Organic farming systems benefit biodiversity and natural pest regulation in white cabbage

Natural regulation of cabbage root flies works well in experimental organic cropping systems of white cabbage. Low input and complex organic systems benefit functional biodiversity by providing good living conditions to several groups of natural enemies. Intercropped green manure benefits large predators while small predatory beetles favour low input organic systems with bare soil between crop rows

Økologisk dyrkning af hvidkål fremmer biodiversitet og naturlig regulering af skadedyr

Naturlig regulering af kålfluer er effektiv i økologisk dyrkede hvidkålsparceller. Økologiske dyrkningssystemer med lavt input og høj strukturel kompleksitet skaber gode livsbetingelser for en række nyttedyr. Mellemafgrøder af foregående sæsons grøngødning gavner de store arter, mens små løbe- og rovbiller bliver tilgodeset i et økologisk system med bar jord mellem afgrøderækkerne

Heat stress has immediate and persistent effects on immunity and development of Tenebrio molitor

The yellow mealworm (Tenebrio molitor) is a promising insect species for mass-rearing for the production of feed and food. In mass-production systems, insects may be exposed to abiotic stressors such as heat stress as well as potentially lethal pathogens. To ensure mass-reared T. molitor populations are healthy and productive there is a need to understand both the risks, and potential benefits of heat stress, on the fitness of insects and their susceptibility to pathogens. In this study, we investigated the effects of a short (2 h) or a long (14 h) heat stress (38 °C) exposure on the susceptibility and the immune responses of T. molitor larvae exposed to a fungal pathogen (Metarhizium brunneum). Larvae were exposed to the pathogen either immediately or five days after the heat stress treatments. The development of heat stressed larvae and their offspring was also assessed. A short heat stress immediately before exposure to M. brunneum increased the survival probability of T. molitor larvae, which correlated with increased antibacterial activity in the hemolymph. The exposure of larvae to short, or long heat stresses five days before pathogen exposure did not affect their survival, despite a temporary lowered body mass gain of heat stressed larvae. However, heat stressed larvae showed decreased hemocyte concentrations when exposed to M. brunneum. We also found an increased body weight in larval offspring of females that had been exposed to a short heat stress as larvae themselves. These findings demonstrate the importance of understanding the effects of heat stress in the long-term. The beneficial effects of heat stress on pathogen susceptibility in T. molitor and the negative effects on body mass gain are only transient, whereas negative effects on immune response (hemocyte concentrations) persist over an extended period

Human exposure to airborne fungi from genera used as biocontrol agents in plant production

The fungi Trichoderma harzianum, T. polysporum, T. viride, Paeciliomyces fumosoroseus, P. lilacinus, Verticillium/lecanicillium lecanii, Ulocladium oudemansii, U. atrum and Beauveria bassiana are used or considered to be used for biocontrol of pests and plant diseases. Human exposure to these fungi in environments where they may naturally occur or are used as biocontrol agents has not been directly investigated to date. This review aims to provide an overview of the current knowledge of human exposure to fungi from the relevant genera. The subject of fungal taxonomy due to the rapid development of this issue is also discussed. B. bassiana, V. lecanii, T. harzianum, T. polysporum, P. lilacinus and U. oudemansii were infrequently present in the air and thus people in general seem to be seldom exposed to these fungi. However, when V. lecanii was present, high concentrations were measured. Fungi from the genera Trichoderma, Paecilomyces and Ulocladium were rarely identifi ed to the species level and sometimes high concentrations were reported. T. viride and U. atrum were detected frequently in different environments and sometimes with a high frequency of presence in samples. Thus, people seem to be frequently exposed to these fungi. Sequence data have led to recent revisions of fungal taxonomy, and in future studies it is important to specify the taxonomy used for identifi cation, thus making comparisons possible

Variable effects of organic farming systems on ground beetle abundance and diversity

Organic farming should support high levels of biodiversity and rely on biological pest control by natural enemies. Management of organic systems must comply with specific regulations, but within this frame management is not clearly defined. In experimental cabbage fields we studied ground beetle abundance and diversity in three different organic farming systems (O1, O2, and O3). All systems complied with regulations for organic production, but relied on either high (O1) or low (O2 and O3) external input of nutrients. The systems O2 and O3 also included green manures, and in O3 strips of green manure were left between crop rows. A conventional system was included as control. Only organic systems O2 and O3 showed benefits for ground beetles, but in different ways. Abundance of all ground beetle species was highest in May in O2, while O3 supported the highest abundance of habitat specialists with preferences for field margins reflecting the conservation of green manure strips. The ground beetle community of O3 was most diverse characterized by highest number of species and evenness (equitability among species). Organically farmed fields can therefore be designed to promote specific predators or high ground beetle diversity at the field scale by implementing different management practices

Isolation of Metarhizium spp. from root systems of different crops: Are specific genotypes associated with certain plants?

Isolation of Metarhizium spp. from root systems of different crops: Are specific genotypes associated with certain plants