IOBC Canada 2017 – Part III

Posted on Categories Notes, Programs, Uncategorized

This post is a part of a series of notes taken at the International Organization of Biological Control 2017.

Go back to Monday’s Agenda

Foraging and egg-laying behaviour of the coccinellid predator Rhyzobius lophanthae
Marjolein Kruidhof, Wageningen University & Research, BU Greenhouse Horticulture

  • Diaspis boisduvalii scales in cymbidium; major problem in Netherlands and they don’t know what to do anymore to control
    • Due to restrictions of use of chemicals (i.e. neonics), they have been unable to control the scale
  • Cage experiment; comparison of different natural enemies of Diaspis boisduvalii scales
  • Tried 8 different treatments, different release rates and frequencies of release of Rhyzobius lophanthae larvae or adults (with or without ephestia eggs)
  • In control, plant was covered with the scale at the end (5 weeks later)
    • When releasing R. lophanthae adults and ephestia eggs, got excellent control
  • R. lophanthae is a predatory beetle
    • Adults are about 2.5mm in small
    • Specialist predators of the Diaspididae family
    • Lays eggs under the shields of adult female scales

Conducted greenhouse experiments:

  • 2 replicates. Each replicate was 10 x 10 plants, with 8 cages on the outside with a single plant with scale only (control).
  • Created patches of infested plants with small, medium or large-size scale colony
    • Cymbidium plants were infested 9 or 5 weeks before the start of the experiment to create small, medium and large scale colonies
  • 10 R. lophanthae adults were introduced in each of the 6 scale-infested plants of two diagonally opposite corners
  • The introduction were repeated after 1 week

Rhyzobius was able to sneak into many of the control cages!

In conclusion:

  • R. lophantae; excellent searching behavior, but quickly disperse from the plants
  • Small-sized scale colonies are not well controlled by R. lophantae
  • Addition of ephestia eggs can improve control of small-scale colonies, but not medium-sized colonies

Improved monitoring of vine weevil (Otiorhynchus sulcatus) adults

Tom Pope, Harper Adams University

  • Vine weevil control challenges on hardy nursery stock (NHS)
    • Knowledge gaps identified
      • Most serious pest of container-grown NHS
      • Limited choice and restrictions on use of insecticides
      • Drenches of entomopathogenic nematodes time-consuming
      • Lack confidence in using entomopathogenic fungi
      • More knowledge needed on biology

5 Main objectives:

  1. Understand impact of temp on biology and behavior to optimize control timing
  2. Develop monitoring methods to detect early infestations and inform control timing
  3. Improve best-practice IPM approaches
  4. Develop novel control approaches
  5. Disseminate knowledge

Conducted controlled environment experiments

  • Feeding and egg laying recorded at 6, 9, or 12C
  • Leaf area consumption analyzed using ImageJ software
  • Egg numbers and egg viability recorded

At the temperatures 6, 9, and 12 did not affect leaf area consumed

Temperature effected egg laying, but none of the temperatures stopped the egg production

  • Egg laying occurs at 6C and potentially even lower than that.

Adult vine weevils are nocturnal and adults aggregate

Growers currently monitor using night-time assessments of adults

  • Leaf notching of crop or indicator plant
  • Use of grooved boards or corrugated material as a trap

A little and often system for application of entomopathogenic nematodes for vine weevil control

Jude Bennison, Adas Boxworth

  • Demand high quality, pest-free plants
  • Limited choice & restrictions on use of substrate-incorporated insecticides
  • Pressure to use IPM rather than insecticides
  • Lack of confidence in Met52; temperature requirements

Biological control of larvae – nematodes applied drenches are time consuming & expensive

Little and Often control with nematodes?

  • Some strawberry growers trying this approach in Scotland
  • Splitting the nematode dose instead of full rate late August & September
  • Application of 20% rate several times over the season


Go back to IOBC Canada 2017 – Part II

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