Resistant and susceptible tomato genotypes have direct and indirect effects on Podisus nigrispinus preying on Tuta absoluta larvae

Abstract

Studies that focus on understanding complex interactions among resistant plants, herbivores, and their natural enemies are fundamental to elucidating whether plant herbivore defenses impose beneficial, adverse, or neutral effects on natural enemies. The impacts of resistant plant genotypes on natural enemies can determine the feasibility of integrating host plant resistance with biological control in IPM programs. We investigated direct and indirect effects of tomato trichomes on the predatory stink bug Podisus nigrispinus by assessing the development, predatory capacity, and foraging behavior of bugs fed Tuta absoluta larvae reared on resistant and susceptible tomato genotypes in both the presence and absence of the plant. We also characterized and quantified glandular leaf trichomes on the tomato genotypes to assess correlations between these and observed effects on the predator. The resistant tomato genotype did not affect P. nigrispinus development in the absence of the plant, but survival, adult longevity, number of larval prey consumed, and foraging behavior were all negatively impacted in the presence of resistant plants. These negative effects on P. nigrispinus were associated with higher densities of type I and type IV glandular leaf trichomes on resistant plants compared to susceptible ones. We infer that resistant genotypes possessing high densities of glandular trichomes, especially those of type I and IV, could be antagonistic to biological control of T. absoluta by P. nigrispinus in tomato fields. Additional research is warranted to assess other effective and environmentally safe control methods for integration with P. nigrispinus biological control in tomato IPM.