JOURNAL OF ENTOMOLOGICAL RESEARCH
Year:2012 | Volume:4 | Issue:3 (15)|Papers Count:8

When females encounter either an already parasitized host or a parasitoid mark on the substratum, they move away from the area. The present study investigates the mutual interference of T. busseolae on Sesamia spp. eggs, at 29±1oC, 65±5% and 16: 8 (L: D) photoperiod. In this experiment the constant density of 150 fresh host eggs were allocated for each wasp density. Densities of 1, 2, 4, 6 and 8 female wasps (with maximum age of 24 hours) were chosen randomly from the wasp rearing colony from the Sugarcane Research Center of Khuzestan, placed separately in vials and fed with 10% sugar solution. The wasps removed after 24 hours. The relationship between the logarithm of the densities of searching parasitoids and the logarithm of searching efficiency for each wasp was linear (F=619.5, r2=0.995, P=0.001). The coefficient of the regression line (m) was -1.4063. The negative value of (m) indicates that the mutual interference acts as reverse density dependence factor. With parasitoid density increasing from 1 to 8, the per capita parasitism and per capita searching efficiency decreased from 135 to 12.4 and 2.40 to 0.14, respectively. These studies can lead to an improvement in mass rearing techniques at insectariums and rate of natural enemies release in green houses.

Fecundity rate of natural enemies changes by sublethal doses of pesticides. In this research side effects of two insecticides, hexaflumuron and pymetrozin and acaricide, spirodiclofen and four plant extracts; Calotropis procera (Willd.) R. Br. (Asclepiadaceae), poleigamander Teucrium polium (Labiatae), Fumaria parviflora Lam. (Fumariaceae) and Thymus vulgaris L. (Labiatae) were evaluated on survival rate and reproductive parameters of Chrysoperla carnea (Stephens) in controlled condition. For this purpose, 154 fresh eggs and 40 third instar larvae treated by dipping and tapical application method respectively. The life duration of the predator on eggs treated on T. vulgaris, F. parviflora, hexaflumuron, spirodiclofen, pymetrozin, T. polium, C. procera treatments and control plots (water & Aceton) were 69, 78, 97, 98, 100, 104, 105, 106 days respectively. It showed that the T. vulgaris had the lowest and the C. procera had the highest survival period. Also the maximum survival period of adults belonged to C. procera treatment (83 day) and the minimum to T. vulgaris (47 days). The maximum fecundity of females was 519.59 eggs in pymetrozin and the minimum was 231.10 eggs in T. vulgaris. Also the fertility rates were 6.15 and 2.93 egg/female/day for spirodiclofen and T. vulgaris respectively. Extracts of C. procera are the best choices for some IPM programs because of their relative immunity on C. carnea as a biological control agents.

Ephestia kuehniella Zeller. is a major pest of stored products especially the it depreciates the quantity and quality of the cereal flour economically. To control the pest in warehouses, usage of essential oils is considered as an appropriate alternative to synthetic pesticides. Therefore, In this research, Lc50 and fumigant toxicity of Pinus eldarica and Cupressus arizonica were determind on 5 day-old adults of flour moth. Also repellency effects of essential oils were investigated on one day-old adult of flour moth by an two way olfacterometer. Results showed that C. arizonica oil with LC50 values of 38.04 ml/l.air had least toxicity and P. eldarica oil with LC50 values of 3.11 ml/l.air had the most toxicity. Mortality increased as oil concentration and exposure time increased. The most repellency effect has been observed in P. eldarica oil with 6ml/l.air concentration (%84.61) and the lowest repellency in C. arizonica with 10ml/l.air concentration (%23.52). Also Repellency effect increased significantly by increasing essential oil concentration. It is concluded that the essential oil used in this research can be a candidate as a safety pesticide for stored product pests control.

S. exigua, S. litura and S. littoralis with a wide host range are the most important pests of beet. spread all over the word while two other species S. littoralis and S. litura are more limited. Spread seasonal fluctuations of these species population along the growing season were studied by green funnel traps that were bated by sexual pheromone in a beet farm near Esfahan in 2010. S. exigua and S. littoralis were captured in traps but S. litura was not captured in pheromone traps because S. exigua and S. littoralis are similar concerning their molecules and their proportion. From mid- October as the weather gets cold, it reduced to the least. The average of trapped of S. littoralis was low till August and almost was fixed and any max or min was not observed. But trapped pests increased from 9Th September and it became maximum in mid-October. Results showed that the time of activation of these species were different in that the population of S. exigua was more than S. littoralis in the beginning of growing season of beet till late summer. But in the end of growing season means the population of S. littoralis was increase in late summer till autumn and over numbered to S. exigua population.

In order to study the fauna of Tetranychoidea on fruit trees in Mashhad Region, Iran, a sampling program was conduated during 2006-2007. Samples were taken directly from leaves, stems and branches by shaking on white tray or use of Berlese funnel trap. Microscopic slides were provided according to valid methods. In this study 8 species from 8 genus belonging to two families (Tetrnychidae and Tenuipalpidae) were collected and identified:Tetranychus urticae, Panonychus ulmi, Olygonychus bicolor, Eotetranychus pruni, Bryobia rubrioculus, Meyernychus emeticae, Tenuipalpus granati and Cenopalpus irani.Results showed that T. urticae had the greatest host range and activity during the sampling periods. Predatory mites belonging to 8 families were collected mostly on apple and pear trees in regions with lower than 1000 meter altitude. Most of the predatory mites were from Cunaxidae but the most varied host range and distribution of was Tydeidae. Torogh destrict had the fughest species richness. Most species diversity was recorded from Torogh district.

Sensitivity and tolerance rate of common cultivars were evaluated in complete randomized block design with six treatments (Local Red, Local White, Savanasuit, Primavera, Early White Grano and Riobravo) to Thrips tabaci Lind. Of onion and four replications in the field condition in Hormozgan province. Sensitivity of cultivars was evaluated based on number of larvae and adults. Every two weeks adults and larvae of the plant were separated and counted using washing method. The tolerance rate in two experiments (treated and untreated) was evaluated based on thrips and yield at the end of the season. Soil applications of Imidiacolopride 35% suspension were used to eliminate the pest from plants in treated experiment. Results showed that there was no significant difference among treatments in term of number of adults. There were significant differences among treatments in terms of larvae and sum of the adults and larvae. Local Red and White cultivars with average of 22.88 and 21.18 thrips/plant (sum of adults and larvae) were the most sensitive and Pri- mavera and Savanasuit cultivars with 8.8 and 11.17 thrips/plant were the most tolerant cultivars. Thus Local Red and White cultivars are the more sensitive, Primavera and Savanasuit cultivars are relatively resistant and Early White Grano and Riobravo cultivars are semi susceptible. Also there were significant differences in yield between treated and untreated experiments. So, in both ex- periments (treated and untreated) cultivar Riobravo with the average yield of 41667 and 51000 kg/ha had the highest tolerance. Despit relatively large population of thrips on Riobravo variety (similar to susceptible cultivars Local Red and Local White), this cultivar produced the highest amount of yield (24% more) compare to unsprayed most tolerant.

The effects of sub-lethal doses of the fungi, B. bassiana, B. brongniartii and M. anisopliae on feeding ability of the larvae of the datehorned 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 efficiencyof the date- pest larvae. The highest and lowest abilities belonged to M. anisopliae and B. bassiana with the EC50 of 4.27×104 and 7.95×104 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.

The cabbage aphid, Brevicoryne brassicae (L.), has been remained one of the most important pests of horticultural and oil-seed Brassica crops, despite all attempts to control its infestation. This research was conducted to evaluate the resistance of 48 rapeseed (Brassica napus L.) genotypes to cabbage aphid, Brevicoryne brassicae (L.) at Borujerd agricultural research station, Iran. during 2001-2003. In the first year, out of 48 genotrypes 8 showed a moderately resistance in comparison to rest. In the second year these 8 geotypes and a susceptible one (VDH8003.98) were evaluated in the field and laboratory condition. In the field condition, two similar but separated trials (treatment with insecticide and no treatment) were done in a randomized complete block design with four replications. Results showed that the most and the least infestation index and rm (intrinsic rate of natural increase) belonged to VDH 8003.98 and PF7045.91 respectively. Based on the field and laboratory investigations, among 48 genotypes, the most susceptible was VDH 8003.98 and the most resistant one was PF7045.91 and the other varieties were placed between these two.