Pine monoterpene deterrence of pine processionary moth oviposition

The pine processionary moth (PPM) is a major pest of the Mediterranean area. Considering the severe damage the PPM may cause to pine forests, humans, and other warm-blooded animals control management is particularly needed to protect urban areas. Many plant volatiles have been studied as pest control tools, In this paper we look at (1S)-(-)-beta-pinene, (+/-)-limonene, (R)-(+)-limonene, and (S)-(-)-limonene, which were tested in 2003 and 2004 against the PPM. The chemical cues were explored for both years: (1S)-(-)-beta-pinene and (R)-(+)-limonene both clearly affected PPM egg-laying, reducing the number of egg masses per tree. Pine tree height and distance from the plantation's edge also proved to be influential, with highest trees, and trees closest to the plantation edge, having greater numbers of egg masses. Climatic factors, affecting monoterpene evaporation rates, may need to be taken into consideration by pest control managers.