نشریه نامه انجمن حشره شناسی ایران
سال سی و سوم شماره 1 (پیاپی 52، بهار 1392)

Population density and spatial distribution of Neoseiulus barkeri Hughes and its prey، Tetranychus urticae Koch، in cucumber fields of Sarab-e Chengaei region in west of the city of Khorramabad، Lorestan province، were studied in 2008-2009. The population densities of both species in the first year was higher than the second year. The population densities for T. urticae and N. barkeri reached their peaks in late July and late August 2008، respectively. In 2009، the population peaks for both species occurred in late August. The reaction of N. barkeri to different population densities of its prey، with linear regression، was described as density independent. It was also found that mated females of N. barkeri overwintered in soil. The Taylor''s power law regression method was used for finding the spatial pattern of the predator and prey، which was aggregated for both species. The correlation between the population fluctuation and spatial distribution pattern of the pest and its predator can effectively help to improve the strategy for a successful IPM program.

The olive fruit fly، Bactrocera oleae (Rosii)، is one of the injurious pests of olive that has caused considerable damage to olive orchards in recent years. An investigation was carried out at Tarom Olive Research Station، Zanjan، Iran، during 2008 to 2010 to determine the optimal height and direction of yellow sticky traps + sex pheromone for capturing B. oleae. A split plot design with four replicates was used in experiments، where the four main directions and three heights of one، two، and three meters were considered as the main and sub-main plots، respectively. Due to the past occurrence of the pest in Tarom، the traps were placed on olive trees in late September and weekly sampling was conducted throughout the autumn. Results revealed that the height of trap، unlike direction، significantly affected the capture of the olive fruit fly in all three years. The effect of trap direction was only significant in 2009، when the region experienced the highest density of the pest. Mean comparison of the effect of height in each year showed that the highest and lowest number of catches was in heights of three and one meter، respectively. In 2008، 2009 and 2010، total catches (both males and females) per trap in heights of one and three meters were 5. 25 and 9. 63، 21. 46 and 53. 46، and 1. 33 and 3. 27، respectively. In 2009، the traps in the west and south directions captured the high numbers of 46. 39 and 42. 04 olive fruit flies، respectively; while the minimum number of catches، 29. 20، occurred in the north direction. In Tarom، based on the results، it is recommended that yellow sticky traps baited with sex pheromone be placed at a height of three meters being in the direction of west and south.

In order to increase the efficiency of essential oils، the use of formulations with controlled release of the oil encapsulated in micro- and nano-scales would be the best option. In this research، the antifeedant activity of nanoencapsulated essential oil of Carum copticum C. B. Clarke was investigated on Plutella xylostella (L.) larvae. To determine the nutritional indices of the larvae affected by the formulated essential oil، weight of ingested food، larval biomass and weight of feces produced were recorded daily for three days. The experiments were conducted at 27 ± 1°C، 65 ± 5% RH and photoperiod of 16:8 h light: dark. Results indicated a significant decrease in nutritional indices such as relative consumption rate، relative growth rate، efficacy of conversion of ingested food and efficacy of conversion of digested food as concentration of the oil increased. Moreover، digestibility was decreased significantly، 72 h after feeding. However، feeding deterrence index was not significantly increased as compared with control. The finding led to a conclusion that nanoencapsulated oil has potential to control release of the essential oils and increase in post-ingestive toxicity of the insect.

Melon weevil، Acytopeus curvirostris persicus Thompson، is one of the most important pests of melons that is spread in the Middle East countries. In this study، diurnal and seasonal locomotor and flight activity of melon weevil were investigated under field condition using bucket traps (baited with conspecifics male and cucumber fruit) and also mating behavior pattern and its effect on fecundity (under semifield conditions) and fertility (under laboratory conditions). The results showed that both males and females of melon weevil have distinct daily activity. Two activity peaks were observed at 7:00-9:00 am and 17:00-19:00 pm. Maximum flight activity was observed in the afternoon (14:00 hours) in field condition. Both sexes emerged in early cultivation season (late June) simultaneously and the number of captured weevil was the highest in early October (6. 1 ± 2. 6 weevils per week). Emerged adults from pupal cocoon mated after about eight days. Peak of mating occurred during 14:30-16:30 pm. Number of mating during lifetime of males (18. 3 ± 3. 4) was nearly two times greater than females (9. 6 ± 2. 2). The mean number of eggs laid during reproduction period in single and multiple mating were 29. 2 ± 3. 5 and 52. 4 ± 6. 2 eggs per female، respectively. Oviposition was maximum on 12 and 36 days after mating. Hatching rates of eggs in single and multiple mating were 85 ± 7% and 82. 5 ± 9%، respectively. Multiple mating had no significant effect on fecundity and fertility. There was no relationship between mating frequency and temperature.

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.

The host-pathogen interaction is a very complex process. Like many entomopathogenic fungi during infection process، Beauveria bassiana produces enzymes which are able to destroy the cuticle of insects in order to penetrate into the host. Chitinases are considered to be the important enzymes for the hydrolysis of chitin and play an important role in the biological control of various pests including onion thrips، Thrips tabaci Lind. In the present study، specific primers for CHit1 and CHit2 genes were designed to study the expression pattern of these two chitinases from B. bassiana IRAN 789C strain before and after interaction with the second instar larvae of onion thrips using RT-PCR. Larval inoculation was carried out using three concentrations، 104، 105 and 106 conidia per ml. The results showed that both genes were expressed in all conidial concentrations، after parasitic interaction. Increasing the conidial concentration of B. bassiana caused the upregulation of chitinases expression level. Expression of these genes during the parasitic interaction of the fungus and insect larvae reflects the importance of chitinases gene as an effective factor in biological control of target organisms.

A study was taken up to investigate the biological and population attributes of Trissolcus basalis (Wollaston) on eggs of Eurygaster integriceps Puton (EI) and Graphosuma lineatum (L.) (GL). First، immature development، time of adult eclosion، offspring sex ratio and rate of emergence were recorded by random selection of 25 parasitized egg masses of each host (350 eggs with 0-4 h old) separately at 25 ± 0. 5 °C، 65 ± 5% RH and 16:8 L: D. In addition، percent parasitism، immature survival rate، adult longevity and first 10 days fecundity of females were calculated using 25 newly emerged pairs (0-4 h) confined in tubes and provided with two masses of respected host eggs daily under the same conditions till they died. Results revealed that T. basalis males had significantly shorter development period (11. 75 ± 0. 058 and 12. 57 ± 0. 96 d on EI and GL eggs، respectively) compared to that of females (12. 62 ± 0. 06 and 13. 72 ± 0. 69 d on eggs of EI and GL، respectively). Similarly، it was noticed that males’ longevity (54. 72 ± 1. 63 d) on EI eggs was significantly higher compared to their sibling females (43. 16 ± 2. 045 d) and male and female wasps on GL eggs which had significantly shorter longevity. In general، T. basalis reared on EI eggs had significantly longer oviposition period (39 ± 1. 79 d)، higher fecundity (292. 4 ± 11. 14 egg/female) and greater % parasitism (84. 09 ± 1. 56%) when compared with those on GL eggs. Moreover، immature survival rate was 82 and 64 % for wasp reared on EI and GL eggs، respectively. Finally، rm، λ and R0 were 0. 316 and 0. 224 d-1، 1. 372 and 1. 252 d-1 and 118. 5 and 51. 08 f/f/gen for wasps on EI and GL eggs، respectively. The population age distribution demonstrated that، totally، 95-98 and 2-5 % of the population were immature and adult stages for both hosts.

During 2009، in the course of a faunistic survey of terrestrial Parasitengona mites in Jahrom region، Ronaldothrombium bellator (Southcott، 1986) (Acari، Trombidiidae) was collected and identified for the first time from Iran. It was collected as ectoparasite of an unidentified Araneae، which is a new host for R. bellator.

A larval parasitoid of carob moth، Ectomyelois ceratoniae (Zeller)، was collected in pomegranate orchards in Fars province، Iran، during 2009-2010. This parasitoid، which is newly recorded from Iran، was identified as Goniozus legneri Gordh (Hym.: Bethylidae) by J. de Rond (Lelystad، The Netherlands).

In the course of a faunistic survey of oribatid mites in Mazandaran province، Iran، five species belonging to the genus Hermanniella Berlese were collected and identified، of which the following four species are new records for the fauna of Iran: H. grandis Sitnikova، H. granulata (Nicolet)، H. septentrionalis Berlese and H. serrata Sitnikova.