Saeid Moharramipour

Chemical constituents and fumigant toxicity of essential oil from Carum copticum against two stored product beetles

Abstract Plant secondary metabolites play an important role in plant‐insect interactions and therefore such compounds may have insecticidal or antifeedant activity against insects. Carum copticum C. B. Clarke (Apiaceae) is one of these plants that have medicinal effects on humans. The chemical composition of the essential oil from dry seeds of C. copticum was studied by gas chromatography (GC) and gas chromatography mass spectrometry (GC‐MS). Thymol (41.34%), α‐terpinolene (17.46%) and ρ‐cymene (11.76%) were found to be the major constituents of the oil. In fumigant toxicity tests with the essential oil against adults of Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) at 27 ± 1°C and 60%± 5% RH, it was observed that S. oryzae (LC50= 0.91 μL/L) were significantly susceptible than T. castaneum (LC50= 33.14 μL/L). The mortalities of the insect species reached 100% at concentrations higher than 185.2 μL/L and 12‐h exposure time. The findings indicate the strong insecticidal activity of C. copticum oil and its potential role as a fumigant for stored‐product insects.

Comparative life history and fecundity of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) on different soybean varieties.

The effect of different soybean varieties (Glycine max 356, M4, M7, M9, Clark, Sahar, JK, BP, Williams, L17, Zane, Gorgan3 and DPX) on the life history and fecundity of the gram pod borer Helicoverpa armigera (Hubner) (synonym Heliothis armigera (Hubner), also known as the American or African bollworm) was determined at 25 ± 1°C, 65 ± 5% r.h. and a light : dark cycle of 16:8 h. The larval period ranged 17.30 to 26.20 days on M7 and L17, respectively. The longest development time was on L17, BP and Sahar (42.71, 40.29 and 39.20 days, respectively) and the shortest was on M7, M9, Williams and Clark (34.21, 36.06, 36.60 and 36.82 days, respectively). The development index of overall immature stages varied from 1.39 to 2.41, with the minimum on L17 and BP and the maximum on M7. The highest daily fecundity and total fecundity (118.92 and 582.70 eggs, respectively) and the lowest (37.88 and 177.10 eggs, respectively) were observed on DPX and 356, respectively. Cluster analysis of the biological parameters of H. armigera on different soybean varieties demonstrated that BP, Sahar and L17 were partially resistant to H. armigera. Knowledge of the extent of susceptibility or resistance of crop varieties and biology of a pest on that crop are fundamental components of integrated pest management (IPM) programs for many crops. Such information can help to detect and monitor pest infestation, variety selection and crop breeding.

Chemical Composition and Insecticidal Activity of Artemisia scoparia Essential Oil against Three Coleopteran Stored-Product Insects

Abstract Chemical composition of the essential oil from Artemisia scoparia Waldst et Kit, and its fumigant and repellent activity were investigated against three stored product insects, Callosobruchus maculatus (Fab.), Sitophilus oryzae (L.), and Tribolium castaneum (Herbst). Dry ground leaves were subjected to hydrodistillation using a modified clevenger-type apparatus and the chemical composition of the volatile oil was studied by GC-MS. Nineteen components (99.51% of the total composition) were identified. β-Pinene (19.01%), capillin (17.45%), limonene (15.11%), myrcene (10.95) were found to be the major constituents of the oil. The mortality of 1-7 day old adults of the insect pests increased with concentration from 37 to 926 μL per L air and with exposure time from 3 to 24 h. A concentration of 37 μL per L air and exposure time of 24 h was sufficient to obtain 100% kill of the insects. Callosobruchus maculatus was more susceptible than S. oryzae and T. castaneum. A second more detailed bioassay gave estimates for the LC50 of C. maculatus as 1.46 μL per L air, S. oryzae 1.87 μL per L air and T. castaneum 2.05 μL per L air. Also, the essential oil was significantly more repellent to T. castaneum and S. oryzae than C. maculatus. However, half-life time of the oil for C. maculatus was longer than S. oryzae and T. castaneum. These results show the efficacy of A. scoparia oil for use in organic food protection.

Insecticidal Activity and Chemical Composition of Artemisia sieben Besser Essential Oil from Karaj, Iran

Abstract Atremisia sieberi Besser is a widely distributed plant that grows in many areas of Iran and has strong insecticidal activity against stored product pests, so an experiment was conducted to investigate fumigant toxicity of the A. sieberi oil collected from Karaj region of Iran. The oil was applied against one to seven day old adults of three major stored product insects including: Callosobruchus maculatus (Fab.), Sitophilus oryzae (L.), and Tribollium castaneum (Herbst). The potency of fumigant toxicity of A. sieberi on C. maculatus was higher (LC50: 1.64 μL per L) than S. oryzae (LC50: 4.41 μL per L) and T. castaneum (LC50: 20.31 μ.L per L). The relationships between the time exposure and oil concentration on mortality show that the mortality was increased as oil concentration and exposure time was increased. The concentration of 185 μL per L and exposure time of 24h was enough to obtain 100% kill of the insects. It was also found that the regions where A. sieberi grows affect essential oil components of the plant and can play an important role in properties of fumigant toxicity.

Cold hardiness and supercooling capacity in the overwintering larvae of the codling moth, Cydia pomonella.

Abstract The codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), a worldwide apple pest, is classified as a freeze-intolerant organism and one of the most cold-tolerant pests. The objectives of this study were to examine the supercooling point of overwintering and non-diapausing larvae of C. pomonella as an index of its cold hardiness, and to assess larval mortality following 24 h exposure to extreme low temperatures ranging from -5 to -25°C. The mean (±SE) supercooling point for feeding larvae (third through fifth instars) was -12.4 ± 1.1°C. The mean supercooling point for cocooned, non-diapausing larvae (i.e., non-feeding stages) decreased as the days that the arvae were cocooned increased and changed between -15.1 ± 1.2°C for one to two day cocooned arvae and -19.2 ± 1.8°C for less than five day cocooned larvae. The mean (±SE) supercooling point for other non-feeding stages containing pupae and overwintering larvae were -19.9 ± 1.0°C and -20.2 ± 0.2°C, respectively. Mean supercooling points of C. pomonella larvae were significantly lower during the winter months than the summer months, and sex had no effect on the supercooling point of C. pomonella larvae. The mortality of larvae increased significantly after individuals were exposed to temperatures below the mean supercooling point of the population. The supercooling point was a good predictor of cold hardiness.

Preimaginal Development Response to Constant Temperatures in Hypera postica (Coleoptera: Curculionidae) : Picking the Best Model

ABSTRACT Immature survival and development of alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), were examined at 15 constant temperatures ranging from 9 to 37°C. At 9 and 37°C, eggs did not develop. Embryos developed to adulthood between 11.5 and 36°C, although survival was low at both ends of the temperature range. Distribution of development times for all stages of alfalfa weevil were skewed toward longer times mainly at moderate temperatures. Constant proportion of time spent in egg, larva, and pupa indicated rate isomorphy within the range 14–31.5°C. No significant difference was shown between development time of males and females at any of the temperatures tested. Two linear and 23 nonlinear models were fitted to describe development rate of immature stages of H. postica as a function of temperature, as well as estimating the thermal constant and critical temperatures (i.e., Tmin, Topt, and Tmax). There was no statistical difference between the estimated parameters, using Ikemoto and ordinary linear methods. Of the nonlinear models fitted, the Logan-6/Lactin-2, Analytis-3/Briere-2, and Analytis-3/Briere-2 models were found to be the best for modeling development rate of egg, larva, and entire immature stages of H. postica, respectively. Our findings will be incorporated in more efficient phenological models of this pest and its population dynamics.

Deciphering the Metabolic Changes Associated with Diapause Syndrome and Cold Acclimation in the Two-Spotted Spider Mite Tetranychus urticae

Diapause is a common feature in several arthropod species that are subject to unfavorable growing seasons. The range of environmental cues that trigger the onset and termination of diapause, in addition to associated hormonal, biochemical, and molecular changes, have been studied extensively in recent years; however, such information is only available for a few insect species. Diapause and cold hardening usually occur together in overwintering arthropods, and can be characterized by recording changes to the wealth of molecules present in the tissue, hemolymph, or whole body of organisms. Recent technological advances, such as high throughput screening and quantification of metabolites via chromatographic analyses, are able to identify such molecules. In the present work, we examined the survival ability of diapausing and non-diapausing females of the two-spotted spider mite, Tetranychus urticae, in the presence (0 or 5°C) or absence of cold acclimation. Furthermore, we examined the metabolic fingerprints of these specimens via gas chromatography-mass spectrophotometry (GC-MS). Partial Least Square Discriminant Analysis (PLS-DA) of metabolites revealed that major metabolic variations were related to diapause, indicating in a clear cut-off between diapausing and non-diapausing females, regardless of acclimation state. Signs of metabolic depression were evident in diapausing females, with most amino acids and TCA cycle intermediates being significantly reduced. Out of the 40 accurately quantified metabolites, seven metabolites remained elevated or were accumulated in diapausing mites, i.e. cadaverine, gluconolactone, glucose, inositol, maltose, mannitol and sorbitol. The capacity to accumulate winter polyols during cold-acclimation was restricted to diapausing females. We conclude that the induction of increased cold hardiness in this species is associated with the diapause syndrome, rather than being a direct effect of low temperature. Our results provide novel information about biochemical events related to the cold hardening process in the two-spotted spider mite.

Chemical composition and insecticidal activity of essential oil from Perovskia abrotanoides (Lamiaceae) against Sitophilus oryzae (Coleoptera: Curculionidae) and Tribolium castaneum (Coleoptera: Tenebrionidae)

Perovskia abrotanoides Karel is a wild growing plant in Iran and has been used in traditional Iranian herbal medicine. The present study was conducted to investigate chemical composition and fumigant toxicity of the essential oil from P. abrotanoides against Sitophilus oryzae (L.) and Tribolium castaneum (Herbst). Dry flowering aerial parts of the plant were subjected to hydrodistillation using a modified Clevenger-type apparatus. The composition of the essential oil was analysed by gas chromatography (GC) and GC mass spectrophotometry. Twenty-four compounds representing 98.8% of total oil were identified. The predominant components in the oil were camphor (28.38%) and 1,8-cineole (23.18%). Fumigant toxicity was tested against 1-to 7-day-old adults of S. oryzae and T. castaneum with five replications at 25 ± 1 °C and 65 ± 5% relative humidity in dark conditions. The mortality was increased with concentrations of 32, 161, 322, 483 and 645 μl/l air and with exposure time from 2 to 15 h. The lowest concentration (32 μl/l air) of the oil induced 100% mortality of S. oryzae and T. castaneum after 15 and 8 h exposure, respectively. The oil at 322 μl/l air caused 100% mortality for S. oryzae and T. castaneum within 13 and 7 h exposure, respectively. At 645 μl/l air, the LT50 values (lethal time for 50% mortality) were 8 and 2.84 h for S. oryzae and T. castaneum, respectively. In the probit analysis, LC50 values (lethal concentration for 50% mortality) showed that T. castaneum (LC50 = 11.39 μl/l) was more susceptible than S. oryzae (LC50 = 18.75 μl/l). The essential oil of P. abrotanoides can play an important role in stored grain protection and reduce the need for the same, and also the risks associated with the use of synthetic insecticides.

Digestive proteolytic and amylolytic activities of Helicoverpa armigera in response to feeding on different soybean cultivars

BACKGROUND Digestive proteolytic and amylolytic activities of the larvae of Helicoverpa armigera (Hübner) fed either on artificial diet or on different soybean cultivars (356, M4, M7, M9, Clark, Sahar, JK, BP, Williams, L17, Zane, Gorgan3 and DPX) and response of the larvae to feeding on some soybean-based protease inhibitors were studied. RESULTS The highest general and specific proteolytic activities were in artificial-diet-fed larvae. Although the highest general proteolytic activity was in the larvae fed on L17, M4 and Sahar cultivars, the lowest tryptic activity was on L17 and Sahar, which may be due to the presence of some serine protease inhibitors in these two cultivars, resulting in hyperproduction of chymotrypsin- and elastase-like enzymes in response to the inhibition of these enzymes. The highest amylolytic activity was on M4, and the lowest was on Williams and DPX. General proteolytic activity of SKTI-fed larvae was the highest compared with SBBI- and STI-fed larvae. CONCLUSION The findings demonstrated that the cultivars L17 and Sahar were partially resistant to this pest, probably because of some secondary chemicals or proteinaceous protease inhibitors of these cultivars.

Evaluation of Potential Resistance in Seeds of Different Soybean Cultivars to Helicoverpa armigera (Lepidoptera: Noctuidae) using Demographic Parameters and Nutritional Indices

ABSTRACT The use of resistant cultivars is a key component of any integrated pest management (IPM) program. Here, we assess the resistance status of 10 different soybean cultivar seeds according to their effects on demographic and nutritional indices of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) when incorporated into artificial diets. All experiments were conducted at 25 ± 1°C, 60 ± 5% RH, and a photoperiod of 16:8 (L:D) h. Life table, reproduction, development, adult longevity, and nutritional indices of H. armigera were significantly affected by the cultivars examined. Mean developmental time of across all immature stages varied from 57 d on ‘L17’ to 32 d on ‘Clark’, Efficiency of conversion of digested food (ECD) for old larvae ranged from 36.4% on ‘Sari’ to 14.8% on ‘Sahar’. The adults that emerged from these larvae had very different rates of reproduction; the highest and lowest values for net reproductive rate (R0) were 270 and 17 on Clark and L17, respectively. The most important demographic parameter, intrinsic rate of increase (rm), ranged from 0.114 on Sari to 0.09 on L17. H. armigera did not perform well on Sahar, L17, ‘Gorgan3’, and ‘M4’, These cultivars show antibiosis resistance compared with other tested cultivars and are key candidates for field tests to determine usefulness in an IPM system.