Nesting Behaviour and Ecology of a Common Disjunct Bee, Megachile disjuncta (Fabricius, 1781) (Hymenoptera: Megachilidae) from India

Megachile disjuncta is a common solitary bee widely distributed and has been reported as an effective pollinator of legume crops in India. A study was conducted using the trap-nest methodology during 2023, and the new information on nesting behaviour and ecology of M. disjuncta is presented here. The species successfully occupied artificial nests provided in the form of hollow reeds of Ipomoea and bamboo canes. Bees exhibited a clear and significant preference for nesting in bamboo canes compared to Ipomoea reeds (χ² = 19.572, df = 1; P-value: <0.0001). M. disjuncta remained active from March to September, with activity peaking in April. Artificial nests were modified using the mud and resin collected from different plants. The resin was used to construct partition walls between the cells, and mud was used to plug the nest entrance. The average number of brood cells observed was 6.1 ± 2.42, with an average nest length of 10.83 ± 3.05 cm. There is no significant difference in the observed sex ratio [F: M = 1:1.66; χ² = 0.23, Critical value (α = 0.05, df = 1) = 3.84], and protandry was observed in the adult emergence pattern. Approximately 49-56 per cent of bees failed to complete their nests due to the high incidence of natural enemies. Reported here for the first time, M. disjuncta nest infestation by the clepto-parasitic megachilid bees, ectoparasitic leucospid wasps, and parasitisation by the bombyliid fly. The success of colonising trap nests makes it an interesting and potentially valuable opportunity to utilise the same to pollinate cultivated crops.