Phacelia tanacetifolia can enhance conservation of honey bees and wild bees in the drastic hot-arid subtropical Central Arabia

Phacelia tanacetifolia is a widely used food plant in the beekeeping and conservation of pollinators. The present work is the first report for its value as bees and insectary plants in Saudi Arabia. Insect species visiting on flowers of P. tanacetifolia were identified and clustered as pollinators, pests and natural enemies. Out of 54 recorded insect species, 26 species were from Hymenoptera followed by Diptera (eight species), Lepidoptera (eight species), Coleoptera (six species), Hemiptera (five species) and Neuroptera (one species). Hymenopterous insect (bees, wasps, and ants) were the abundant flower visitors and out of them, bees were at the top with the highest recorded species (18). Apis mellifera and Apis florea were the most common honey bee species visiting on P. tanacetifolia, and exhibited daytimes and flowering season-dependent foraging activity (visits/m(2)). Apis species showed preferential high foraging visits for nectar than pollen collection. The major flower visitor was A. florea and the time spent by A. florea in the flower was significantly higher than A. mellifera. Insect-pollinated flowers of P. tanacetifolia presented significantly high-seed set percentage (62%) than non-insect-pollinated flowers (14%). Nectar secretion of P. tanacetifolia fluctuated significantly during daytimes and months with the highest amount during noon-afternoon and March. Blooming period (six weeks: fore-March to mid-April), seed harvesting (late-April), flower density (9069 flowers/m(2)/day), nectar productivity (4 g/m(2)/day) and honey potentiality (1791 kg/ha/season) of P. tanacetifolia was also monitored. P. tanacetifolia can be an ideal potential plant to support honey bees and other insect pollinators in the hot-dry ecosystem of central Saudi Arabia.