The sex pheromone component of several fruit pests have been identified and synthesised and monitoring traps have been developed. Growers benefit through more accurate predictions of pest attack and focussed rather than prophylactic application of insecticides. The team continues to investigate the further use of these insect sex pheromones for more direct pest control by mating disruption, attract and kill and mass trapping.
To date, sex pheromones for apple, pear and blackcurrant leaf curling midges, blackberry and pear midges, raspberry cane midge, strawberry blossom weevil, European Tarnished Plant Bug (Lygus rugulipennis; ETPB) and the Common Green Capsid (Lygocoris pabulinus; CGC), have been elucidated and marketed. The researchers are currently working on blackcurrant and gooseberry sawfly and Rhynchitis weevil pheromones.
The traps recently developed for ETPB (green, cross vane, funnelled bucket trap) and CGC (cone-shaped blue sticky trap) were the first practical monitoring traps for this group of bugs in the world and were used in UK horticulture for the first time in 2012. Two ETPB traps were sufficient to monitor up to 2 ha of a uniform planting and in 2012, ETPB in strawberry was detected in high numbers in pheromone traps four weeks earlier than by more traditional tap sampling. Without accurate monitoring information, growers are forced to use remedial applications of broad spectrum insecticides. Although these treatments can be effective against capsids, they disrupt the biological control of other pests and can lead to the application of further sprays. For example, recent outbreaks of pesticide-resistant Western Flower Thrips on strawberry are due, in part, to routine spraying against capsids.
The team have recently identified the female sex pheromone of the blackcurrant sawfly, Nematus olfaciens, a notoriously sporadic, highly damaging pest, and demonstrated strong attraction of males to synthetic lures in the field for the first time. The pheromone is an unusual blend of esters which, unlike previous claims for a related sawfly, are not air oxidation products of cuticular hydrocarbons. This is probably the first time a sex pheromone of a pest in the Tenthredinidae family has been identified together with strong attraction to a synthetic lure.
A trap developed for the Strawberry Blossom Weevil uses a combination of an aggregation pheromone (catches males and females) and a wild strawberry plant volatile compound. It is very similar to the ETPB trap, only with white cross vanes instead of green, with an excluder grid to prevent bees being trapped.
A new four-year research project funded under the EU Core Organic Scheme in collaboration with research groups from Denmark, Latvia, Norway, Sweden and Switzerland was started in 2012. It aims to develop multiple-species mass traps for capsid bug, blossom weevil and raspberry beetle.