Intra‐ and interspecific density dependence mediates weather effects on the population dynamics of a plant–insect herbivore system

Temperature and precipitation are two major factors determining arthropod population densities, but the effects from these climate variables seldom evaluated in same study system combination with inter‐ intraspecific density dependence. In this study, I used a 19 year time series on plant (shoot height flowering incidence) insect order to understand direct indirect of climatic fluctuations densities. The includes closely related leaf beetle species ( Galerucella spp.) flower feeding weevil Nanophyes marmoratus attacking purple loosestrife Lythrum salicaria . Results suggest that both dependence weather affected interactive rain temperature densities depended timing relative life cycles. spring, high temperatures increased only when combined rain, as low implies drought risk. Low beneficial if little cause chilly wet conditions bad for insects. summer, different because induce wilting plants, thus reducing food availability larvae. contrast, was less by directly, more indirectly interspecific dependent through reduced resource caused previous damage.