“Cuddlemone”- Pheromone-based Attraction in Codling Moth Larvae

Pheromones are airborne signals used by insects to communicate with other members of the same species. Codlemone is the main component of the sex pheromone blend of codling moth, emitted by calling females to attract males. It would seem, however, in the case of codling moth, that cocoon-spinning larvae also emit pheromones which are attractive to other larvae seeking sites in which to pupate.

Both male and female larvae produce and respond to this aggregation pheromone. They respond to it over distances of at least 20 cm. (This may not sound like much, but larvae seeking pupation sites are very mobile and move repeatedly over the trunk of the tree.) These aggregation pheromones result in clumps of several codling moth pupae in the field.

There may be a cost associated with larval aggregations. The cocoon-derived aggregation pheromone of codling moth also attracts a parasitoid, which essentially “eavesdrops” onthe communication system of its host.

Why would these insects have adapted this behaviour and what is the potential significance from a management standpoint? Female codling moth pupae release their sex pheromone precociously, before they even emerge as adults, and male moths are attracted to them. Researchers have proposed that larval pheromones are part of the insect’s reproductive strategy, in that aggregated individuals are able to find mates more quickly when they complete their development and emerge as adults.

From a management standpoint, the biology offers some potential opportunities for enhanced control in some management systems. In BC, for example, many organic producers place cardboard bands around the trunks of trees. The codling moth larvae find these bands irresistible as pupation sites, so growers can reduce numbers in the field by removing them in the spring or late fall. By adding a synthetic blend of the aggregation pheromone to the bands, researchers demonstrated a tactic with potential to increase the efficacy of this tactic. While there is no commercial product available at present, the technique would provide an intriguing management tool.

I’d like to propose that this pheromone blend be dubbed “cuddlemone”, since it doesn’t appear anyone else has done so yet!

Duthie, B. et al. 2003. Does pheromone-based aggregation of codling moth larvae help procure future mates? J. Chem Ecol. 29:425-436

Jumean, Z. et al 2005. Identification of the larval aggregation pheromone of codling moth, Cydia pomonella. J Chem Ecol. 31(4):911-924

Jumean, Z. et al. 2006. Pheromone-based trapping of larval codling moth, Cydia pomonella, in apple orchards. Entomoogio Experimentalis et Applicata 122:87-91

Z. Jumean et al. 2008. Does larval aggregation pheromone of codling moth, Cydia pomonella, induce attraction or arrestment of receivers? Bull. Entomol. Res. 98:425-429.