Reducing oviposition, development and damage of Mexican bean beetle (Epilachna varivestis) on snap beans (Phaseolus vulgaris) using reflective plastic mulches

Mexican bean beetle (MBB), Epilachna varivestis Mulsant, is a pest of snap beans, Phaseolus vulgaris L., in many regions of North America.  Previous research on the climatic limitations of MBB has shown that increases in temperature and light intensity can reduce survivorship of egg, larval and adult stages, as well as oviposition.  Because reflective plastic mulches are known to increase ambient temperature and canopy-level light intensity, we tested the efficacy of planting snap beans on reflective plastic mulch to reduce MBB abundance and damage.

Our experimental treatments were metalized plastic mulch, white plastic mulch, black plastic mulch, and bare ground.  Treatments were organized in a completely randomized block design with four replicates.  Each replicate was sown with 100 ‘dragon’s tongue’ snap bean seeds in an eight meter row. 

Counts of all MBB life stages, as well as predatory arthropods, were conducted once weekly for five weeks.  Our results show that significanly fewer MBB adults and eggs were found in metalized mulch plots than all other treatments.  Beans grown on metalized mulch also produced significantly greater bean pod yields than all other treatments (plants grown on metalized mulch produced five times greater yield than plants grown on bare ground).  No differences of predator arthropods were observed among our treatments.  Our results suggest that metalized plastic mulch can serve as a useful control strategy in an IPM program for snap beans.