Effect of tower base painting on willow ptarmigan collision rates with wind turbines

1. Birds colliding with turbine rotor blades is a well‐known negative consequence of wind‐power plants. However, there has been far less attention to the risk of birds colliding with the turbine towers, and how to mitigate this risk.
2. Based on data from the Smøla wind‐power plant in Central Norway, it seems highly likely that willow ptarmigan (the only gallinaceous species found on the island) is prone to collide with turbine towers. By employing a BACI‐approach, we tested if painting the lower parts of turbine towers black would reduce the collision risk.
3. Overall, there was a 48% reduction in the number of recorded ptarmigan carcasses per search at painted turbines relative to neighboring control (unpainted) ones, with significant variation both within and between years.
4. Using contrast painting to the turbine towers resulted in significantly reduced number of ptarmigan carcasses found, emphasizing the effectiveness of such a relatively simple mitigation measure.

     

Host gall size and oviposition success by the parasitoid Eurytoma gigantea

Abstract. 1. Eurytoma gigantea Walsh is a specialist parasitoid of the tephritid gallmaker Eurosta solidaginis (Fitch).
2. In the natural environment the incidence of parasitism by Eurytoma is greater in small galls than in large ones.
3. Laboratory experiments demonstrated that small galls are not more frequently discovered; however, oviposition attempts on small galls were more likely to be successful.
4. Eurytoma spends much time probing galls too big to penetrate; this leads to a decrease in foraging efficiency when many large galls are present.
5. The chance of successfully penetrating a gall depends on the thickness of the gall wall and the length of the parasitoid's ovipositor.
6. A simulation model was constructed which shows that a gallmak-er's chance of being parasitized depends on gall size, the number of parasitoids that discover the gall, and their ovipositor lengths.     

Autumnal moth – why autumnal?

1. As for some other spring‐feeding moths, adult flight of Epirrita autumnata (Lepidoptera: Geometridae) occurs in late autumn. Late‐season flight is a result of a prolonged pupal period. Potential evolutionary explanations for this phenological pattern are evaluated. 2. In a laboratory rearing, there was a weak correlation between pupation date and the time of adult emergence. A substantial genetic difference in pupal period was found between two geographic populations. Adaptive evolution of eclosion time can thus be expected. 3. Metabolic costs of a prolonged pupal period were found to be moderate but still of some ecological significance. Pupal mortality is likely to form the main cost of the prolonged pupal period. 4. Mortality rates of adults, exposed in the field, showed a declining temporal trend from late summer to normal eclosion time in autumn. Lower predation pressure on adults may constitute the decisive selective advantage of late‐season flight. It is suggested that ants, not birds, were the main predators responsible for the temporal trend. 5. Egg mortality was estimated to be low; it is thus unlikely that the late adult period is selected for to reduce the time during which eggs are exposed to predators. 6. In a laboratory experiment, oviposition success was maximal at the time of actual flight peak of E. autumnata, however penalties resulting from sub‐optimal timing of oviposition remained limited.     

Estimates of protozoan- and viral-mediated mortality of bacterioplankton in Lake Bourget (France)

1. We performed three, 1‐week in situ experiments in March‐April (expt 1), May (expt 2) and August (expt 3) 2003 in order to assess protozoan and virus‐induced mortality of heterotrophic bacteria in a French lake. Viral and bacterial abundances were obtained using flow cytometry (FCM) while protozoa were counted using epifluorescence microscopy (EFM). 2. A dilution approach, applied to pretreated grazer‐free samples, allowed us to estimate that viral lysis could be responsible for 60% (expt 1), 35% (expt 2) and 52% (expt 3) of daily heterotrophic bacterial mortality. Flagellate (both mixotrophic and heterotrophic) grazing in untreated samples, was responsible for 56% (expt 1), 63% (expt 2) and 18% (expt 3) of daily heterotrophic bacteria removal. 3. These results therefore suggest that both viral lysis and flagellate grazing had a strong impact on bacterial mortality, and this impact varied seasonally. 4. From parallel transmission electron microscopy (TEM) analysis, we found that the burst size (i.e. the number of viruses potentially released per lysed cell) ranged from nine to 25 (expt 1), 10 to 35 (expt 2) and eight to 25 (expt 3). The percentage of infected heterotrophic bacteria was 5.7% (expt 1), 3.4% (expt 2) and 5.7% (expt 3) so that the calculated percentage of bacterial mortality induced by viruses was 6.3% (expt 1), 3.7% (expt 2) and 6.3% (expt 3). 5. It is clear that the dilution‐FCM and TEM methods yielded different estimates of viral impact, although both methods revealed an increased impact of viruses during summer.     

The relationship between the reduction of nonstructural carbohydrate induced by defoliator and the growth and mortality of trees

Large scale herbivorous insect outbreaks can cause death of regional forests, and the events are expected to be exacerbated with climate change. Mortality of forest and woodland plants would cause a series of serious consequences, such as decrease in vegetation production, shifts in ecosystem structure and function, and transformation of forest function from a net carbon sink into a net carbon source. There is thus a need to better understand the impact of insects on trees. Defoliation by insect pests mainly reduces photosynthesis (source decrease) and increases carbon consumption (sink increase), and hence causes reduction of nonstructural carbohydrate (NSC). When the reduction in NSC reaches to a certain level, trees would die of carbon starvation. External environment and internal compensatory mechanisms can also positively or negatively influence the process of tree death. At present, the research of carbon starvation is a hotspot because the increase of tree mortality globally with climate change, and carbon starvation is considered as one of the dominating physiological mechanisms for explaining tree death. In this study, we reviewed the definition of carbon starvation, and the relationships between the reduction of NSC induced by defoliation and the growth and death of trees, and the relationships among insect outbreaks, leaf loss and climate change. We also presented the potential directions of future studies on insect-caused defoliation and tree mortality.     

Mesocyclops longisetus effects on survivorship of Aedes aegypti immature stages in car tyres

Abstract .The effect of the introduction of the entomophagous copepod Mesocyclops longisetus (Acuacultura F.C.B. strain) on the survival of Aedes aegypti immature stages in car tyres was evaluated under semi-natural conditions in the municipality of Merida, Yucatan, Mexico. Life tables were constructed for the immature stages of the mosquito in the presence and absence of M. longisetus , and the survival data were compared using log–linear models. The data set was adjusted using the GLIM statistical package and the quality of adjustment was evaluated with a chi-squared test . Survivorship curves were constructed for each treatment.
In the absence of M. longisetus , the survivorship of Ae. aegypti immature stages averaged 9%. The highest mortality rate was observed during the fourth larval instar (54%) and the resulting survival pattern corresponded to a type II survivorship curve. The mortality rate of Ae. aegypti first-instar larvae (fifty per tyre) increased more than 200-fold in the presence of M. longisetus (twenty per tyre) and the highest mortality was during the first two larval instars, where it reached 98.9%, with a resulting survivorship of 0.2%. Overall mortality was sixfold greater in the presence of the copepod than in its absence. The survival pattern of immature stages of Ae. aegypti in the presence of the copepod corresponded to a type III survivorship curve. As M. longisetus was so effective against Ae. aegypti immature stages in tyres under semi-natural conditions, its long-term effectiveness should be evaluated under socially and ecologically realistic field conditions in Mexico.     

Infectivity,viability and effects of Paranosema locustae (Microsporidia) on juveniles of Dichroplus maculipennis (Orthoptera: Acrididae: Melanoplinae) under laboratory conditions

Infectivity and effects on host of a long-term stored aqueous suspension of Paranosema locustae on juveniles of Dichroplus maculipennis, a pest grasshopper in parts of the Pampas and Patagonia, were evaluated. Infections developed in 90–97.8% of treated individuals. Mortality increased with time, reaching highest values at 30–40 days post-inoculation (79.5–100%). Infected nymphs showed significantly slower development.     

Condition and fate of larvae from insecticide-treated female tsetse flies Glossina palpalis

Many larvae from wild-caught female Glossina palpalis palpalis R.-D. treated topically with dieldrin or sumicidin or sumithrin or permethrin failed to pupariate and many larvae from mothers treated with sumicidin or sumithrin or neopynamin formed small or malformed puparia which failed to eclode. Puparia produced soon after maternal handling often did not emerge and many produced by flies starved more than 3 days also did not emerge. Very many puparia from dieldrin-treated mothers failed to emerge and non-emergence was common for puparia from flies treated with endosulfan or sumithrin or deltamethrin. Non-emerging puparia were produced soon after pyrethroid-treatment, probably due to effects on larval integumentand muscles, but were produced later after organochlorine-treatment, due to ingestion of insecticide by larvae while in utero.

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Résumé Les expériences ont porté sur des femelles sauvages de Glossina palpalis palpalis R.D. capturées dans la nature. Les comparaisons ont porté sur l'état et les performances de lots de pupes provenant de mouches non-traitées et de larves mûres traitées localement avec de l'acétone (témoin) ou avec 14 insecticides différents.Toutes les larves témoin se sont nymphosées, mais le taux d'échec augmentait avec la diéldrine, la sumicidine, la sumithrine et la permethrine. Les pupes anormales (petites ou déformées) étaient plus nombreuses dans le lot témoin que dans le lot non-traité, et les fréquences étaient plus élevées que chez le témoin avec la sumidicine, la sumithrine et la néopynamine.Seulement 3 mouches sont issues de 107 pupes anormales; il n'y a eu aucune éclosion pour 28% des pupes du lot témoin contre 15% pour le lot non-traité. Pour le témoin le taux d'émergence était faible dans les pupes formées le premier jour (jour du traitement), par suite de la manipulation maternelle; il n'a pas augmenté jours 2 et 3, mais a diminué par la suite à cause du jeûne in utero. Les doses élevées de tous les insecticides réduisent plus les émergences que les doses faibles. Les organophosphates et le propoxur ne limitent pas les émergences, mais elles sont réduites par l'endosulfane, la sumithrine et la deltaméthrine, et très fortement par la diéldrine. Les pupes stériles ont été surtout formées dès le traitement aux pyréthroïdes (jour 1); et surtout plus tard (jours 2 et 3) lors des traitements aux organochlorés. L'ingestion par la larve in utero de grandes quantités d'insecticides pendant les 3 jours précédant la parturition était la principale cause de mortalité, et aussi de la forte tolérance aux organochlorés des femelles prégnantes. Les effets de pyréthroïdes sur l'activité musculaire réduisent aussi les émergences.Aucune mouche ne s'est alimentée après les traitements.