Iranian Journal of Plant Protection Science
Year:2010 | Volume:41 | Issue:1|Papers Count:18

The flour moth, Ephestia kuehniella Zeller and Indianmeal moth, Plodia interpunctella (Hubner) are reported as important pests of stored products in many countries throughout the world. In recent years Harobracon hebetor (Say) wasp has been employed as a biological control agent of the moths' larvae in peanut warehouses as well as in packaged cereal products. In this study the functional responses of H. hebetor to larvae of flour moth and Indianmeal moth were compared across a range of host densities (1, 2, 4, 8, 16 and 32 larvae/arena) and under some controlled conditions of 25±1oC, 65±10 RH and 14: 10 h (L:D). The resulting data were appropriately fit to type III functional response models in two parasitoid – host interactions, namely: (1) H. hebetor to last instar larvae of flour moth (b = 0.0327 h-1 and Th = 1.061 h), and (2) H. hebetor to last instar larvae of Indianmeal moth (b = 0.0296h-1 and Th = 1.045 h). The b value of H. hebetor to different densities of flour moth larvae was significantly greater than that of Indianmeal moth larvae; whereas the handling time (Th) of H. hebetor to larvae of flour moth was not significantly different as compared with the Indianmeal moth larvae. These results indicate that H. hebetor was the preferred larvae of flour moth in comparison with Indianmeal moth larvae.

Survival of Pichia guilliermondii Yeast Isolate in Powder Formulation and Its Potential for Biological Control of Blue Mold of Apple Development of resistant strains of pathogens to many fungicides as well as fungicide residues in food stuff have been resulted in attemps to develop biological agents as alternative methods to control post-harvest diseases. Practical use of microorganisms requires formulated products that meet a number of criteria. In this study different carriers for powder formulation of P.guilliermondi were compared. Yeast, grown on a cane molasses-based medium was combined with adjuvants and added to talc, kaolin, rice, and wheat bran. Viability of yeast in 4 formulations was determined over a six month period. Wheat bran based formulation had a significantly higher viable yeast cell content (2.2×1010) over a six month period. Kaolin based formulation had a significantly lower viable yeast cell (7.6×107). Formulations stored at 4oC had a longer shelf life than those stored at 24oC. These formulations were tested on apple control blue mould, although the lesion size of apples treated with fresh cells were significantly less than those on apples trated with formulations stored for six months, but all formulations effectively controlled blue mould on apple.

The reaction of four field tomato cultivars (Super Strain B, Super Chief, Mobil, and Royal) along with two greenhouse cultivars (Polaris and ES 1002 F1) was evaluated agianst M. javanica under greenhouse conditions. The soil around tomato seedlings (bearing 5-6 leaves) was inoculated with two levels of the nematode inoculum i.e. 1000 and 2000 eggs as well as second stage juveniles per every kg of soil in pots. Control treatments received only sterile water lacking any nematode. For the experiments, completely randomized design was employed and each treatment was repeated in ten replications. Sixty days past inoculation, data of growth factors related to plants as well as to nematode reproduction were recorded and nematode reproduction factor (Pf/Pi), final nematode population, root gall, and egg mass indices assessed. Final results showed that all the cultivars were infected by the nematode, but Super Chief was found more sensitive and was figured out as a susceptible cultivar. Polaris and ES 1002 F1, both greenhouse cultivars, were evaluated as tolerant vs. relatively resistant cultivars, respectively.

During 2007 – 2008 different fruit gardens in Shiraz (Fars Province, Iran) were surveyed for samples being collected from infected apple, pear and quince trees. Symptoms of the infected trees included water soaking of infected tissue, wilt and tissue necrosis, scorched and blackend of blossom bracts or young shoots. A total of 47 strains were isolated from infected trees using NA medium. On the basis of standard physiological, biochemical and nutritional tests the isolates were identified as Erwinia amylovora. The isolates were compared through physiological and biochemical characters, pathogenicity test, polymerase chain reaction (PCR) and rep-PCR. The isolates were gram and oxidase negative, catalase positive and facultative anaerobs with shiny smooth cream colonies on NA and translucent, smooth, large, light blue with entire margin colonies on CCT medium. All isolates induced hypersensitive reaction on tobacco, produced levan and acetoin and reduced substances from sucrose but were negative in induced potato soft rot and fluorescent pigment production on KB medium, pink pigment on YDC medium, reduction of nitrate, growth at 39?C and urease. Wound inoculation of bacterial suspension into apple pear and quince seedlings led to the slight formation of wilting, necrosis and chlorosis as well as necrosis of leaves and shephered crook at the tip, after a passage of three weeks. In PCR assay, 47 isolates identified as E. amylovora, produced predicted 1000bp with A/B specific primers. In rep-PCR assay, representative strains identified as E. amylovora, produced different fingerprints in weight with REP, ERIC and BOX primers. The results of this study demonstrated that E. amylovora strains isolated from different hosts in Shiraz Province are genotypically homogenous.

Sunflower, (Helianthus annuus) is considered as an important oilseed crop grown in many countries including Iran. In recent years, Tobacco streak virus (TsV) has been found in sunflower fields in Iran. TsV is a type member of Ilarviruses, and infects a wide range of crops as well as weeds. In this survey and during 2008, two isolates of sunflower and one isolate of faba bean collected from, Iran, India and Sudan respectively were taken for a study where some of the biological and molecular characterization of these isolates were compared. The molecular weights of coat protein of the isolates (employing SDS-PAGE) were estimated as 30.9 kDa. Western blotting confirmed the results. In laboratory inoculation tests, the virus was found to infect some plants. The host range and diversity of symptoms were different in the three isolates. In TAS-ELIA test, no serological diversity observed among the isolates using TsV monoclonal antibody (AP-696 DSMZ). A fragment of 747nt was amplified for each isolate through the specific primer pair of the CP region. Following the cloning and sequencing of the fragments of each isolate, phylogenetic analysis with nucleotide and amino acid sequences of coat protein of these isolates revealed that Iranian and Sudanese isolates being close to each other stood in one group whereas the Indian isolate with 91% similarity belonged to another.

The spider mite, T. turkestani, is considered as one of the most important polyphagous pests of many crops. Its reproductive ability, developmental time, preimaginal mortality and reproduction rate were determined on kidney bean at 20, 25 and 30oC, 70±5% RH and 16L:8D. Female longevity and immature developmental period (6.74 and 5.8 days, respectively) were shorter at 30oC than at 20 and 25oC. These parameters decreased with temperature increasing. Maximum mortality was obtained at 30oC during the protochrystalisd stage (5.32%) and the highest number of produced eggs per female (131.9 eggs) was obtained at 20oC. The intrinsic rate of natural increase (rm) was obtained as 0.18, 0.29 and 0.36 at 20, 25 and 30oC, respectively. Maximal value for rm was observed at 30oC .The highest net reproductive rate (R0) was obtained at 25oC (78.27). Generation time was 23.99, 14.96 and 9.33 at 20, 25 and 30oC, respectively.

Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is an important injurious pest of such crop plants as cotton, clover, alfalfa, sugar beet and vegetables as well. Larvae of this pest feed on about 40 plant families many of which are of high economic importance. Demography of S. littoralis was studied on an artificial diet at 25±2oC, 65±5 % RH and 16L:8D in the laboratory. Data analysis was done on an age-stage, two-sex life-table, to take both sexes and their varying development into consideration. The intrinsic rate of increase (rm), finite rate of increase (l), net reproductive rate (R0), gross reproductive rate (GRR), mean generation time (T), birth rate (b), survival rate, death rate (d) and fecundity of S. littoralis were estimated as 0.1145d-1,1.1145d-1, 80.26 female/female, 190.4 female/female, 40.44d, 0.1219, 0.9926, 0.0074 and 276.76±55.25, respectively. In conclusion, life table parameters obtained in this study revealed that the artificial diet used in this research was a suitable regime to rear the pest under laboratory conditions.

Glomerella cingulata is the causal agent of anthracnose disease on citrus that attacks weakened trees. The sexual stage is rare in nature but can be produced in laboratory under certain conditions. Sixty-seven single-spore isolates were selected from citrus in Mazandaran province to be used in this study. Isolates were cultured on YPSS for investigating heterothallism and homothallism. To understand homothallism of isolates, they were cultured on YPSS alone and then placed at 21oC with 12h dark and 12h light for 15-21 days. An 8.8% of isolates were homothallic, while others were paired in YPSS of the above conditions to be investigated for heterothallism. 25% of the isolates were found as heterothallic. Perithecia of smooth walls along with necks were produced. Asci were in groups with any ascus containing 8 one celled ascospores. For VCG determination, forty one isolates were employed. Isolates were cultured on 5% MMC for selecting nit mutants. Two isolates could not grow on MMC and were found as wild types. After selecting nit mutants, they were cultured in media of different nitrogen sources for detecting phenotypes of nit mutants. The maximum percentage of nit occurred in the case of nit 1 (66%). Nit 3 was 56% and nit M 53%. The inter-isolate combinations started in MM among different nits of any isolate with two HSI isolates being found. Other 37 isolates were crossed together with different nits on MM with all the cultures being placed at 25oC in the dark. Thirty five VCGs were identified. The isolates that produced perithecium were different from the ones producing heterokaryons. Sexual stage along with sexual fertility is one of the factors of diversity that ended up with many groups in vegetative compatibility.

Sexual behavior in most moths is limited to a precise duration period of either the day or the night. These behaviors as well as the calling behavior are specific. Information on reproductive behavior is important in the chemical ecology studies. Experiments were conducted to determine the developmental biology, adult time emergence and calling behaviors of three populations of carob moth, Ectomyelois ceratoniae under laboratory conditions (29±1oC and 70±10% relative humidity in a 16-hr light-8-hr dark photoperiodism). Results revealed that mean egg developmental period in Saveh, Kerman and Arsanjan populations were 3.7, 3.19 and 3.6 days and mean total egg to adult developmental period of females were 39, 40.4 and 41.3 days and for males 37.4, 38.5 and 40.2 respectively. Adults began to emerge from the last hour of photophase with a peak occurrence at 1st hour of scotophase. The virgin females started the calling behavior on the first night after eclosion. Regardless of population, the majority of the calling on the side of the females occurred at third and fourth days after emergence with the peak occurring at the 8th hour of scotophase. The mean time spent in calling and the duration per calling bout by any of the three populations were equal, but there was no significant difference between the onset time of calling and number of calling bout by either Saveh or Kerman populations while being significantly different from Arsanjan population. Only a few females of the Saveh and Kerman populations exhibited calling during the first hours after the onset of photophase whereas many of Arsanjan females called at this time. This reflects that protandries occur in E. ceratoniae and for both sexes. Egg to adult developmental times were significantly different and females needed a minimum time for sexual maturation. Differences in calling behavior and biological characters under the same experimental and rearing conditions have a genetic basis which are the outcome of natural selection that are inheritable. These differences resulting from adaptation to different climatic conditions also suggest that the gene flow between these populations is limited.

Susceptibility of eggs, nymphs and adults of greenhouse whitefly (Trialeurodes vaporariorum Westwood) and adults of green peach aphid (Myzus persicae Sulzer) to pirimicarb (Pirimor®) and citowett oil alone vs. in combination was evaluated under greenhouse conditions. The glass vial and leaf dipping methods were employed for bioassay of adults vs. the immature stages (egg, nymph and pupa) of greenhouse whitefly respectively. Green peach aphid adults were treated through spraying technique. LC50 values of pirimicarb for greenhouse whitefly adult, egg and nymph stages were estimated 0.08, 2.55 and 0.98 g/l respectively, while the LC50 values of citowett oil for those developmental stages were estimated 2.58, 1.31 and 0.25 ml/l in the same previous order. The LC50 values of pirimicarb and citowett oil for adults in the case of green peach aphid were 0.04 g/l and 0.14 ml/l respectively. For a determination of the compounds interactions, the LC25 values of pirimicarb and citowett were assessed and a mixture of these compounds applied at a concentration of their LC25 rate. The mixture caused a mortality rate of 65.18, 65.55 and 66.85% on the adults, eggs and nymphs of greenhouse whitefly respectively and resulted in mortality of 68.92% on the adults of green peach aphid. Mortality resulted from the mixture was greater than that of pirimicarb at the concentration of LC50, hence, a noticeable synergistic effect observed. It was concluded that due to the cheap price of citowett oil, compatibility with environment and also synergistic effect on pirimicarb, a mixture application of these compounds at the concentration of 0.339 ml/l citowett oil and 0.372 g/l pirimicarb could be recommended for simultaneous control of greenhouse whitefly as well as green peach aphid.

Charcoal rot caused by Macrophomina phaseolina is an injurious and economically important disease which causes heavy loss of yield to field and horticultural crops. Thirty-three isolates of M. phaseolina were obtained from different host plants such as: soybean (Glycine max.), melo (Cucumis melo), bean (Phaseolus vulgaris), pea (Pisum sativum), pinus (Pinus sp), blak-eyed susan (Rudbeckia fulgida), kiwifruit (Actiniadia deliciosa), cotton (Gossypium arboreum), and sesame (Sesamum indicum). Pathogenicity test was performed on seeds of melo in in vitro conditions. To study the genetic diversity of isolates PCR-RFLP and RAPD markers were employed. Amplification of the ITS region using ITS5 and LR5 primers produced only one DNA fragment of 1600 bp. Results indicated genetic variability among isolates of M. phaseolina through application of RAPD marker. RAPD data based on five random primers tested on sixteen isolates revealed a high degree of polymorphism in different isolates. UPGMA dendrogram based on RAPD data, produced 9 clusters at the level of 70% similarity. Isolates from the same locations showed a tendency to belong to closer groups, indicating closer genetic relatedness.

In order to study the primary inoculum source, apothecium production, as well as overwintering of Monilinia laxa, the causal agent of sweet cherry brown rot, this study was carried out in Guilan Province during 2005-2006. Apothecium production by the fungus was investigated under natural and laboratory conditions. The mummified fruits collected in early October didn't produce apothecia under either natural field or laboratory conditions, but the mummified cherry fruits remaining on the trees produced many sporodochia following overwintering. Conidia recovered from sporodochia exhibited considerable viability. Mummified cherries on orchard floor were rotted with either no sporodochia or apothecia produced on their surfaces during the following year. M. laxa were observed only in one case and from peach twig canker in natural conditions and another one case on cherry opening bud in laboratory conditions. Therefore, it seems that the asexual form of last year mummified fruits is the most important source of overwintering and dispersal of the pathogen in Guilan Province.

Pistachio green stink bug, Acrosternum heegeri, is one of the most injuriously important and key pests of pistachio in Iran. This pest causes major damages to fruits by feeding on them, and transmitting fungo desease Nematospora coryli as studied on a selected population. Biological characteristics and fertility life table parameters of the insect were collected from Rafsanjan area. The bugs were reared on pistachio kernels at 25±1oC, 55±10% R.H. and of 16:8 h (L:D) photoperiodism. The results indicated that incubation period and duration of the first and second nymphal stages were 11.05±0.51, 3.91±0.03 and 4.091±0.06 respectively. Duration of the third, fourth and the fifth nymphal stages of females' longivity up to adult stage were obtained as 5.57±0.21, 5.08±.17, 8.21±.15 and 47.02±3.43 days respectively. Those of the males were found as 4.03±.23, 5.03±.23, 8.16±.23 and 31.77±5.12 days. Student's t-test showed a significant difference between males and females in development of the 3rd nymphal stage as well as in the adults' longevity (both p<0.01). Net reproductive rate (R0; ♀♀/♀/generation), intrinsic rate of natural increase (rm; ♀♀/♀/day), mean generation time (T;day), doubling time (DT;day) and finite rate of increase (l;♀♀/♀/day) were estimated to be 7.87±1.75, 0.033±.004, 63.43±1.77 days, 20.76±2.58 days and 1.034±.004 respectively.

Fumigant toxicity of rosemary essential oil on abamectin-resistant vs. susceptible populations of two spotted spider mites, Tetranychus urticae Koch was studied under laboratory conditions. Results indicated that fumigant toxicity of rosemary essential oil on the susceptible population was 3.06 times higher than that of the resistant one. Accordingly, there was a slight cross resistance observed between abamectin and rosemary essential oil vapors. In addition, in this survey, the effects of LC50 of rosemary essential oil on detoxifying enzymes were investigated in two treatment periods of 24 and 48 hours on resistant and susceptible populations. Assessment of esterase activity indicated that the enzyme activity of resistant population did not decrease in the treatment period of 24 hours but decreased significantly in the treatment period of 48 hours compared with the treatment periods of 24 hours and control. In the case of susceptible population, the esterase activity in treatment periods of 24 hours decreased significantly, whereas the activity significantly increased in the treatment periods of 48 hours as compared with the 24-hour ones. Results of variance analysis of glutathione-S-transferases enzyme activity data indicated that the enzyme activites are not affected by the 24 and 48 hours of treatment with rosemary essential oil. No significant difference was observed between the level of monooxygenases of susceptible populations in the treatments vs. control. However, the level of this enzyme in the resistant populations decreased significantly through passage of time.

Fertility status and distribution of mating type alleles of Gibberella moniliformis and G. intermedia, both the causal agents of the foot rot and bakanae of rice, as well as stalk and root rot of corn were studied using specific primers. One hundred and twenty eight single-spore isolates were collected from rice growing areas of Guilan and Mazandaran and from various corn-growing areas of Iran. Sixteen isolates of G. moniliformis from rice and 54 isolates from corn, 28 isolates of G. intermedia from rice and 30 isolates from corn were taken into account for the study. Also 30 isolates of G. intermedia from corn and 12 isolates from rice, 5 isolates of G. moniliformis from rice were paired with standard tester isolates. A multiplex PCR technique was employed to distinguish idiomorphs MAT-1 and MAT-2 by using two pairs of specific primers GFmat1a, GFmat1b, and Gfmat2c, Gfmat2d. Among 68 isolates of G. moniliformis, 47 (69%) were identified as MAT-1 and 21 isolates (31%) belonged to MAT-2. Among 53 isolates 0f G. intermedia, 33 (62%) were identified as MAT-1 and 20 isolates (38%) belonged to MAT-2. Among 42 isolates of G. intermedia which were crossed with tester isolates, 26 (62%) were MAT-1 and 16 (38%) were MAT-2. The results of PCR were similar to those predicted as based on the results of crosses. Field isolates belonging to MAT-1 and MAT-2 were crossed with each other but no perithecium was formed. This indicated that all the isolates are female-sterile or male-fertile. The existence of both opposite mating type alleles with favorable frequency and different parents is an important occurrence of genetic diversity in the population of fungi. With regard to that, two mating type alleles found in the studied populations were of relatively high frequency of MAT-1 but because of the low level of female-fertile, occurrence of genetic diversity in the populations of G. moniliformis and G. intermedia coming from rice and corn could be attributed to other mechanisms of variability.

Coccinellids play a major role in aphid control. Hippodamia variegata Goeze is an aphidophagous predator of worldwide distribution that could be found in different parts of Iran. One of the criteria for evaluating the efficiency of a predator is its response to change in prey population density (functional response). The functional responses of males and females of Hippodamia variegata were studied at different densities of Aphis fabae under laboratory conditions (23±1oC, 70±10% RH, and 16:8 L:D photoperiodism). Experiments were carried out using the aphids of the same age on bean leaf disks in Petri dishes and in 15-20 replications. After 24 hours, the number of hunted preys was recorded. The results revealed that both male and female H. variegata exhibited a type II functional response to different densities of black bean aphid (2, 4, 8, 16, 32, 45, and 60 for male and 2, 4, 8, 16, 40, 60, 80, and 100 for female adults). Rogers’ random predator equation was employed in estimation process of searching efficiency (a) and handling time (Th). The mentioned parameters were estimated to be 0.1589 and 1.1945 h for male and 0.0926, 0.4098 h for females, respectively. Use of an equation with indicator variable revealed that there is a significant difference between handling times of females vs. males. Based upon handling times, females vs. males could hunt 58.6 and 20.1 aphids per day, respectively, indicating that the hunting power of females is more than twice as much as males.

In the present survey 194 gram positive bacteria isolated from the rhizosphere of bean from Markazi province and also 41 isolates from the collection of Research Center of Biological Control at Tehran Universitiy were evaluated on the basis of inhibitionry zone of fungal growth. Finally eight more appropriate strains of B. subtilis were selected for greenhouse trials. Results indicated that antagonistic bacterium B. s M36, isolated from the rhizosphere of bean fields of Markazi province exhibited the greatest effect on reducing the Fusarium root rot bean. In greenhouse trials, after six weeks, between nine formulations of strain B. s M36, the one obtained from M1 culture medium with Arabic Gum as the sticker with 68.42% of control, depicts the greatest effect on reducing Fusarium root rot was more effective than two fungicides Rovral-TS and Trichomix-HV with 56.14% and 54.38% of inhibition respectively. The results indicated that the population of B. s M36 grown from in powder formulations decreased during the storage at 4 and 25oC over a 150-day period. In addition, formulation of strain B. s M36 stored at 4oC presented a longer shelf life than those stored at 25oC. Long-term stability of formulation (M1-AG) of strain B. s M36 was the most appropriate. A study of the media on population of the effective strain, exhibited that M1 medium was the most effective, in this study.

Different species of aphids in rapeseed fields of Khuzestan province were identified and the dominant ones were determined during 2002-2004 field sampling. Base upon the collected data, population fluctuations of rapeseed aphids vs. their natural enemies were assessed. Also biology of the aphids, major species was studied under controlled conditions. The results showed that Lipaphis erysimi (Kalt.), Brevicoryne brassicae (L.) and Myzus persicae (Sulzer) were active in rapeseed fields of Khuzestan with 66.71, 24.99 and 8.29 percent of population, respectively. The contamination index of L.erysimi was minimum in February (10.5–28.6) while maximum (224–1072) in early until mid March at an average temperature of 17-17.6oC and %50 R.H. The contamination index in 2004 was more than in 2003. Controlled conditions indicated that L. erysimi bears a life cycle of 7.65±1.12 days along with the ability to reproduce 43.5±18.5 nymphs in her life time. The major predators were Cocinella septempunctata L., and Episyrphus balteatus F. which emerged in December and January with their peaks occuring in March. Two parasitoid wasps Diaeretella rapae M. and Aphidius ervi H. with 78.2 and 21.8 percentage of total population respectively, parasitized the aphids with 1.76–8 percents during the studing period. The above natural enemies could not control the increased population of the aphids because of limited fecundity and feeding and as well lack of synchrony with the aphid life cycle.