The Essential Oils of the Greek Endemic Satureja horvatii ssp. macrophylla in Relation to Bioclimate

The essential oils of the Greek endemic Satureja horvatii subsp. macrophylla collected from 36 areas (among them, 23 are included in twelve sites of the EU network NATURA 2000) belonging to different bioclimatic types were studied. The total essential‐oil content is negatively related to the altitude. The variation of the essential oil composition follows a geographical pattern, which is related to the bioclimatic belts along the taxon's range. Carvacrol dominates in areas with Mediterranean and Submediterranean bioclimate (mainly in the S and C part of the taxon's distribution), linalool or trans‐sabinene hydrate, and/or borneol in the Submediterranean or Temperate Axeric bioclimates (in the N part of distribution), whereas thymol is found as main oil constituent in all three bioclimates.     

Variation of Satureja douglasii monoterpenoids in relation to light intensity and herbivory

Genotypic variation of monoterpenoid yield and composition in Satureja douglasii was shown by growth of clonal transplants under uniform conditions. Differentiation of monoterpenoid yield was correlated with light intensity and degree of herbivory along transects. High-yielding genotypes occurred under low light, high herbivory conditions, whereas low-yielding genotypes occurred in high light, low herbivory conditions. Differentiation of monoterpenoid composition was more weakly correlated with herbivory and light intensity than was yield. There was also some evidence for seasonal variations of yield.     

Flight behaviour of the black bean aphid, Aphis fabae, and the cabbage aphid, Brevicoryne brassicae, in host and non-host plant odour

Abstract. Walking alate virginoparae of Brevicoryne brassicae (L.) and Aphis fabae Scopoli were presented with odours of steam-distilled extracts of the non-host plants summer savoury ( Satureja hortensis L.) and tansy ( Tanacetum vulgare L.) in an olfactometer. No effects of the extracts were observed on B. brassicae. However, A.fabae were repelled by summer savoury and tansy odour; both extracts also masked an attractant response to bean (host plant) odour. In a flight chamber, air permeated with odour from host or non-host plants was blown over flying alates of both species, with a green, plant-mimicking target presented once a minute. The incidence of targeted (host-responsive) flight of B.brassicae was not affected by odour from a growing host plant ( Brassica oleoracea ) or a non-host plant tansy. Host plant ( Vicia faba ) odour did not affect the initial rate of climb or the incidence of targeted flight of A.fabae , but when the bean odour was alternated with odour from non-host tansy plants a greater number of targeted flights occurred in the host plant odour. The volatile extracts of tansy and summer savoury were also presented to flying A.fabae. Aphids flying in air permeated with tansy odour at 450g plant equivalents initiated fewer targeted flights than when flying in clean air. However, no differences in flight behaviour were observed with summer savoury extract. In a horizontal wind tunnel the tansy extract at 90 g plant equivalents blown across the surface of yellow targets reduced the numbers of alate A.fabae landing. The results indicate that plant odours can affect flight and landing of aphids.