Spatial distribution and temporal dynamics of Frankliniella occidentalis Pergande, 1895 and Thrips palmi Karny, 1925 (Insecta: Thysanoptera: Thripidae) in orchids in Singapore

Abstract

The spatial distribution and temporal dynamics of the Western Flower Thrips, Frankliniella occidentalis, and of the Melon Thrips, Thrips palmi (both Thysanoptera: Thripidae), were studied in five orchid farms in Singapore. The population of T. palmi was more abundant and dominant than that of F. occidentalis during the study. Frankliniella occidentalis occurred in the farms only from February to June 2011 and Thrips palmi was present for the entire sampling period, January to November 2011. Blue traps trapped T. palmi more effectively while WFT traps were more suitable for population monitoring of F. occidentalis. Both F. occidentalis and T. palmi tend to aggregate themselves at the tested population size of 10 thrips/trap in average. Parameters "a" and "b" of the Taylor's Power Law and parameters of "alpha" and "beta" of the Iwao's Patchiness Regression Index[needspace]indicate that individuals of F. occidentalis and T. palmi tend to form aggregation patches. While T. palmi aggregate in patches, the patches are uniformly distributed. In contrast, for F. occidentalis, both individuals and patches are aggregated. Parameters to be considered for a surveillance strategy for F. occidentalis are also discussed.