Entomopathogenic Fungus Metarhizium Anisopliae Research Articles

Compatibilidade entre Metarhizium anisopliae e fungicidas registrados para a cultura do feijão (Phaseolus vulgaris L.)

O objetivo da pesquisa foi analisar em condições laboratoriais a compatibilidade entre o fungo entomopatogênico Metarhizium anisopliae e fungicidas registrados para a cultura do feijão (Phaseolus vulgaris L.). Os agrotóxicos analisados foram Manzate WG® (i.a. mancozebe) (500 g × 100 L-1), Nativo® (i.a. tebuconazol + trifloxistrobina) (300 mL × 100 L-1), Portero® (i.a. carbendazim) (250 mL × 100 L-1) e Tebuco Nortox (i.a. tebuconazol) (250 mL × 100 L1). O efeito tóxico dos fungicidas sobre o entomopatógeno foi determinado em condição laboratorial, através da adição dos produtos químicos em meio de cultura BDA. Após solidificação do meio, foram inoculadas as estruturas reprodutivas do entomopatógeno, na concentração de 107 conídios/mL, totalizando oito repetições por tratamento. A viabilidade dos conídios foi analisada 24 h após inoculação, e após sete dias foi mensurada a área de crescimento da colônia (cm2), e contabilizado o número de conídios em cada tratamento, sendo as médias comparadas pelo teste de Tukey (P < 0,05), e padronizadas pela classificação de compatibilidade. Todos os fungicidas inibiram por completo o crescimento vegetativo e a conidiogênese de M. anisopliae. Apenas o ingrediente ativo mancozebe propiciou a viabilidade de conídios de M. anisopliae, representado por 7,25 ± 1,11% de conídios viáveis. Todos os fungicidas testados são tóxicos ao fungo entomopatogênico M. anisopliae, sob condição laboratorial.

Herbivore insects and predatory arthropods in freshwater swamp rice field in South Sumatra, Indonesia sprayed with bioinsecticides of entomopathogenic fungi and abamectin

Abstract. Herlinda S, Prabawati G, Pujiastuti Y, Susilawati, Karenia T, Hasbi, Irsan C. 2020. Herbivore insects and predatory arthropods in freshwater swamp rice field in South Sumatra, Indonesia sprayed with bioinsecticides of entomopathogenic fungi and abamectin. Biodiversitas 21: 3755-3768. Herbivore insect population and predatory arthropods in rice field may be effected by the application entomopathogenic fungi or synthetic insecticide. The objective of this research was to analyze individual quantity of herbivore insects and predatory arthropod inhabiting freshwater swamp rice fields treated with bioinsecticides and abamectin (commercial insecticide). This research was conducted in the freshwater swamp rice field located in Village Pelabuhan Dalam, Sub District Pemulutan, District Ogan Ilir, and South Sumatra. The experiment was arranged in a Completely Randomized Block Design consisted of four plots of treatment. The research used the bioinsecticides made from entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae, and Cordyceps military), and abamectin. Sampling to collect arthropods inhabiting rice canopy was also conducted using an entomological net in the study locations. This research found 12 families of herbivore insects with 22 species dominated by Nilaparvata lugens and Leptocorisa acuta and 32 species of spider belonged to eight families dominated by Tetragnatha virescens and Oxyopes matiensis. The species diversity of spider was higher in the plots of the bioinsecticide compared to that of the abamectin. Predatory insects found belonged to 14 species belonged to eight families dominated by species of Ophionea nigrofasciata, Verania discolor, and Paedorus fuscipe. The abundance of predatory insects in plots sprayed with the bioinsecticides was higher compared to that of the abamectin plot. The abundance and species diversity of predatory arthropod sprayed with bioinsecticide of B. bassiana, M. anisopliae, and C. militaris did not decrease, while the population of herbivore insect tended to decrease.

Roles of selenoprotein T and transglutaminase in active immunization against entomopathogenic fungi in the termite Reticulitermes chinensis

Active immunization can protect individuals from infectious diseases in social insects. It is well established that trace elements are essential to the host immune system, but the related gene functions in insect social immunity are unknown. Here, we found that the levels of three free elements (Se, Ca and Cr) and selenoprotein T (SELT) expression were significantly decreased in the termite Reticulitermes chinensis Snyder during active immunization against the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin. Thus, we further explored the role of the SELT gene in the active immunization of termites. After SELT was significantly silenced by RNAi, the nestmates of fungus-contaminated termites exhibited reduced antifungal activity and increased mortality, along with increased expression of the immune genes transglutaminase (TG) and transferrin (Tsf), indicating that the active immunization of termites was disrupted by SELT silencing. Moreover, the TG-knockdown nestmates of fungus-contaminated termites significantly decreased grooming behavior, antifungal activity and survival, despite the upregulation of SELT expression, also suggesting that the active immunization of termites was disrupted by the silencing of TG. These findings demonstrated that both SELT gene and TG gene play important roles in driving active immunization against the entomopathogenic fungus M. anisopliae in R. chinensis.

Mass multiplication of Metarhizium anisopliae on different media

Entomopathogenic fungi (EPF) Metarhizium anisopliae are fungal species that is the frequently occurring and destructive pest management to the pathogenic soil and insects. The effect of different substrates for the mass production of Metarhizium anisopliae spore/ml was significantly higher recorded The results revealed that all the treatments were significantly producing spore per ml and thus increasing the yield significantly as compared to other substrates. The results revealed that all the treatments were significantly higher effective in producing spore/ml as compared to other substrates overall finding showed that substrate tested, for Metarhizium anisopliae spore/ml production was significantly higher recorded 240.53 and 195.26 spore/ml were recorded on substrate irrespective of the temperature.

The aggregation pheromone phenylacetonitrile: Joint action with the entomopathogenic fungus Metarhizium anisopliae var. acridum and physiological and transcriptomic effects on Schistocerca gregaria nymphs

The combined use of entomopathogenic fungi and sublethal rate of chemical insecticides or other biological control agents have been proposed as an environmentally and sustainable strategy in the control of locust pests. In this paper, the quarter and the half of the recommended dose of Metarhizium anisopliae var. acridum (¼ and ½ Ma) and the aggregation pheromone (Phenylacetonitrile: PAN) were applied simultaneously and sequentially to Schistocerca gregaria fifth-instar nymphs. In addition, the physiological effects of PAN on locusts were assessed at the behavior, immune response, and biochemical level by evaluating for glutathione-S-transferase (GST), acetylcholinesterase inhibition (AChE), and malondialdehyde accumulation (MDA). Results showed that simultaneous application of PAN and the entomopathogenic fungus exhibited additive interaction. Synergistic interaction was also demonstrated when nymphs were exposed to PAN first, then treated with M. anisopliae var. acridum. Behavioral bioassay revealed that fifth-instar nymphs avoided the PAN odour and tended to remain away from the stimulus cup. In the choice assay, the pheromone significantly repelled the locusts at 2, 4, and 6 h of exposure which selected the PAN-free arena chamber. Moreover, treated nymphs become hyperactive and disoriented as evidenced by the cumulative distance travelled and the trajectory of locusts during the experiment. Immunological studies showed that PAN significantly decreased the differential haemocyte counts (prohemocytes and plasmatocytes) with a dose-response relationship. Data of biochemical analyzes showed that the PAN exposure reduced the activity of acetylcholinesterase and induced significantly the glutathione S-transferases and MDA concentration in the desert locust fifth-instar nymphs. Moreover, transcriptomic responses to the PAN exposure were evaluated using gene expression levels of CYP540 and GST. The transcript levels showed an up-regulation in GST expression level particularly in nymphs exposed for 4 and 6 h. A significant increase in CYP450 transcript level was also observed after 2 h of exposure, which decreased significantly after 4 and 6 h.

Bioinsecticidal effect of Tagetes erecta (Asteraceae) on the pine sawfly Zadiprion vallicola (Diprionidae)

The present study was carried out with the purpose of evaluating the bioinsecticidal effect of Tagetes erecta leaves on larvae of Zadiprion vallicola. Water, acetone and ethanol extracts of T. erecta leaves were extracted by maceration. The extracts were applied in concentrations of 250 mg/L, 500 mg/L, 750 and 1000 mg/L and distilled water used as control. Mortalities were corrected in proportion and an analysis of variance was performed. In addition, the LC50 was calculated for the various extracts obtained. There were differences in mortality in concentrations (F = 171.4, p < 0.001), between solvents (F = 1060, p < 0.001) and in their interactions (F = 7.3, p < 0.001). For the control group the mortality was null, due to the extracts; the greater mortalities were presented in applications greater than 500 mg/L. As concentrations increased, mortality marked a tendency to stabilize. Acetone and ethanolic extracts, with mortalities of 0.81 and 0.96, were highly effective compared to water extracts with a mortality of 0.64. The ethanol extracts produced an LC50 of 63.1 mg/L and the acetonic extracts of 64.5 mg/L, low concentrations compared to that produced by the water extracts of 398.1 mg/L. The effects of these extracts on the mortality of Z. vallicola are similar to those reported for the entomopathogenic fungus Metarhizium anisopliae, and therefore represent a valuable alternative for its control, especially in the case of ethanol extracts.

Trichoderma Species Attract Coptotermes formosanus and Antagonize Termite Pathogen Metarhizium anisopliae.

Although subterranean termites live within soil, little attention has been paid on the potential interaction among subterranean termites and soil microbes. Herein, we conducted different choice tests to investigate aggregation and tunneling behaviors of Coptotermes formosanus Shiraki responding to soil/sand treated with conidia of seven soil fungi, Trichoderma longibrachiatum Rifai, Trichoderma koningii Oud., Trichoderma hamatum (Bon.) Bain., Trichoderma atroviride Karsten, Trichoderma spirale Indira and Kamala, Trichoderma harzianum Rifai, and Trichoderma viride Pers. ex Fries. In aggregation-choice test, soil treated with nearly all Trichoderma species tested (except T. koningii) significantly increased termite aggregation compared with untreated soil. In tunneling-choice tests, termites produced significantly larger tunnels in sand treated with T. longibrachiatum or T. koningii than that in untreated sand. We hypothesized that Trichoderma species could benefit termites by protecting them from infection of the entomopathogenic fungus Metarhizium anisopliae (Metschn) Sorokin, and three Trichoderma species that attracted termites (T. longibrachiatum, T. atroviride, and T. harzianum) were tested. The antagonism tests showed that the three Trichoderma species suppressed growth of M. anisopliae. Also, the median lethal time (LT50) of termites exposed to both Trichoderma species and M. anisopliae was significantly longer than termites exposed to M. anisopliae alone. Interestingly, though significantly fewer termites aggregated in soil treated with M. anisopliae conidia compared with untreated soil, M. anisopliae conidia mixed with T. longibrachiatum or T. harzianum were no longer repellent to termites. Our results showed that the fungi in the genus Trichoderma (1) exerted generally attractive effects on termites, (2) protected termites from the infection of entomopathogenic fungus, and (3) altered pathogen-avoiding behaviors of termites. Future studies will be required to understand the mechanisms underlying these newly discovered effects.

Biological Control of Tomato Gray Mold Caused by Botrytis Cinerea with the Entomopathogenic Fungus Metarhizium Anisopliae.

Gray mold disease caused by Botrytis cinerea is a devastating disease that leads to serious financial loss. In this study, the entomopathogenic fungus Metarhizium anisopliae that acts against the gray mold pathogen B. cinerea was evaluated. M. anisopliae produced a significant inhibition zone in front of the B. cinerea colony in the dual culture test. In addition, volatile organic compounds generated by M. anisopliae were shown to have an inhibitory effect on B. cinerea mycelia growth and reduced 41% of gray mold severity of postharvest tomatoes. The 10% concentration of the culture filtrate of M. anisopliae inhibited 88.62% of colony radial growth as well as 63.85% of sclerotia germination and all conidia germination of B. cinerea. Furthermore, the culture filtrate of M. anisopliae retained its inhibitory effect against the radial growth of B. cinerea even after heating for 15 min at 100 °C. Feasible mechanisms of M. anisopliae involved in the control of B. cinerea were explored, and it was demonstrated that the plasma membrane of B. cinerea conidia was damaged by the product of metabolism of M. anisopliae. In addition, after treating with culture filtrate of M. anisopliae, the B. cinerea phenotype was shown to be abnormal, and cell organelles of B. cinerea mycelia were damaged significantly. A significant control efficacy of M. anisopliae against tomato gray mold was detected on both the detached leaf assay (84.24%) as well as the whole plant (72.38%). In addition, a 78% reduction in tomato fruit mold was detected at a 10% treated concentration of M. anisopliae. These findings suggest that M. anisopliae possesses potential as a biocontrol agent against tomato gray mold in the greenhouse and during the postharvest stage.

Efficacy of a native isolate of the entomopathogenic fungus Metarhizium anisopliae against larval tick outbreaks under semifield conditions

This study aimed to evaluate Metarhizium anisopliae (Metschn.) Sorokin (Hypocreales: Clavicipitaceae) persistence in the soil and its impact on Rhipicephalus microplus Canestrini (Acari: Ixodidae) larval recovery in a semifield trial after the treatment of female ticks. Nine strains from the genus Metarhizium Sorokin were isolated from the soil in Brazil and taxonomically classified using the ef1-α gene. The thermotolerance of the strains and their in vitro virulence to tick larvae were tested. One M. anisopliae strain was selected and formulated for the semifield test. The presence of M. anisopliae in the soil ranged from 0.4 × 105 to 1.4 × 105 colony forming units per gram of soil after the treatment during the five months of the survey. The fungus-treated grass pots had significantly fewer larvae than did the control pots. Evidence was gathered about the soil persistence of a native M. anisopliae strain and its efficacy in the biological control of ticks.

Transcriptomic Analysis of the Brown Planthopper, Nilaparvata lugens, at Different Stages after Metarhizium anisopliae Challenge.

Nilaparvata lugens is one of the major pests of rice and results in substantial yield loss every year. Our previous study found that the entomopathogenic fungus Metarhizium anisopliae showed effective potential for controlling this pest. However, the mechanisms underlying M. anisopliae infection of N. lugens are not well known. In the present study, we further examined the transcriptome of N. lugens at 4 h, 8 h, 16 h, and 24 h after M. anisopliae infection by Illumina deep sequencing. In total, 174.17 Gb of data was collected after sequencing, from which 23,398 unigenes were annotated by various databases, including 3694 newly annotated genes. The results showed that there were 246 vs 75, 275 vs 586, 378 vs 1055, and 638 vs 182 up- and downregulated differentially expressed genes (DEGs) at 4 h, 8 h, 16 h, and 24 h after M. anisopliae infection, respectively. The biological functions and associated metabolic processes of these genes were determined with the Clusters of Orthologous Groups (COG), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The DEGs data were verified using RT-qPCR. These results indicated that the DEGs during the initial fungal infection appropriately reflected the time course of the response to the fungal infection. Taken together, the results of this study provide new insights into the molecular mechanisms underlying the insect host response to fungal infection, especially during the initial stage of infection, and may improve the potential control strategies for N. lugens.

Interactions of Destruxin A with Silkworms' Arginine tRNA Synthetase and Lamin-C Proteins.

Destruxin A (DA), a cyclodepsipeptidic mycotoxin produced by entomopathogenic fungus Metarhizium anisopliae, has good insecticidal activity and potential to be a new pesticide. However, the mechanism of action is still obscure. Our previous experiments showed that DA was involved in regulation of transcription and protein synthesis and suggested that silkworms’ arginine tRNA synthetase (BmArgRS), Lamin-C Proteins (BmLamin-C) and ATP-dependent RNA helicase PRP1 (BmPRP1) were candidates of DA-binding proteins. In this study, we employed bio-layer interferometry (BLI), circular dichroism (CD), cellular thermal shift assay (CETSA), and other technologies to verify the interaction of DA with above three proteins in vitro and in vivo. The results of BLI indicated that BmArgRS and BmLamin-C were binding-protein of DA with KD value 5.53 × 10−5 and 8.64 × 10−5 M, but not BmPRP1. These interactions were also verified by CD and CETSA tests. In addition, docking model and mutants assay in vitro showed that BmArgRS interacts with DA at the pocket including Lys228, His231, Asp434 and Gln437 in its enzyme active catalysis region, while BmLamin-C binds to DA at His524 and Lys528 in the tail domain. This study might provide new insight and evidence in illustrating molecular mechanism of DA in breaking insect.

Metarhizium anisopliae CQMa128 regulates antioxidant/detoxification enzymes and exerts acaricidal activity against Psoroptes ovis var. cuniculi in rabbits: A preliminary study

The entomopathogenic fungi Metarhizium anisopliae is highly pathogenic toward arthropods. Here, we evaluated the efficacy of a commercial formulation of M. anisopliae against P. ovis var. cuniculi in vivo and in vitro and explored the acaricidal mechanism of M. anisopliae by determining the antioxidant/detoxification-related enzymes activities including glutathione S-transferase (GST), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in mites. The results showed that M. anisopliae had high acaricidal activity against P. ovis var. cuniculi in vitro, in a time- and dose-dependent manner, with 83.33 % mortality at day 9 and a median lethal time (LT50) of 6.10 days after applying 6.14 × 109 conidia/ml of M. anisopliae. In vivo experiments, M. anisopliae achieved 100 % therapeutic effect after 3 days, compared with only 62.21 % for ivermectin. Enzyme assays showed that M. anisopliae significantly upregulated activities of GST, SOD and CAT in Psoroptes mites. The results indicate that M. anisopliae may be an effective biological agent for control of P. ovis var. cuniculi infestations in rabbits and the acaricidal activity may be associated with the changes of enzyme activities of the detoxification and antioxidant system in Psoroptes mites.

Heat stress during development affects immunocompetence in workers, queens and drones of Africanized honey bees (Apis mellifera L.) (Hymenoptera: Apidae).

Though social insects generally seem to have a reduced individual immunoresponse compared to solitary species, the impact of heat stress on that response has not been studied. In the honey bee, the effect of heat stress on reproductives (queens and males/drones) may also vary compared to workers, but this is currently unknown. Here, we quantified the activity of an enzyme linked to the immune response in insects and known to be affected by heat stress in solitary species: phenoloxidase (PO), in workers, queens and drones of Africanized honey bees (AHBs) experimentally subjected to elevated temperatures during the pupal stage. Additionally, we evaluated this marker in individuals experimentally infected with the entomopathogenic fungus Metarhizium anisopliae. Differences in PO activity were found between sexes and castes, with PO activity generally higher in workers and lower in reproductives. Such differences are associated with the likelihood of exposure to infection and the role of different individuals in the colony. Contrary to our expectation, heat stress did not cause an increase in PO activity equally in all classes of individual. Heat stress during the pupal stage significantly decreased the PO activity of AHB queens, but not that of workers or drones, which more frequently engage in extranidal activity. Experimental infection with Metarhizium anisopliae reduced PO activity in queens and workers, but increased it in drones. Notably, heat stressed workers lived significantly shorter after infection despite exhibiting greater PO activity than queens or drones. We suggest that this discrepancy may be related to trade-offs among immune response cascades in honey bees such as between heat shock proteins and defensin peptides used in microbial defence. Our results provide evidence for complex relationships among humoral immune responses in AHBs and suggest that heat stress could result in a reduced life expectancy of individuals.

Additive Effect of Botanical Insecticide and Entomopathogenic Fungi on Pest Mortality and the Behavioral Response of Its Natural Enemy.

Sustainable agricultural intensification employs alternatives to synthetic insecticides for pest management, but these are not always a direct replacement. Botanical insecticides, for example, have rapid knockdown but are highly labile and while biological pesticides are more persistent, they are slow acting. To mitigate these shortcomings, we combined the entomopathogenic fungus (EPF) Metarhizium anisopliae with pyrethrum and evaluated their efficacy against the bean aphid, Aphis fabae. To ascertain higher trophic effects, we presented these treatments to the parasitoid, Aphidius colemani, on an aphid infested plant in a Y-tube olfactometer and measured their preferences. Aphid mortality was significantly higher than controls when exposed to EPF or pyrethrum but was greater still when exposed to a combination of both treatments, indicating an additive effect. This highlights the potential for applications of pyrethrum at lower doses, or the use of less refined products with lower production costs to achieve control. While parasitoids were deterred by aphid infested plants treated with EPF, no preference was observed with the combination pesticide, which provides insight into the importance that both application technique and timing may play in the success of this new technology. These results indicate the potential for biorational pesticides that combine botanicals with EPF.

Detection of local isolates of the entomopathogenic fungus Metarhizium anisopliae using specific primers

The entomopathogenic fungus Metarhizium anisopliae is a promising biological control agent of several insect pests in agriculture. Molecular approaches (PCR and DNA sequence analysis) were used as tools for the identification of different local isolates (Ma88, Ma19 and Ma29) and imported isolate (Ma-h). Primer sequences used were5'-TCCTCCGCTTATTGATATGC-3(ITS4) and 5'-GGAAGTAAAAGTCGTAACAAGG-3 '(ITS5). The DNA sequences of the amplified regions showed that the high homology (90%) was between the isolates Ma88 and Ma29,while it was 88% between Ma88 and Ma19 isolates and 89% between the Ma19 and Ma29 isolates. there were more heterogeneous between the three local isolates (Ma88, Ma19 and Ma29) and the imported isolate (Ma-h). The homogeneity among local isolates and their heterogeneity with imported isolate is due to many reasons, including geographical isolation and differences in environmental conditions such as high or low temperature and humidity.

Home economics in an oak gall: behavioural and chemical immune strategies against a fungal pathogen in Temnothorax ant nests.

Nest architecture is a fundamental character shaping immune strategies of social insects. The arboreal ant Temnothorax unifasciatus nests in cavities such as oak galls where the entire colony lives in a unique small chamber. In these conditions, physiological and behavioural strategies likely prevail over compartmentalisation and are presumably tuned with colony size. We designed two experiments to study chemical and behavioural immune strategies against the entomopathogenic fungus Metarhizium anisopliae in colonies of different sizes. First, we compared spore germination and length of germinal tubes inside artificial nests, designed to impede the contact between the ants and the fungus, in colonies of different size. In the absence of direct contact, Temnothorax unifasciatus colonies inhibit fungal growth inside their nests, presumably through volatile compounds. The analysis revealed a positive correlation between fungistatic activity and colony size, indicating that workers of smaller colonies do not invest a higher per capita effort in producing such substances compared to larger colonies. Second, we performed a removal experiment of contaminated and non-contaminated items introduced inside the nests of colonies of different size. Small colonies challenged with contaminated fibres showed an increased removal of all the items (both contaminated and non-contaminated) compared to small colonies challenged with non-contaminated fibres only. Conversely, larger colonies moved items regardless of the presence of the spores inside the nest. Colony size qualitatively affected removal of waste items showing a pathogen elicited reaction in small colonies to optimise the reduced workforce, while the removal behaviour in larger colonies revealed to be expressed constitutively.

Conservation of Agricultural Soil Using Entomopathogenic Fungi: An Agent With Insecticides Degradation Potential

A major current focus in agricultural soil conservation is to ensure a pest control program is sustainable, and therefore, entomopathogenic fungi have been considered and extensively studied as biopesticides. However, the ecological role of entomopathogenic fungi in degrading insecticides in soil is not well understood. In this study, the potential of entomopathogenic fungi Metarhizium anisopliae (Met.) in degrading two common agricultural insecticides, chlorpyrifos and cypermethrin was investigated by introducing M. anisopliae into autoclaved soils artificially contaminated with 500 ppm of chlorpyrifos, and cypermethrin. The concentration of chlorpyrifos and cypermethrin were determined after 21 days using UPLC/PDA detector. The residues, rate, and percentage of degradation between insecticides treated and control soil were compared using an independent t-test (SPSS 20.0). The degradation of both insecticides in Met. treated soil (>80%) was significantly higher than control soil (47-61%). The residues for chlorpyrifos and cypermethrin residue in Met. treated soils were 19.39±0.10 ppm and 19.68±0.36 ppm, respectively, significantly lower than control (residues of chlorpyrifos-262.6±7.6 ppm and cypermethrin-194.4±4.3 ppm, at p<0.05). The results suggested M. anisopliae may play a role in the bioremediation of soil.

Combined applications of an entomopathogenic fungus and a predatory mite to control fungus gnats (Diptera: Sciaridae) in mushroom production

The fungus gnat Lycoriella auripilla Winnertz (Diptera: Sciaridae) is a key pest of mushroom production in Iran where it can be a year-round problem on commercial farms. We evaluated the entomopathogenic fungus Metarhizium anisopliae (Hypocreales: Clavicipitaceae) and the predatory soil mite, Gaeolaelaps aculeifer (Canestrini) (Mesostigmata: Laelapidae) as biocontrol agents of L. auripilla larvae when applied alone or in combination. Concentrations of M. anisopliae ranging from 103 to 108 spores/ml were tested with and without the addition of G. aculeifer in both small container trials and larger scale experiments. No mite mortality was observed in container trials with M. anisopliae and mite presence increased mortality of L. auripila larvae, more notably at lower fungal concentrations. In production scale experiments, treatments were applied just after the casing stage, and two weeks later, with very similar results. The addition of 15 mites/replicate (a basket containing 4 kg of mushroom compost) increased fungus gnat mortality significantly across all fungal concentrations, but applications of the mites alone gave a level of control comparable to the highest fungal concentration alone (108 spores/ml). Treatment with M. anisopliae at 108 spores/ml yielded an efficiency of conversion of compost into mushrooms better than untreated controls, and efficiency was even higher with the addition of G. aculeifer. However, the treatment with mites alone produced mushrooms with the same efficiency as the combined treatment, suggesting that the mites alone might be sufficient for controlling L. auripila larvae if application rates could be optimized for commercial scale production.

Sequences of Acretocins, Peptaibiotics Containing the Rare 1-Aminocyclopropanecarboxylic Acid, from Acremonium crotocinigenum CBS 217.70.

Sequences of Acretocins, Peptaibiotics Containing the Rare 1-Aminocyclopropanecarboxylic Acid, from Acremonium crotocinigenum CBS 217.70.

Effect of natural toxins and adipokinetic hormones on the activity of digestive enzymes in the midgut of the cockroach Periplaneta americana.

This study examined the effect of two natural toxins (a venom from the parasitic wasp Habrobracon hebetor and destruxin A from the entomopathogenic fungus Metarhizium anisopliae), and one pathogen (the entomopathogenic fungus Isaria fumosorosea) on the activity of basic digestive enzymes in the midgut of the cockroach Periplaneta americana. Simultaneously, the role of adipokinetic hormones (AKH) in the digestive processes was evaluated. The results showed that all tested toxins/pathogens elicited stress responses when applied into the cockroach body, as documented by an increase of AKH level in the central nervous system. The venom from H. hebetor showed no effect on digestive enzyme activities in the ceca and midgut in vitro. In addition, infection by I. fumosorosea caused a decrease in activity of all enzymes in the midgut and a variable decrease in activity in the ceca; application of AKHs did not reverse the inhibition. Destruxin A inhibited the activity of all enzymes in the midgut but none in the ceca in vitro; application of AKHs did reverse this inhibition, and no differences between both cockroach AKHs were found. Overall, the results demonstrated the variable effect of the tested toxins/pathogens on the digestive processes of cockroachesas well as the variable ability of AKH to counteract these effects.