province, Iran, during October 2013.This aphid has been collected extensively from almost all water fern samples during 2013 and 2014. AlthoughR. nymphaeae was reported from numerous host plants in Iran, this species was collected for the first time from water fern. This aphid is heteroecious holocyclic with a sexual phase on Prunusspp., but it is the first report of its sexual phase formation on water fern as secondary host plant.

The pea aphid, Acyrthosiphon pisum (Harris) is one of the most important pests of pea throughout the world. Host stage preference under choice and no-choice tests and age-specific functional response of Praon volucre (Haliday) parasitizing A. pisum were investigated. The experiments were carried out under laboratory conditions at 25± 1oC, 60 ± 5% RH and a photoperiod of 14: 10 h (L: D). Functional response of P. volucre was evaluated in adult lifetime at seven host densities (2, 4, 8, 16, 32, 64 and 128).Praon volucrestrongly preferred to oviposit into first and second instar nymphs in both choice and no-choice conditions. Parameter estimation of logistic regression revealed type III functional response for P. volucre in first and second days and type II from third to the end of parasitoid lifetime. The handling time (Th) and searching efficiency (a or b) were estimated using the Rogers equation. The shortest and longest handling times were at fourth day (Th=0.19 ± 0.04) and 8th day (Th=0.94 ± 0.15), respectively. The highest searching efficiency (a) was 0.048 ± 0.007 h-1 on third day and lowest searching efficiency was observed at the end of parasitoid lifetime (6th day-8th days). The maximum attack rate ranged from 126.31 nymphs/24 h on fourth day to 25.53 nymphs/24 h on 8th day. The results of this study revealed that the age of adult parasitoid can change the functional response from type III to type II, indicating that this factormay contribute to stabilization of parasitoid–prey dynamics.

The sub-lethal effect of Metarhizium anisopliae and imidacloprid as well as combination of the two control agents was examined on life table parameters of Myzus persicae on different cultivars of canola under laboratory condition at 25 ± 1oC, 85% RH and photoperiod of 16L: 8D. The offspring resulting from fungus-infested adults were placed onto leaf discs in Petri dishes separately to record their development time till they reached to adulthood. The number of nymphs produced by each adult aphid was recorded daily. The intrinsic rate of increase (rm) had no significant differences among the three cultivars, and was nearly similar to the net reproductive rate (R0). The concurrent application of M. anisopliaeand imidacloprid significantly shortened the aphid longevity on the RGS003 cv compared to the other cultivars. The type of cultivars had no impact on the finite rate of increase (l) of green peach aphid in any of the treatments. The values of T showed that there was no significant difference among the treatments.Despite having no significant effect on life table characteristics of M. persicae by most of the treatments, the method would be a favorable procedure to control the aphid by raising the fungal concentration. Conducting such research would be worthwhile since there are no antagonistic interactions between the entomopathogenic fungus and the insecticide.

Soil-dwelling mites and especially Gamasina (Mesostigmata) are very important to soil ecosystems. They are one of the major groups rich in species and abundance. In order to study mesostigmatic mite fauna, soil samples were collected from different oak forests of Lordegan region. The mites were extracted using Berlese-Tullgren funnels and then cleared in Lactic acid and mounted in Hoyer's medium. This study reports on the distribution of soil mesostigmatids in Iran and world-wide. Twenty species belonging to 13 genera of five families were collected and identified. Species are listed as follows: Ascidae: Arctoseius cetratus (Sellnick, 1940), Gamasellodes bicolor (Berlese, 1918), Antennoseius (Antennoseius) bacatus Athias-Henriot, 1961, Antennoseius (Antennoseius) masoviae (Sellnick, 1943). Blattisociidae: Lasioseius youcefiAthias-Henriot, 1959. Laelapidae: Cosmolaelaps rectangularisSheals, 1962, Euandrolaelaps karawaiewi (Berlese, 1903), Gaeolaelaps aculeifer (Canestrini, 1883), Gaeolaelaps minor (Costa, 1968), Gaeolaelaps oreithyiae(Walter & Oliver, 1989), Haemolaelaps fenilis (Megnin, 1875), Haemolaelaps shealsi (Costa, 1968), Haemolaelaps schusteri (Hirschmann, 1966), Laelaspis kamalii Joharchi and Halliday, 2012, Laelaspis missouriensis(Ewing, 1904), Gymnolaelaps canestrinii (Berlese, 1903), Gymnolaelaps obscuroides(Costa, 1968). Ologamasidae: Sessiluncus hungaricusKarg, 1964, Allogamasellus sp.; Veigaiidae: Veigaia planicola Berlese, 1882.The genusAllogamasellus and Haemolaelaps schusteri are reported for the first time for Iranian mite fauna and the male ofLaelaspis kamalii is reported for the first time for world fauna.