Inbreeding in the coffee berry borer, Hypothenemus hampei (Coleoptera : Scolytidae) estimated from endosulfan resistance phenotype frequencies

An estimate of the inbreeding coefficient, Fis, of the coffee berry borer, #Hypothenemus hampei Ferrari, was calculated from genotype frequencies of endosulfan resistance in beetles collected from berries in 41 fields on the East Coast of New Caledonia. Two different estimates were obtained as a function of sampling date : Fis = 0,491 + ou - 0,059 (s.e.) for samples collected in September, and Fis = 0,215 + ou - 0,108 for samples collected in April. These values of Fis are very high in comparison to those of more insects, but surprisingly low given current understandings of #H. hampei mating patterns. The difference between April and September Fis estimates is discussed in terms of insecticide regimes and seasonal variability of sib inbreeding levels. The high level of inbreeding in the coffee berry borer increases frequencies of homozygotes relative to heterozygotes. Inbreeding will accelerate resistance evolution whenever the fitness of homozygous resistant insects exceeds that of heterozygotes, and will undermine any high - dose strategy to control resistance evolution. (Résumé d'auteur

Can vibrational playbacks disrupt mating or influence other relevant behaviours in Bactericera cockerelli (Triozidae: Hemiptera)?

Behaviours of insects can be manipulated by transmitting vibrational signals to host plants in order to develop pest management techniques. Bactericera cockerelli is an important pest and uses vibrations for mate-finding. In order to design a future control strategy for B. cockerelli, three different bioassays were performed to assess whether vibrational signals could affect relevant behaviours. Single males or pairs were treated with a female playback in test 1 and 2, respectively. In test 3, mixed sex groups received either different disturbance playbacks. The use of a female playback significantly reduced the mating success of males, since they were attracted towards the source of the stimulus. Moreover, test 2 revealed that B. cockerelli females are competitive, since they used their signals to cover the playback and to duet with males, while in test 3, the disturbance playback, consisting of broadband noises significantly reduced male signalling activity. However, none of the treatments of test 3 negatively affected the mating success of males, which tended to mount the other conspecifics present on the same leaf. The role of vibrations in sexual communication and their potential application as control technique for B. cockerelli are discussed as well