MSc

The present study entitled ‘Augmentation of pollination in culinary melon (Cucumis melo var. acidulus L. Naudin) with Indian bee (Apis cerana indica Fab)’ was conducted at Department of Agricultural Entomology, College of Agriculture, Vellayani and at farmers field, Thiruvananthapuram during 2017 to 2019. The objectives were to study the foraging behaviour of A. c. indica and to standardise the number of bee hives required for yield enhancement in culinary melon.
Preliminary observations on pollinator diversity and on relative abundance of insects were carried out for assessing the dominant pollinator and to study its foraging behaviour. These observations were made at different time periods of the day (0600–0700 h, 1000–1100 h, 1400–1500 h, 1700–1800 h) at weekly intervals during peak flowering stage of plant. The floral biology of culinary melon was also studied to assess plant to pollinator relation. Culinary melon was raised in an area of 1 acre during February to April, 2019 for estimating the number of hives required per hectare for optimum pollination. For the same, an Indian bee hive with six frame bee strength was installed at the centre of plot at 10 per cent flowering. Four radial distances (T1- 10 m, T2- 20 m, T3- 30 m and T4- 40 m) from bee hive were the treatments and four plants each at different distances were considered as replications. The statistical frame work, CRD was followed for the experiment and control plot without bee hive was also maintained to compare the yield difference due to augmented pollination.
Studies on pollinator diversity revealed that the pollinators or flower visitors of culinary melon alone comprised of 14 insect species. The common pollinators observed were A. c. indica, Ceratina hieroglyphica, Braunasis sp., C. binghami, Tetragoula travancorica, Lampides boeticus, Aulacophora foveicollis, Luperomorpha vittata, and Camponotus sp. Maximum number of pollinators was recorded during 1000-1100 h with A. c. indica as the dominant pollinator (12.87 bees m-2 in 5 minute duration) in terms of relative abundance.
Observations on foraging behaviour of dominant pollinator, A. c. indica indicated that they were nectar foragers with their peak activity during 1000 to 1100 h. The bees commenced foraging on 0700 h and ceased activity on 1800 h, thus rendering eleven hours of foraging time. Maximum foraging rate was 14.17 flowers min.-1 while foraging intensity was 1.60 bees m-2 min.-1. Minimum time spent by bees was recorded as 2.37 sec. on male flowers and 12.07 sec. on female flowers. All bees were alighting directly on stigma and hence regarded as top workers.
Studies on floral biology of culinary melon revealed that female flowers were receptive only for one day. Length of stamen (0.45 cm) and proboscis of bees (0.49 cm) were almost same which enabled top working by bees and thereby enhanced pollination through the pollen adhered on the bifid hairs of bees. .
For standardising the requirement of bee hives ha-1, yield parameters and foraging intensity were recorded at varying distance. Significantly high foraging intensity and yield parameters were recorded at 10 m distance (fruit set- 75.44%, fruit weight- 0.75 kg) which was immediately followed by 20 and 30 m, which were on par. Economic analysis using B:C revealed that both treatments 10 m (B:C-2.7) and 30 m (B:C-2.5) were economically feasible. Considering the economic and technical feasibility, 30 m was selected as an effective radial distance for adequate bee pollination based on which the number of hives required per ha was estimated as four. Plants at this effective distance recorded significantly higher (p < 0.05) yield parameters, both quantitatively and qualitatively (fruit set- 66.62 %, fruit weight- 0.55 kg) compared to that of plots without hives. Thus, a yield increase of 57.50 per cent was obtained from the plot with bee hive. Deformed fruits were recorded least in augmented plots (39.00 %) than the control plot (54.91 %).
Thus the present study indicated that four A. c. indica colonies with six frame bee strength were required for adequate pollination of culinary melon in 1 ha. The peak foraging activity was observed during 1000 to 1100 h with a foraging rate of 14.17 flowers min.-1. Augmented pollination resulted in increased yield both in terms of the quantitative and qualitative parameters, with 57.50 per cent yield enhancement over the control plants.