The swede midge, Contarinia nasturtii Kieffer, is a serious pest in crucifers. Its pheromone is a blend of (2S,9S)-diacetoxyundecane, (2S,10S)-diacetoxyundecane and (2S)-acetoxyundecane. The pheromone is used in monitoring traps, and this study examines possible ways to optimise the traps.
Two dispenser types were compared: polyethylene dispensers and cotton dispensers. Polyethylene dispensers attracted male C. nasturtii for more than 6 weeks, whereas cotton dispensers were attractive for only 2 weeks. All three pheromone components were important for attraction of male midges in the field. The importance of the stereoisomeric compositions of the pheromone compounds was also tested-both in the wind tunnel and in the field. In the case of 2,9-diacetoxyundecane and 2-acetoxyundecane, the non-natural stereoisomers did not inhibit male C. nasturtii attraction, whereas one or both of the stereoisomers of 2,10-diacetoxyundecane did.
Pheromone traps with the synthetic pheromone in a 1:2:0.02 ratio emitted from PE dispensers were highly effective and long lasting. As the mixture of stereoisomers of 2,10-diacetoxyundecane strongly inhibited attraction of male C. nasturtii while those of 2,9-diacetoxyundecane and 2-acetoxyundecane did not have any inhibitory effect, it is possible to produce traps that are effective and long lasting but cheaper to produce and maintain.
"mixture of (2S,9S)- diacetoxyundecane:(2S,10S)-diacetoxyundecane:(S)- 2-acetoxyundecane extracted from the femaleÕs ovipositor could effectively attract Swede midge males under laboratory and Þeld conditions with very high species speciÞcity. The Swede midge sex pheromone blend maintained its attractiveness to Swede midge males for only 2 wk in Þelds if cotton dispensers were used; however, if polyethylene dispensers were used, its attractiveness could extend to Ͼ6 wk in Switzerland (Boddum et al. 2009). However, under Ontario Þeld conditions, cotton wicks and polyethylene dispensers were found to be attractive for only 2 and 4 wk, respectively (R.H.H. et al. unpublished data). "
[Show abstract][Hide abstract] ABSTRACT: The Swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae), a common insect pest in Europe, is a newly invasive pest in North America that constitutes a major threat to cruciferous vegetable and field crops. Since its first identification in Ontario, Canada, in 2000, it has rapidly spread to 65 counties in the provinces of Ontario and Quebec and has recently been found in canola (one of two cultivars of rapeseed, Brassica napus L. and Brassica campestris L.) in the central Prairie region where the majority of Canada's 6.5 million ha (16 million acres) of canola is grown. The first detection of Swede midge in the United States was in 2004 in New York cabbage (Brassica oleracea L.), but it has now been found in four additional states. Here, we review the biology of Swede midge, its host plant range, distribution, economic impact, pest status, and management strategies. We provide insight into this insect's future potential to become an endemic pest of brassica crops in North America. We also proposed research needed to develop tactics for handling this invasive pest in brassica crops.
[Show abstract][Hide abstract] ABSTRACT: In this thesis, the sense of olfaction and its links to behavior was studied in the cetoniid chafers Pachnoda interrupta and P. marginata, and the bark beetle Ips typographus. P. interrupta is a pest on sorghum in Ethiopia, and I. typographus is a spruce pest in the palearctic, and an aim was to uncover new control methods. In I. typographus, the olfactory receptors (ORs) that determine response specificity in olfactory receptor neurons (ORNs) were investigated. Phylogenetic analysis showed that I. typographus and Tribolium castaneum ORs form a Coleoptera-specific subgroup. At the next level of the olfactory system, ORN response to food odorants was compared between P. interrupta and P. marginata. Both are opportunistic polyphages on fruits and flowers, but are present in disparate habitats. P. interrupta is found in savannah, and P. marginata in tropical Africa. The two species showed a high degree of overlap in their ORN arrays, indicating that a similar sensory strategy for food search is viable in both habitats. Field trapping with compounds eliciting strong ORN response identified a powerful attractant for P. interrupta, 2,3-butane diol. In a P. interrupta study, coupled gas chromatographic-electroantennographic detection identified antennally active compounds from sorghum, Sorghum bicolor, and another food host, Abutilon figarianum. Field tests indicated that single compounds (e.g. methyl salicylate) were more important than mixtures in attraction to these two hosts. Field studies of mating and aggregation in P. interrupta showed that unmated females were attractive to males, and to both sexes when combined with food. Female-specific compounds were identified by mass spectrometric comparison of male and female extracts. Field tests of these established that phenylacetaldehyde was highly attractive to both sexes, implying that it is part of the P. interrupta pheromone. These findings create novel possibilities for control. Phenylacetaldehyde and attractive food compounds could be used for mass trapping of P. interrupta. The identified I. typographus ORs make a search for pheromone and repellent receptors possible. Compounds that hyper-excite these receptors could be used for mass trapping or disruption of host search.
[Show abstract][Hide abstract] ABSTRACT: This study describes the morphology and function of the antennal sensilla in two gall midge species, Contarinia nasturtii and Mayetiola destructor, where multi-component sex pheromones have been identified. Both species possess sensilla trichodea, s. coeloconica, s. chaetica and s. circumfila. Sensilla circumfila, which consist of several sensilla that bifurcate and fuse into one structure, are unique for the gall midges. In C. nasturtii s. circumfila are sexually dimorphic. In males, they form elongated loops suspended on cuticular spines, whereas in females they run like worm-like structures directly on the antennal surface. Single sensillum recordings demonstrated that olfactory sensory neurons housed in male s. circumfila in C. nasturtii responded to the female sex pheromone. In M. destructor, s. circumfila were attached to the antennal surface in both sexes, and displayed no response to sex pheromone components. A sexual dimorphism was also found in the number of s. trichodea per antennal segment in both C. nasturtii (male 1 vs. female 7) and M. destructor (male 13 vs. female 10). OSNs located in male M. destructor s. trichodea responded to the sex pheromone. This is the first gall midge single sensillum study, and the first demonstration of the functional significance of s. circumfila.
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