Early mass-flowering crops mitigate pollinator dilution in late-flowering crops

Previous studies focused mainly on the provision of ecosystem services by species movements between semi-natural and managed habitats, whereas data on spillover effects between two managed habitats or between habitats that provide target resources in non-overlapping time periods are lacking. We studied densities of three pollinator groups on sunflower fields as a late mass-flowering crop in 16 landscapes that differed in the relative cover of oil-seed rape as an early mass-flowering crop, in the relative cover of sunflowers and in the relative cover of semi-natural habitats. Our aim was to evaluate dynamics between two crops with non-overlapping flowering periods. Densities of bumble bees in late-flowering sunflower fields were enhanced by early-flowering oil-seed rape. Highest bumble bee densities in the late-flowering crop were reached in landscapes that combined high relative covers of oil-seed rape and semi-natural habitats. Further, low relative covers of oil-seed rape in spring led to decreased bumble bee densities in late-flowering sunflower fields in landscapes with high relative covers of sunflower fields (dilution effect), whereas in landscapes with high relative covers of oil-seed rape, no dilution of bumble bees was found. Thus, our results indicate that early mass-flowering crops can mitigate pollinator dilution in crops flowering later in the season. We conclude that the management of landscape-scale patterns of early and late mass-flowering crops together with semi-natural habitats could be used to ensure crop pollination services. Similar processes could also apply for other species groups and may be an important, but so far disregarded, determinant of population densities in agroecosystems.     

Tagung der Deutschen Gesellschaft für angewandte Entomologie und 21. Vortragstagung der Entomologischen Gesellschaft der BRD vom 5. bis zum 11. September 1971 in München

Ohne Zusammenfassung     

Clinical field study to evaluate the efficacy and safety of the amino-acetonitrile derivative, monepantel, compared with registered anthelmintics against gastrointestinal nematodes of sheep in Australia

Objective   To determine the efficacy of monepantel, a developmental compound from the amino-acetonitrile derivative class of anthelmintics, against field infections of gastrointestinal nematodes in sheep.
Procedures   Comparisons of efficacy (using standard faecal worm egg count reduction tests) and safety (on the basis of visual observations) were made in a large-scale field study in Australia, between groups of sheep treated with either an oral solution of monepantel or a registered anthelmintic. The sheep were naturally infected with the major gastrointestinal nematode genera present in Australia.
Results   The post-treatment efficacy results for monepantel were: at 7 days (±1 day) efficacy was >98%; at 14 days (±1 day) it was generally close to or >99%; and at 21 days (±1 day) efficacy was consistently >99%. A high proportion of the targeted nematode populations were confirmed as being resistant to one or more of the currently available anthelmintic classes.
Conclusions   Monepantel when used under field conditions at a minimum dose rate of 2.5 mg/kg was highly effective against mixed-genus natural field infections of the major gastrointestinal nematode genera including Haemonchus , Teladorsagia ( Ostertagia ), Trichostrongylus , Nematodirus , Chabertia and Oesophagostomum . This result included efficacy against some populations resistant to the currently available broad-spectrum anthelmintics. Few Cooperia spp. were present to allow confirmation of efficacy against this genus. On no occasion after treatment did any commercial anthelmintic-treated groups have significantly lower faecal egg counts than the monepantel-treated groups. Monepantel was safe for the target animals and human operators when used in a field situation.