The influence of odour on the oviposition behaviour of the cabbage root fly

Summary. Host plant odours are known to be important in long-range host location by the cabbage root fly, whereas at short distances orientation is mainly visual. We show that olfaction also plays a significant role after a fly lands on a plant and before it moves down onto the soil to oviposit. Host plant acceptance by the cabbage root fly seems to result from a synergistic response to simultaneously perceived olfactory and contact chemostimulation. Received 12 May 1999; accepted 24 July 1999     

Expanding Carbon Stocks in Existing Forests – A Methodological Approach for Cost Appraisal at the Enterprise Level

The study presents a comprehensive methodology for the appraisal of C-stock expansion in existing forests as a forest management activity according to Art. 3.4 of the Kyoto Protocol. It allows for producer costs of carbon sequestration in forest enterprises to be derived. The methodology is based on a non-linear programming approach considering economic optimisation as well as ecological, social and sustainability needs through constraints and risk integration. While introducing further constraints on carbon stocks, the carbon stored in forest biomass was increased in periodic increments. However, while extending the carbon stocks, the ecological and social constraints as well as sustainability requirements are not to be violated. Costs were derived for every additional Mg (Megagrams) of C per ha sequestered in comparison to a baseline management. Two basic cases were considered: First, a permanent carbon sequestration was assumed. Secondly, a temporary storage of additional carbon over 10 years was supposed. The potential willingness of buyers of carbon certificates to pay for temporary carbon sequestration was derived by a financial consideration. We assumed that, for a buyer, the value of a temporary carbon sequestration certificate would be equivalent to the return on the savings because an investment in technical measures on reduction of carbon emissions can be postponed.     

Intraventricular haemorrhage in a fetus with cerebral cytomegalovirus infection

Cytomegalovirus (CMV) is the leading infectious cause of prenatal neurological damage, which is particularly severe when primary maternal infection occurs during the first 16 weeks of gestation, at the time of organ development and neuronal migration. Vascular involvement has been suggested to be among thepossible pathogenic mechanisms of virus-induced pathology, in addition to direct viral effects. We report on a fetus with cerebral CMV infection, which had intraventricular haemorrhage, together with oligohydramnios and hyperechogenic bowel, following maternal primary CMV infection. Copyright © 2002 John Wiley & Sons, Ltd.     

Molecular evidence of facultative intraguild predation by Monochamus titillator larvae (Coleoptera: Cerambycidae) on members of the southern pine beetle guild

The southern pine bark beetle guild (SPBG) is arguably the most destructive group of forest insects in the southeastern USA. This guild contains five species of bark beetles (Coleoptera: Curculionidae: Scolytinae): Dendroctonus frontalis, Dendroctonus terebrans, Ips avulsus, Ips calligraphus, and Ips grandicollis. A diverse community of illicit receivers is attracted to pheromones emitted by the SPBG, including the woodborers Monochamus carolinensis and Monochamus titillator (Coleoptera: Cerambycidae). These woodborers have been traditionally classified as resource competitors; however, laboratory assays suggest that larval M. carolinensis may be facultative intraguild predators of SPBG larvae. This study used polymerase chain reaction (PCR)-based molecular gut content analyses to characterize subcortical interactions between M. titillator and members of the SPBG. The half-lives of SPBG DNA were estimated in the laboratory prior to examining these interactions in the field. A total of 271 field-collected M. titillator larvae were analyzed and 26 (9.6?%) tested positive for DNA of members of the SPBG. Of these larvae, 25 (96.2?%) tested positive for I. grandicollis and one (3.8?%) for I. calligraphus. Failure to detect D. terebrans and D. frontalis was likely due to their absence in the field. I. avulsus was present, but primers developed using adult tissues failed to amplify larval tissue. Results from this study support the hypothesis that larval Monochamus spp. are facultative intraguild predators of bark beetle larvae. Additionally, this study demonstrates the capabilities of PCR in elucidating the interactions of cryptic forest insects and provides a tool to better understand mechanisms driving southern pine beetle guild population fluctuations.     

Eggs of cabbage root fly stimulate conspecific oviposition: Evaluation of the activity and determination of an egg-associated compound

Summary. Previous studies indicated the presence of antennally-active compounds in extracts of eggs laid by female cabbage root flies, Delia radicum, that stimulated oviposition by conspecific females. We confirmed that previously laid D. radicum eggs stimulated oviposition by other D. radicum females, in a dose-dependent manner. Methanol extracts of conspecific eggs stimulated oviposition by females D. radicum, whereas egg extracts of D. antiqua and Psila rosae had no effect. Electrophysiological recordings from the tarsal sensilla of D. radicum females indicated that neurones of the C₅ sensillum responded to the egg extracts from both D. radicum and D. antiqua, but not P. rosae. Chemical analysis revealed that the extract of eggs from D. radicum contained the thia-triaza-fluorene compound, 1,2-dihydro-3-thia-4,10,10b-triaza-cyclopenta[.a.]fluorene-1-carboxylic acid (CIF-1), an oviposition stimulant found previously only in cruciferous plants. Another potentially active component has yet to be identified.