Comparative effects of three insect growth regulator insecticides and a dipteran-active strain of Bacillus thuringiensis on cropping of the cultivated mushroom Agaricus bisporus

Three insect growth regulator insecticides and an entomopathogenic strain of Bacillus thuringiensis (GC327), products effective against the mushroom sciarid, Lycoriella auripila, were compared for their effect on mushroom cropping. Cyromazine and diflubenzuron were applied as a surface drench to mushroom compost before or after pasteurisation (at filling or spawning, respectively); admixed into casing material (at casing); or at a combination of these times. Hexaflumuron and GC327 were applied only at filling and casing, respectively. The presence of the target pest, L. auripila, had no effect on treatment trends, although it was accounted for in the analysis by use of a yield model. The trial was notable for the disparate effects that cyromazine and diflubenzuron casing treatments had on mushroom cropping. Cyromazine treatments that included application at casing resulted in increases in yield, compared to the untreated control whereas, with diflubenzuron, the opposite was true, with treatment at casing alone causing the greatest reduction overall (10%). GC327 applied at casing was also conspicuous for giving a 13% increase in yield. Treating the crop at casing with either cyromazine or GC327, therefore, resulted in a 15% or 24% increase in yield, respectively, compared to a similar treatment with diflubenzuron. Hexaflumuron applied at filling caused increases in yield compared to application of cyromazine at filling and cyromazine or diflubenzuron at spawning. There were also effects on crop timing. The addition of a cyromazine casing treatment normally caused the distinct flushes of mushrooms to be produced significantly earlier than the untreated control (up to 2.5 days), as did GC327. With diflubenzuron, the earlier flushes were only produced by those treatments that did not include a casing application. The combinations that included a casing treatment with diflubenzuron initially produced mushroom flushes earlier than the untreated control. They became either synchronous with the control or they were delayed. From the crop tolerance perspective, therefore, cyromazine and GC327 would be the sciarid control products of choice for a commercial mushroom grower.     

The comparative effects of three formulations of diazinon on cropping of a hybrid and a non-hybrid strain of the cultivated mushroom Agaricus bisporus

Three formulations of diazinon: flowable granules (FG); wettable powder (WP); and emulsifiable concentration (EC), which are used for the control of mushroom pests, were compared for toxicity towards a hybrid and non-hybrid strain of the cultivated mushroom, Agaricus bisporus. With all formulations, yield and number of mushrooms were reduced according to dosage (linear trend). The EC was the most toxic and persistent formulation – equally so to both mushroom strains – and produced the most severe responses in all the parameters considered. The WP was the least toxic formulation. The hybrid strain was more susceptible to diazinon than the non-hybrid, but not markedly so.     

Effects of Caenorhabditis elegans (Nematoda: Rhabditidae) on yield and quality of the cultivated mushroom Agaricus bisporus

Thirteen species of saprobic rhabditid nematodes (11 genera) were identified from samples of compost and casing material collected from mushroom farms in the British Isles. Caenorhabditis elegans, the most frequently found saprobe, was mass-produced monoxenically and its effects on the cultivated mushroom, Agaricus bisporus (strain U3) were studied. C. elegans did not multiply in well-prepared, pasteurised, spawned compost, whereas casing material proved to be a highly suitable environment for its reproduction. An initial casing inoculum of 10⁶ nematodes/crate of compost (7.5 kg), caused a significant reduction in mushroom yield. Losses in total mushroom yields of 11%, 20% and 26% were caused by initial inoculum rates of 10⁶, 10⁷and 2 × 10⁷ nematodes/crate, respectively. Yields were negatively correlated with the initial nematode inoculation level and regression equations were derived. The nematode treatments caused fewer mushrooms to be produced and an absence of the usual distinctive flushing patterns. C. elegans caused considerable deterioration in mushroom quality and characteristic distortion of mushrooms. Individual sporophores were mis-shapen, notched and had brown or violet coloured grills. Up to 3.8%, 6.7% and 10.8% of total weight and 3.5%, 5.4% and 8% of total numbers of mushrooms were distorted at the three highest nematode inoculum rates tested. Weights and numbers of distorted mushrooms were positively correlated with the initial nematode population. C. elegans commonly colonised sporophores.     

Comparative effects of Steinernema feltiae (Nematoda: Steinernematidae) and insecticides on yield and cropping of the mushroom Agaricus bisporus

In a mushroom crop (Agaricus bisporus) affected by a very low level of sciarid fly (Lycoriella auripila) infestation, the effects of an indigenous isolate of insect-parasitic nematode (Steinernema feltiae) and of two commonly used insecticides (diazinon and diflubenzuron) were studied. When compared with untreated plots, nematodes applied to the casing had no adverse effects on mushroom yields whereas insecticides decreased yields. At a rate of 3 × 10⁶ infective juveniles per tray (surface area = 0.56 m²), S. feltiae elicited increases of 28.5% and 19% in the mean total numbers and weights of mushrooms respectively. Treatment only with diflubenzuron resulted in 14.6% and 6% reductions in mean total numbers and weights of mushrooms, respectively; treatment with both diazinon and diflubenzuron caused 18.5% and 9.4% losses. Application of nematodes generally reduced the mean weight per mushroom whereas insecticides increased it; nematodes delayed the onset of mushroom production (first flush) whereas diflubenzuron delayed the third and fourth flushes. Nematode contamination of sporophores was minimal when S. feltiae was applied at casing. Although their numbers declined with time, the nematodes persisted, in the casing layer, throughout the cropping period of seven weeks. It is concluded that yield benefits associated with nematode application can result mainly from nematode effects on A. bisporus and not solely from suppression of a damaging pest population.     

Effects of methoprene and permethrin on paedogenetic larvae of Heteropeza pygmaea and Mycophila speyeri (Diptera: Cecidomyiidae)

The effects of methoprene and permethrin on larvae of Heteropeza pygmaea Winnertz and Mycophila speyeri (Barnes), two Cecidomyiid species of paedogenetic insect mushroom pest, were investigated in sterile culture at concentrations of 0.1-100 micrograms/g. The two highest concentrations of permethrin caused complete mortality of M. speyeri but only low mortality of H. pygmaea. The main sublethal effects of permethrin on both species were reduced fecundity and reduced mother-larval width. Methoprene had only sublethal effects on both species. At all doses, methoprene caused an increase in H. pygmaea generation time but a reduction in hemipupal width and fecundity according to dosage. The effects on M. speyeri were similar but more severe.     

The use of chemicals, antagonists, repellents and physical barriers for the control of Lycoriella auripila (Diptera: Sciaridae), a pest of the cultivated mushroom Agaricus bisporus

The sciarid, Lycoriella auripila, is a serious pest of commercial mushroom production. A series of trials demonstrated that the use of early, specifically-targeted, treatments of insecticides and/or antagonists and repellents, which distance treatment time from crop harvest, have the potential to play a useful part in the control of initial and subsequent generations of this pest. Of the treatments examined, those involving a drench treatment of the compost at filling (before pasteurisation) proved to be the most effective. Cyromazine and diflubenzuron were the most active insecticides tested, with cyromazine achieving a superior level of control of the initial infestation. Repellents and antifeedants were also effective, with calcium oxalate and sinapic acid both achieving about 50% control when applied at filling. Treatments applied later during the production cycle, unless in combination with a treatment at filling, were progressively less effective at controlling both the initial sciarid infestation and later generations of larvae. Multiple treatments caused greater reductions in fly populations than did the single treatments and continued to do so throughout the cropping cycle, the greatest reduction in the initial generation (79%) occurring with a triple treatment of cyromazine. With the exception of some diflubenzuron treatments, those that were effective resulted in increases in yield. The use of a physical paper barrier caused significant increases in both fly numbers and total yield.     

Properties of peat-based casing soils and their influence on the water relations and growth of the mushroom (Agaricus bisporus)

Different combinations of peat and chalk or lime sources with differing moisture contents were used to determine how specific physical and chemical properties of the casing soil relate to the growth and water relations of the mushroom. The peat types varied in terms of decomposition and extraction method; the lime addition varied in terms of rate and type (chalk or sugar beet lime). During the colonisation of the casing soil before fruiting, the extension growth rate of mushroom mycelium was most closely correlated (negatively) with the volumetric moisture content of the casing soil. Scanning electron microscopy showed that mycelium growing at a lower casing soil matric potential (Ψ_m) had a much finer and branched structure than mycelium growing at a higher Ψ_m. Across all the peat and lime source treatments, a relationship was found between the mean Ψ_m of the casing soil and mushroom yield, with an optimum Ψ_m of -7.9 to -9.4 kPa. Mushrooms are produced in ‘flushes’ at about 8-day intervals and during the development of each flush of mushrooms, there was a significant decrease in casing soil Ψ_m . This decrease (to below -40 kPa) was greatest in the second flush, which was the highest yielding. There were no relationships between mushroom yield and casing soil osmotic potential Ψ_π within the range -93 to -154 kPa or any of the other chemical properties and water and air holding characteristics of the casing soils which were determined. Across different casing soil treatments, mushroom dry matter content was negatively correlated with mushroom yield and positively correlated with mushroom tissue osmotic potential. This revised version was published online in June 2006 with corrections to the Cover Date.     

Comparison of the effect of two types of whole mushroom (Agaricus bisporus) powders on intestinal fermentation in rats

The effects of two types of mushroom (Agaricus bisporus; white, WM; brown, BM) powders on intestinal fermentation in rats were investigated in terms of the physical characteristics of animals and by bacterial and HPLC analyses of cecal contents. Short-chain fatty acid levels were found to be significantly higher in the WM group than in the BM and the control (CN) groups; coliform bacteria levels in the BM group were significantly lower than those in the CN group, with the WM group inducing an apparent but insignificant decrease in coliforms. Anaerobe levels in the WM group were significantly higher than those in the CN group and, compared with the CN group, the BM and WM groups exhibited significantly increased feces weight and cecum weight, respectively. These results indicate that the mushroom powders, and in particular the WM powder, have beneficial effects on the intestinal environment in rats.     

Use of molecular markers to differentiate between commercial strains of the button mushroom Agaricus bisporus

Agaricus bisporus is an edible basidiomycete cultivated industrially for food production. Different spawn and mushroom producers use genetically related A. bisporus strains frequently marketed as different products. In this paper we show that the use of suitable molecular markers reveals the high level of genetic homology of commercial strains of A. bisporus, and allows, at the same time, to distinguish between them. In the course of this work, a molecular marker potentially linked to the agronomic character 'mushroom weight' has been identified by bulked segregant analysis.     

Resource allocation ability of wild isolates of Agaricus bisporus on conventional mushroom compost

Abstract: Twenty-one wild isolates from two distinct sites and six cultivated strains of Agaricus bisporus were cultivated on a conventional mushroom compost. Their degradative abilities were studied by measuring 12 extracellular enzyme activities produced during mycelial growth. Differences in production of enzyme activities and in compost colonisation were observed between the three groups of strains and within each group. They were used to define the mechanisms of resource allocation in mushroom compost. The ability to grow and produce sporophores on mushroom compost appeared to be linked with the production of a balanced pool of enzymes including moderate levels of polysaccharidases active on straw cell walls and of enzymes able to degrade microbial biomass and microbial products.     

浙江短角瘿蚊属一新种记述(双翅目:瘿蚊科)

记述采自浙江省的短角瘿蚊1新种:狭短角瘿蚊Anarete angusta Mo et Xu,sp.nov..     

The indigenous coastal Californian population of the mushroom Agaricus bisporus, a cultivated species, may be at risk of extinction

This study employed nuclear and mitochondrial markers to assess the present-day composition of the population of Agaricus bisporus in coastal California. Favourable weather in the fall, winter and spring of 1990–91 furnished an uncommon opportunity to collect and study field material of the ‘button mushroom’A. bisporus, a cultivated species, from the region. The previous such season occurred 13 years earlier. Ninety-five nonredundant cultures from field material were prepared and genotypically characterized. These data were combined with data from earlier studies. Multilocus nuclear and mitochondrial genotypes were determined for 123 individuals. Genotypes were compared in pairwise fashion both within the sample and between this sample and others of diverse geographical origin or commercial provenance. Using parametric analysis and cluster analysis of nuclear similarities, and also mitochondrial data, two elements – indigenous and European – were apparent within the sample. This was consistent with our earlier results on a much smaller sample. At least 10 mitochondrial haplotypes (MTs) were present; based on genotypic similarities of associated nuclei, five (or six) MTs were Californian, four were European, and one was ambiguous. Based on MT origins, 54% of the 121 classifiable individuals in California were of European ancestry; natives constituted a minority at 46%. Even in the indigenous Monterey cypress habitat, where 84% of all individuals from California were sampled, non-native A. bisporus appeared to have achieved parity (at 48–49%) with the native population. In all other habitats, which are far more extensive, European individuals outnumbered Californian natives by 4:1. Some evidence of hybridization between the two ancestral groups was found. European strains appear to have been resident in California for approximately one century. The extensive occupancy of the native habitat by non-native germ plasm, the apparent inability of native strains to occupy or compete in non-native habitats, and the disproportionately large inoculum reservoirs represented by non-native habitat and agronomic activities all suggest that the native population is under considerable competitive pressure in what may be a very dynamic situation. If this surmise is correct, the native population may be at serious risk of further contraction, irreversible dilution through interbreeding, and possibly even extinction.     

Male germ line,spermatogenesis and karyotypes of Heteropeza pygmaea winnertz (Diptera: Cecidomyiidae)

The germ line during the development of the male of the gall midge Heteropeza pygmaea was followed cell generation by cell generation. The development of the male egg begins with two meiotic divisions, followed by fusion of one of the resulting nuclei with (usually) two somatic nuclei (regulation), after which the regulated nucleus passes through 9–10 mitoses, and finally a further two meiotic divisions producing the spermatids. The chromosome numbers (determined by colchicine and air-drying techniques) of the race studied are 55 in the female germ line, very variable with a mean near 47–48 in the male germ line after regulation, 5 or 6 in the sperms, 10 in the female somatic nuclei and 5 in the male somatic nuclei. Statistical techniques for analysis of the different karyotypes are developed and a model explaining the known cytological events in Heteropeza is presented.     

The effect of sciarid larvae (Lycoriella auripila) on cropping of the cultivated mushroom (Agaricus bisporus)

Significant linear relationships between the mean number of sciarid, Lycoriella auripila, larvae/125 g-sample of casing and yield, numbers of mushrooms and weight/mushroom were demonstrated at all stages of a mushroom crop. Negative relationships were obtained for yield throughout the cropping period. There was no injury threshold for this pest, although an economic threshold of one larva/sample was deduced. Loss in yield was mostly due to the destruction of mushroom primordia and presumed interruption of nutrient supply to the developing sporophores. Numbers of mushrooms were severely reduced in the first, second and third flushes, more so than yield, although a large increase in numbers was demonstrated in the fourth flush. The size of mushroom was inversely related to numbers, although the increases in size in the first three flushes were insufficient to compensate for the reduction in numbers. A reduction in size was evident in the fourth flush.     

环境因子对双孢蘑菇损伤敏感性的影响（英文）

在机械损伤过程中,白色双孢蘑菇极易被损伤并迅速褐变,使得机械采收的鲜菇质量低下,并且影响机械采收技术的应用和发展。机械采收双孢蘑菇的褐变程度(损伤敏感性)受栽培环境条件的影响。本文应用因子设计分析的方式研究多个因子对双孢蘑菇机械损伤敏感性的影响。以4个菌株为材料测试3个环境因子对双孢蘑菇损伤敏感性的影响,即覆土的厚度(分为2.5cm和5cm两个水平),覆土的湿度(分为干覆土和正常覆土两个水平),以及菇房内的相对湿度(分为80%和87%两个水平)。目的是找出能够在不敏感菌株和敏感菌株间产生最大敏感性差异的环境条件,由此得到的环境条件将应用到后续的群体分离分析中以得到最大的敏感性变异率。根据方差分析结果得出基因型(菌株)和覆土厚度是影响损伤敏感性的显著性因子,因子间相互作用显著。能够在不敏感菌株和敏感菌株间产生最大的损伤敏感性差异的环境条件为正常湿度的5cm厚覆土材料和87%的菇房内相对湿度。     

Relative contribution of nematodes (Caenorhabditis elegans) and bacteria towards the disruption of flushing patterns and losses in yield and quality of mushrooms (Agaricus bisporus)

Laboratory tests of bacteria isolated from the body surface, or from the gut, of a saprophagous rhabditid nematode Caenorhabditis elegans infesting mushrooms (Agaricus bisporus) showed that some bacteria enhanced nematode reproduction and that others inhibited it. As some bacteria were shown to inhibit mycelial growth of the mushroom, the effects of Acinetobacter calcoaceticus var. anitratus, Enterobacter cloacae and Serratia liquefaciens, either alone or in combination with C. elegans, on the flushing patterns, quality and yield of A. bisporus (strain Horst U3) were studied. Bacteria alone had little effect on flushing patterns whereas C. elegans delayed the onset of mushroom production and significantly disrupted the growth pattern of crops, with mushrooms appearing more regularly and not within obvious flushes. Inoculation with bacteria resulted in ‘browning’ of mushrooms that was even more pronounced in C. elegans treatments. Characteristic distortion of sporophores was observed only in the presence of C. elegans. Nematodes commonly colonised sporophores. Bacteria affected the size of nematode populations both on the sporophores and in the casing. Significant yield loss occurred; up to 10% when bacteria were inoculated, up to 27.8% when C. elegans was inoculated, and up to 35% with both bacteria and nematodes. Synergism between C. elegans and A. calcoaceticus var. anitratus was observed; the combination resulted in significantly greater reduction in mushroom yield than any other treatment. It is concluded that bacteria contribute to yield loss and quality deterioration in A. bisporus but that the effects are far greater in the presence of C. elegans.     

Selective breeding of Steinernema feltiae (Filipjev) (Nematoda: Steinernematidae) for improved efficacy in control of a mushroom fly,Lycoriella solani Winnertz (Diptera: Sciaridae)

A method of selecting a Steinernema feltiae strain that is effective against a mushroom fly, Lycoriella solani, is described in detail. The pest control efficacy of the selected nematode strain was evaluated and compared with the efficacy of two unselected strains. The selection procedure was designed to give preference to nematode individuals with the greatest ability (1) to search effectively for the target insect larvae in their natural habitat, (2) to infect them shortly after application and (3) to reproduce in their haemocoel. Thirty‐four rounds of selection achieved a 4‐fold improvement in nematode ability to find and parasitize third‐ and fourth‐instar larvae of the pest in the mushroom substrate. In 24‐h laboratory experiments, mortality of the insect caused by nematode juveniles rose from 22.5%, recorded for the original unselected isolate, to 92.5% for the selected strain. In a 51‐day experiment conducted on a mixed age mushroom house population of L. solani, the enhanced pest control ability of the selected strain was detected shortly after nematode application and remained high throughout the experimental period. During the first 4 weeks of the trial the selected nematode strain was significantly better than both unselected strains and caused 91.1–92.7% reduction of the fly emergence from the mushroom substrate. No difference was observed between the efficacy of the selected nematodes applied at 1 × 10⁶ and 3 ×10⁶ infective juveniles per m², while the unselected strains performed significantly better at the higher concentration. All the nematodes examined showed good persistence in the mushroom casing apparently due to recycling in the insect host.     

Effects of Caenorhabditis elegans (Nematoda: Rhabditidae) on the spread of the bacterium Pseudomonas tolaasii in mushrooms (Agaricus bisporus)

The effects of mass-produced saprobic rhabditid nematodes, Caenorhabditis elegans on the spread of the bacterial blotch pathogen, Pseudomonas tolaasii , were studied in mushroom growth chambers. C. elegans significantly reduced the intensity of blotch on sporophores. Repeated isolations of the bacterial flora from the gut of C. elegans recovered from mushroom sporophores during cropping, revealed the presence of Pseudomonas fluorescens biovar reactans . All the isolates of P. fluorescens biovar reactans isolated from nematodes were antagonists of P. tolaasii .
C. elegans produced much larger populations in monoxenic cultures with P. fluorescens biovar reactans than with P. tolaasii . It is suggested that as C. elegans selects P. fluorescens biovar reactans rather than P. tolaasii as a food substrate it probably spreads the antagonist in the mushroom crop and may contribute to the control of bacterial blotch.     

原生质体紫外诱变选育姬松茸新菌株

对姬松茸原生质体进行紫外诱变处理,选育出在液体培养条件下生物量明显高于原始菌株的诱变株。经10代传代培养及摇瓶培养,表明该菌株稳定性良好,与出发菌株相比生物量提高5.5%,胞外多糖产量提高6.1%。