plz compare environment and repeat treatment

Hallo Marwa,

I agree with Aziz, it must be because of a difference in the environment. Was this a lab or field study? If it was a field study, did you use a randomized design? 

it is laboratory  experiment . I know that fungal filtrates are rich of organic compounds (secondary metabolites) do you think that any of theses cpds may antagonist the effect of the another ??

In this article they found B. bassiana to be more efficient at lower concentrations, but they don't explain why. I would do one more replication to be sure. 

Journal of  Applied Entomology 133 (2009) 473–483

Possibly the intraspesific competition is too great and the fungus dies, if you are applying it to an insect such as ants possibly they will eat the fungus which is rich in nutrients which will increase fecundity. 

Autotoxicity (a type of intraspecific allelopathy) is also a possibility. It might be possible that the compounds are antagonists the effect of the other. It will be interesting to investigate as there is not a lot of research on this topic.

Sonnica 

thank you very very much. I hope i can find a paper which has an explanation of such result . I am keeping search and reading books, but as you said there is not a lot of research on this topic

HI,

I think the answer of Sonnica interesting.

I'd like to add few comments, quite at the edges of your question.

in some case and in field  I observed efficacy of fungi for biocontrol, but not on all the different strata of the plants (certainly due to micro-climatic conditions). Sometime, we seen pests (targeted) walking in area with important fungus networks because of no effect of the fungus at this stage or because of the strain (maybe adapted) of this pest: we don't know.

We highlighted in the case of T. urticae and A. cucumeris interaction a more complex interaction with a fungus (pathogens - powdery mildew) with different and antagonist effect. Both mites (pest and predator) eat the fungus since spore are rich in nutrients. Despite that the predator consume more prey after eating fungus, the pest lay more eggs in the presence and in the fungus network.

Acta Horticulturae, 797 (2008), 229-234.

I think biotic interaction with arthropods and fungus is quite complex, and should evolves and effects change at short, middle and long term.

So I think this biotic interaction needs further studies. Sometimes the result appear not logic, not like previous studies, how can I put such result in my paper without reference and what is the agreeable explanation ?

I again say about the abiotic condition check ups, if you use Beauveria bassiana, it needs higher humidity in its propagation, development of disease at the cuticle of insect, that trigger more and more options......................cz i faced a lot of dilema, thanks my supervisor he gave me a path, that was to check abiotic stresses to the fungi and fungal stresses to the insect in vitro.

Can you give any information on the insect species and the genus of the entomopathogenic fungus. 

That would make it easier to answer.

Sometimes especially fungi can exhibit a self Inhibition due to high spore densities - it can be explained by evolutionary processes: It does nót make sense to kill massively the plant or the insect in few hours or days before getting reproduced inside or on the surface. Please check the germination rate in the spore suspension sprayed on a neutral surface, like membranes.

Additionally I agree to check also the environmental experimental conditions. Good luck!

thank you doctor but I did not use spore suspension, it is exposure of  a pest to fungal filtrate in a beaker ....

Yes we can use them. Grow the fungal culture then use the supernatant.

Regards

Hala

Could you check the environmental conditions especially temperature and relative humidity and if you could do a small experiment to check the spore germination in vitro (on Petri dishes). In addition, could you give  more information about the fungus isolates that you assessed and your experimental design to help you more. Best wishes

Dear Marwa,

Your question is too general. Look at Bauveria bassiana preparations.

Hello Marwa,

Your answer is yes but very broad as the establishment, development and sustainability of fungi in the field is greatly influence by climate. I think your best is to study the preparation of Bauveria bassiana as suggested by Andras Bozsik and also Metarhizium anisoplia. Oilbased formulation of B. bassiana in Burundi, Uganda and most other African countries against the sweet potato weevil Cylas puncticollis and banana weevil Cosmopolites sordidus have been incorporated in the integrated management of these pest.

In 2004, I observed severe mortality of oil palm leaf miners, Coelaenomenodera lameensis in Oil Palm field and further investigation using their supernatant on the beetles resulted in early motality of all the stages of the insect’s development with clear growth of the fungi. Proposal for proper isolation, identification, rearing and formulation of the causal agent as bio control was made but unfortunately funding was not secure.

Yes, your question is very general. use Metarrhizium aniosopiliae suspension for sucking pests and granules for subterranean pests. 

we  are using beauveria bassiana against termites and also mosquito control and very good results in field also.only thing is to sparay in the early mng or late evening

yes.  many species are used for control of insect pests.