Sexual dimorphism in the wing shape and size of the carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae)

The carob moth, Ectomyelois ceratoniae (Zeller), belongs to the family Pyralidae and the subfamily Phycitinae. In spite of some features of sexual dimorphism in size and shape in the order Lepidoptera and the mentioned family, it has not been recorded in this species. In the current study, sexual dimorphism in the wing shape and size of carob moth on four hosts (pomegranate, fig, pistachio and walnut) were detected using landmark- based geometric morphometric and analysis of partial warp scores and centroid sizes. The analysis showed significant wing shape differences (fore wing: P = 1.315E-011, hind wing: P = 1.168E-007) which was the same on all tested hosts. Geometric changes in the fore and hind wing of both sexes were illustrated. Analyses of size showed wings of the females are bigger than those of the males (fore wing: F = 23.19, P = 0.000; hind wing: F = 16.73, P = 0.000) on tested hosts and in spite of allometric growth in test specimens, significant shape differences are still remain in constant size

Effect of strip cropping of sugar beet-alfalfa on population density of the sugar beet weevil, Lixus incanescens (Col.: Curculionidae) and species diversity of its natural enemies

The sugar beet weevil, Lixus incanescens Boheman, is an important insect pest of sugar beet, Beta vulgaris L., in many parts of Iran. Strip cropping of sugar beet and alfalfa, Medicago sativa L., is a suitable strategy for improving the effectiveness of biocontrol agents of the sugar beet weevil. In this research, the population density of the sugar beet weevil and diversity of its natural enemies were studied in the strip cropping of sugar beet-alfalfa in comparison with the monoculture of sugar beet, in Juvein countryside, Khorasan Razavi province, from 2012 to 2013. In each sampling, the abundance of the sugar beet weevil and its natural enemies per plant were recorded. The densities of the sugar beet weevils in the strip cropping were significantly lower comparing to the monoculture. The larva of the hymenopteran parasitoid species Bracon intercessor Nees in both culture systems as well as seven egg predator species in strip cropping system and three egg predator species in the monoculture system were found. The percentage of larval parasitism and the densities of each predator in the strip cropping were significantly higher than the monoculture. The Shannon diversity index for the complexity of natural enemies in the strip cropping was higher comparing to the monoculture. The value of Morisita-Horn index for the complexity of the natural enemies between the experimental sugar beet cropping systems was calculated as 0.923. Based on these results, we have concluded that the strip cropping of sugar beet-alfalfa leads to higher diversity of natural enemies of the sugar beet weevil and lower population density of L. incanescens. In addition, the quantification of the predators’ species richness and abundance in the sugar beet fields remains as an effective method to improve the management of the sugar beet weevil

Evaluation of two wheat cropping systems for enhancing biological control of the wheat thrips, Haplothrips tritici (Thys.: Phlaeothripidae)

The wheat thrips, Haplothrips tritici Kurd., is an important pest of wheat crop, Triticum aestivum L., in Ardabil region, northwestern Iran. Strip cropping of wheat and alfalfa, Medicago sativa L., is a suitable strategy for improving the effectiveness of biocontrol agents of the wheat thrips. In this research, population density of the wheat thrips, and species richness and abundance of its predators were studied in the strip cropping of wheat and alfalfa (three-year old) and the monoculture of wheat during field surveys from 2010 to 2011. Sampling from each of two wheat cropping systems was conducted from the stem elongation until ripening stages. Number of the wheat thrips and predators per plant were recorded in each sample date. The population density of the wheat thrips in the strip cropping of wheat-alfalfa was significantly lower than that of monoculture of wheat. Five species of predators were recorded in the monoculture of wheat and 15 species of predators were recorded in the strip cropping of wheat-alfalfa. The Shannon diversity index for predators in the strip cropping of wheat-alfalfa was significantly higher than that for monoculture of wheat. The Morisita-Horn index between two wheat cropping systems was calculated 0.842. The species richness and abundance of predators in the strip cropping of wheat-alfalfa were greater than the monoculture of wheat. Therefore, it can be concluded that the strip cropping of wheat-alfalfa increases the species diversity of the predators and reduces the population density of H. tritici. Quantifying the species richness and abundance of predators in the wheat fields is an important step in the management of the wheat thrips

Report of four hymenopteran species of Eulophidae, parasitoids of Liriomyza trifolii (Dip.:Agromyzidae) in Shiraz, Iran

A survey was conducted to identify parasitoids of vegetable leafminer, Liriomyza trifolii (Burgess), in Shiraz region from April 2004 to September 2005. A total of eight eulophid species, viz. Baryscapus impeditus Nees*, Closterocerus formosus Westwood, Diaulinopsis arenaria Erdos*, Diglyphus crassinervis Erdos, Diglyphus isaea Walker, Diglyphus pulchripes Crawford*, Hemiptarsenus zilahisebessi Eros and Ratzeburgiola cristatus Ratzeburg* were collected, of which the four species marked with an asterisk are new records for Iran

Study on the resistance components in 33 commercial potato cultivars to Colorado potato beetle, Leptinotarsa decemlineata (Col.: Chrysomelidae)

Greenhouse and field experiments were conducted to evaluate the resistance components in 33 potato commercial cultivars to Colorado potato beetle, Leptinotarsa decemlineata (Say) in 2008. In a field choice test, the numbers of attracted beetles to the cultivars was determined as antixenosis index. To evaluate the antibiosis, potato tubers were planted in pots under greenhouse conditions and on each pot, one sleeve cage was set up, in which 15 first instar larvae were released and reared. The Larval weight after 12 days of releasing, mortality percentages of larvae and pupae and the durations of developmental stages were analyzed as the antibiosis indices. To study the level of tolerance of cultivars, the infested and non infested plots were isolated and arranged based on a randomized complete block design in field. In infested plots, each plant was infested by 40 medium larvae (second and early third instars) 15 days prior to the blooming of plants. At the end of the season, defoliation and yield loss among infested plots were determined and compared to non infested plots for each cultivar. Significant differences were observed in all studied traits. The cultivars Cardinal, Carlita and Sinja showed antixenosis effects with the least numbers of attracted beetles, whereas cultivars Carlita, Sinja, Delikat, Aparet and Bridjet showed antibiosis effects in comparison to the others. The cultivars Santana, Satina, Nicola and Bridjet showed tolerance to damage of the pest. Using cluster analysis, UPGMA procedure was based on Euclidean distance and 33 experimental cultivars were grouped in 7 distance groups

Evaluation of relative suitability of six cultivars of potato to the tomato leafminer, Tuta absoluta (Lep.: Gelechidae)

The tomato leafminer, Tuta absoluta (Meyrick), is an important pest of potato, Solanum tuberosum L., in the world. In this research, life history parameters of this pest were studied on six potato cultivars including: Impala, Agria, Savalan, Florida, Emeraude and Markies. The development time of larvae on Florida and Impala was significantly longer than of that on Markies and Emeraude. The lowest survival rate from egg to adult was observed on Florida (60.48%). The number of eggs laid per female on Florida was significantly lower than on Agria, Savalan, Markies and Emeraude, but no significant difference was found between Impala and Florida. The lowest intrinsic rate of increase (rm) (0.058 day-1) and the lowest finite rate of increase (λ) (1.059 day-1) were recorded on Florida. Moreover, the longest generation time (T) (33.60 days) and the longest doubling time (DT) (11.93 days) was significantly observed on Florida. Therefore, it could be concluded that Florida is the least suitable host to T. absoluta amongst the six tested cultivars of potato. These results could be useful in integrated management programs of T. absoluta in potato fields

Life history parameters of Phthorimaea operculella (Lep.: Gelechiidae) on tuber of some potato germplasms

Potato tuberworm, Phthorimaea operculella (Zeller), is an important pest of potatoes in the storage. In this study, the life history parameters of P. operculella were studied on eight potato germplasms including five potato cultivars (Agria, Savalan, Morene, Sprit, Kondor) and three potato clones (PI 397097-2, PI 396124 and PI 397082-2) in the laboratory at 25 ± 1°C, 65 ± 5% RH and 0: 24 (L: D) h. Feeding on the tubers of different potato germplasms had significant effect on development of immature stages, adult longevity and life span of P. operculella. The highest immature stage development time, the lowest survival rate of immature stages and the lowest fecundity were observed on PI 397097-2, and in contrast, the shortest immature stage development time, the highest survival rate of immature stages and the highest fecundity were observed on Savalan. The lowest intrinsic rate of natural increase (rm = 0.135), the lowest finit rate of increase (λ = 1.149), the lowest net reproductive rate (R0 = 15.4), the highest mean generation time (T = 20.1 days) and the highest doubling time (DT = 5.1 days) were observed on PI 397097-2. Because of longer immature development time and lower intrinsic rate of natural increase, finit rate of increase and net reproductive rate of the potato tuberworm on PI 397097-2, it was concluded that this clone is less suitable host for the potato tuberworm compared to other potato germplasms studied in this research. Therfore, it can be used in potato tuberworm IPM programs

Mass screening of different rice genotypes to rice striped stem borer, Chilo suppressalis Walker (Lep.: Pyralidae), under the field condition

In this study, a total of 98 Iranian and exotic rice genotypes were tested for their resistance to the Striped Stem Borer, Chilo suppressalis, under field conditions in Rice Research Institute of Iran, Mazandaran branch, Amol. The experiment was carried out in a randomized complete blocks design and three replications. At the reproductive stage, five whole plants per plot were randomly selected and cut off at the base, and percent of white head, number of larvae per hill, plant height, stem diameter, and tiller number per hill were measured. The rice genotypes Novator, G2-Gan74, Estrella, Rashtline-1, and IR72860, had the lowest amount of percent of white head, with means of 1.6%, 2.7%, 2.3%, 2.8%, and 3.2%, respectively, and the genotypes IR72-B, Iranian-New-Hybrid, Fars promising line, IR64-MutantW, IR50 had the highest amount of percent of white head with means of 43.5%, 43.4%, 37.6%, 35.8 %, and 34.8%, respectively. Moreover, genotypes Novator, Estrella and G2-Gan74 had the lowest mean larvae per a whole plant (0.1, 0.1 and 0.2, respectively), while genotypes Chinese-Hybrid1, IR72-B, and Binam had the highest mean larvae per a whole plant, with means of 10.3, 9.7, and 8.9, respectively. Rasht-Line-1 had the lowest mean plant height (74.4 cm), Fars promising line had the lowest mean number of tillers per hill (9.13), and Iranian New-Hybrid had the lowest mean stem diameter (4.44 mm). On the other hand, the Tarom-ARG2 genotypes had the highest mean plant height (138.26 cm), Sahel had the highest mean number of tillers per hill (17.6), and Dorfak had the highest mean stem diameter (12.72 mm).There were significant correlations between percent white head and the number of larvae per a whole plant, and between percent white head and number of tillers per hill, but there no significant correlations was found with plant height and stem diameter. The rice genotypes were grouped on Ward’s clustering procedure into two main clusters, totally four sub-cluster. The rice genotypes such as Novator, Estrella, Rashtline-1 were found to be less sensitive to Chilo suppressalis. Also, in this study, 19 rice genotypes including Novator, Estrella, G2-Gan74, Rashtline-1, Shirodi, Nemat, IR64-Mutant-F3076, MashhadDomsiah/Neda, {(A78.1/LocalAbiji)/(khazar/Tarom)} were recognized as resistant genotypes at field condition. Some of them can be tested in further experiments

Comparison of Resistance Index Some Potato Cultivars to the Colorado Potato Beetle, Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae)

Introduction: Potato, Solanum tuberosum L. is an important crop with 5.24 million tons of production on 210,000 hectares of irrigated land in Iran. Several pests attack the potato crop which among them the Colorado potato beetle, Leptinotarsa decemlineata (Say), is the most important defoliating pest of potato throughout the world and Iran and considerably reduce crop yield. Growers rely on pesticides to control this pest in the field but this insect is well known for its rapid resistance development to pesticides, so that it has developed field resistance to nearly all insecticides used against it and it is now resistant to more than 40 chemical insecticides. The problems of insecticide resistance, combined with continuing environmental concerns associated with chemical pesticide use, have provided a considerable stimulus over the past 50 years for the development of alternative control methods. Host plant resistance is considered to be an important part of integrated pest management (IPM) system of this pest, which is compatible with sustainable control methods and can reduce the use of chemical insecticides .With the aim of identifying the existence of resistance resources, a study was conducted to evaluate and comparison the resistance index (PRI) of 33 potatocultivarsto the Colorado potato beetle. Detected resistant variety (ies) could be used as a resistance source for IPM programs of this pest. Materials and Methods: Greenhouse and field experiments were conducted to compare resistance index (PRI) of 33 potato cultivars to the Colorado potato beetle, Leptinotarsa decemlineata (Say), in Naghadeh region during 2007-2008. In a choice test, the numbers of attracted beetles to each cultivar was determined as antixenosis index in the field. Also, Percentage of larval and pupal mortality were determined and used as the antibiosis index under greenhouse conditions. To evaluate the tolerance index, infested and non infested plots were planted and arranged based on a randomized complete block design under field conditions. In infested plots, each plant was infested by 40 medium larvae (second and early third instars) 15 days prior to the blooming of plants. At the end of season, yield loss in infested plots were determined and compared with non infested plots for each cultivar and used as the tolerance index. Normalized values for each category were computed on a zero-to-one scale by dividing the mean value of each variety evaluated by the maximum mean value of all entries. Normalized tolerance values were calculated as percent reductions of plant biomass relative to a non-infested control. Normalized indices for antibiosis (X), antixenosis (Y) and tolerance (Z) were used to calculate PRI in the formula: PRI = 1/(XYZ) (Inayatullah et al., 1990). Results and Discussion: Combined analysis of variance showed that interactive effect of cultivar × year was significant for all of the indices at P=0.01. The cultivars Sinja, Bridjet and Cardinal with the least antixenosis index (Y), had the highest antixenosis resistance to the Colorado potato beetle in 2007, also the cultivars Cardinal, Carlita and Elles with the least antixenosis index (Y), had the highest antixenosis resistance to the pest in comparison to other cultivars in 2008. The highest antibiosis (X) resistance was observed in the cultivars Delikat, Carlita, Armada and Sinja with the least antibiosis index, in two studied years. The cultivars Satina, Cardinal, Santana and Nicola with the least tolerance index (Z), had the highest tolrence to the Colorado potato beetle in comparison to the other cultivars during 2007-2008. The cultivars Delikat,Bridjet and Cardinal ere the most resistant cultivars with 52.63, 36.30 and 29.87 PRI, respectively in 2007. In this year, the cultivars Diamont, Aparet and Velox were the most sensitive cultivars with 1.90, 2.06 and 2.26 PRI, respectively in comparison to other cultivars. In 2008, the cultivars Santana, Bridjet and Sinja were the most resistant cultivars with 48.56, 28.36 and 25.80 PRI, respectively and the cultivars Velox, Agria and Bright were the most sensitive cultivars with 1.90, 2.71 and 3.20 PRI, respectively in comparison to the other cultivars in 2008. Conclusion: Significant positive correlation was observed between the plant resistance indices (PRI) in two study years (r= 0.499, P= 0.01). Results of this research revealed that the cultivars Bridjet, Delikat, Cardinal, Carlita, Sinja and Nicola with the highest PRI were the most resistant cultivars to the Colorado potato beetle in comparison to other cultivars during 2007-2008, suggesting that these cultivars can be used in the IPM program of the pest and resistance transfer to high yield varieties through plant breeding programs