Dusky Ladybird

Dusky Ladybird

Scymnus loewii - Dusky Ladybird

The Dusky Ladybird is a small predatory ladybird. It is primarily an aphid predator, however it will also predate on a large variety of alternative prey, including psyllid and whitefly eggs, and the eggs of larger insects such as butterflies and moths.

The Dusky Ladybird appears to survive well in glasshouse grown capsicums when feeding on the peach aphid, and colonises cucumber as well. The use of this species is still experimental, and there are no guarantees that they will colonise your crop or eat a particular aphid species. They are known predators of aphids from the genera Myzus and Aphis.

In New Zealand we call them ladybirds, much the same as the British do, however in other parts of the world they are known as ladybugs.

The Dusky Ladybird is a small predatory ladybird 3-4 mm in length.

Adults and juveniles are aphid predators, feeding on aphids of all life stages. Larvae paralyse aphids and suck their body fluids out, generally through a leg or antenna.

Both adults and larvae predate on the tomato/potato psyllid, both eggs and juveniles.

Eggs are tiny and laid singly on the woodier parts of the plant.

Our ladybirds are reared in our insectary, we do not collect ladybirds from the wild (for sale) as is practised in other parts of the world.

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The pest: whitefly (left) & the solution: Encarsia (right)

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Normal whitefly pupa (white) and parasitized pupa (black). An adult Encarsia will emerge from the black scale(right)

The Pest: Aphids (as well as Psyllids)

Many different species of aphid are present in New Zealand, and not all species are necessarily suitable prey for the Dusky Ladybird. Some aphid species are quite specific to particular crops, while other species infest a wide range of crops.

Aphids are soft-bodied insects that have globular bodies, long thin legs and antennae. Adult body length is normally 2-3 mm, and colour varies from pale yellow, green to dark brown or black. Some forms have wings and they can disperse rapidly.

Under optimum conditions, the life cycle of an aphid can be completed in 10-12 days. Many species reproduce asexually, and therefore populations can build up very rapidly.

Aphids feed with piercing-sucking mouthparts and can cause stunting and distortion, especially to younger leaves. Aphids are often plant virus vectors, and therefore rapid and effective control is essential to minimize crop losses.

Symptoms and signs of aphids include:

  • Stunting and distortion of the leaves and flowers

  • Yellowing and wilting of leaves

  • Honey dew and sooty mould present on the plants

  • Aphids visible on the stem, leaves and flower buds

Life Cycle

The Dusky Ladybird undergoes an egg stage and 4 larval stages before pupating and emerging as an adult. Development time from egg to adult takes around three weeks at 25⁰C, and longer at lower temperatures. Eggs hatch approximately 2-3 days after dispatch, and juvenile stages will begin searching for aphid prey almost immediately.

The Solution - Dusky Ladybird

The Dusky Ladybird is a small predatory ladybird 3-4 mm in length.

Adults and juveniles are aphid predators, feeding on aphids of all life stages. Larvae paralyse aphids and suck their body fluids out, generally through a leg or antenna.

Both adults and larvae predate on the tomato/potato psyllid, both eggs and juveniles.

Eggs are tiny and laid singly on the woodier parts of the plant.

Our ladybirds are reared in our insectary, we do not collect ladybirds from the wild (for sale) as is practised in other parts of the world.

Packaging

Enforce is supplied as black parasitized greenhouse whitefly nymphs or black 'scale' on cardboard tags, and the adult wasp emerges from this 'scale'.

Two tag sizes are available:

Application Rates

Wasps per metre squared:

Group 273

Enforce should ideally be introduced to the crop when greenhouse whitefly populations are low as a preventative.

It is recommended that Enforce is introduced regularly when whiteflies are present, initially at a minimum of every 2 weeks over at least an 8 week period.

Release and Storage Instructions

Enforce will not attack adult whiteflies, if you have large numbers of whiteflies present on the plants, it is recommended that a soap spray or other spray with low residual activity (such as neem), is used prior to the first introduction of Enforce. These sprays will kill adult Enforce wasps, so it is not recommended to use these after having introduced the Enforce unless presented with no other option.

Enforce tags need the following handling and treatment:

  • Do not touch the black 'scale' on the tags

  • Do not expose the tags to direct sunlight

  • Hang the tags immediately within the crop,

  • If the tags must be stored, store them in darkness at 10-15 C.

  • DO NOT REFRIGERATE

  • Do not store the tags for more than 2 days

  • Tags come in strips of 10 tags and should be separated and hung individually

  • Hang tags one metre below heads of crop, so the wasps work upwards

  • Hang tags in shade

  • Ensure tags are hung in different places each week

  • Tags should be distributed evenly through the crop

  • Leave tags in crop for at least 14 days

Post Release

Enforce adults will begin to emerge from the black 'scale' on the tags within 2-6 days at 20 C. The black case will stay attached to the tags. A small hole should be visible with a hand lens once the adult has emerged.

After three weeks it is safe to assume all Enforce wasps have hatched, so the tags may be removed if desired.

Within four weeks of release, black 'scale' should be present within your crop, on the lower leaves of your plants. Adult wasps should emerge within 2-3 weeks.

Before introducing Enforce into your crop, please check residual chemical effects and ensure you know chemical compatibilities and products that may be applied.

Before introducing Enforce into your crop, please check residual chemical effects and ensure you know chemical compatibilities and products that may be applied.

Lists of compatible pesticides and persistence periods can be found in the publication "The Good Bug Book", Second edition (2002), editor Richard Llewellyn. Excerpts of the book can be obtained from the Encarsia page of the Australasian Biological Control Association website.