Applied Chemical Ecology of Forest Insects

Forests provide diverse and complex services, including contributing directly to the livelihood of more than 1.5 billion people, providing habitat to ca. 80% of terrestrial species and combating climate change. With the continued growth of human populations, the significance of the ecosystem services provided by forests will increase.

Pest management in forest ecosystems is inherently more complex than in agricultural ecosystems, in part due to the spatial and temporal scales involved. In addition, forest ecosystems are comparatively more variable ecologically than agroecosystems. As a result, the development and implementation of pest management tactics in forest ecosystems are less advanced than in agroecosystems.

In terms of the impacts and numbers of species and individuals, insects are an important natural component of forest ecosystems. Forest insects not only have a strong impact on tree growth and reproduction but also interact closely with other animals and plants in forest ecosystems. Some insects have negative impacts on tree health. In addition, some species reach high population densities, primarily due to ecological imbalances caused by disturbances (including climate change), and this can result in significant levels of tree mortality and impacts at the stand level. As a result of globalization, international travel and climate change, many species have expanded their ranges, and some have become new and serious pests. Native and non-native insect pests and pathogens are one of the most common disturbances that threaten the health of forest ecosystems globally. The frequency and intensity of these disturbances will continue to increase with increasing globalization and the changing climate.

Chemical ecology is the study of chemically mediated intra- and interspecific interactions and, consequently, has immense potential to provide biorational pest management tactics. For example, chemically mediated interactions involving forest insects include the role that semiochemicals play in mate location and mediating interspecific interactions, including the detection and avoidance of host/non-host trees, predator–prey interactions and interactions with microorganisms (including symbionts) in forest ecosystems. This Special Issue on the “Applied Chemical Ecology of Forest Insects” invited original research articles and reviews on recent progress in semiochemical biology/ecology, chemical identification/synthesis and the application of synthetic semiochemicals in the pest management (including monitoring, mass-trapping, mating disruption, attract–kill and push–pull) of important native and invasive forest insect pests.

The Special Issue includes 10 papers from six countries based on the affiliations of the first authors: China (2), the Czech Republic (1), Italy (1), South Africa (1), Sweden (1) and the United States of America (1). Three of these papers were reviews, and the remaining seven were based on original data. The topics reviewed include the chemical ecology of the Western Pine Beetle [1], the attractant semiochemicals of North American species of Dendroctonus Bark Beetles [2] and the life history traits of the Pentatomidae and IPM [3]. The original data contributions included two manuscripts that looked at push–pull tactics in Ips typographus [4,5], two manuscripts that looked at semiochemicals and tree–insect herbivore interactions (Dendroctonus simplex and Endoclita signifer) [6,7], two manuscripts looked at aspects of the pheromone biology of forest insects (Lycorma delicatula and Diprion jingyuanensis) [8,9] and one manuscript explored the functional role of intestinal symbionts in Anoplophora glabripennis [10].