Journal of Entomological Society of Iran
Year:2017 | Volume:37 | Issue:1|Papers Count:14

This study was intended to investigate the diversity of parasitoid wasps of the family Braconidae in different habitats dominated by the plant species Medicago sativa L., Mentha pulegium L., Sophora alopecuroides L. and Rubus sp. About 563 braconid specimens of four subfamilies, Macrocentrinae, Alysiinae, Braconinae and Rogadinae were collected between May and December 2014. Alfalfa (450 individuals) and pennyroyal (28 individuals) had the highest and the lowest collected specimens respectively. The similarity index of Morisita-Horn showed that sophora and alfalfa had the highest similarity in terms of collected genera. The higher density of alfalfa lowered the value of biodiversity (0.566) while the highest diversity occurred in sophora (339.1). CCA analysis showed that the differences in dispersion of the genera were due to differences of habitats. The Jackknife index suggested higher number of expected genera than collected ones.

Learning new cues in all branches of biological organisms, ranging from unicellular organisms to mammals, occurs in different ways. In spite of their small size and short life span, insects have an extraordinary ability to learn, memorize and use environmental cues associated with the hosts and their food sources. Having the ability to learn and recalling the cues associated with the presence of prey / host is a key factor that increases the performance and foraging capacity of biocontrol agents including the ichneumonid parasitoid wasp Venturia canescens which is one of the most important parasitoids of the family Pyralidae in the world. In this research the learning ability of V. canescens in presence of peppermint and lemon odors was investigated by Y- Olfactometer. Results showed that the wasp had no significant preference towards peppermint or lemon, but after conditioning the female wasp, a meaningful difference was observed between her response to the conditioned odor (peppermint) and unconditioned odors (lemon). Her memory's lasting period continued for 27 hours after conditioning in the absence of the learned cues. Recognizing the learning ability and memory retention of the biocontrol agent V. canescens helps improve the efficiency of its application in biological control programs.

Glutathione S-transferase (GST) genes control vital traits for metabolism of the variety of toxins that expose insects to the environment (insecticide) or plant defense systems. Sunn pest is the most important pest of wheat and barley in the Middle East where it threats food security throughout the region. Sequencing the sunn pest's RNA provides an opportunity to identify the structure and function of the different gene families.To our knowledge, this is the first study to identify 43 GST candidate genes in sunn pest using bioinformatics tools. The identified candidate genes clustered in 5 cytosolic GST (Delta, Theta, Zeta, Omega, and Sigma) and Microsomal GST using phylogenetic analysis. The Sigma subclass was identified as the biggest subclass with 22 candidate genes, while microsomal GST found to be the smallest group with one candidate gene. Given the role of GST in the interactions among the insect, toxins, and environment, our results facilitate future investigations on insecticide resistance and their utilization in pest management programs against sunn pest.

The date palm spider mite, Oligonychus afrasiaticus (MCG.), is one of the important pests of date palm in the south of Iran where the application of a wide range of chemical acaricides by growers adversely affects the quality of harvest. Acaricidal activity of water extracts from Azadirachta indica A. Juss and Melia azedarach L., on adult O. afrasiaticus, was evaluated and compared with a commerical formulation of A. indica (Neemgold) under laboratory condition. Additive effect of the essential oil of Salvia mirzayanii Rech. f. & Esfand on these plant extracts was studied through dipping the date fruits in the extracts. Both plants showed acaricidal activity against O. afrasiaticus and the LC50 were 0.06% (commercial Neemgold), 2.23% (A. indica) and 3.25% (M. azedarach). The additive effect of S. mirzayanii in combined application with palnt extracts against O. afrasiaticus was observed as well.

Carob moth, Ectomyelois ceratoniae (Zeller) (Lep.: Pyralidae), is the most important pest of pomegranate fruit in Iran where the cryptic activity of its larva makes the application of insecticides practically impossible. In this research, we evaluated the viability of the sterile insect technique against the carob moth in two isolated regions in Yazd province (Aqda and Mehriz). The mass rearing of the pest was performed in clean rooms on artificial diet under environmental conditions, 29±1oC and 75±5%RH applying 165 Gy gamma ray as sterilizing doze.The sterile insects were released periodically in Aqda orchards (45 hectares) and in Chah Sheida (12 hectares) in Mehriz between March and November 2015. The infestation rate of carob moth in Aqda and Mehriz significantly reduced, in both target regions and control areas, by 12.27% and 44.02%, as well as 12.06% and 50.11%, for Aqda and Mehriz, respectively. It was concluded that periodical release of sterile carob moths can effectively lower the density of pest population and its economic loss on the harvest.

During a faunistic survey on heterostigmatic mites (Acari: Heterostigmatina: Caraboacaridae, Podapolipidae, Microdispidae, Neopygmephoridae), associated with insects in northwestern Iran, eight species were identified. The species Eutarsopolipus harpali Khaustov & Husband, 2004 (Podapolipidae) and Petalomium pseudomyrmecophilus Mahunka, 1970 (Neopygmephoridae) are here recorded for the first time from Iran and Asia. The six remaining species are as follows: Caraboacarus stammeri Krczal, 1959 (Caraboacaridae), Coccipolipus macfarlanei Husband, 1972 (Podapolipidae), Premicrodispus rackae Khaustov, 2006 (Microdispidae), Parapygmephorus magnisetosus Khaustov & Zalozhnaya, 2011, Acinogaster microchaetosus (Sevastianov, 1967) and Petalomium gottrauxi Mahunka, 1977 (Neopygmephoridae). We have also provided a new host record along with the world distribution of the mites.

Changing of host plant quality via agricultural practices such as application of fertilizer may influence the behavioral traits of natural enemies. In this study, the effect of improving cucumber plants with different vermicompost: soil ratios (0: 100 (control), 10: 90, 20: 80 and 30: 70 % by volume) were studied on the functional response of the parasitoid wasp Aphidius colemani Viereck to the melon aphid, Aphis gossypii Glover. The logistic regression analyses revealed that the functional response of the parasitoid wasp to the melon aphid was type II in all treatments. The different vermicompost: soil ratios were differently affected the parameters of the functional response of the wasp. The results suggest that A. colemani can be efficiently used in integrated management programs against the melon aphid using vermicompost.

In this study, Neuro Fuzzy network was used to estimate the spatial distribution of Bemisia tabaci in a cucumber field in Behbahan. Pest density assessments were performed based on a 10 m×10 m grid pattern pattern and a total of 100 sampling units in. In this method latitude and longitude information was used the input data and output of method showed the number of pest. To determine the sensitivity of this method to different levels of the pest after collecting samples, automatic clustering method was used to determine the number of clusters Davies and Bouldin index was used to evaluae criterion. In order to finding the answer, Clustering Search Space Genetic Algorithm was used. Davies and Bouldin index (0.46) showed that the data should be divided into three clusters. Results indicated average, variance, statistical distribution and also coefficient of determination in the observed and the estimated Bemisia tabaci density were not significantly different. Our map showed that patchy pest distribution offers large potential for using site-specific pest control on this field.

Melon aphid, Aphis gossypii, is an important pest of cucumber in greenhouses. In this research the possibility of using induced resistance for reducing population growth rate of the pest has been investigated. The life history parameters of aphid were determined in a growth chamber at 25±2oC, 60±5% R.H and 14: 10 L D conditions in a completely random design in a split plot experiment. The main factor was two cucumber cultivars of Royal and Storm and the subplot consisted of five different pre-infestation periods (0, 2, 4, 6 and 8 days pre-infestation with five melon aphid/plant). At the end of each pre-infestation period, the aphids were removed and the plants kept aphid-free for 48 h. The life history and population growth parameters of aphid were determined through 40 replications. The results indicated that there were significant differences among the treatments in aspect of the nymph growth duration, duration of reproduction of adult aphids and the longevity of the adult aphids. Furthermore, among the treatments R0, r, l and DT had significant differences in both cultivars, but there was no significant difference among the treatments in terms of generation time (T).The lowest and highest R0 in Royal (19.27 and 49.65 nymph/female/generation) and the lowest and highest r (0.311 and 0.480 /day) were observed on 6 and 0 days pre-infestation period treatments, respectively. The lowest and the highest R0 in Storm (13.25 and 44.63 nymph/female/generation) and the lowest and highest r (0.273 and 0.463 /day) were observed on 6 and 0 days pre-infestation period treatments, respectively. WE conclude that the pre-infestation of the cucumber plants with A. gossypii can induce resistance in cucumber within 6-8 days leading to population growth rate reduction in the melon aphid.

Biological Control of mosquito vectors with insect parasitic nematodes is of importance in Integrated Mosquito Management (IMM) due to its benign nature. The mosquito parasitic mermithid Strelkovimermis spiculatus normally parasitizes larval stages of Culex pipiens and rarely do adults of Culex get infected by this nematode in wild. This infrequent phenomenon is assumed as the way of nematode dispersal. We hypothized that infected mosquito adults can be obtained through laboratory manipulations. Parasite: host ratio and host stage were two main parameters to consider. To determine the optimal larval instar and parasite: host ratio, late third, early fourth, late fourth instar larvae and 5: 1, 10: 1, 20: 1, 40: 1 ratios were compared and the percentage of infected adult mosquitoes obtained recorded. Average nematode emergence time was measured to to estimate the proper release time of the mosquitoes in larval habitats. The sex ratio, number and length of post parasites emerged from adults were also calculated and compared in quality control process. Only late fourth instars infected adult host at 5: 1 with a maximum proportion of infected adults of 17.39%. The ratio of 10: 1 was chosen as standard infection ratio (P=0.87). The average duration between infection and nematode emergence was 7.37±0.51 (days). The proportion of females to total emerged nematodes from adults was 0.4: 1 which is an acceptable ratio for nematodes’ colonization in water bodies.There was no statistical difference between the length of nematodes emerged from mosquito adults and larvae (P=0.14). Infecting late fourth instars individually at 10: 1 infection ratio in an aliquot of nematode suspension and release of infected males seven days post-infection is a feasible strategy for application of this nematode in wild.

The study was intended to investigate the morphological, morphometric and molecular characterization of eight geographical isolates of the entomopathogenic nematode Steinernema feltiae from northwest of Iran.The results showed no detectable morphological variations, but significant morphometric variations were recorded among the isolates. Clustering based on morphometry of infective juveniles, classified the isolates in the following three separate groups: group I consists of IRA30 and IRA25; group II includes IRA21, IRA23, IRA34, IRA28 and IRA21 and group III contains of IRA17. Clustering the isolates based on the male' s morphometric characters, yielded nearly similar results and four groups were constructed as follows: group I is made up of IRA22, IRA23 and IRA21; group II holds IRA25, IRA34 and IRA28; group III contains IRA30 and IRA17 constitutes group IV. No intraspecific variation was observed among PCR-RFLP patterns of the Steinernema native isolates resulted from16 restriction enzymes but significant variations were recorded within the isolate Pumping by HinfI, MspI and MboI. Although these markers serve as effective tools in separating the native isolates from the exotic ones, they are unable to detect variations among native isolates. Therefore, only ITSrDNA sequence based phylogenetic analysis can effectively clarify the intraspecific variations of S. feltiae.

We conducted a study to identify the parasitoid and hyperparasitoid wasps of Ceroplastes sinensis on Hedera helix L. in Mazandarn province in 2013. Primary parasitoid wasps were identified as the aphelinid species Aphytis hispanicus (Mercet, 1912) and Coccophagus lycimnia (Walker, 1839), the encyrtid Microterys nietneri (Motschulsky, 1859) and a hyperparasitoid wasp was identified as Pachyneuron muscarum (Linnaeus, 1758) (Pteromalidae) from Juybar. The species Metastenus concinnus (Walker, 1834) (Pteromalidae) and Isodromus flaviscutum (Hoffer & Trjapitzin, 1978) (Encyrtidae) were found to be parasitoids of the natural enemies of C. sinensis from Juybar. I. flaviscutum is newly recorded from Iran.