فصلنامه تحقیقات حشره شناسی
سال سوم شماره 4 (پیاپی 12، زمستان 1390)

This pest strongly demonstrates resistance against chemical pesticides and decreases the yield of cotton and worsens its quality as well. Since Biorational pesticides are generally desirable، believing to have less disturbance of the environment; this research covers the study of susceptibility of different developmental stages of Bemisia tabaci Gennadius to pyriproxyfen، citowett oil and their mixture too. Citowett oil and pyriproxyfen have been used in 5 concentrations and control treatment. The LC50 value of pyriproxyfen for adult، egg، and immature stages was 10، 45. 04 and 11. 47 PPM، respectively. This criterion to citowett oil for adult، egg; and immature stages was 1554، 884. 79 and 684. 70 PPM in the same order. To evaluate the synergistic effect of citowett oil on pyriproxyfen we used the mixture of LC25 of either compound. The results revealed that there are 52. 36%، 62. 32% and 69. 19% mortality rate for adult، egg، immature stages respectively. The experiments showed that citowett oil is able to enhance efficiency of pyriproxyfen.

Species diversity of Coccinellids (Col.، Coccinellidae) was studied in Zarand region during 2009-2010. Samples were by collected net-trap and aspirator. Altogether 13 species from 9 genera، 3 tribe and 3 subfamilies were collected and Identified. External characters plus characteristics ofthe male and females genitalia were used in order for identification. Some species were also sent to Dr. Helmut Fursch in Germany for identification or confirmation. Among coccinellid species collected، six species were new records for Kerman province. Many species were predacious، preying on various species of aphids، mites and coccids

Host-plant resistance is one of the effective and sustainable strategies in pest management programs against diamond-back moth، Plutella xylostella (L.) (Lepidoptera، Plutellidae). In this regard، the effect of host plant type on life-history parameters، such as survival and developmental period of P. xylostella was determined under the constant environmental condition. The experiments were carried out with five host plants، including Brassica pekinensis (Chinese cabbage) cv. Hero، B. oleracea var. botrytis (cauliflower) cv. Royal، B. oleracea var. capitata (common cabbage) cv. Globe Master and cv. Red Dynasty، and B. napus (rape) cv. SLM046. Batches of 10 neonate P. xylostella larvae were placed on leaf discs within individual Petri dishes (6 cm dia.) containing a moistened filter paper. To prevent starvation of larvae، the leaf discs were replaced every 24 h. Pupae were transferred to Petri dishes and kept until eclosion. Life stage and mortality were recorded every 24 h until all the insects had either died or emerged as adults. Each treatment (plant) was replicated 17 times (in total، 170 host larvae for each plant). Theresults showed that there were significant differences between host plants for life-history parameters measured. The highest and lowest developmental times (from neonate larva to eclosion) of the host occurred on Red Dynasty (17. 3 days) and Hero (10. 5 days)، respectively. The most survival (from neonate larva to eclosion) of the host was observed on Hero (72%)، whereas the least survival happened on Red Dynasty (16%) and SLM046 (20%). The mean pupal weight of the hosts fed on Hero (4. 3 mg) was significantly greater than that on Royal (3. 8 mg) and Red Dynasty 3. 7 mg)، which in turn، were significantly greater than that on SLM046 (2. 9 mg). These results indicated that Hero was the most susceptible host plant to be attacked by P. xylostella، whereas Red Dynasty and SLM046 were partially resistant compared to other host plants. These findings emphasize on using the partially-resistant varieties such as Red Dynasty and SLM046 in pest management programs against diamondback moth.

Two spotted spider mite، Tetranychus urticae Koch is the most important pest of common bean in most areas of Iran، including Lorestan province. In this study the geostatistical charachteristics of this pest were evaluated in Borujerd common bean fields in 2009. To do this research، two red common bean (Goli variety) fields that each one was about four hectares were selected. In each field، about 300 points (stations) were identified and marked. Sampling was started in mid July. At each station on three point of plant height (bottom، middle and top) three leaves were sampled. In the laboratory، the samples were observed and mite population density were counted with respect to each life stage. Results showed that the spherical model provided the best fit (based on r2-values) for the semivariogram data in 20 data sets out of 25 at the beginning of the pest attak in late July and early August. In this time، nugget/sill ratio was very low and by passing the time this ratio increased so that the spatial dependence among points decreased. Thus in August and early September more semivariogram curves fitted with the model of pure nugget effect and did not show any spatial corrdation among points selected in the fields. The effective range of spatial correlation of this pest were relatively high at the beginning of the pest attack. This range for adult females، nymphs and eggs were 357-641، 510-710 and 610-711 meters respectively. These distances were reduced by passing the time and by approaching end of season. Based on these results، application of geostatistics is recommended to monitoring and forecasting of two spotted spider mite، T. urticae in common bean fields at the beginning of the pest attack.

One of the most important pest of vineyards in Iran is the Lobesia botrana Den & Schiff (Lep.، Tortricidae). Damage from this pest on grapes has considerable economic importance. Currently، the most common method of control is using chemical pesticides. According to this fact that spraying of pesticides makes serious problems with health care and environment، so controlled spraying using the effective estimation of pest due to growth period by pheromones traps are the important manner in combating. In our present research، we used pheromones traps in 5 villages of Urmia city in West Azerbaijan at various heights as selected points in study. Hunted insect was counted twice in a week at the same intervals of time. Results show that this pest has three complete generations in Urmia city region. The first appearance of moths was accrued in first half of April and three moth peaks were seen in first half of May، third decade of June to first half of July and second half of August، respectively. According to the obtained results، the best time to chemical control of pest was 7-10 days after appearance of the first generation peak and for the second and third generations were 5-7 days after generations peaks are considered.

During recent years، many investigations have been conducted on different plant products in order to obtain safer and more effective alternatives than chemical insecticides for controlling stored-product insects. Antifeedant activities of plant essential oils extracted from Cuminum cyminum L. and Carum copticum C. B. Clarke using hydro-distillation was tested against Tribolium confusum Jaquelin du Val. Several experiments were designed to measure the nutritional indices such as relative growth rate (RGR)، relative consumption rate (RCR)، efficiency of conversion of ingested food (ECI) and feeding deterrence index (FDI). Treatments were evaluated by the method of flour disc bioassay in the dark، at 27±1ºC and 65 ± 5 % R. H. Aliquots of 50 ml of acetone (controls) or an acetone solutions of essential oils (2000-40000 ppm) were spread evenly on the flour discs، then 10 adults insects were introduced into each treatment. After 72-h، nutritional indices were calculated. Results demonstrated that nutritional indices were significantly varied as essential oils concentration increased. In this study، C. copticum was effective than C. cyminum essential oil and decreased RGR، RCR and ECI significantly in some concentrations. Feeding deterrence index (FDI) of C. copticum essential oil was increased significantly as essential oilconcentration increased. The essential oil of C. copticum was more effective on FDI than C. cyminum in some concentration.

One of the most important pests in the warehouses is the flour moth Ephestia kuhniella (Zel.) (Lep.، Pyralidae). Regarding the high degree of damage of stored product pests and dangerous effects of the chemical control، using plant extracts and their components are some of the best approaches to control these pests. Therefore an investigation was carried out to find the insecticidal effects of Populus alba (Salicaceae) and Populus nigra (Salicaceae) extracted in acetone، hexane،alcohol and water on the flour moth larva. The plants were identified in the Center of Agricultural Research in Hamedan province and their extracts were produced in the solvents. At 100% concentration، the watery extract of P. alba had the highest insecticidal effect with the mean of 54. 66 percent. After that the watery extract of P. nigra and acetone extract of P. alba had the highest effect with means of 31. 48 and 28. 23 percent، respectively. Also hexane extract of P. alba and P. nigra at 100% concentration، water and acetone extract of P. alba had repellent effect on the last instar larvae. These findings reveal that only the watery extract of poplar has insecticidal effect. This shows its potential to be used as an effective insecticide and repellent material.