Occurrence of white grubs and its biocontrol by Metarhizium anisopliae in golf course

Investigation of white grubs occurrence was carried out in 2 golf courses of Shenzhen city in spring.The grub population was different at various sampling sites,ranged 0~16 grubs/m2.The population had a negative correlation with moisture and a positive correlation with temperature in soil.The lawn luster and root integrality had a distinct negative correlation with grub population.The grass grew thick at the less grub site.On the other hand,pathogenicity of Metarhizium anisopliae to white grubs,which from ovipositing and the hatching by Anomala cupripes adults collected from golf course,was tested in laboratory.The experiment results showed that Metarhizium anisopliae was virulent to various instars of the grubs.The larvae of 1st instar were most sensitive to the fungus.When fungal quantity was 66.7×108 and 33.3×108 spores/kg soil,mortality of 1st instars could get to 90% in 6 d and 9 d respectively.When fungal quantity was 16.7×108 spores/kg soil,their LT50 were 7.3 d,14.3 d and 18.0 d respectively for 1st,2nd and 3rd instars.Synergistic agent added in the fungal agent could advance infection to the grubs.