Synergistic effects of the entomopathogenic fungus Isaria javanica and low doses of dinotefuran on the efficient control of the rice pest Sogatella furcifera

The rice planthopper,Sogatella furcifera,is a piercing-sucking insect pest of rice,Oryza sativa.It is responsible for significant crop yield losses,and has developed moderate to high resistance to several commonly used chemical insecticides.We investigated the effects of the insect fungal pathogen Isaria javanica,alone and in combination with the chemical insecticide dinotefuran,on S.furcifera under both laboratory and field conditions.Our results show that I.javanica displays high infection efficiency and mortality for different stages of S.furcifera,reducing adult survival,female oviposition and ovary development.Laboratory bioassays showed that the combined use of I.javanica with a low dose(4-16 mg L^(-1))of dinotefuran resulted in higher mortality in S.furcifera than the use of I.javanica or dinotefuran alone.The combined treatment also had more significant effects on several host enzymes,including superoxide dismutase,catalase,peroxidase,and prophenol oxidase activities.In field trials,I.javanica effectively suppressed populations of rice planthoppers to low levels(22-64%of the level in untreated plots).Additional field experiments showed synergistic effects,i.e.,enhanced efficiency,for the control of S.furcifera populations using the combination of a low dose of I.javanica(1×10^(4) conidia mL^(-1))and a low dose of dinotefuran(~4.8-19.2%of normal field use levels),with control effects of>90%and a population level under 50 insects per 100 hills at 3-14 days post-treatment.Our findings indicate that the entomogenous fungus I.javanica offers an attractive biological control addition as part of the integrated pest management(IPM)practices for the control of rice plant pests.

The effect of ergosterol on the allogrooming behavior of termites in response to the entomopathogenic fungus Metarhiziumanisopliae

Termites have physiological and behavioral immunities that make them highly resistant to pathogen infections,which complicates biocontrol efforts.However,the stimuli that trigger the pathogen-avoidance behaviors of termites are still unclear.Our study shows that workers of Coptotermes formosanus exposed to the conidia of Metarhizium anisopliae exhibited a significantly higher frequency and longer duration of allogrooming behaviors compared with untreated termites.Volatile compounds in the cuticle of control termites and termites previously exposed to a suspension of M.anisopliae conidia were analyzed and compared using a gas chromatography-mass spectrometer(GC-MS).Our results showed that the amount of ergosterol differed between the fungus-exposed and control termites.Choice tests showed that termites significantly preferred to stay on filter paper treated with ergosterol(0.05,0.1,or 1.0 mg/mL)compared with control filter paper.In addition,termites exposed to ergosterol followed by M.anisopliae conidia were allogroomed at a significantly higher frequency and for a longer duration than termites exposed to alcohol(the solvent used with the ergosterol in the ergosterol trials)alone followed by M.anisopliae conidia.These results showed that ergosterol may enhance the allogrooming behavior of termites in the presence of entomopathogenic fungi.

Further compatibility tests of the entomopathogenic fungus Lecanicillium muscarium with conventional insecticide products for control of sweetpotato whitefly, Bemisia tabaci on poinsettia plants

The effect on spore germination of the entomopathogenic fungus Lecanicillium muscarium following direct exposure for 24 h to the insecticides Majestik, Spray Oil, Agri- 50E, Savona and Oberon for the control of both egg and second instar stages of the sweetpotato whitefly, Bemisia tabaci, was determined. Exposure to both Agri-50E and Oberon was followed by acceptable spore germination. Infectivity rates ofL. muscarium on poinsettia foliage in the presence of dry residues of the insecticides were also investigated. No significant detrimental effects on the levels of control of B. tabaci were recorded compared with fungus applied to residue-free foliage. Sequential application of the chemicals Savona, Spray Oil and Majestik with the fungus all produced mortalities of second instar B. tabaci above 90%. Incorporation of these chemicals with L. muscarium into integrated control programs for B. tabaci is discussed.

萝卜蚜新蚜虫疠霉的分离鉴定及其致病性测定(英文)

[Objective] The study was to isolate and identify the pathogen of Pandora neoaphidis and to determine its pathogenicity against turnip aphid （Lipaphis erysimi）.[Method] Based on the morphological characteristics,the species of pathogenic fungus was identified.Spore shower method was used to carry out bioassay on the pathogen against turnip aphid.[Result] Primary conidia were ovoid,bitunicate and uninucleate,（24.7±1.4）μm×（10.7±0.9）μm,L/D=2.3±0.2.Secondary conidia had the similar shape with the primary ones,（18.6±2.1）μm×（13.3±1.3）μm,L/D=1.4±0.2.Hyphal body was like mycelium with the diameter of （10.6±0.8）μm.Conidiophores had palmate branch with the diameter of （10.0±0.9）μm.Pseudocystidia was not branched,which had rough base with the diameter of （19.2±1.7）μm,and gradually became more angular towards the apex with the diameter of （8.0±0.9）μm at tips.Rhizoid was like monohyphal shape with the diameter of （21.0±3.0）μm at base,the terminal apex had regular discoid holdfast.No resting spores were observed.The lethal dose of the pathogen against turnip aphid was 18.2/mm2.[Conclusion] The entomopathogenic fungus against turnip aphid was identified to be Pandora neoaphidis,and the pathogen was confirmed to have strong pathogenicity against turnip aphid.

Toward the efficient use of Beauveria bassiana in integrated cotton insect pest management

Background:For controlling the resistance to insects,in particular carpophagous and phyllophagous caterpillars,using chemical pesticides has led to contamination of cotton area in Benin.Facing this problem,alternative methods including the use of entomopathogenic fungi as biopesticide could be a sound measure to preserve the environment,biodiversity and ensure good quality of crops.Previous studies have revealed the insecticidal potential of the entomopathogenic Beauveria bassiana on some insect pest species.However,little is known about its effectiveness on cotton Lepidopteran pests.This review is done to learn more about B.bassina for its application in controlling cotton insect pests,especially Lepidopteran species.Main body:Different sections of the current review deal with the related description and action modes of B.bassiana against insects,multi-trophic interactions between B.bassiana and plants,arthropods,soil and other microbes,and biological control programs including B.bassiana during last decade.Advantages and constraints in applying B.bassiana and challenges in commercialization of B.bassiana-based biopesticide have been addressed.In this review,emphasis is put on the application methods and targeted insects in various studies with regard to their applicability in cotton.Conclusion:This review helps us to identify the knowledge gaps related to application of B.bassiana on cotton pest in general and especially in Lepidopteran species in Benin.This work should be supported by complementary laboratory bioassays,station and/or fields experiments for effective management of cotton Lepidopteran pests in Benin.

Optimization of the Chitinase Production by Different Metarhizium anisopliae Strains under Solid-State Fermentation with Silkworm Chrysalis as Substrate Using CCRD

Entomopathogenic fungi, such as Metarhizium anisopliae, are able to control various insect pests. These fungi attack the integument of the host using an enzymatic complex. Among the enzymes found in this complex, chitinase is an important component. However, the relation between the chitinase production and the virulence from different M. anisopliae strains has not been analyzed. In this manuscript it is presented the chitinase production by four M. anisopliae strains with different potential of virulence in Solid-State Fermentation using silkworm chrysalis as substrate. The higher chitinase level was obtained with the strain IBCB 360 (7.14 U/g of substrate) with potential virulence of 68% on Diatrea saccharalis. The enzyme production was optimized for all strains using a factorial planning (CCRD) considering the cultivation time and medium humidity as independent variables. The maximal production of chitinase was obtained at a range from 8 to 12-days old cultures and from 45% to 62% of moisture according to the surface response plot, with high R2 value. The enzyme production by the strain IBCB 167 was increased two-folds under optimized conditions, while for the strains IBCB 360 and 425 the chitinase production was increased four-folds and nine-folds for the strain IBCB 384.

Efficacy of Metarhizium anisopliae in controlling the two-spotted spider mite Tetranychus urticae on common bean in screenhouse and field experiments

The efficacy of aqueous and emulsifiable formulations of the fungus Metarhizium anisopliae isolate ICIPE78 was evaluated on the population density of Tetranychus urticae infesting common bean plants under screenhouse and field conditions. Synthetic acaricide abamectin was included as a check. Bean plants were artificially infested with T. urticae and allowed to multiply. Three treatments were applied in the screenhouse and 1 treatment in field trials. Mite density was recorded 2 d before spraying and weekly postspraying. The number of pods per plant, number of seeds per pod, and the dry weight of seeds per plant were recorded only in the screenhouse trials. In both screenhouse and field trials, fungal formulations applied at the concentration of 108 conidia/mL and the aearicide reduced the population density of mites as compared to the controls. There were signif- icant differences in T. urticae population densities between the treatments at the various post-spraying sampling dates. In the screenhouse, the mite densities were near zero from 3-week postspraying in the treated leaves. At 4-week postspraying, there were no more leaves in the untreated control （T1） and in the control water ＋ Silwet-L77 （T2）. Fungal formulations were as effective as abamectin in reducing mite densities in both screenhouse and field experiments. There were significant differences in the production parameters during the 2 screenhouse trials, with fungal and abamectin treatments generally having the highest yield. Results of this study underline the potential of the M. anisopliae isolate ICIPE78 as an alternative to acaricides for T. urticae management.

Fungal infection dynamics in response to temperature in the lepidopteran insect Galleria mellonella

This study examines how the dynamics of fungus-insect interactions can be modulated by temperature. The wax moth, Galleria mellonella, is a well-studied and important model insect whose larvae in the wild develop optimally at around 34 ℃ in beehives. However, surprisingly little research on wax moths has been conducted at relevant temperatures. In this study, the entomopathogenic fungus Metarhizium robertsii inflicted rapid and substantial mortality on wax moth larvae maintained at a constant temperature of 24 ℃, but at 34 ℃ a 10 fold higher dose was required to achieve an equivalent mortality. The cooler temperature favored fungal pathogenicity, with condial adhesion to the cuticle, germination and hemocoel invasion all significantly enhanced at 24 ℃, compared with 34 ℃. The wax moth larvae immune responses altered with the temperature, and with the infective dose of the fungus. Enzyme-based immune defenses （lysozyme and phenoloxidase） exhibited enhanced activity at the warmer temperature. A dramatic upregulation in the basal expression of galiomicin and gallerimycin was triggered by cooling, and this was augmented in the presence of the fungus. Profiling of the predominant insect epicuticular fatty acids revealed a 4-7 fold increase in palmetic, oleic and linoleic acids in larvae maintained at 24 ℃ compared with those at 34 ℃, but these failed to exert fungistatic effects on topically applied fungus. This study demonstrates the importance of choosing environmental conditions relevant to the habitat of the insect host when determining the dynamics and outcome of insect/fungus interactions, and has particular significance for the application of entomopathogens as biocontrol agents.