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The objective of this study was to evaluate the role of host volatiles in the relationship between a blueberry plant Vaccinium corymbosum L. and the raspberry weevil Aegorhinus superciliosus (Guérin) (Coleoptera: Curculionidae), the principal pest of blueberry in the south of Chile. Volatiles from the aerial part of different phenological stages of the host were collected on Porapak Q and analyzed by coupled gas chromatography-mass spectrometry (GC-MS). Several chemical groups were identified including green leaf volatiles, aromatic compounds, and terpenes. The olfactometric responses of A. superciliosus toward different odor sources were studied in a four-arm olfactometer. Blueberry shoots at the phenological stages of fruit set, and blue-pink fruit color elicited the greatest behavioral responses from weevils. Five compounds (2-nonanone, eucalyptol, R- and S-limonene, and 4-ethyl benzaldehyde) elicited an attractant behavioral response from A. superciliosus. The results suggest the host location behavior of A. superciliosus could be mediated by volatiles derived from V. corymbosum. This work has identified a number of compounds with which it is possible to develop a lure for the principal pest of blueberry in southern Chile.

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Root rot caused by Fusarium oxysporum is a disease that reduces red clover persistence. Agronomical management of red clover includes MCPA application, and there is no information regarding the effects of this herbicide on the disease. MCPA was evaluated for its effects on F. oxysporum root rot and red clover (Trifolium pratense) growth in a greenhouse experiment. Additionally, in vitro mycelial growth and conidial germination of F. oxysporum were studied. For shoot dry weight and crown diameter of seedlings, the interaction of herbicide and inoculum was significant at 30 d. The herbicide–inoculum treatment reduced shoot dry weight by 20% at 1X rate and by 24% at 2X rate, and crown diameter was reduced by 10% at the high rate. The MCPA treatment caused a 40% reduction of root dry weight by the end of the experiment. Application of MCPA caused fusarium root rot to increase in severity on red clover seedlings and caused phytotoxicity at the high rate. Interaction with the other growth parameters was not significant, indicating that the effects of herbicide and inoculum were independent. Conidial germination and mycelial growth in vitro were reduced by MCPA. Results suggest that red clover growth could be negatively affected by F. oxysporum after MCPA application and that root rot severity increases at high rates of MCPA.

Plant growth inhibitory effects of acetophenones 1-6, tremetones 7-12, and MeOH and CH(2)Cl(2) extracts from the aerial parts of Baccharis linnearis, Baccharis magellanica, and Baccharis umbelliformis collected in Chile were assayed as growth inhibitory activity in ranges of 10-500 microM and 0.1-150 ppm, respectively. The effects on seedling growth, germination, and respiration of ryegrass, lettuce, green tomato, and red clover weedy target species were measured. In addition to the inhibitory activity on bleaching of crocin induced by alkoxyl radicals, these compounds also demonstrated scavenging properties toward 2,2-diphenyl-1-picrylhydrazyl in thin-layer chromatography autographic and spectrophotometric assays. In addition, acetophenones and tremetones also showed inhibition of H(+) uptake and oxygen uptake respiration in isolated chloroplasts and mitochondria, respectively. Our results indicate that 1, 4, 7-12, and CH(2)Cl(2) extracts interfere with the dicot preemergence properties, mainly energy metabolism of the seeds at the level of respiration. These compounds appear to have selective effects on the radicle more than shoot growth of dicot seeds. Also, the levels of radicle inhibition obtained with some compounds on Physalis ixocarpa and Trifolium pratense are totally comparable to those of ovatifolin, a known natural growth inhibitor. This behavior might be responsible for its plant growth inhibitory properties and its possible role as an allelopathic agent.

Numerous studies of insect species have shown that a subset of female cuticular hydrocarbons is used as short-range or contact pheromones. Here, we studied the possible use of contact pheromones in the mating behavior of the weevil Aegorhinus superciliosus, a native species of Chile. Males mounted females only after antennal contact with the female's cuticle, and only 33% of the males attempted to mate with dead females washed with solvent. When a glass rod (dummy) was coated with female cuticular extracts, males exhibited behaviors similar to those observed with females. A preliminary gas chromatography-mass spectrometry (GC-MS) analysis of cuticular extracts indicated that males and females share a series of aliphatic hydrocarbons but that the relative abundance of some of these compounds differ between the sexes. These results suggest that cuticular lipids mediate mating behavior of the raspberry weevil and provide the first evidence of contact pheromones in curculionids.

Red clover (Trifolium pratense L.) is a valuable forage legume grown alone or in mixture with grasses in temperate regions of the world. Red clover is adapted to a wide range of soil types, pH levels, environmental and management conditions. However, the main limitation of this species is the lack of persistence related to the high mortality of plants. In Chile the main biotic factor affecting survival of plants is the root borer Hylastinus obscurus (Marsham) (Coleoptera; Scolytidae). In 1989, a red clover (T.