Laeveld
Agrochem

Targeting mealybug with Eco-Bb® (Andermatt)

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For more information visit
www.andermatt.co.za or contact
your local Andermatt Madumbi Biospecialist.

The recent approval and registration of Eco-Bb®, for the control of mealybug on pome fruit (apples, pears), citrus and grapes has attracted great interest and attention from growers.

Mealybugs are one of the most important pests of citrus and vines in South Africa and are also of economic importance in many other crops such as apples, pears, mangoes, macadamia nuts, blueberries, peppers and other vegetables and ornamentals.

Mealybugs can cause significant loss of revenue in the agricultural sector, especially in the citrus and grape industries. The loss may be further compounded as some mealy- bug species are vectors of plant viruses. Numerous countries list mealybugs as a phytosanitary pest which, if identified on export produce, the whole consignment will be destroyed.

Mealybugs are important economic pests on a wide range of cultivated and ornamental crops in agriculture and horticulture.

The most important species occurring on citrus are Citrus mealybug (Planococcus citri), Oleander mealybug (Paracoccus burnerae) and the Long-tailed mealybug (Pseudococcus longispinus), while the most important species occurring on grapevines is the Vine mealybug (Planococcus ficus). Many different species of mealybugs can be found on a variety of host plants.

Mealybugs damage crops in a variety of ways including retarding plant growth, fruit malfor- mations, cosmetic damage and fruit drop.

Mealybugs also secrete honeydew, a substrate for a group of fungi commonly known as Sooty Mould. Sooty Mould attracts ants and together these visual factors are often an indication of pest infestation.

Which life stages are most susceptible?

Laboratory bioassays conducted at Andermatt-PHP have shown the following:

  • Crawlers are highly susceptible to Eco-Bb® (Figure 1) and death occurs within 3 days under favourable conditions.
  • Mealybug feeding decreases after inoculation with Eco-Bb®.
  • It is possible that newly moulted instars (i.e. without the waxy layer) are also susceptible to Eco-Bb® infection, but this is still to be confirmed with further bioassays.
  • Adult females have zero to low susceptibility, this is most likely due to their waxy cuticles.
  • Mealybugs co-exist with several other microorganisms, and Sooty Moulds, such as Penicillium (Figure 2.2), can colonise the crawler cadavers following Eco-Bb® applications.

How to optimise the use of Eco-Bb® against mealybug

1. Start applications at first signs of mealybug infestation.

It is vital that the first application be made while pest pressure is low (as soon as the infestation is first noticed), or preventatively. This will target the crawlers from the initial population, and prevent these individuals reaching later instars and adults, which are less susceptible to infection.

2.  Multiple applications are required to achieve sustained efficacy.

Eco-Bb® does not kill the adult female stage and therefore females continue to produce eggs for their full lifespan (up to 29 days). Multiple applications are required to target new crawlers that are continuously hatching and entering the population. Apply as a full cover spray at intervals of 7 to 14 days, depending on severity of the infestation.

3. Spray coverage is essential.

Mealybugs are sucking insects and use long, thin, threadlike mouthparts (stylets) to draw sap from the plant. Mealybugs do not ingest Eco-Bb® and can only be infected if the spores come into direct contact with the integument (outer protective skin) of the mealybug.

Spray equipment used must provide good coverage. A wetter/spreader can assist in reaching the hiding places of the crawlers, such as in crevices and underneath adults within the mealybug colony.

4.  Effective scouting,

Local scouting guidelines should be followed in order to detect early infestations. Eco-Bb® applications should start as early as possible to prevent an increase and spread of the mealybug population (mainly via crawlers).

5. One application is not enough!

Multiple applications will increase the efficacy provided by Eco-Bb®. Under low pest pressure, a maximum interval of 14 days should be used, and under higher pest pressure, a shorter interval (7 – 10 days) is recommended.

Using the lower application rate (600 g/ha) with frequent applications will be more effective than using the high dose rate (1 kg/ha) with fewer applications. If only one or two applications are possible, then the high rate should be used.

Eco-Bb® contains a living fungus and must be treated with care

To maximise the efficacy of Eco-Bb®, it must be handled and applied correctly:

  • Maintain viability by storing Eco-Bb® in the fridge and transporting it in cool conditions. At temperatures above 35 ºC, the viability of Eco-Bb® could be immediately
  • Eco-Bb®must not be mixed with incompatible Equipment used to apply these fungicides must be thoroughly cleaned before using Eco-Bb®.
  • Ideally, Eco-Bb® should be sprayed in the late afternoon or evening as UV can cause the spores to become nonviable.
  • The powder or solution must not be left standing in the sun.
  • Do not apply Eco-Bb® when temperatures are below 15 ºC or above 35 ºC.

Why use Eco-Bb® against mealybug?

  • Eco-Bb® can help break the mealybug life cycle by targeting the first The crawler stage is most susceptible and early applications are key to effective suppression.
  • Once adults are present, multiple applica- tions are required to target newly hatched crawlers. Be aware that once a colony is established, it is likely that all life stages will be present.
  • Independent laboratory tests have shown that Eco-Bb® is not harmful to parasitoid wasps used as Biological Control Agents for different species of mealybug, Anagyrus spp. In fact they should be complementary, as Anagyrus will target the second and third instars and adult females, which are more difficult to suppress with Eco-Bb®, and Anagyrus does not target the crawlers.
  • Eco-Bb® does not have MRL constraints and can be used up until harvest.
  • Eco-Bb® is non-toxic and it is safe to continue work in the orchard immediately after spraying.
  • Eco-Bb® has a unique and complex mode of action, as such it is an excellent resistance management tool.
  • Contact is critical to Area-specific sprays are most effective.

Eco-Bb® contains Beauveria bassiana. Reg. No. L8469, Act No. 36 of 1947. Andermatt PHP (Pty) Ltd, PO Box 207, Nottingham Road, 3245, KwaZulu Natal, South Africa. Reg. No. 2003/007987/07. 3280.

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