Biology and Demography of a Springtail, Xenylla sp., Reared on a Substrate Treated With Effective Microorganism (EM)

Abstract

Effective Microorganism (EM) is a proprietary liquid containing many co-existing microorganisms and is widely used to increase crop yields in Thailand. However, there is little knowledge and no scientific proof on the influence of EM on soil microarthropods which serve as bioindicators of soil fertility. There is a possibility that EM promotes their growth and indirectly improves the soil fertility. EM was added to the substrate and the biology of Xenylla sp. was compared to substrate treated with molasses and a control added with water only. Observations under a stereo microscope were made to record the life history and a life table was constructed. EM caused a significantly lower hatching percentage and adult life expectancy and the developmental time from the juvenile to adult stage was delayed when compared to the control, but not to the molasses (P < 0.05). However, the effects on net reproductive rate, finite capacity of increase, intrinsic rate of natural increase, generation time and doubling time were not significant, probably due to the rapid growth of fungi that covered the egg surfaces causing water loss and lower egg viability. The lower relative humidity and accumulation of metabolic wastes by fungi are believed to suppress the well being of the insects. EM did not demonstrate significantly positive effects on the biological performance of this Xenylla species.