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1.
Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT50) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT50 values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC50 values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.  相似文献   

2.
Resource limitation is an important determinant of life history and behavior while mediating competition and reproduction among organisms. Discreet and closed systems such as grain kernels and seeds impose drastic restrictions to grain beetles that spend their immature stages within a single kernel selected by their mother. This is the case of internally feeding stored grain beetles, such as the grain weevils. Female egg-laying decisions and larval competition largely determine resource limitation for such insects where clustered egg distribution and contest competition with larval interference and cannibalism take place. As the clustered eggs within a grain lead to larval competition and conspecific weevil larvae face each other off during development allowing the emergence of one or two larvae per kernel, we hypothesized that such competition and consequent cannibalism will have fitness consequences for the competing individuals and their offspring. Thus, larvae of the granary weevil (Sitophilus granarius L.) and the maize weevil (Sitophilus zeamais Motsch.) were subjected to larval competition with cannibalism, and lack of it, to assess the potential fitness consequence of cannibalism on these non-carnivorous pest species of stored grains. Larval cannibalism reduced developmental time of maize weevil, but not of granary weevil. However, such condition led to heavier adult weevils of both species exhibiting higher reproductive output generating more and better quality progeny than non-cannibal weevils. These findings indicate direct nutritional benefits of cannibalism to grain weevils favoring their status of key pest species of stored cereal grains.  相似文献   

3.
The aphidophagous ladybird beetle, Hippodamia variegata (Goeze), is an important predator in many agricultural ecosystems. However, information on the influence of the prey’s host plant species on its life history characteristics is still absent in the literature. Therefore, five host plant species of Aphis gossypii Glover, viz. Cucumis sativus L., Cucurbita pepo var. medullosa L., Cucurbita moschata var. melonaeformis Poiret, Cucumis melo var. cantalupensis L. and Lagenaria siceraria var. gourda Standl., were selected to study the influence of the prey’s host plant species on the development, survival, reproduction and life table parameters of H. variegata in the laboratory at 25°C. The results showed that all of A. gossypii from five host plant species used were acceptable for the growth, development and reproduction of H. variegata. However, the suitability of aphids from various host plants was different for this ladybird beetle. The complete pre-imaginal development was longest (14.51 ± 0.17 days) when reared with aphids on C. melo var. cantalupensis and shortest (12.60 ± 0.11 days) on L. siceraria var. gourda. Total immature survival from egg to adult was highest (58.97%) on L. siceraria var. gourda and lowest (44.06%) on C. melo var. cantalupensis. Based on the intrinsic rate of increase as an index of suitability of prey host plant species on the population increase of H. variegata, the suitability in decreasing order was: L. siceraria var. gourda > C. moschata var. melonaeformis > C. pepo var. medullosa > C. melo var. cantalupensis > C. sativus. This study offered opportunities for better understanding the tritrophic interactions of the plant–aphid–predator relationship.  相似文献   

4.
A micropropagation method for Jaal (Salvadora persica)—a tree of arid horticulture and forestry has been developed. Nodal segments of fresh shoot sprouts originated from axillary buds obtained from a plant around 35–40 years old lopped plant were used as explants for establishment of in vitro cultures. Surface-sterilized explants produced optimum number of shoots through activation of axillary buds on Murashige and Skoog’s (MS) medium containing 8.88 μM BA (6-benzyladenine) + additives (25 mgl−1 each of adenine sulphate, arginine, citric acid, 50 mgl−1 ascorbic acid). The shoot multiplication was influenced by the successive transfer of the mother explants for 4–5 passages. The maximum number (23.1 ± 0.73 shoots per explant) of shoots were regenerated on MS supplemented with 1.11 μM BA + 1.16 μM Kn (Kinetin) + 0.54 μM NAA (α-naphthalene acetic acid). About 90% shoots pulse-treated with a combination of 2460.27 μM Indole-3-butyric acid (IBA) + 494.56 μM NOA (2-naphthoxy acetic acid) were rooted ex vitro on soilrite within 15–18 days. Over 80% cloned plantlets were hardened successfully in a green house and transferred to polybag/pots.  相似文献   

5.
The insecticidal activity of an entomopathogenic fungus, Isaria farinosa on pine bark-weevil (Pissodes punctatus) at different life stages underwent laboratory testing. Larvae, pupae and adults of Pissodes punctatus were exposed to a range of concentrations of fungal conidia in suspension for 5 s; mean mortality and LC50 values were calculated. The results showed I. farinosa can effectively infect larvae, pupae and adult pine bark-weevils, and the highest mean mortalities at each life stage can exceed 88%. The mean mortalities increased with higher concentrations of I. farinosa. Larvae were most susceptible with LC50 1.2 × 106 conidia ml−1 (15 days), pupae (30 days) exhibited the second largest effects, and adults (15 days) with LC50 1.72 × 106 and 1.99 × 106 conidia ml−1, respectively, at end of the experiments. This suggests that I. farinosa could be a potential bio-control agent against the pine bark-weevil.  相似文献   

6.
A digestion trial was conducted to estimate the potential contribution of the chaparral browse Quercus durata (leather oak) and Adenostoma fasciculatum (chamise) on intake and nutrient digestion in goats and sheep. Four wether Kiko goats (avg. wt. 22.9 kg) and four wether Targhee sheep (avg. wt. 39.6 kg) were housed in metabolism cages. Alfalfa pellets were used as a dietary supplement. Digestibility of the shrubs was measured by difference and metabolizable energy (ME) and ME intake (MEI) were calculated from digestibility and plants intake values. Oak and chamise had low crude protein (CP) content (6.5 and 4.3% DM) and high content of extractable condensed tannins (17.8 and 9.8% DM). In vitro organic matter digestibility (OMD) and ME for oak and chamise were 35.6 and 33.1% and 5.0 and 4.7 MJ/kg DM, respectively. In vivo OMD (calculated by difference with alfalfa) and MEI, for browse were greater (P < 0.01) for goats fed chamise compared to sheep. In oak, OMD was similar for both animal species but MEI was greater (P < 0.01) for goats. Greater (P < 0.05) DM and CP intakes (per kg BW0.75) were observed for goats fed either oak or chamise compared with sheep. When an energy source was given as supplement, the potential contribution of chamise and oak to total ME requirements for maintenance was about 58.3 and 60.4% in goats and about 17.1 and 32.9% in sheep, respectively. In consequence, metabolizable energy supplied by these shrubs may not be adequate for maintenance when, during grazing, they are consumed in high proportions with other chaparral plants that may have lower nutritional value than the alfalfa supplemented in this study. Under an appropriate supplementation program, goats could be more effective than sheep to control fuel load in California chaparral, as they consume more chamise and leather oak and obtain more nutrients from them.  相似文献   

7.
Fumigants and residual insecticides are commonly used to combat stored grain pests. In recent years, consumer awareness of the health hazard from residual toxicity and the growing problem of insect resistance to these conventional insecticides have led the researchers to look for alternative strategies for stored grains protection. For example, diatomaceous earth (DE) can be effective against stored grain insects. In this study, DE was used to design amorphous nano sized hydrophilic, hydrophobic, and lipophilic silica in 15–30 nm size range. Nanocides are expected to reduce the volume of application and kinetics of development of resistance in pests. We hypothesized that surface-functionalized silica nanoparticle (SNP) might be a viable alternative to conventional pesticides. Entomotoxicity of SNP was tested against rice weevil Sitophilus oryzae and its efficacy was compared with bulk-sized silica (individual particles larger than 1 μm). Amorphous SNP was found to be highly effective against this insect pest causing more than 90% mortality, indicating the effectiveness of SNP to control insect pests.  相似文献   

8.
The efficacy of NeemAzal powder, two local neem (Azadirachta indica ) products [neem seed powder (NSP) and neem seed oil (NSO)], as well as a local Lamiaceae, Plectranthus glandulosus leaf powder, applied at four different rates for the control of Sitophilus zeamais was determined. Mortality was recorded 1, 3, 7 and 14 days after S. zeamais infestation, followed by the determination of F1 progeny production. Grain damage, population increase and grain germination were assessed for treated grains that were stored for 4 months. Grains treated with P. glandulosus powder and NSP had relatively low mortality (5.0–22.5%) after 3 days whereas NeemAzal and NSO had higher mortality (55.0–98.8%). Maximum mortality of 99, 100, 96 and 74% were achieved for NeemAzal (12 g/kg after 14 days), NSO (4 ml/kg after 7 days), NSP (40 g/kg after 14 days) and P. glandulosus powder (40 g/kg, after 14 days), respectively. In the same order, 7-day LC50 values were 0.02 g/kg, 1.46 ml/kg, 12.44 g/kg and 28.9 g/kg. The three neem products greatly reduced progeny emergence, while P. glandulosus powder was less effective. NeemAzal protected the grains against S. zeamais damage better than the local neem products, which in turn provided far better grain protection against the weevil damage than P. glandulosus powder. NeemAzal was superior to the local neem products in grain protection against germination loss, with P. glandulosus being the least effective. NeemAzal and NSO had sufficient efficacy to be a component of an integrated management package for S. zeamais.  相似文献   

9.
Poplar leaf defoliator, Clostera fulgurita (Walker) larvae were reared on three Populus deltoides clones (PL1, PL5 and PL7) in the laboratory. The nutritional indices were computed for working out the relationship between food consumption and growth rate of 3rd, 4th and 5th instar larvae on three clones. The result showed that the consumption index (CI), approximate digestibility (AD), growth rate (GR), relative growth rate (RGR) and efficiency of conversion of ingested food (ECI) decreased with the increase in the age of the larvae. Efficiency of conversion of digested food (ECD) increased with increase in age of the larvae. GR and RGR varied significantly, indicating that larval development was enhanced on PL1 as compared to PL5 & PL7. The values of AD, ECI and ECD were not affected by the different clones. Feeding and growth indices could be useful to define a defoliation prediction model.  相似文献   

10.
Present study evaluated growth of Populus deltoides G48 and Toona ciliata over a period of 6 months, in nursery soil amended with 10% fly ash (v/v), 5% distillery waste (v/v), 20% farmyard manure (v/v) and microbial consortium of Pseudomonas striata and Azotobacter sp. @ 30 ml/pot in different combinations leading to 12 different treatments with 16 replicates in completely randomized block design. Biometric parameters such as plant height, collar diameter and total dry biomass were analyzed which indicated that the treatment (T8) comprising of fly ash @ 10% (v/v), farmyard manure @ 20% (v/v) and microbial consortium @ 30 ml/pot promoted growth of P. deltoides. The results indicated that combined addition of fly ash, farm yard manure and microbial inoculants can be used as a good potting mixture for improving survival rates and plant growth in forestry nurseries.  相似文献   

11.
The function of an Arabidopsis thaliana gene, At5g54160 annotated as a caffeic acid O-methyltransferase CAOMT gene was characterized. The recombinant enzyme of this gene (AtOMT1) catalyzed the O-methylation of phenylpropanoid and flavonoid substrates. The specificity constants (k cat/K m) for 5-hydroxyconiferaldehyde (5-HCAld) and quercetin were both 0.11 μM−1·min−1. On the other hand, lignins of At5g54160-knockout Arabidopsis mutants lacked syringyl units. In addition, we showed that the gene silencing also resulted in significant accumulation of caffeyl alcohol (CaAlc). These results strongly suggested that At5g54160 gene is involved in syringyl lignin synthesis for the methylation of both 5-hydroxyconiferaldehyde and 3,4-dihydroxyphenyl compound(s). Part of this work was presented at the Annual Meeting of Japan Society for Bioscience, Biotechnology, and Agrochemistry, March 24–27, 2007  相似文献   

12.
Citrus mealybug Planococcus citri (Risso) (Hemiptera: Pseudococcidae) is one of the main pests on citrus trees. Biological control of the pest is based on the release of hymenopterous parasitoids and coccinellid predators at present. The effectiveness of entomopathogen fungus Isaria farinosa (Holmsk.) Fries ([Sordariomycetes: Hypocreales] (Syn: Paecilomyces farinosus), as an alternative biological control agent on citrus mealybug, was investigated using four different inoculum densities and different relative humidities (RH). The entomopathogen caused 89.39% mortality in ovisacs, 84.07% mortality in second larval stage, 84.53% mortality in adult females, and 78.71% mortality in first larval stage at 95% RH and at 1 × 108 conidia ml−1 inoculum concentration. Percent mortalities were between 50 and 60 in ovisac, first and second larval stage at 95% RH and at 1 × 107 conidia ml−1. Percent mortality was decreased parallel to the decrease in humidity level and inoculum densities; however, the fungus caused significant infection in 70% and 80% RH. These results demonstrated that the effectiveness of the entomopathogen is promising for biocontrol of citrus mealybug.  相似文献   

13.
In honeybee, Apis mellifera, colonies infested with larval and adult small hive beetles (SHB), hive material, and in particular honey, tends to ferment, probably due to SHB-associated yeasts such as the predominant Kodamaea ohmeri. Here, we test the effects of organic acids on K. ohmeri and on SHB-infested honey/pollen combs. Organic acids were applied at standard concentrations used by beekeepers to control other pests. In laboratory tests, the growth of K. ohmeri was significantly inhibited by lactic, formic and acetic acids. Treatments of SHB-infested honey/pollen combs (N = 18 colonies) with acetic acid significantly increased mortality of adult SHB and treatments with formic acid significantly reduced larval infestation. Our data suggest that treatment of honeybee colonies and storage rooms with organic acids could also help in reducing SHB damage.  相似文献   

14.
The sensitivity of the Mediterranean flour moth, Ephestia kuehniella, eggs in different stages of development to gamma irradiation was studied and the acceptability of irradiated eggs by Trichogramma cacoeciae females was examined. Eggs ranging in age from 1–24 to 49–72 h were exposed, at 24 h intervals, to gamma radiation dosages ranging from 25 to 400 Gy and effects of gamma radiation on egg hatch and adult emergence was investigated. In addition, the developmental rate of immature stages (larvae and pupae), resulting from irradiated eggs, to the adult stage was examined and the acceptance of irradiated eggs to T. cacoeciae females was evaluated. Results showed that the radio-sensitivity of E. kuehniella eggs decreased with increasing age. Egg hatch in 1–24-h-old eggs was significantly affected at 25 Gy dose and at 75 Gy dose, no egg hatch was observed. When irradiating 25–48-h-old eggs, however, egg hatch was less than 5% at 100 Gy dose, and eggs 49–72-h-old were more resistant; 50 Gy had no significant effect on egg hatch and 300 Gy did not completely prevent it. Irradiation also negatively affected survival to the adult stage. When 25–48-h-old eggs were irradiated, survival to the adult stage was completely prevented at 75 Gy dose and no survival was observed beyond 100 Gy dose in 49–72-h-old eggs. In addition, the rate of development of immature stages resulting from irradiated eggs was negatively affected. While more than 97% of control moths emerged within 30 days, this ratio decreased to 53 and 69% in 1–24 and 25–48-h-old eggs exposed to 25 Gy dose. Furthermore, irradiation positively affected the degree of acceptance of eggs to parasitization; irradiated eggs (≤49-h-old) were more acceptable to T. cacoeciae than cold-treated ones.  相似文献   

15.
A dramatic decline in forest cover in eastern Africa along with a growing population means that timber and poles for building and fuelwood are in short supply. To overcome this shortage, the region is increasingly turning to eucalyptus. But eucalyptus raises environmental concerns of its own. Fears that it will deplete water supply, affect wildlife and reduce associated crop yields have caused many countries in the region to discourage farmers from planting this exotic. This paper is part of a series of investigations on the growth and water use efficiency of faster growing eucalyptus hybrids, which was introduced from South Africa to Kenya. The hypothesis is that the new hybrids are more efficient in using water and more suitable for the semi-arid tropics than existing eucalyptus and two popular agroforestry species. Gas exchange characteristics of juvenile Eucalyptus grandis (W. Hill ex Maiden), two eucalyptus hybrids (E. grandis × Eucalyptus camaldulensis Dehnh.), Grevillea robusta (A. Cunn) and Cordia africana (Lam) was studied under field and pot conditions using an infrared gas analyzer was used to measure photosynthetic active radiation (PAR), net photosynthetic rate (A), stomatal conductance (g s) and transpiration rate (E) at CO2 concentrations of 360 μmol mol−1 and ambient humidity and temperature. A, E and g s varied between species, being highest in eucalyptus hybrid GC 15 (24.6 μmol m−2 s−1) compared to eucalyptus hybrid GC 584 (21.0 μmol m−2 s−1), E. grandis (19.2 μmol m−2 s−1), C. africana (17.7 μmol m−2 s−1) and G. robusta (11.1 μmol m−2 s−1). C. africana exhibited high E values (7.0 mmol m−2 s−1) at optimal soil moisture contents than G. robusta (3.9 mmol m−2 s−1) and eucalyptus (5.3 mmol m−2 s−1) in field experiment and G. robusta (3.2 mmol m−2 s−1) and eucalyptus (4.2 mmol m−2 s−1) in pot-grown trees. At very low soil moisture content, extremely small g s values were recorded in GC 15 and E. grandis (8 mmol m−2 s−1) and G. robusta (14 mmol m−2 s−1) compared to GC 584 (46.9 mmol m−2 s−1) and C. africana (90.0 mmol m−2 s−1) indicating strong stomatal control by the species. Instantaneous water use efficiency ranged between 3 and 5 μmol mmol−1 and generally decreased with decline in soil moisture in pot-grown trees but increased with declining soil moisture in field-grown trees.  相似文献   

16.
Pea weevil (Bruchus pisorum) is a damaging insect pest affecting pea production worldwide. The aim of this study was to identify sources of resistance to pea weevil in a Pisum spp. germplasm in multi-environment field tests. Seed infestation and larval development were assessed in each environment and subjected to a heritability-adjusted genotype and genotype x environment biplot analysis. Results showed that seed infestation and larval development are independent traits. Accessions P669 (P. sativum ssp. elatius) and P656 (P. fulvum) showed a stable reduction in seed infestation across environments. Meanwhile, accessions P314 (P. sativum ssp. elatius) and P1 (P. abyssinicum) showed a stable reduction in larval development. The most promising accession was P665 (P. sativum ssp. syriacum) which showed resistance at both pod and seed levels. This study demonstrates the importance of environmental conditions for pea weevil infestation. Moreover, by submitting data to a CCA, the influence of climatic parameters over seed infestation and larval development has been elucidated.  相似文献   

17.
The use of biological control in turf has increased to avoid possible negative effects on humans. Entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae have control potential against many economically important insect pests. In the present study, the efficacy of Heterorhabditis bacteriophora against a new pest on turf, Dorcadion pseudopreissi, was examined in the field. Cages (1 × 1 × 1 m) with female and male D. pseudopreissi were placed on two kinds of turf: Lolium perenne and Festuca arundinacea. After beetles had deposited eggs into the moist soil surface, the cages were removed and H. bacteriophora was applied at 0.5 million infective juveniles/m2 to half the plots. Application of H. bacteriophora caused a statistically significant reduction in numbers of beetle larvae in L. perenne plots and a non-significant reduction in F. arundinacea plots. The area damaged by D. pseudopreissi was significantly reduced by nematode application in both turf species. The number of nematodes declined after application, but small numbers could still be detected after 6 months.  相似文献   

18.
In sterile insect technique (SIT) programs, the released sterile males are important for their effectiveness. The use of sex pheromones to collect males is economical; however, pre-exposure to sex pheromones may affect male mating behavior, and would thus reduce the effectiveness of the SIT programs. Males exposed to sex pheromone may become attractive to other males due to pheromone adsorption on their body impregnation, prevent mating and reduce the dispersal of sterile males. We examined the effect of pre-exposure to sex pheromone on the mating behavior of male sweetpotato weevil Cylas formicarius. Pre-exposure to high-dose sex pheromone for 24 h did not affect the male mating behavior of C. formicarius, and the exposed males did not attract other males. These results suggest that male C. formicarius that were collected from a mass-rearing facility using sex pheromone can be effectively used in SIT programs.  相似文献   

19.
Toxicity of ivermectin (Ivecop-12), a derivative of avermectin B, produced by a soil actinomycete, Streptomyces avermitilis, was evaluated in laboratory against the larvae of Spirama retorta Cramer (Lepidoptera: Noctuidae), a major stenophagous insect defoliator of Albizia spp. (family Leguminosae) in nurseries and young plantations. The study was conducted with eight treatment concentrations of lethal and sub-lethal doses. Results revealed that ivermectin is highly toxic and induce larval mortality when applied separately on host plant leaves and larvae, and on leaves and larvae of the insect pest together. The nature of treatment affects the larval mortality. Treatment of host plant leaves alone as well as leaves together with larvae showed 100% mortality by the treatment of 0.075% concentration whereas only 95% larval mortality was recorded due to larval treatment by the concentration of 1.2%. The LC50 value of the tested product was worked out to be 0.014, 0.170 and 0.012% for leaf and larval treatments separately and leaf and larval treatments together, respectively, against the insect pest. This clearly shows that ivermectin is more effective in larval killing when ingested through food. Further, the adults developed from treatments of sub-lethal concentrations and subsequently, when mated laid significantly (P < 0.05–0.01) less number of eggs and also showed significant (P < 0.05–0.01) reduction in hatching percentage compared to control. These observations suggest that the tested bioproduct, ivermectin, interfere physiological programming of larvae thereby causing alteration in fecundity and fertility of the target insect pest.  相似文献   

20.
The effect of herbaceous vegetation on growth and survival was assessed in planted eucalyptus saplings grown under four levels of weed cover. Seedlings of Eucalyptus globulus subsp. maidenii were planted with 0 (W0), 25 (W25), 50 (W50) and 100% (W100) weed cover. Weed species composition and aboveground biomass was determined. Soil water content was evaluated by the gravimetric method. Seedling leaf area, diameter and height were evaluated at planting and during the 3 months following establishment. Tree height, diameter and stem volume was estimated at 12, 24 and 36 months. First year tree survival was recorded. The ratio of cumulative stem growth under W100: cumulative stem growth under W0 was used to measure competitive performance. Regression analysis was used to determine competition thresholds. Weeds seriously threaten the growth of E. globulus subsp. maidenii. Early negative effects of competition on growth were evident as from the second month after establishment, and both seedlings and 1-year-old saplings were more affected than 2- and 3-year-old ones. A “minimum-response threshold” was determined near 500 kg/ha (corresponding to W25 cover). No clear effect was found between sapling survival and weed biomass.  相似文献   

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