Two components of the female-produced sex pheromone of the hornet moth, Sesia apiformis, were identified as (3Z,13Z)-octadeca-3,13-dien-1-ol (3Z,13Z-18:OH) and (2E,13Z)-octadeca-2,13-dienal (2E,13Z-18:Al), a pheromone structure new in Sesiidae. Pooled gland extracts showed the two major compounds in a proportion of ca. 2:3, while SPME-investigations on single calling females revealed a ratio of ca. 1:7. Although the single compounds were not attractive, a 2:3 mixture proved to be highly active towards males in field tests. Small amounts of (2E,13Z)-octadecadienol (2E,13Z-18:OH) were found in the sex pheromone gland of females, however, the biological significance of the compound remains unclear. Methyl sulfide was found to readily react with 2-alkenals, providing an effective new method for the characterization of this type of compound upon GC/MS. The derivatives, 1,1,3-tris(methylthio)alkanes, are the products of the addition of methyl sulfide to the double bond and the transformation of the carbonyl group into the corresponding bis(methylthio)acetal. The mass spectra of these compounds are characterized by diagnostic signals at m/z 107 and/or m/z 121. These fragments represent the first carbon unit or the first two carbon units of the derivative, respectively. The parent signal in the spectra of thiomethyl derivatives of 2-alkenals showing no other double bonds is represented by m/z M+ - 121, formed upon loss of the first two carbon units. By employing a solution of methyl sulfide in dimethyl sulfide, the double bond positions in 2E,13Z-18:Al could be fully characterized by GC/MS.
Males of the currant clearwing moth (Synanthedon tipuliformis) preferred yellow and green pheromone-baited traps. Electrophysiological and behavioural experiments were conducted to determine whether this phenomenon was caused by the ability of currant clearwing moths to discriminate colours and their preference for some of them. The electroretinogram (ERG) study revealed 2 sensitivity peaks in the dark adapted eye: in the UV zone (λ max = 350 nm) and in the green zone (λ max = 500 nm). According to the ERG data on the bright orange adapted eye, the latter peak might be the sum response of the blue receptor with λ max ~ 470 nm and the green receptor with λ max ~ 530 nm. In field experiments with traps of equal contrast against the background but different in colour, light-yellow traps were significantly more attractive, providing evidence, that S. tipuliformis moths possess colour vision and use it while reacting to the female sex pheromone. Although it was proved that currant clearwing moths are able to perceive the UV-colour, the addition of the UV-colour did not affect attractiveness of traps.
1. To further knowledge regarding habitat requirements of the threatened species Boros schneideri, a total of 1522 dead standing Scots pine (Pinus sylvestris) were checked for the presence of B. schneideri larvae. For the 245 trees inhabited by larvae (16% of all examined trees), tree characteristics and occupancy patterns were measured.2. As most of the investigated forests were 40-80 years old and were dominated by comparatively thin dead trees (5-20 cm diameter at breast height), B. schneideri larvae were mainly found under the bark of trees with a diameter in the range of 10-20 cm. However, the probability of a tree being inhabited by B. schneideri increased progressively with tree diameter and forest age.3. Most of the trees with B. schneideri (79%) were in medium-dense and sparsegrowth pine forests where the canopy cover was 60-80%. The presence of Norway spruce (Picea abies) in Scots pine forests was an important factor affecting the probability of trees being inhabited by B. schneideri. Only 6% of trees inhabited by B. schneideri were found in mixed Scots pine-Norway spruce forests, where the shadowing was higher than 80%.4. All dead trees inhabited by B. schneideri had loose and at least slightly fragmented bark. A bark area of 0.08 m 2 was found to be sufficient for the survival of B. schneideri. The critical bark thickness for B. schneideri larvae was 5 mm.5. The data obtained are important for the optimisation of conservation measures implemented during forest management operations.
Field screening tests of 21 saturated and monounsaturated straight chain C,2 and C,, alcohols and their acetates as well as some binary mixtures in dosages of 1 and 0.2 mg/dispenser were carried out in Lithuanian in 1993 and 1994. New sex attractants were determined for males of five moth species of the family Gracillariidae (E10-12:OH for Phyllonorycter sorbi, EI0
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