Investigation on the Temporal and Spatial Distribution of Flower Thrips Population in Nyctanthes arbor-tristis Linn.

Author: Manjunath Kenchannavar, M. Thippaiah, Y.B. Srinivasa and R.R. Rachana

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Abstract

We made a preliminary examination of the flowers of Nyctanthes arbor-tristis, with longevity for about 12 hours, and their association with three species of thrips in terms of understanding their distribution and accumulation patterns. Thrips are among the most common flower feeding insect groups in the world. We compared the time of anthesis with theentry time of the thrips. We also studied the distribution of the three species of thrips across and within flowers of Nyctanthes arbor-tristis. Thrips florum, Thrips hawaiiensis (Thripidae; Terebratia) and one unidentified species (Phlaeothripidae; Tubulifera) were the three species occurring concurrently in the flowers of N. arbortristis. Flower sampling was done at three full-grown trees of N. arbor-tristis located at considerable distance from each other. Observations were recorded on the opening and dropping times of the flowers, and entry time of each species of thrips into the flowers and the density of individual species of thrips in each flower at various stages of flower development Flowers open between 5:10 PM and 6:45 PM the next day [Rs1]. All three species of thrips entered flowers ~1 hour prior to flower opening. The higher thrips density was recorded in freshly opened flowers with 292 thrips occupying 62%of the 180 flowers sampled. Later, both population density and flower occupancy decreased to 34 thrips in 28 flowers 24 hours post anthesis. Population density and flower occupancy were positively correlated. Interestingly, 37% of flowers were unoccupied when the population density of thrips was maximum, indicating that both threshold level of occupancy and threshold level of population density played a role in the distribution of thrips among the flowers. The proportion of empty flowers reveal aggregated distribution of thrips rather than random distribution.

Keywords

Thrips, Nyctanthes arbour-tristis, Population density, Occupancy, Aggregated distribution

Conclusion

As a highly short duration flower N. arbor-tristis attracts specific flower inhabitants like thrips. Thrips species T. florum dominate in population, density and distribution in flowers utilising maximum resource followed by T. hawaiiensis. It appears that there is a threshold level of density that affects the distribution pattern of thrips. These tendencies appears to give rise to an aggregated distribution pattern among the thrips found to exist in the flowers of N. arbor-tristis. However, an attempt has been made in this work to theorise the different distribution patterns exhibited by thrips species with respect to the anthesis and duration of flower remain open. This can open up new directions in our understanding of thrips behaviour in inhabiting type of flowers and their distribution.

References

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How to cite this article

Manjunath Kenchannavar, M. Thippaiah, Y.B. Srinivasa and R.R. Rachana (2023). Investigation on the Temporal and Spatial Distribution of Flower Thrips Population in Nyctanthes arbor-tristis Linn.. Biological Forum – An International Journal, 15(1): 383-387.