JOURNAL OF CROP PROTECTION
Year:2015 | Volume:4 | Issue:2|Papers Count:16

A faunistic survey was conducted to identify the leafhoppers in the southwest of Iran (Khouzestan Province) in 2014. Among the collected materials, Aconurella nuristana Dlabola, 1957 is recorded for the first time for Iranian leafhoppers fauna. Diagnostic characters and geographical distribution of the newly recorded species is presented briefly.

The genusPhaneroserphus Pschorn–Walcher, 1958 is recorded for the first time from Iran and its allied species, Phaneroserphus punctibasis Townes, 1981 is recorded from West Palaearctic region for the first time. The specimens were collected from Mazandaran Province during 2011 using Malaise traps. Diagnostic characters and geographical distribution of the newly recorded genus and species is briefly discussed.

The beet moth, Scrobipalpa ocellatella (Boyd) (Lepidoptera: Gelechiidae) is one of the most destructive pests of beet. The insect overwinters as larvae of different instars in beets which are left in the field.Supercooling point (SCP) of individual larvae showed broad range variation from -6 to -25 °C. In the present study, factors affecting the broad range of SCP were investigated. Larvae showed a great increase in SCP when they were induced by exogenous ice nucleation. Defensive oral discharge (DOD) decreased SCP but it had no significant effect on supercooling ability of larvae. The presence of sufficient food in guts of field collected larvae induced an increase in SCP. Therefore it could be concluded that surface moisture and food particles in the gut may act as ice nucleating agents (INAs) that cause freezing of the body fluids at higher temperatures. Furthermore, second and third instar larvae, owing to their small size, had greater capacity to supercool in comparison to fifth feeding instars. Broad range in SCPs might be due to diversity in overwintering larvae which have different capacity for supercooling.

Fauna of Ichneumonidae of Isfahan province was studied in 2012. Specimens were collected using sweep net and Malaise trap on various plants from different places in Isfahan. Totally, 18 species belong to 16 genera and 7 subfamilies were collected and identified as: Anomalon cruentatum (Geoffroy, 1785) (Anomaloninae); Exetastes syriacus Schmiedeknecht, 1910 (Banchinae); Diplazon laetatorius(Fabricius, 1781), Enizemum ornatum (Gravenhorst, 1829), Homotropus nigritarsus(Gravenhorst, 1829), Homotropus signatus (Gravenhorst, 1829), Promethes sulcator (Gravenhorst, 1829) and Syrphophilus bizonarius(Gravenhorst, 1829) (Diplazontinae); Anisobas cingulatellus Horstmann, 1997, Diadromus collaris (Gravenhorst, 1829), Heterischnus filiformis(Gravenhorst, 1829) and Spilothyrateles nuptatorius (Fabricius, 1793) (Ichneumoninae); Exochus castaniventris Brauns, 1896 (Metopiinae); Itoplectis alternans(Gravenhorst, 1829), Itoplectis tunetana (Schmiedeknecht, 1914), Pimpla spuriaGravenhorst, 1829 and Zaglyptus multicolor (Gravenhorst, 1829) (Pimplinae) andAneuclis incidens (Thomson, 1889) (Tersilochinae). All species are new record for Isfahan province except forExochus castaniventris and Heterischnus filiformisis newly recorded from Iran.

The cotton leaf roller moth, Haritalodes derogata (Fabricius, 1775) (Lepidoptera: Crambidae) was collected on two kinds of flowering shrubs, Hibiscus syriacusL. and Hibiscus mutabilis L., in Rasht, Guilan Province, during August 2013. This species represents a generic new record for the fauna of Iran. A brief description of the species is provided to facilitate the identification.

A study was carried out to map dispersal of Trichogramma brassicae Bezd. on tomato in a 0.5 ha field. First, 1, 5, 10, 15, 20 and 25 meter distances from the central point of the field were marked in form of squares. On each square, 8 points were selected and a wooden stake of 1.5 m length was vertically secured into the soil at each point equal to plant height and bearing a yellow sticky trap (YST, 10 x 20 cm) on the top. Moreover, three egg batches each containing ~200 freshSitotroga cerealella Oliv. eggs on cardboards (SEC) were stapled on top leaf of three plants around the wooden stake arranged in a 0.75 m arch. Evaluation was done two days before and 2, 4, 6 and 8 days after a release of 50000 newly emergedT. brassicae (~1: 1 Male: Famale) from the central point. The number of T. brassicae trapped by YST, and number of parasitised eggs on SEC were counted under a stereomicroscope and noted down. The coefficient of fitting YST data to the model (R2) for all 4 sampling dates was as high as 86%. The average diffusion coefficient was equal to 16.89 m2/day for four times sampling. In general, the distance encompassing 98% of trapped T. brassicaepredicted by the model was up to maximum 29.9 m from the central point 8 days after the release. The mean percent parasitism was 44.7, 5.5, 5 and 0.9 per SEC during 2, 4, 6 and 8 days after release, respectively. It is concluded that, the farther the distance from the releasing point and the longer the time elapsed after release, the less number of wasps were recaptured. Therefore, multiple releasing points are required to achieve even distribution and enough population of parasitoids in the field.

The fauna of the superfamily Bombylioidea was studied in Alborz province, Iran during 2012. Two families (Bombyliidae and Mythicomyiidae), eight genera and ten species were identified, of which two species, Exoprospora dispar Loew, 1869; Parageron lutescens (Bezzi, 1925), are new records for the Iranian fauna. An identification key for the species of the family Mythicomyiidae known from Iran is given.

During the past decade, natural plant products as environmentally safe option have received attention for controlling phytopathogenic diseases. Investigation of plants containing natural antimicrobial metabolites for plant protection has been recognized as a desirable method of disease control. The fungus Fusarium oxysporum causes diseases such as root rot, damping off and Fusarium wilt and it infects many plant species and crops. Methanolic crude extracts of 30 plant species belonging to 17 families collected from the west of Iran were screened for antifungal activity against F. oxysporum during 2012. Bioassay of the extracts was conducted by agar dilution method with five replications. The inhibitory effect of the extracts was examined at concentration of 2000 ppm. Twenty out of 30 tested plant species (67%) showed inhibitory activity against mycelial growth of F. oxysporum. The most effective extracts with more than 50% inhibition belonged to Haplophyllum perforatum and Calendula officinalis. High number of plants with antifungal activity in this experiment showed that the flora in the west of Iran could be regarded as a rich source of plants with antifungal activity. Therefore, further screening of other plant species, identifying active fractions or metabolites and in vivo application of active extracts are in progress.

Considering the importance of parasitic wasps in biological control of pests, a faunal study was conducted in the year 2012 on eulophid wasps (Hym.: Chalcidoidea) in rice fields in the east of Guilan province, southern coast of Caspian Sea. Several specimens were captured via Malaise traps. The specimens were identified as Aprostocetus deobensis (Graham), Aprostocetus mycerinus (Walker), Elasmus phthorimaeae Ferrière and Hemiptarsenus sp. Two species, A. deobensis and A. mycerinus are new records for Iran. In addition, association of A. deobensis, A. mycerinus and E. phthorimaeae with rice is new.

Spotted Amber Ladybird, Hippodamia variegata (Goeze, 1777) (Coleoptera: Coccinellidae) is an important predator of aphids and some other insect pests. Since shape and size variation may affect biological characteristics of an insect, multivariate analysis of shape variations in four geographically isolated populations of H. variegata (Isfahan, Shahrekord, Shiraz, Yasuj) was performed based on eight landmarks of hind wing. According to the analysis, significant difference in weight matrices (as shape variable) was detected. The cluster analysis separated Isfahan population from other populations. According to ANOVA, we found significant difference in centroid size (as size variable), so that the two populations, Isfahan and Shahrekord, had larger wings than the two other populations. Distribution of 80 individuals based on partial warps on the relative warp axis placed Isfahan population in a separate group while the others had overlap and irregular distribution.

In several parts of the world, important yield losses are caused to Faba bean due to attack by the black bean aphid Aphis fabae Scopoli. Although resistance could be a good alternative to chemical control, its genetic basis is still largely unknown; and its phenotypic expression is still poorly described, making crucial the permanent evaluation of genetic resources available in different countries; together with using adequate agronomic parameters and statistical inference. In this study, two Faba bean collections provided by Faba bean breeding programs of Tunisia and Spain were evaluated for resistance to A. fabae during two consecutive years in the field, based on infestation rates and three yield parameters: number of grains (NG), weight of grains (WG) and weight of pods (WP). Principal components analysis (PCA) showed that the most effective parameters contributing to response variation were the weight of pods (WP) and the number of grains (NG). Genotypes were grouped based on clustering patterns inferred from PCA and UPGMA, both showing the existence of two distinct groups: a resistant group characterized by high WP; and in most cases high NG values; and a susceptible group characterized by a low WP; and in most cases a low NG+WG. Furthermore, tolerance to infestation was identified in one genotype from the Spanish collection. Our results demonstrate that WP is the most reliable parameter for resistance selection; and that the genotypes V1, V9 and V16 from the Tunisian collection and V2e and V7e from the Spanish one should be exploited for their resistance potential.

Some safer strategies were designed and evaluated for management of apical leaf curling (ChiLCV) in chilli Capsicum annum L. and its vectors. The strategies were designed emphasizing on the repellent crop theory and the components like physical barrier, adult-trapping, plant sanitation, foliar application of phytochemicals and minimal application of synthetic organic pesticide. The crop was infested by some sucking pests namely, Chilli thrips Scirtothrips dorsalis Hood, aphid Aphis gossypii Glover, yellow mite Polyphagotarsonemus latus (Banks) and whitefly Bemsia tabaci (Gennadius). However, the populations of aphid and whiteflies were low and leaf curl virus which is vectored by any of the above creatures, did not appear in the present studies. Some management strategies were devised to suppress the pest populations as well as their damage and obtain good yields. However, strategies with phytochemical-based treatments which utilized neem seed kernel extract (NSKE) and rose apple Syzygium Jambos leaf extract (rose apple LE), could not offer satisfactory protection and yield was also quite low. But when these treatments had the support of a limited quantity of synthetic/semi-synthetic pesticides like emamectin benzoate (one application) and chlorfenapyr (one application) along with the plant fractions, showed much better suppression of pest populations like thrips and yellow mite as well as apical leaf curling intensity (0.94–1.12%). In all the treatments except chemical check and untreated check, some components were utilized as common part and these were: yellow sticky trap, repellent cropping with coriander and holy basil and plant sanitation. The strategies effectively suppressed the landing response and development of the pest populations which resulted in lower crop damages and sponsored good yields. These were safer to non-target beneficial creatures, costeffective and comparable to chemical method.

Field experiments were conducted to determine the optimum application rate of sunn hempCrotalaria juncea leaf residue in the management of Meloidogyne incognita on tomato. Sunn hemp applied at rates of 0 (control), 2, 4 and 6 kg/ha showed a varied effect on second stage juveniles of M. incognita. There were no differences in plant height and stem girth. The 6 kg/ha treatment reduced the M. incognita population by 94% compared with the control. The highest yield of tomato (168.7 kg/ha) was recorded in 6 kg/ha treatment of sunn hemp.

In 2011-2012 surveys for phytoplasma diseases, eggplant (Solanum melongena L.) plants with phyllody symptoms were observed in eggplant fields of Roodan (Hormozgan province of Iran). Agent of Roodan Eggplant Phyllody (REP) was transmitted from phyllody affected eggplant to eggplant and tomato by grafting and to periwinkle via dodder inoculation inducing phytoplasma-type symptoms. Phytoplasmal infection also was demonstrated by positive direct PCR reaction with phytoplasma universal primer pair P1/P7 and nested PCR using P1/P7 and R16F2n/R16R2 primer pairs. A P1/P7 primed PCR product from a naturally phyllody affected eggplant was cloned and sequenced and submitted to GenBank under accession number JX464669. Restriction fragment length polymorphism (RFLP) analysis of P1/P7-primed PCR product indicated the presence of a pigeon pea witches' -broom (16SrIX) group related phytoplasma in naturally phyllody affected eggplants. Using 16S rRNA and SR sequences, Blast search, phylogenetic and virtual RFLP analyses and nucleotide homology percent revealed that REP associated phytoplasma is classified with members of 16SrIX-C subgroup. To our knowledge eggplant is reported for the first time as a host for a 16SrIX group related phytoplasma.

Laboratory and field experiments were conducted to determine the efficacy of some insecticides on the control of Sarta longhorned beetle, Aeolesthes sarta Solsky adults and larvae. In the laboratory, three pairs of mated and non-oviposited adults were released on the logs of field elm, Ulmus minor Mill that had been treated with chlorpyrifos, carbaryl, permethrin or imidacloprid. In the field experiments, artificially infested U. minor var. umbraculifera Rehd trees were treated by imidacloprid and oxydemeton-methyl through soil and trunk injection. In the laboratory test the best results were obtained from imidacloprid and permethrin applications, because of occurrence of high adult mortality after short period and also preventing egg laying. Despite a few eggs that were laid on the chlorpyrifos treated logs, there were no living larvae in the sprayed logs. Results of the field tests showed that the number of living larvae did not differ significantly between oxydemeton-methyl and control treatment, however, imidacloprid injection was effective in controlling this pest.