Phaseolus vulgaris L. cv. 'Black Valentine' bean is a host for the plant pathogen bean pod mottle virus (BPMV). The Mexican bean beetle, Epilachna varivestis Mulsant, is a vector of BPMV. The Mexican bean beetle acquires BPMV when it feeds on an infected plant. The virus is retained in the beetle's foregut. It does not enter the hemacoel or replicate in the beetle. The beetle spreads the virus when it regurgitates during feeding on other plants. The objective of this study was to determine if the interaction of BPMV with 'Black Valentine' bean affects Mexican bean beetle behavior and growth. In an adult feeding preference test, beetles preferred and ingested more of the virus-infected leaf discs. In a larvae weight experiment, beetle larvae that fed on virus-infected plants weighed more than those that fed on healthy plants. These data suggest that there may be a mutualistic relationship between the Mexican bean beetle and bean pod mottle virus. The virus benefits from being transmitted and the beetle benefits from being a vector. The beetle preferred the virus-infected plants, which seem to help the growth of the beetle larvae. A possible mechanism for this behavior is that by transmitting the virus, the systemic acquired resistance pathway (detrimental to plant pathogens) is triggered; consequently, the induced resistance pathway (detrimental to insect herbivores) becomes less effective toward the beetle.
Species 1: Coleoptera Coccinellidae Epilachna varivestis (Mexican bean beetle)
Species 2: Phaseolus vulgaris (black Valentine bean)
Species 3: (bean pod mottle virus, southern bean mosaic virus)
Keywords: Induced Resistance, Systemic Acquired Resistance
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA