Starvation of pine-tree lappet Dendrolimus pini fourth instar larvae and recovery on different pine species—Can they recover from transport and start a new way of life?

Abstract

Economic progress affects the intensity of commercial and recreational transport globally. The combination of these two factors may lead to the unintended dispersion and subsequent invasion of insect species which, in turn, may pose a threat to native organisms. There are many reasons to study the survival of pests after starvation, which occurs during transport conditions, and examine their recovery on different plants, other than their primary host, to predict their likelihood of using these plants as alternative suitable hosts. In this study, we sought to answer the following question: after the starvation period, are the economically important pest of Scots pine, Dendrolimus pini larvae, able to feed on other species of pine as potential hosts? Ten morphologically varying species of pine from different regions of the world were used for the experiment. Control individuals of D. pini fed on the primary host ad libitum, without a period of starvation. We found that although the recovery of D. pini is optimal on Scots pine, the basic host plant, this insect can regenerate comparably well on different species of pine. Following starvation, re-feeding on pine species other than the basic host plant caused a decrease in overall survival and a reduction in the body mass (pupal and adult) and fecundity of individuals compared with control individuals that were fed the appropriate dose of the basic host. On the basis of the various investigated parameters, we could conclude that larvae regenerated best on pine species from Europe and North America, or when they fed on species with two-needle fascicles, as compared to Asian pine species, and species with three- or five-needle fascicles, respectively. We conclude that D. pini larvae are characterized by their ability to survive without food and then recover using different Pinus species as hosts, thereby confirming that D. pini could survive starvation periods compatible with migration to almost anywhere in the world via anthropogenic vectors, and then start a new way of life on a novel host.