The Mystery

   Yes, I said that root grubs in my plot is reducing.But how?   Is it from the insecticide application? If it is so from which insecticide?
      Last year my plot was divided into six parts and each part had different insecticide treatment.Amongst them one part was left untreated.This year we could see reduced number of grubs in the whole plot.Even in the plot where no insecticide was applied,grubs number is reduced.Then the question remains-which insecticide did the wonders? I do not know. I think that if the methodology and time is maintained any good soil insecticide will do the work.It is for the scientists to explain.
      One thing must be clarified.Still grubs are there in my plot.If the treatment last year was a failure young larvae    of the last year will grow to adult and we could find a large number of third instar or adult grub this year.If the treatment was a success young larvae's of that year would die,but adult grubs will remain.That grubs will go to pupa stage and then became beetle.The beetles will emerge from the soil in the month of May or June and will lay eggs in the soil. Larvae's will emerge from the eggs later and hence we have young larvae's in the plot.When we say that reduced number of grubs we mean reduced number of grown grubs.
       Then what is the effect of nematodes in the plot? Earlier I said that I had seen dead grubs in the plastic basket  due to nematodes. But the problem is we cannot find dead grubs in the plot.Because if any grubs died in the plot it will decompose in the soil.Then how can we attribute reduced number of grubs to nematodes?Even with the nematodes,as Dr.Nagesh told adult grubs would not die easily.
        Even if the grub problem seems to be reduced and I am now very happy person several questions were unanswered.Normally when I say grub problem is controlled I face one question-which insecticide did it? Frankly I could not answer.