Effects of dipping alfalfa leaf-cutting bee nesting materials on chalkbrood disease.
Before use in commercial field shelters, some artificial nesting blocks (wooden) for Megachile rotundata were dipped in 3% calcium hypochlorite solution for 3 min. In 1985 the amount of chalk brood disease (caused by Ascosphaera aggregata) that developed in larvae in these blocks was not significantly different from the amount in larvae in untreated blocks, but it was significantly less in larvae in treated blocks in 2 subsequent cage tests. In 1986 the amount of chalk brood that developed in larvae was significantly less in treated blocks in both field and cage tests, and it is concluded that the use of sodium hypochlorite in commercial systems would be effective in reducing losses due to chalk brood.<new para>ADDITIONAL ABSTRACT:<new para>The effect of dipping nesting materials of Megachile rotundata, a primary pollinator of lucerne, in calcium hypochlorite to reduce chalkbrood disease caused by Ascosphaera aggregata was investigated in lucerne fields in Washington in 1985-86. When nesting materials were dipped for 3 min in 3% calcium hypochlorite the incidence of chalkbrood disease was significantly reduced. The treatment had no effect on pollen ball/immature mortality or total number of cells produced.