Complex Blends of Synthetic Pheromones are Effective Multi-Species Attractants for Longhorned Beetles (Coleoptera: Cerambycidae)

The wood-boring larvae of longhorned beetles (Coleoptera: Cerambycidae) can be important pests of woody plants, particularly as invasive species introduced by international commerce. Previous research has revealed that cerambycid species native to different parts of the world often share the same aggregation-sex pheromones and that pheromones of different species can be combined to create multi-species attractants that would be advantageous for surveillance monitoring for a number of species simultaneously. To explore the extent to which these chemicals can be combined into single lures, we developed four different blends of six to eight compounds and tested their effects as attractants for a community of longhorned beetle species in Iowa. The blends included known pheromones of species native to the study site, as well as pheromones identified from cerambycid species native to other parts of the world. The experiment confirmed that several cerambycid species were attracted by specific blends, in accordance with their known pheromone chemistry, and despite the presence of pheromone components of heterospecifics. This finding lends further support to developing multi-component blends that can effectively monitor for new incursions of multiple exotic species concurrently.

Functional significance of phytochemical lures to dacine fruit flies (Diptera: Tephritidae): an ecological and evolutionary synthesis

While lures of plant origin are vital tools in dacine (Diptera: Tephritidae) pest management, the ecological and evolutionary significance of this lure response remains enigmatic. Two hypotheses (the ancestral host hypothesis and sexual selection by female choice) have been invoked to explain the functional significance of these chemicals to dacine fruit flies. These hypotheses are often treated as alternatives to one another and evidence favouring one is used to reject the other. This review highlights that these two hypotheses are not logical alternatives to each other as the ancestral host hypothesis attempts to explain the ultimate function of the response of Dacinae to these plant-derived parapheromones while the sexual selection hypothesis provides a proximate explanation for lure response. Research on lure response, dacine mating behaviour, functional significance of lures, plant phylogeny and biochemistry and dacine pheromone chemistry are used to evaluate the evidence in relation to both these hypotheses. Some of the key findings are that there is evidence both in support of and against these two hypotheses. Response of fruit flies to related phenyl propanoids to those commonly used as lures in pest management and distribution of phenyl propanoids attractive to dacines among plant orders strongly support the ancestral host hypothesis. Evidence from pheromone chemistry, dacine mating behaviour and the functional significance of lures both support and contradict the sexual selection hypothesis. Lures appear to have different proximate functions in different dacine species. Considerably greater research is needed to clarify the functional role of phytochemical lures to dacine fruit flies. The two prevalent hypotheses should be investigated independently. Specific research on dacine phylogeny and distribution of lures in plants in relation to ecological roles played by adult dacines is required to elucidate the ultimate roles of the chemicals. Exploration of female response to lures and the behavioural consequences of dacine response to these chemicals to both the insect and plant may shed light on the proximate functions of these chemicals.