فصلنامه تحقیقات حشره شناسی
سال ششم شماره 1 (پیاپی 21، بهار 1393)

Increase in cetrus damage by Pulvinaria aurantii in recent years and more pressure of pesticides application by farmer are two urgent problems of citrus production in north of Iran. To apply pesticides in a right time that is a component of integrated pest management (IPM), seasonal changes of citrus soft scale, Pulvinaria aurantii (Cockerell) densities was studied in central and eastern part of Mazandaran province from 2007 to 2009. There wene two annual generations per year. The first, designated as the summer generation, appeared from June to September, and the second, designated as the autumn generation, appeared from September to the following June. The maximum population of crawlers and first instar of second generation were seen during the last 10 days of june and for first generation during the late of September and beginning of October which is the best time for controlling the pest. Parameter b of Taylor's power low is an index of dispersion that in ordinary population was 9.4, suggested an aggregated dispersion pattern on one tree, however in high population (b= 1.57) it became close to random. There was no significant difference between the number of P. aurantii in different geographical direction and inside canopy of the tree in comparison with outside the tree canopy. However, in orchard with no suitable pruning, always P. aurantii population was high. Furthermore, the enough spaw between trees and pruning, cause to decrease infestation by the pest from 25.1% to 8.3%.

The use of Insect growth regulators (IGRs) together with entomopathogenic fungi is one of the strategies of IPM against these pests. In this study, The effect pyriproxyfen with M. anisopliae was assayed on worker termite of Amitermes vilis. In order to determine the LC50 of insecticides, bioassay tests were carried out on worker termites. The LC50 of M. anisopliae was 8.5× 103 spores/ml and LC50 for pyriproxyfen was 9.56 mg/L. Three concentrations of entomopathogenic fungus including 5 ×101, 5 ×102 and 103 spores/ml were mixed with LC15 (0.5 ppm) of pyriproxyfen. The bioassay of the three mixtures on worker termites showed that M. anisopliae and pyriproxyfen had an additive interaction and the mixture of fungi concentrations with pyriproxyfen can be used for termite control.

The effect of aphid species and its host plant on feeding rate and longevity of green lacewing(Chrysoperla carnea) was studied. The Sitobion avenae and Aphis nerri were selected as the hosts of green lacewing. In this study, we used A. nerri, S. avenae fed on wheat as main host and S. avenae fed on oleander as compulsory host to study feeding rate and longevity of Ch. carnea The experiments were conducted in laboratory conditions (25 ± 2° C 7 ± 05 % RH and photoperiod of 16L: 8D). Based on the data obtained, Significant effects of aphid species and their the host plants on feeding rate and longevity of green lacewing were observed. The average feeding rate of 2nd instar larvae of Ch.. carnea on wheat aphid fed on wheat, oleander aphid and wheat aphid fed on oleander were 40.30,±0.98, 19.50,±50 and 30.6±1.1 aphids respectively. In addition, the longevity of 2nd instar larvae of green lacewing which fed on different mentioned hosts were recorded as 3.7±0.15, 7.8±0.29 and 6±0.21 days, respectively. The results showed that biological characteristics of larvae of Ch. carneaare were influenced by their food quality.

Pomegranate fruit moth (PFM), Ectomyelois ceratoniae Zeller (Lep.: Pyralidae), is the most important pest of pomegranate in Iran. The larvae of PFM damage pomegranate fruits. One way that may prevent fruits infection is obstruction from laying eggs by the moth inside the fruit crown.In the present study, the effect of crown covering time of pomegranate by fabric net, including different times of covering (2, 4 & 8 weeks after flowering) and number of covering stages on fruit infection rate were cpmpared in Kashmar and Garmsar regions,Iran in 2009. The result showed that the mean percentages of infection were 11.70 in control and 3.50 and 2.80 for two and three stages of crown-covering, respectively. So the two and three stages of crown-covering reduced the fruit damage by 70 and 76%, respectively. Comparison of flower and fruit drop, cover stability and PFM infection indices among the treatments indicated that using two stages crown-covering with a cop made by fabric net, at 4 & 8 weeks after flowering (in early May to early July) can be recommended for PFM control.

According to the high damage of stored pests and adverse effect of chemical pesticide research on the use of secondary metabolites and essential oil of plants are necessary for controlling stored product pest. In this research have been investigated the fumigant toxicity and persistency of essential oil of orange peel Citrus sinensis (L) on rice weevil Sitophilus oryzae L. and flour beetle Tribolium castaneum Herbst. have been investigated The experiment was conducted in a completely randomized design. Essential oil of orange peel was extracted by Clevenger apparatus. The bioassay was done in 40 ml glass Jar at 25±2 °C and 65±5% R. H. under dark condition. Filter paper was used as the sources of evaporating facility. Based on data the LC50 values were 264.25 and 171.45μl/Lair on S. oryzae and T. castaneum at 48 h post- treatments respectively. The persistency of the essential oil on flour beetle (25 days) was significantly more than on the rice weevil (21 days). The LT50 and LT90 were 12.56 and 8.68 days on rice weevil and 15.37 and 11.5 days on flour beetle, respectively. The results showed that the toxicity and persistency of essential oil of orange peel on these pests was acceptable and this oil can be further investigations might be an alternative to chemical pesticides on these product pests.

The effects of sub-lethal doses of the fungi, B.bassiana, B.brongniartii and M. anisopliae on feeding ability of the larvae of the date horned beetle and the indices of digestion, absorption and excretion of this pest were studied in laboratory condition. First, the sub-lethal doses of 50 and 90% of reducing power ability (EC50 and EC90)was calculated and then the physiological feeding indices including Relative Consumption Rate) RCR), Efficiency of Conversion of Ingested food (ECI, Efficiency of Digested food (ECD), Approximate Digestibility (AD) were estimated. The results showed that the isolates of all three pathogenic fungi had a significant different high ability to reduce the feeding efficiency of the date- pest larvae. The highest and lowest abilities belonged to M. anisopliae and B. bassiana with the EC50 of 4.27×and 7.9 ×spores/ml, respectively. There was a significant difference between physiological feeding indices of the pest larvae when they were exposed to applied doses of spores. In all three pathogenic fungi species, increasing doses of spore decreased the values of MRG, ECI, ECD and AD, but increased the value of PCR. The highest of the regression lines of the indices on log scale of doses was recorded in M. anisopliae and then the two other species, B. brongniartii and B. bassiana.

Over the past few decades, many investigations have been conducted on different plant products in order to obtain safer and more effective alternatives rather than chemical insecticides for controlling store-product insects. For this purpose, in search of alternatives agents for conventional pesticides, the fumigant activity of essential oils from Mentha longifolia L., Tagetes minuta L. and Salvia macrosiphon Boiss. were tested against adult insects of Sitophilus oryzae L. (Coleoptera: Curculionidae) on laboratory condition. The experiment was conducted using a completely randomized design of factorial experiment with five concentrations and three replications at 25±10C, 60±5% R.H in darkness. The results showed that the percentage of mortality was increased with increase in concentration and exposure period. The highest fumigant toxicity was related to M. longifolia and the lowest toxicity was recorded for S. macrosiphon against insects. At the highest concentration of essential oils (25μl/L of air) by M. longifolia, T. minuta and S. macrosiphon the mortality were recorded as 80%, 73.3% and 66.6% after 12h and 96.6%, 86.6% and 73.3% after 24h against S. oryzae, respectively. The LC50 values were evaluated by M. longifoli, T. minuta and S. macrosiphon 8.166, 11.488 and 14.161 μl/L of air after 12h and 5.898, 7.814 and 11.068 μl/L of air after 24h for S. oryzae. According to the results, the essential oils of M. longifolia, T. minuta and S. macrosiphon are source of biologically active vapor that can be used in protection of stored grains against rice weevil.

Two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important pests of cucumber. In order to investigate the effect of different concentrations of potassium on biology and life table of this mite, cucumber plant was nourished by three levels of potassium including deficiency level of potassium K1 (5 meq/l K+), standard level of potassium K2 (7 meq/l K+) and excess level of potassium K3 (9 meq/l K+). The experiments were performed under laboratory conditions at 25±1 C°, 60±5% relative humidity and a photoperiod of 16:8 (L:D) hours. Based on the obtained results, the mean of pre-imaginal developmental time in deficiency, standard and excess levels of potassium was 11.66, 12.15 and 11.35 days for males and 12.2, 11.78 and 10.73 days for females, respectively. The highest mean of females life span was observed in plants which nourished by the lowest concentration of potassium and showed significant different with two other levels of potassium. The maen of oviposition period in mentioned levels was 13.71, 8.18 and 11.72 days, respectively. Also the maximum value of total fecundity was recorded in deficiency level of potassium. Mortality percentage of pre-imaginal stages was estimated 30.74, 23.65 and 20.34% in mentioned levels, respectively. Age specific survival rate (lx) at adult emergence in deficiency, standard and excess levels of potassium was estimated 0.55, 0.66 and 0.73, respectively. The highest value of life expectancy (ex) in the start of the experiments was recorded as 35.31 days in 9 meq/l K+ concentration. The results showed that deficiency of potassium in cucumber plants is caused more reproduction in two- spotted spider mite. So proper management of plant nutrition can be one of the most effective strategies to control this pest in integrated pest management programs.

The common pistachio psyllid, Agonoscena pistaciae, is known as a key pistachio pest in Iran. The two spotted coccinellid, Adalia bipunctata was reported as a psyllophagous beetle and the most abundant predator in pistachio plantations of Rafsanjan, south of Iran. The present research was carried out to examine the influence of temperature on biological parameters of A. bipunctata using psyllid nymphs as diet and under controlled conditions e.g., constant temperatures (ranged from 17.5 to 35°C), 55±5% r.h. and 16L:18D. The reproduction, developmental thresholds, thermal constant and the intrinsic rate of natural increase of this ladybird were all tested. The lower threshold for A. bipunctata while fed on nymphs of A. pistaciae was estimated 13.1. Thermal constant for development of this ladybird from egg to adult was obtained 200°DD (Degree-Day) while reared on nymphs of A. pistaciae. The intrinsic rate of natural increase (rm) and finite capacity for increase were obtained 0.172 and 1.19 respectively. Based on present results, A. pistaciae is considered as a suitable diet for this ladybird.

During 2008-2009, in a faunal study of Miridae in agricultural farmlands and orchards of Arak central province of iran, 25 species belonging to 17 genera of 5 subfamilies were identified; A species marked with asterisk, is newly recorded from Iran. Most of collected species, are phytophagous.where, some of them have been already introduced as agricultural pests. For example Lygus rugulipennis Poppius 1911, as an important agricultural pest in Arak the most abundant species among the harmful collected species (35/09%), but few studies have been conducted regarding its economic importance. The rest of the species (6 species) were predator which among them Deraeocoris punctulatus (Fallen, 1807) was determined as the dominant predator. The list of the collected species is as follow.