Foraging behavior of stingless bee (Geniotrigona thoracica and Heterotrigona itama) on star fruit trees (Averrhoa carambola L.)

Abstract

Star fruit produce flowers and fruits nearly the whole year round and it require cross- pollination for good fruit set and yields. An inadequate pollination rate is one of the factor that contributes to low yield. One of the effective way of increasing the pollination rate is by having insect pollinators such stingless bees in the star fruit farm. Malaysia is rich with native pollinator such as stingless bee, but there still lack of study related on their foraging behaviour. Therefore, the objectives were to study the foraging behaviour of Geniotrigona thoracica and Heterotrigona itama on star fruit trees. The colonies of G. thoracica and H.itama were selected for observation of activity foraging of stingless bee. Foraging bees was enumerated by using a manual tally counter to determine the number of individuals that flew out and into their hive within a 10 minute period each hour for each colonies. Then 10 of foragers' G. thoracica and H.itama were selected randomly and marked using insect colouring on their thorax The period for each flower that visited by G. thoracica and H.itama was recorded by using stopwatch. The number offlower visited by G. thoracica and H.itama also recorded in 3 minutes. Result showed the peak time foraging activity of both stingless bees were in between 8.00am until 10.00am The foraging activity for each hours showed there was not significant differences, p > 0.05. Then the highest number flower visited by G.thoracica in 3 minute is 31 flowers while the lowest number flower visited in 3 minute is 7 flowers. However, for H.itama the highest number visited flowers are 27 and lowest number visited flowers are 8, for the longest average visited period for each flower is 14.76 seconds and the shortest period is 3.57 seconds. Meanwhile for G.thoracica longest average visited period for each flower is 12.88 seconds and the shortest average visited period for each flower is 2.72 seconds. In conclusion, this experiment showed that stingless bees have the characteristic for effective pollinator and have the potential to be used as a pollinator for star fruit trees. However, temperature, humidity and weather gave big influence on the foraging activity of stingless bees on star fruit plant.