Chemical ecology of Apion spp.: Are cuticular hydrocarbons involved in mating behaviour?

Apion species (Coleoptera: Apionidae) are important pests of clover seed production in Sweden and severe reduction in yield of especially organic clover (Trifolium spp.) has been reported. Recent surveys in clover seed production areas in southern Sweden¹ indicate massive infestation by clover weevils. In red clover seed fields the most common species are A. trifolii Linnaeus and A. apricans Herbst., while in white clover A. fulvipes Geoffroy dominates. The overwintered adults will arrive in clover field in early summer, where they feed on the leaves of clover plants². Eggs are laid in the bud or early flowering stage of the clover flowers and the seed-eating larva is responsible for the major damage. Previous studies^3,4 have shown a relationship between volatiles from clover and host choice of weevils, which use the volatiles for orientation and locating the food, but how they distinguish between clover species and find their mates is still unknown. During the courtship behavior, we observed that the male taps with the antennae and tarsi on the female’s body, as for detecting the presence of pheromone on the elytra. We extracted the cuticular hydrocarbons present on the elytra of Apion spp. females and males from different stages and compared the chromatographic profiles. We found differences between species for female chromatographic profiles but males presented a very similar composition. Compounds responsible to elicit any mating behavior are in evaluation process.

Key words: red clover weevils, white clover weevils, short-range pheromone.

¹Lundin (2013) Ecology and management of crop pollination and pest control. Doctoral thesis. Swedish University of Agricultural Sciences, Uppsala. Acta Universitatis agriculturae Sueciae 20013:39;

²Ohlsson B (1968) Studies of Apion species on clover in Sweden (Col., Curculionidae). Stockholm.

³Andersson MN, Larsson MC, Svensson GP, Birgersson G, Rundlöf M, Lundin O, Lankinen Å, Anderbrant O (2012) Characterization of olfactory neurons in the white clover seed weevil, Apion fulvipes (Coleoptera: Apionidae). J Insect Physiol 58: 1325-1333;

⁴Nyabuga FN, Carrasco D, Ranåker L, Andersson MN, Birgersson G, Larsson MC, Lundin O, Rundlöf M, Svensson GP, Anderbrant O, Lankinen Å (2015) Field abundance patterns and odor-mediated host choice by clover seed weevils, Apion fulvipes and Apion trifolii (Coleoptera: Apionidae). J Econ Entomol 108: 492-503