Suppression of insect pest populations and damage to plants by vermicomposts

Combined effects of gibberellin and vermiwash on the life history and antioxidant system of Phthorimaea absoluta (Meyrick) in tomato plants

Tomato (Lycopersicon esculentum Miller), is a globally important agricultural product, yet it is under significant threat from pests such as the tomato leaf miner, Phthorimaea absoluta (Meyrick) (Lepidoptera: Gelechiidae). This study investigates the combined effects of gibberellin and vermiwash treatment on the life history and antioxidant system of P. absoluta. Given the pest's resistance to many chemical pesticides, alternative control methods are crucial. Gibberellins are plant growth hormones known for their role in plant development and stress responses, while vermiwash is a bio-fertilizer rich in nutrients and microbial agents. We applied gibberellin and vermiwash (GV treatment) to tomato plants and assessed the impact on P. absoluta developmental stages, reproduction, and enzymatic activities. Our results show significant differences in larval development times (32.06 ± 0.39) and survival rates (0.53 ± 0.09) between treated and control groups (27.38 ± 0.35 and 0.80 ± 0.07, respectively). The GV treatment prolonged the total lifespan of P. absoluta (44.31 ± 0.51) but reduced its intrinsic rate of increase (r) (0.086 ± 0.009) and finite rate of increase (λ) (1.090 ± 0.009). Enzymatic assays revealed altered antioxidant and detoxifying enzyme activities in treated larvae. This study suggests that gibberellin and vermiwash treatments could be incorporated into pest management strategies for sustainable tomato production.

Opportunities and challenges in upcycling agri-food byproducts to generate insect manure (frass): A literature review

A range of issues related to sustainability in the agrifood industry have spurred interest in mass production of insects as human food and animal feed alternatives. This rapidly evolving sector addresses several challenges, including the management of food waste or agrifood by-products and the production of alternative animal proteins demonstrating low environmental impacts that improve sector circularity. The mass production of insects on agrifood processing wastes or by-products represents an opportunity to address these challenges. While the production of insects offers prospects for sustainable protein production, a major side stream is the production of frass or larval excrement including uneaten feed and chitin-rich exuviae (derived from multiple larval moults). The production of each tonne of edible insects generates 2 to 4 tonnes of frass with an interesting potential in agriculture versus traditional organic amendments (compost, manure, biochar). This review aims to demonstrate the characteristics of frass, its common harvest and conditioning methods, its optimal application rates for planting crops, the mechanisms by which it can protect plants against biotic and abiotic stresses and demystify the risks and potential associated with its application in agriculture. The characteristics of frass are compared with those of conventional fertilizers or other. This report also compiles the Canadian, US and European regulatory frameworks as a novel plant fertilizer and aims to pave the way for future research necessary for its valorization in plant production.

Effect of post-production vermicompost and thermophilic compost blending on nutrient availability

Composting is a common waste management strategy for recycling nutrients from organic household or agricultural wastes. However, thermophilic (e.g. windrow) composting and vermicomposting (using earthworms) produce different nutrient and enzyme profiles. Vermicompost is purported to have greater fertility benefits, but is also more expensive than thermophilic compost. The objective of this study was to examine a novel approach to designing organic fertility amendments by blending mature vermicompost and thermophilic compost. To examine the effect of blending, vermicompost was admixed to thermophilic compost at 20, 50 and 70 % by mass, with and without the addition of coir (cocopeat). Electric conductivity, water-extractable, immediately available N, P and K were measured. Vermicompost and coir synergistically affected the availability of these nutrients. Synergistic effects were between 15 and 40 % for total inorganic N in blends with coir. Without coir, synergism occurred only at vermicompost additions ≥50 %. Synergism for available P and K was present in all blends and ranged from 10% to 35%. Electrical conductivity measurements suggest that blending affected compost within three days of starting the incubation. The activity of five of seven measured enzymes were linearly and positively related to the fraction of vermicompost in the blend. Blending mature composts with differing properties may be another tool, in addition to adjusting feedstock and process parameters, to affect positively the fertility properties of composts.

Soil Fertilization With Medicinal Plant Processing Wastes Suppresses Tuta absoluta (Lepidoptera: Gelechiidae) and Aphis gossypii (Hemiptera: Aphididae) Populations

Organic soil amendments can influence insect pest populations and the damage to plants they cause. In this study, the effects of medicinal plant processing wastes (MPPWs) applied as organic fertilizers on the host preference and performance of Tuta absoluta and Aphis gossypii were investigated on tomato and cucumber plants, respectively. Processing wastes of cumin, rosemary, thyme, artichoke, chamomile, fenugreek, and nettle were applied in four levels of 0, 20, 40, and 80 g dry matter/1kg culture media in pot experiments. Results showed the application of MPPWs, especially 80 g of nettle, reduced the number of T. absoluta eggs (from 0.8 to 0.4 egg/leaf) and their hatching percentage (from 90 to 76%). The highest and lowest number of aphids were observed in control (36 aphids/plant) and treated cucumbers with 80 g of cumin (18 aphids/plant). Also, the lowest intrinsic rate of increase (0.08 d-1) and net reproductive rate (20 offspring) of T. absoluta were observed in tomatoes fertilized with nettle. The highest and lowest net reproductive rate of A. gossypii were obtained on control and treated plants with 80 g of nettle, respectively. Results of damage assessment showed that the percentage of dry weight loss in the aphid-infested plants was reduced by the use of MPPWs, so that lowest weight loss was observed in the treatment with 80 g of nettle. In conclusion, soil amendment using MPPWs could result in lower pest populations and may improve plant tolerance to insect pest stress, thus these by-products could be considered a valuable tool in pest management.

An exploratory method to determine the plant characteristics affecting the final yield of Echium amoenum Fisch. & C.A. Mey. under fertilizers application and plant densities

Employing of advanced statistical methods to quantify agricultural information has helped to carry out targeted planning to alleviate the problems of farmers, researchers and policy section. One of these exploratory methods, is multivariate statistical analysis that examines and models the relationship between variables. Considering the importance of Echium amoenum and its use growing trend in traditional medicine and the pharmaceutical industry, also the lack of information on the correlations between its yield and morpho physiological traits, the objective of this study was to determine the causality path in which the Echium amoenum characteristics affects the yield of Echium amoenum as regards of application of organic and chemical fertilizers under different plant densities. The employed method revealed that organic fertilizers increased flower yield compared with the control. The flower yield as a result of application of compost, vermicompost and cattle manure were increased by 25, 28, and 27% compared with the control, respectively. The results of multiple regression showed that variables of plant height, shoot dry weight, flower number per plant were the main factors affected the flower yield. The relative contribution of shoot dry weight was 16 and 25% more than plant height and flower number per plant, respectively. Causality analysis identified that shoot dry weight per plant had indirect effect on flower yield in different paths, as mainly was imposed through plant height considering the path coefficients. This study suggests that optimum production of Echium amoenum with application of ecological inputs along with effective agronomical managements of the causal paths of flower yield forming, including increase in shoot yield and plant height could be achieved through an ecological cropping system with reduced costs and no health concerning due to agrochemicals residual.

Effects of Amendment with Various Vermicomposts on the Soil Fertility, Growth of Brassica chinensis L., and Resistance of Spodoptera litura Fabricius larvae

Amendments with vermicomposts can reduce the incidence of pests. In this study, earthworms were fed different foods to produce four vermicomposts. A pot experiment was then conducted to assess different vermicomposts’ effects on soil fertility, and the secondary metabolite content and antioxidant capacity of Brassica chinensis L., and on the growth of Spodoptera litura larvae. The results showed that the characteristics of vermicomposts are mainly affected by food supplements, and that the application of vermicomposts can improve soil fertility, whereas increasing the soil and leaf sulfur content can decrease the relative growth rate of S. litura larvae. However, there were no significant differences in the total phenolic content (TPC), total flavonoid content (TFC), nor the DPPH free radical scavenging ability under the different treatments.

An evaluation of selected chemical, biochemical, and biological parameters of soil enriched with vermicompost

The aim of this study was to assess the changes in chemical and microbial properties and enzymatic activity of soil enriched with vermicompost derived from household waste. The vermicompost was tested in the rhizosphere of Larix decidua seedlings cultivated in 10-L pots in: (i) nursery soil (as the control), (ii) soil with 10% v/v vermicompost, and (iii) with 20% v/v vermicompost. The impact of vermicompost was assessed in terms of soil C/N ratio; bacterial, fungal, and nematode counts; and enzymatic activity. It was found that vermicompost increased the C/N ratio from 21 to 32, as well as the content of nitrate from 78 to 134 mg kg^-1, of ammonium from 14 to 139 mg kg^-1, of phosphorus from 92 to 521 mg kg^-1, and of potassium from 142 to 1912 mg kg^-1, compared with the control soil. The abundance of beneficial bacteria was increased (from 8.61 × 10⁷ to 37.9 × 10⁷), along with decreases in microbiological ratios of fungi and bacteria (e.g. fungi/Bacillus from 0.18818 to 0.00425). A significant 2- to 4-fold increase was observed compared with the control in the number of beneficial nematodes belonging to bacterivorous, fungivorous, and predatory groups with no change in the abundance of plant-parasitic nematodes. Addition of vermicompost brought about a change in soil enzyme activity. Vermicompost reduced the activity of alkaline phosphatase only. Both doses of vermicompost led to an increase in the activity of acid phosphatase, inorganic pyrophosphatase, dehydrogenases, β-glucosidase, and urease. Only the higher dose had an effect on increasing the activity of o-diphenol oxidase and proteases. No significant change was observed for nitrate reductase. Also, the presence of antibiotics produced by bacteria was detected depending on the dose of vermicompost, e.g. iturin (ituC) and bacillomycin (bmyB) were found in soil with a dose of 20% v/v vermicompost. Overall, vermicompost produced from household waste can be an excellent organic fertilizer for larch forest nurseries.

Application of Organic Fertilizers Affect the Citrus Leafminer, Phyllocnistis citrella (Lepidoptera: Gracillariidae) Infestation and Citrus Canker Disease in Nursery Plantations

Citrus leafminer (CLM), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is one of the most important insect pests of Pakistan's citrus nursery stock and caused extensive damage to young flushes. The organic compost is a widespread technique used to manage insect pests and plant diseases. Different composts (biofert, tara root and vermicompost) at 0.5 and 0.25 kg/plant concentration in comparison to NPK fertilizer at 0.4 and 0.2 g/plant were evaluated for CLM infestation and the associated citrus canker disease in nursery plantations of Citrus reticulata Blanco. Application of biofert at 0.5 kg/plant reduced the CLM infestation up to 54.5% during Fall-2016 and 39.1% during Summer-2017 in comparison to control treatment. The CLM larval density was also found lower by the application of biofert followed by vermicompost during both seasons. Both concentrations of biofert followed by vermicompost at 0.5 kg/plant resulted in remarkable protection against citrus canker disease in both flushes. The incidence of canker associated with CLM infested leaves was also studied and found lower by the application of biofert and vermicompost compared with control treatment. Conclusively, the soil amendment using biofert and vermicompost affects the CLM population and canker infection in nursery plantations. These organic fertilizers can be used in future citrus IPM programs as a tool to suppress the CLM population and citrus canker disease.

Dietary and developmental shifts in butterfly-associated bacterial communities

Bacterial communities associated with insects can substantially influence host ecology, evolution and behaviour. Host diet is a key factor that shapes bacterial communities, but the impact of dietary transitions across insect development is poorly understood. We analysed bacterial communities of 12 butterfly species across different developmental stages, using amplicon sequencing of the 16S rRNA gene. Butterfly larvae typically consume leaves of a single host plant, whereas adults are more generalist nectar feeders. Thus, we expected bacterial communities to vary substantially across butterfly development. Surprisingly, only few species showed significant dietary and developmental transitions in bacterial communities, suggesting weak impacts of dietary transitions across butterfly development. On the other hand, bacterial communities were strongly influenced by butterfly species and family identity, potentially due to dietary and physiological variation across the host phylogeny. Larvae of most butterfly species largely mirrored bacterial community composition of their diets, suggesting passive acquisition rather than active selection. Overall, our results suggest that although butterflies harbour distinct microbiomes across taxonomic groups and dietary guilds, the dramatic dietary shifts that occur during development do not impose strong selection to maintain distinct bacterial communities across all butterfly hosts.

Efficacy of the Vermicomposts of Different Organic Wastes as “Clean” Fertilizers: State-of-the-Art

Vermicomposting is a process in which earthworms are utilized to convert biodegradable organic waste into humus-like vermicast. Past work, mainly on vermicomposting of animal droppings, has shown that vermicompost is an excellent organic fertilizer and is also imbibed with pest-repellent properties. However, there is no clarity whether vermicomposts of organic wastes other than animal droppings are as plant-friendly as the manure-based vermicomposts are believed to be. It is also not clear as to whether the action of a vermicompost as a fertilizer depends on the species of plants being fertilized by it. This raises questions whether vermicomposts are beneficial (or harmful) at all levels of application or if there is a duality in their action which is a function of their rate of application. The present work is an attempt to seek answers to these questions. To that end, all hitherto published reports on the action of vermicomposts of different substrates on different species of plants have been assessed. The study reveals that, in general, vermicomposts of all animal/plant based organic wastes are highly potent fertilizers. They also possess some ability to repel plant pests. The factors that shape these properties have been assessed and the knowledge gaps that need to be bridged have been identified.

Vermicomposts of Different Origins Protect Tomato Plants Against the Sweetpotato Whitefly

The effect of four vermicomposts, obtained from different organic sources (pistachio waste [PWV], date waste [DWV], cattle manure waste [CMV], and food waste [FWV]), as well as two chemical fertilizers (complete fertilizer [CF] and NPK fertilizer [NPK]) on some life history traits of the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) was investigated in a series of choice and not choice experiments. In a choice experiment, adult whiteflies exhibited significantly lower preference for settling and oviposition on plants treated with vermicomposts than those in control, CF, and NPK groups (P < 0.01), with better results were observed in PWV group. In no choice experiment, adult whiteflies laid significantly fewer eggs in PWV group in comparison with control, CF, and NPK groups (P < 0.01); other treatments had intermediary values. Fertilization had a significant effect on the preadult development time of sweetpotato whitefly, with the longest development times were recorded for plants treated with PWV (24.65 d) and FWV (22.04 d), respectively. The preadult mortality of sweetpotato whitefly increased significantly following fertilization, with the greatest mortal effects were observed in PWV (54.11%) and DWV (44.68%) groups, respectively. Plants fertilized with PWV had significantly higher phenolic content (10 mg/ml) than control (BAGA; 6.08 mg/ml), while those in CMV group exhibited intermediary value (7.28 mg/ml). Altogether, results of this study reveal both antixenosis (nonpreference) and antibiosis (decreased survival and prolonged development time) resistance of tomato plants mediated by vermicomposts. Particularly, plants treated with PWV obtained the best results in terms of both growth and resistance to sweetpotato whitefly.

Developing Biostimulants From Agro-Food and Industrial By-Products

In modern agriculture, seeking eco-friendly ways to promote plant growth and enhance crop productivity is of priority. Biostimulants are a group of substances from natural origin that contribute to boosting plant yield and nutrient uptake, while reducing the dependency on chemical fertilizers. Developing biostimulants from by-products paves the path to waste recycling and reduction, generating benefits for growers, food industry, registration and distribution companies, as well as consumers. The criteria to select designated by-products for valorizing as biostimulant are: absence of pesticide residue, low cost of collection and storage, sufficient supply and synergy with other valorization paths. Over the years, projects on national and international levels such as NOSHAN, SUNNIVA, and Bio2Bio have been initiated (i) to explore valorization of by-products for food and agriculture industries; (ii) to investigate mode of action of biostimulants from organic waste streams. Several classes of waste-derived biostimulants or raw organic material with biostimulant components were shown to be effective in agriculture and horticulture, including vermicompost, composted urban waste, sewage sludge, protein hydrolysate, and chitin/chitosan derivatives. As the global market for biostimulants continues to rise, it is expected that more research and development will expand the list of biostimulants from by-products. Global nutrient imbalance also requires biostimulant to be developed for targeted market. Here, we review examples of biostimulants derived from agricultural by-products and discuss why agricultural biomass is a particularly valuable source for the development of new agrochemical products.

Humic Fertilizer and Vermicompost Applied to the Soil Can Positively Affect Population Growth Parameters of Trichogramma brassicae (Hymenoptera: Trichogrammatidae) on Eggs of Tuta absoluta (Lepidoptera: Gelechiidae)

The tomato leaf miner, Tuta absoluta (Meyrick), is a devastating pest of tomato worldwide. One of the control measures of T. absoluta is the use of biological control agents, such as Trichogramma wasps. Interactions between natural enemies and insect pests may be affected by application of fertilizers, because changes in plant quality through the fertilizer application may therefore affect herbivore characteristics and suitability of them to parasitism. Laboratory tests were carried out to evaluate the life table parameters of Trichogramma brassicae Bezdenko on T. absoluta eggs reared on tomato plants treated either with vermicompost (40%), humic fertilizer (2 g/kg soil), or control (suitable mixture of field soil and sand). Population growth parameters of T. brassicae were affected by fertilizer treatments. Significant differences were found for immature life period and total fecundity of T. brassicae on the treatments. Differences of intrinsic rate of natural increase (r _m), finite rate of increase (λ), net reproductive rate (R ₀), mean generation time (T), and doubling time (DT) of T. brassicae among treatments were also significant. The lowest values of r _m, λ, and R ₀ were recorded for T. brassicae developed on T. absoluta eggs on control treatment, whereas the highest values of these parameters were observed on 2 g/kg humic fertilizer. Furthermore, T. brassicae had the shortest T and DT values on 2 g/kg humic fertilizer and 40% vermicompost treatments. Our results showed that application of humic fertilizer and vermicompost could positively affect population growth parameters of T. brassicae on eggs of T. absoluta fed on tomato plants.

Spectroscopic, thermogravimetric and structural characterization analyses for comparing Municipal Solid Waste composts and vermicomposts stability and maturity

This is the first-ever study of its kind for an extensive assessment and comparison of maturity indexes between compost and vermicompost that have been derived from Municipal Solid Waste (MSW). The spectroscopic (Fourier transform infrared spectroscopy: FT-IR), thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and structural characterization (scanning electron microscope: SEM) were recorded. FT-IR spectra showed an increase in conversion of polysaccharides species and aliphatic methylene groups in vermicompost compared to compost as depicted from the variation of the intensity of the peaks. TG curves of final vermicompost showed a much lower mass loss when compared to compost, indicating higher stability in feedstock. SEM micrographs of the vermicompost reflected strong fragmentation of material than composts which revealed the extent of intra-structural degradation of MSW. These findings elucidate on a clear comparison between composts and vermicomposts in terms of maturity indexes for soil enhancement and in agriculture as organic fertilizer.

Detoxification of parthenium (Parthenium hysterophorus) and its metamorphosis into an organic fertilizer and biopesticide

BACKGROUND

Vermicompost of the toxic and allelopathic weed parthenium (Parthenium hysterophorus) was explored for its possible use as an organic fertilizer. Replicated plant growth trials were conducted using four levels of parthenium vermicompost (0, 2.5, 3.75, and 5 t/ha) to assess their effects on the germination, growth, and fruition of a typical food plant ladies finger (Abelmoschus esculentus). Additionally the role of vermicompost in reducing plant pests and disease was evaluated.

RESULTS

Vermicompost encouraged the germination and growth of ladies finger at all levels of vermicompost application, with best results obtained in 5 t/ha treatments. The positive impact extended up to the fruit yield. Vermicompost application also improved the quality of fruits in terms of mineral, protein, and carbohydrate contents, and reduced the disease incidence and pest attacks.

CONCLUSIONS

The studies establish the fact that parthenium acquires all the qualities of a good organic fertilizer with concomitant loss of its toxic and allelopathic properties after it gets vermicomposted. The findings raise the prospects of economical and eco-friendly utilization of billions of tons of parthenium biomass which is generated annually but goes to waste at present.

Population Growth Parameters of Tuta absoluta (Lepidoptera: Gelechiidae) on Tomato Plant Using Organic Substrate and Biofertilizers

The tomato leafminer, Tuta absoluta (Meyrick) is a devastating pest associated with tomato. In this study, effects of tomato plants treated with vermicompost (20, 40, and 60%), humic fertilizer (2, 4 and 6 g/kg soil) and plant growth promoting rhizobacteria (Pseudomonas fluorescens and Bacillus subtilis) were investigated on the life table parameters of T. absoluta in a growth chamber at 25 ± 2 °C, 65 ± 5% RH, and 16:8 (L:D) h. Significant differences were found for the total developmental time, fecundity, and oviposition period of T. absoluta on the treatments tested. The net reproductive rate (R0), intrinsic rate of natural increase (rm), finite rate of increase (λ), mean generation time (T), and doubling time (DT) of T. absoluta were significantly different among treatments tested. We found that in all vermicompost, humic fertilizer and plant growth promoting rhizobacteria treatments, values of R0, rm, and λ were lower than control treatment. However, the lowest values of these parameters were obtained on 2 g/kg humic fertilizer and 40% vermicompost. Furthermore, T. absoluta had longest T and DT values on 2 g/kg humic fertilizer treatment. Data obtained showed that the addition of 2 g/kg humic fertilizer and 40% vermicompost to the growing soil reduced T. absoluta populations in tomato cultures. In addition, these levels of fertilizers improved growth parameters of tomato seedlings (plant height, wet weight, and dry weight) compared with other treatments. These results could be useful in improving the sustainable management of the moth.

Transformation of toxic and allelopathic lantana into a benign organic fertilizer through vermicomposting

In a first study of its kind, the composition of vermicompost derived solely from the toxic and allelopathic weed lantana has been investigated using UV-visible and Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) and differential scanning calorimetry (DSC), gas chromatography-mass spectometry (GC-MS), and scanning electron microscopy (SEM). The studies reveal that a sharp reduction in humification index, substantial mineralization of organic matter and degradation of complex aromatics such as lignin and polyphenols into simpler carbohydrates and lipids occur in the course of vermicomposting. GC-MS analysis shows significant fragmentation, bio-oxidation and molecular rearrangements of chemical compounds in vermicompost in comparison to those in lantana. SEM micrographs of vermicompost reflect strong disaggregation of material compared to the much better formed lantana matrices. The phenols and sesquiterpene lactones which are specifically responsible for the toxicity and allelopathy of lantana are seen to get significantly degraded in the course of vermicomposting - turning it into a plant-friendly organic fertilizer. The study leads to the possibility that the millions of tons of phytomass that is generated annually by lantana can be gainfully utilized in producing organic fertilizer via vermicomposting.

An overview of the environmental applicability of vermicompost: from wastewater treatment to the development of sensitive analytical methods

The use of vermicompost (humified material) for treating wastewaters, remediating polluted soils, improving agricultural productivity, protecting crop production, and developing sensitive analytical methods is reviewed here, covering the past 17 years. The main advantages of vermicompost, considering all applications covered in this paper, comprise (i) easy acquisition, (ii) low costs, (iii) structural, chemical, and biological characteristics responsible for exceptional adsorptive capacities as well as pollutant degradation, and (iv) the promotion of biocontrol. Specifically, for wastewater decontamination, a considerable number of works have verified the adsorption of toxic metals, but the application of vermicompost is still scarce for the retention of organic compounds. Problems related to the final disposal of enriched vermicompost (after treatment steps) are often found, in spite of some successful destinations such as organic fertilizer. For decontaminating soils, the use of vermicompost is quite scarce, mainly for inorganic pollutants. In agricultural productivity and biocontrol, vermicompost imparts remarkable benefits regarding soil aggregation, plant nutrition, and the development of beneficial microorganisms against phytopathogens. Finally, the use of vermicompost in sensitive analytical methods for quantifying toxic metals is the newest application of this adsorbent.

Microbial diversity of vermicompost bacteria that exhibit useful agricultural traits and waste management potential

Vermicomposting is a non-thermophilic, boioxidative process that involves earthworms and associated microbes. This biological organic waste decomposition process yields the biofertilizer namely the vermicompost. Vermicompost is a finely divided, peat like material with high porosity, good aeration, drainage, water holding capacity, microbial activity, excellent nutrient status and buffering capacity thereby resulting the required physiochemical characters congenial for soil fertility and plant growth. Vermicompost enhances soil biodiversity by promoting the beneficial microbes which inturn enhances plant growth directly by production of plant growth-regulating hormones and enzymes and indirectly by controlling plant pathogens, nematodes and other pests, thereby enhancing plant health and minimizing the yield loss. Due to its innate biological, biochemical and physiochemical properties, vermicompost may be used to promote sustainable agriculture and also for the safe management of agricultural, industrial, domestic and hospital wastes which may otherwise pose serious threat to life and environment.

Use of DGGE and COMPOCHIP for investigating bacterial communities of various vermicomposts produced from different wastes under dissimilar conditions

This study describes the use of denaturing gradient gel electrophoresis (DGGE) and COMPOCHIP (i.e. a microarray targeting typical bacteria of stabilized organic materials and pathogenic bacteria) for investigating the bacterial communities of four different vermicomposts. These included a commercial vermicompost produced from cattle manure (CM) and three vermicomposts produced at pilot-scale by recycling: damaged tomato fruits (DT); olive-mill waste mixed with biosolids (OB); and winery wastes (WW). DGGE provided distinctive fingerprints of each vermicompost, which were statistically related to their particular chemical features. The comparison of the various vermicompost fingerprints showed that they contained bacterial communities with an average similarity coefficient of close to 80%. COMPOCHIP detected the presence of Sphingobacterium, Streptomyces, Alpha-Proteobacteria, Delta-Proteobacteria, and Firmicutes in all the vermicomposts. COMPOCHIP showed differences in the abundance of particular bacterial taxa among the vermicomposts, giving an idea about the usefulness of each vermicompost in the search for bacteria valuable to biotechnology. The joint use of DGGE and COMPOCHIP is a useful tool to compare vermicompost bacterial communities and to assess the potential of different vermicomposts as bioactive organic materials.

Effect of vermicompost and cucumber cultivar on population growth attributes of the melon aphid (Hemiptera: Aphididae)

Worldwide, the developing industry of cucumbers (Cucumis sativus L.) grown in greenhouses is threatened by damage from sucking pests, especially aphids. Among these, the melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is the most serious. We tested the effect of two cucumber cultivars ('Royal' and'Storm') and three vermicompost concentrations (0 [control], 20, and 30%) in field soil on the development and fecundity rates of A. gossypii, by using a randomized complete block design with four replicates as a factorial experiment. The developmental times of nymphs reared on plants grown into the three vermicompost concentrations ranged from 5.5 (0%) to 8.7 (30%) d (on Storm) and from 4.3 (0%) to 7 (30%) d (on Royal). The developmental time of melon aphid's nymphs was greatest on plants grown in the culture medium with 30% vermicompost rate and least on plants reared in the soil without vermicompost. The intrinsic rate of natural increase (r,,) of A. gossypii ranged from 0.204 d(-1) on plants grown in the soil amended with 30% vermicompost rate (on Storm seedlings) to 0.458 d(-1) on plants grown in the soil without vermicompost (on Royal seedlings). Accordingly, our findings confirm that a combination of a low level of vermicompost and a partially resistant cucumber cultivar might play an important role in managing this aphid on cucumbers in greenhouses.

Arabidopsis thaliana resistance to insects, mediated by an earthworm-produced organic soil amendment

BACKGROUND

Vermicompost is an organic soil amendment produced by earthworm digestion of organic waste. Studies show that plants grown in soil amended with vermicompost grow faster, are more productive and are less susceptible to a number of arthropod pests. In light of these studies, the present study was designed to determine the type of insect resistance (antixenosis or antibiosis) present in plants grown in vermicompost-amended potting soil. Additionally, the potential role of microarthropods, entomopathogenic organisms and non-pathogenic microbial flora found in vermicompost on insect resistance induction was investigated.

RESULTS

Findings show that vermicompost from two different sources (Raleigh, North Carolina, and Portland, Oregon) were both effective in causing Arabidopsis plants to be resistant to the generalist herbivore Helicoverpa zea (Boddie). However, while the Raleigh (Ral) vermicompost plant resistance was expressed as both non-preference (antixenosis) and milder (lower weight and slower development) toxic effect (antibiosis) resistance, Oregon (OSC) vermicompost plant resistance was expressed as acute antibiosis, resulting in lower weights and higher mortality rates.

CONCLUSION

Vermicompost causes plants to have non-preference (antixenosis) and toxic (antibiosis) effects on insects. This resistance affects insect development and survival on plants grown in vermicompost-amended soil. Microarthropods and entomopathogens do not appear to have a role in the resistance, but it is likely that resistance is due to interactions between the microbial communities in vermicompost with plant roots, as is evident from vermicompost sterilization assays conducted in this study.

Arthropod pest management in organic crops

Burgeoning consumer interest in organically produced foods has made organic farming one of the fastest growing segments of agriculture. This growth has not been supported adequately by rigorous research to address challenges such as arthropod pest management. The research that has been conducted, however, is complemented by research in aspects of conventional agriculture that may have applicability in organic systems, as well as by research in underpinning fields such as applied ecology. This article synthesizes the available literature in relation to a conceptual model of arthropod pest management strategies suitable for organic systems. The present work uses the four phases of the model to review the strategies in an agroecological context and provides a synthesis of the factors that influence the success of each phase. Rather than constituting a fringe science, pest management research for organic systems draws on cutting edge science in fields such as landscape and chemical ecology and has a bright future.