Journal of Entomological Society of Iran
Year:2019 | Volume:39 | Issue:1|Papers Count:7

The European corn borer, Ostrinia nubilalis Hü bner, is one of the most important pests of corn. In this study, the influences of corn monoculture (C), sainfoin monoculture (S) and strip-intercropping of corn with sainfoin in the four row ratios: 2C: 2S, 2C: 4S, 2C: 6S and 2C: 8S were evaluated on the population density of the European corn borer, diversity and abundance of its natural enemies and yield of both crops in an experimental field during 2016 and 2017. Our results indicated that the densities of eggs and larvae of this pest decreased significantly in the intercrops especially in 2C: 6S and 2C: 8S compared with corn monoculture. The Shannon diversity index (H´ ) for predators in the intercrops was significantly greater than that in the corn monoculture. Moreover, the percentage of parasitized eggs and larvae were higher in the intercrops, especially in 2C: 6S and 2C: 8S, compared with the corn monoculture. Furthermore, the percentage of infested plants was also lower in 2C: 6S and 2C: 8S compared to the other treatments. On the other hand, high values of land equivalent ratio were found in 2C: 6S (1. 16 in 2016 and 1. 15 in 2017) and 2C: 8S (1. 17 in 2016 and 1. 16 in 2017). Therefore, it could be concluded that 2C: 6S and 2C: 8S intercrops are useful in integrated management of the European corn borer in the field.

The red palm weevil, Rhynchophorus ferrugineus (Olivier) is the most destructive pest of palm trees. In this research, the anti-ovipositon effect of the leaf extracts of 3 plant species, including Rhazya stricta Decne. (Apocynacea), Ferula assa-foetida L. (Apiaceae) and Azadirachta indica A. Juss. (Meliaceae), together with three plant volatile compounds, including alpha-pinene, eugenol and thymol, were studied on red palm weevil in a choice test. Each leaf extract and volatile compounds were used in 3 doses (1, 5 and 10%). The number of eggs laid by red palm weevil on the treated tissues were compared to that on untreated date core (as control) during 3 days. Anti-oviposition index (AOI) was used to evaluate the effects of different treatments. The results indicated that the number of eggs on treated palm tissues were significantly lower compared with the untreated ones, except when the tissue was treated with 1% of eugenol or 1% of A. indica. The least number of eggs was observed on tissues treated with 10% of thymol (1. 5± 0. 54) and 10% of R. stricta (1. 6± 0. 66). Also significant differences were found among the AOIs of the tested deterrents. The least AOI was seen for F. assa-foetida (33± 6) significantly less than those of thymol and R. stricta. The most AOIs were for 10% of thymol (85. 63± 4. 75%) and 10% of R. stricta (83. 32± 7. 70%). These results suggest that thymol, can be used, as oviposition deterrence, for treating wounds produced on palm trunks, to prevent the new infestations by the red palm weevil.

This research was conducted to evaluate of inoculated release methods on appropriate isolate of Metarhizium anisopliae for microbial control of the date palm horned beetle (DPHB) Oryctes elegans. Nesting experimental method was used in this study. The nests were includes: minimum, average and maximum inoculate release which used 1, 2 and 4 traps per hectare accordingly, and this daily releasing was continued for three weeks. The results showed; there are significant different at 1 percent level between the efficiency of M. anisopliae in different inoculate releasing methods according theses parameters: Petiole and Bunch injured, number of healthy and infected larvae and adult. The maximum releasing method had highest microbial control on decreasing of DPHB population (larva and adult), also Petiole and Bunch damage. This efficiency was assessed about 90 percent in two years study. Establishment and distribution of M. anisopliae in maximum inoculate release method was higher than other treatments. In this treatment, fungal growth increased from releasing date to 45 days. The results showed that maximum inoculate releasing method, not only had the highest efficiency in control, but also it was suitable considering economical, environmental and sustainability aspects.

Habrobracon hebetor Say is one of the most important ectoparasitoids of the larval stage of many lepidopterous pests. In this study, the effect of different cold storage duration (at 4± 1° C) including 0 (Control), 10, 20 and 30 day were evaluated on fecundity, percentage of egg hatch as well as age-specific functional response of H. hebetor to last instar of Anagasta kuehniella (Zeller) for 10 day. Different densities of 2, 4, 8, 16, 32, 64 and 128 of the host were offered separately to the parasitoids at 27± 1 ° C, 65± 5% RH and a photoperiod of 16: 8 (L: D) h. The numbers of paralyzed larvae, produced and hatched eggs in each host density and treatment were recorded daily. The results revealed a type II functional response for all treatments. The highest and lowest values of attack rates were estimated in 10 th day of control treatment (0. 0816± 0. 0129 h-1 ) and 6 th day of 30 day storage treatment (0. 0474± 0. 0083 h-1 ), respectively. The highest and lowest handling time was observed in eighth day of 30 day storage treatment (1. 5849± 0. 1217 h) and in first day of control treatment (0. 3155± 0. 0176 h), respectively. The lowest values of fecundity and egg hatch of the parasitoid as well as percentage of paralyzed host larvae were obtained in 30 day storage treatment.

Efficacy of methanolic leaf extract of Rosmarinus officinalis on third instar larvae of cotton bollworm, Helicoverpa armigera (Hü bner) was studied. The value of LC50 and LC20 were 5138 and 12347 ppm, respectively. One hundred microliters of the Rosemary’ s mehanolic extract at 5138 ppm was added to 0. 9 gr artificial diet. Efficiency of digested food (ECD), efficiency of conversion of ingested food (ECI), relative consumption rate (RCR) and relative growth rate (RGR) were decreased after 72 h but approximate digestibility (AD) was increased. It also decreased α-amylase, protease and lipase activity in the midgut of third instar larvae of H. armigera. Incubation of dissected midgut with crustacean cardioactive peptide (CCAP) increased lipase activity. Feeding on artificial diet containing plant extract caused decreasing in CCAP level in the brain, hemolymph and midgut of the insect. The results showed feeding on diet containing rosemary’ s extract inhibits release of CCAP in the midgut and brain that itself leads to reduction of α-amylase, lipase and protease activities.

In this study, contact toxicity of Eruca sativa (Miller) (Brassicaceae) oil and its methanolic extract were examined on the adult female of Tetranychus urticae (Red form)) (Tetranychidae) at five concentrations and three replications set at 25 ± 1° C, 65 ± 5% RH and 16: 8 h (light: dark). The mortality was evaluated 24 h after treatment. The LC50s of E. sativa oil and the methanol extract were 3062 and 5674 mg L -1, respectively. Measurement of erucin as the main isothiocyanate compound in the oil and methanolic seed extract using high performance liquid chromatography (HPLC) showed that the amount of erucin in the oil was higher than methanol extract. Also, analysis of fatty acids in the oil using gas chromatography (GC) showed that there were 12 types of fatty acids in oil, high level of arachidonic, oleic and Ƴ-linolenic acids. Due to the biological activity and phytochemical analysis, it can be concluded that the higher amount of erucin and fatty acids in the oil, caused the higher acaricidal activity of E. sativa oil compared to methanolic extract. Therefore, our findings showed that the presence of main active phytochemicals in the E. sativa oil plays a decisive role in its efficacy.

Light, as an environmental factor, affects the biology, physiology and behavior of insects. In this study, the feeding behavior of Hippodamia variegata and parasitism rate of Lysiphlebus fabarum were studied under light and dark conditions. Synchronous cohorts of different growth stages of H. variegata and female parasitoid wasps were produced and then they were singly introduced into experimental arena containing third instar nymphs of Aphis gossypii (20 nymphs for second instar larvae and female wasp; 30 nymphs for other growth stages of ladybird beetle) on a cucumber leaf. The results revealed that, although light did not influence foraging behavior of second instar larvae of the ladybird beetle, the number of killed aphids was significantly higher for fourth instar larvae by female and male adults of H. variegata during foraging in the light condition in comparison with the dark condition. The ratio of partial prey consumption (No. of partially consumed aphids to No. of aphids killed) was significantly greater in fourth instar larvae than in second instar larvae in the dark condition. Female adults displayed significantly more partial consumption of prey in the dark relative to the light condition. Moreover, in both light and dark phases, this ratio was higher in female adults than in males. The results revealed that female wasps parasitized fewer A. gossypii nymphs in the dark than in the light. Based on the acceptable performance of H. variegata in the dark condition, it can be said that in addition to the benefits of simultaneous application of the parasitoid wasp and the ladybird beetle during the day, aphid population decline continues at night.