Ecological studies relevant to the management of<i>Thrips palmi</i>Karny on mango in India

Abstract

Abstract Ecological studies on the spatial distribution, sampling and transformation of data were conducted on Thrips palmi Karny, a new pest on mango, as first steps in formulating a sound management programme. Full bloom panicles of mango were sampled. The distribution was aggregated and better explained by Iwao's patchiness regression, which indicated aggregated distribution, following a negative binomial model with a fixed mean size. The data fitted a negative binomial model with a probability range of 0–01 to 0–70. The four quadrants of the trees, North, South, East and West did not significantly differ, but the lower canopy had significantly more thrips than the upper. Thus the lower canopy seemed a better sampling area, especially with the lower canopy population correlated with the total population. The sample sizes recommended are 55 panicles/tree for control and survey studies, and 92 panicles/tree for the higher precision in life table studies. The sample size based on Iwao's formula was 125 panicles/tree. As this is based on the distribution of the insect, it is more reliable and may be adopted when time and manpower are available. To normalize the data, log(x + 1 ), log(x k/2), log[log(x + 2)] and sinh−1 ‐ suitable. The relevance of these findings to the management of T. palmi are discussed.