Distribution and Invasion of Clearwing Moth Synanthedon Tipuliformis Cl.,a Pest Of Currant, in Latvia

The aim of the present study was to determine the distribution and prevalence of S. tipuliformis in Latvia. In 2008-2009, trials were carried out in blackcurrant plantations aimed at establishing the distribution of S. tipuliformis across the territory of Latvia. To achieve this goal, 13 blackcurrant plantations were surveyed in 2008. The research was continued in three plantations in 2009. To assess of prevalence and level of damage caused by the S. tipuliformis, two methods were used: cutting of branches (five branches were cut from each bush) and pheromone traps with dispensers (distributed in each trial farm with density one trap per ha). The presence of S. tipuliformis was recorded in all 13 horticultural farms surveyed in 2008. Analyses of the branch samples demonstrated that the pest invaded from 3% to 70% of the branches. A total of 2.5 to 35 adults were caught per pheromone trap. The highest proportion of the branches invaded by the S. tipuliformis was in 2008 (70%) and the highest number of males in traps in 2009 was recorded in Jelgava municipality. S. tipuliformis is widely found in blackcurrant growing plantations across the whole territory of Latvia.

Inter- and Intraspecific Activities of Compounds Derived from Sex Pheromone Glands of Currant Borer, Synanthedon tipuliformis (Clerck) (Lepidoptera: Sesiidae)

Gas chromatography and mass spectrometry analyses of crude sex pheromone gland extracts revealed that virgin Synanthedon tipuliformis (Clerck), currant borer (Lepidoptera: Sesiidae) females, produced 6 compounds, structurally related to sex pheromone components of clearwing moths. By comparison of retention times and mass spectra of natural products with corresponding properties of synthetic standards, these compounds were identified as: (2E,13Z)-octadeca-2,13-dien-1-yl acetate (E2,Z13-18:OAc), (3E,13Z)-octadeca-3,13-dien-1-yl acetate (E3,Z13-18:OAc), (13Z)-octadec-13-en-1-yl acetate (Z13-18:OAc), (2E,13Z)-octadeca- 2,13-dien-1-ol (E2,Z13-18:OH), (13Z)-octadec-13-en-1-ol (Z13-18:OH) and octadecan- 1-ol (18:OH) in the ratio 100:0.7:2.7:3.2:traces:traces. The first 3 compounds were previously known to occur in the sex pheromone gland extracts of currant borers, while the last 3 chemicals are now reported for the first time. Trapping tests carried out in the black currant field revealed that E2,Z13-18:OAc, when tested separately, attracted S. tipuliformis males, while addition of E3,Z13-18:OAc to the main component increased the effectiveness of E2,Z13-18:OAc over seven times. The attractiveness of 6 component lures did not differ significantly from the one of the binary mixture, confirming that E2,Z13-18:OAc and E3,Z13- 18:OAc in the ratio100:0.7 are essential sex pheromone components of S. tipuliformis. Trapping tests carried out at the dwelling place of Synanthedon scoliaeformis (Borkhausen) (Lepidoptera: Sesiidae) revealed that, in addition to intraspecific synergistic effect, E3,Z13-18:OAc increased the specificity of the pheromone signal of S. tipuliformis, acting by intraspecific mode as an attraction antagonist against S. scoliaeformis males. By this way, it ensured the specificity of the sex attraction signal of the currant borer. Consequently, both compounds E2,Z13-18:OAc and E3,Z13-18:OAc have to be present in pheromone formulations used for monitoring and/or control of S. tipuliformis to avoid effecting non-target species. Other compounds identified from the sex pheromone gland of S. tipuliformis did not show any significant interspecific activity for males of S. scoliaeformis, however, they provide a basis to achieve specificity of a pheromone signal of S. tipuliformis and could act as attraction antagonists against other clearwing moth species which, like S. tipuliformis, employ E2,Z13- 18:OAc as their sex pheromone component.