Bolldex®: Vertical transmission analysed

Nov 11, 2022 | News

Andermatt Biocontrol Suisse (ABCS) has confirmed that recently completed new lab studies indicate the vertical transmission of the active ingredient in Bolldex®, Helicoverpa armigera NPV, in African Bollworm generations.

 

Two different data sets were generated, a bachelor thesis under supervision of ABCS (2021) and in-house lab trials (2022).

  • Dose rate: approximately 1/3 of standard rate (65 ml/ha)
  • Application done on large larvae
  • Offspring generation was stressed at the early development stage (L1)
  • Stress factors
      • Heat (3 hrs at 40 0C)
      • Sublethal dosage of Chlorantraniliprole (0.0029 μl/kg Chlorantraniliprole in the artificial medium)

A summary of the effects is presented and explained in the below diagram:

    At Andermatt, the effects of Baculovirus solutions on target pest populations may be defined in various ways

    • Direct effect on larvae present in the field. The larvae die after ingestion of treated plant material.

    • Horizontal transmission: After larva death, the larva ruptures, occlusion bodies (or baculovirus particles) are released in the field and may cause new infections.

     

    • Vertical transmission affects the next generation (can occur when virus infection occurs late in the life cycle of the target pest, with late instars ingesting few virus particles leading to a sublethal dose rate):
      • Sublethal virus infection, virus transmitted to the next generation.
      • Next generation larvae may carry a viral infection which only causes an outbreak after activation through stress factors.
      • Pupation rate in next generation is reduced.

    • Fitness effect:
      • Sublethal virus infection occurs.
      • Population growth is reduced.
      • Pupation and moth emergence rate decreases and therefore, fewer larvae become moths.

    • Population effect: A combination of the horizontal effect, vertical effect and fitness effect which spreads within the population and leads to population reduction in the long run.

    “This recent data is of significance to our growers because it demonstrates a unique feature of the baculovirus active ingredient and suggests that pest populations may be stabilised in the long run, as observed in this lab trial. Bolldex® is sprayed at standard dose and interval for a direct effect leading to damage control. In addition, the population effect comes to help to control the population. These two effects together make Bolldex® a unique solution for bollworm control in application programs.”

    – Dr Heidi Widmer.

    Through the power of the collective expertise within the global Andermatt group, Andermatt Madumbi is proud to bring South African growers the best the world has to offer in innovative and sustainable biological solutions.

    Andermatt Biocontrol Suisse (ABCS) het bevestig dat nuut voltooide laboratoriumstudies dui op die vertikale oordrag van die aktiewe bestanddeel in Bolldex®, Helicoverpa armigera NPV, in Afrika-bolwurmgenerasies.

    Twee verskillende datastelle is gegenereer: ʼn baccalaureustesis onder toesig van ABCS (2021) en interne laboratoriumproewe (2022).

    • Dosis: ongeveer 1/3 van die standaarddosis (65 ml / ha)
    • Toediening gedoen op later instar larwes
    • Nageslaggenerasie is in die vroeë ontwikkelingsfase onder druk geplaas (L1)
    • Stres faktore
        • Hitte (3 uur by 40 °C)
        • Sub-dodelike dosis Chlorantraniliprool (0,0029 μl/kg Chlorantraniliprool in die kunsmatige medium)

        ʼn Opsomming van die effekte word in die onderstaande diagram voorgestel en verduidelik:

        Andermatt kan die uitwerking van Bakulovirusoplossings op teikenplaagbevolkings op verskillende maniere definieer:

        • Direkte effek op larwes teenwoordig in die veld. Die larwes sterf na inname van behandelde plantmateriaal.

        • Horisontale oordrag: Na larwe afsterwing, skeur die larwe kadawer oop, word okklusieliggame (of Bakulovirus-deeltjies) in die veld vrygestel en kan dit nuwe infeksies veroorsaak.

        • Vertikale oordrag beïnvloed die volgende generasie (kan voor kom wanneer virusinfeksie laat in die lewensiklus van die teikenplaag plaasvind, met laat instars wat min virusdeeltjies inneem wat dan tot ʼn sub-dodelike dosis lei):
          • Sub-dodelike virus infeksie lei tot die oordra van virus na die volgende generasie.
          • Volgende generasie larwes kan ʼn virusinfeksie hê wat slegs ʼn siekte veroorsaak na aktivering deur stresfaktore.
          • Pupering en ontpoppingstempo in die volgende generasie verminder.

        • Fiksheidseffek:
          • Sub-dodelike virus infeksie vind plaas.
          • Bevolkingsgroei verminder.
          • Pupering en ontpoppingstempo neem af en daarom word minder larwes motte.

        • Bevolkingseffek is ʼn kombinasie van die horisontale effek, vertikale effek en fiksheidseffek wat binne die bevolking versprei en op die lang termyn tot bevolkingsvermindering lei.

        “This recent data is of significance to our growers because it demonstrates a unique feature of the baculovirus active ingredient and suggests that pest populations may be stabilised in the long run, as observed in this lab trial. Bolldex® is sprayed at standard dose and interval for a direct effect leading to damage control. In addition, the population effect comes to help to control the population. These two effects together make Bolldex® a unique solution for bollworm control in application programs.”
        – Dr Heidi Widmer.

        Deur die krag van die gesamentlike kundigheid binne die wêreldwye Andermatt-groep, is Andermatt Madumbi trots daarop om Suid-Afrikaanse produsente die beste innoverende en volhoubare biologiese oplossings te kan bied.