by Gema Vázquez García, Phd, Project Manager, Spain
Published in International Pest Control September/October 2021 Volume 63-5
Botanigard® is a contact insecticide and acaricide formulated based on the entomopathogenic fungus, Beauveria bassiana strain GHA1, which grows naturally in the soil.
Due to its mode of action, it is classified by the Insecticide Resistance Action Committee (IRAC) as UNF (which means entomopathogenic fungi of unknown or uncertain mode of action), so the possibility of the appearance of resistance is not considered to be a risk. However, after several studies, it is a product without harmful effects on beneficial auxiliary fauna.
Apart from its extensive use over many years in horticulture, new uses have recently been incorporated onto its label, such as the control of Tetranychid mites in citrus fruits as well as aphids in stone fruits and Psylla in pears (Table 1).
The product has many potential advantages, including the possibility to use it from the beginning of the crop cycle right through to harvest (BBCH 10-89) and to use it in an integrated pest management (IPM) strategy with conventional or organic products. But to obtain the best it is very important the product is used according tot he instruction and that good coverage of the entire leaf surface of the crop is achieved.
This article, covers the control of Myzus persicae, one of the most damaging aphids that infests peach trees, and which is a pest of global importance that affects many crops.
This species of aphid has developed resistance to different active substances of chemical origin, such as organophosphates, carbamates and pyrethroids. As long ago as March 2011, IRAC published the first “resistance alert” to report the discovery of the resistance of the green peach aphid (Myzus persicae) to neonicotinoids (acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam), which began to be observed in peach trees in southern France and north-eastern Spain.
It is known that the appearance of such resistance is related to the presence of the R81T mutation of the nicotinic acetylcholine receptors (nAChRs). From that moment on, numerous populations of Myzus persicae were monitored in stone fruit plantations in Portugal, Spain, France and Italy confirming the presence of aphids with this mutant R81T gene. Then, in samples collected during 2015, resistant populations were found for the first time in horticultural crops.
Currently, the only neonicotinoid that is registered in fruit trees is acetamiprid, hence the enormous importance of making the best use of the available products in order to attempt to control the development of resistance.
The recommendation of the IRAC together with the local advisory authorities in agriculture and experts in field entomology is to reduce the use of neonicotinoids to one treatment per season, which has led to the use of other active substances such as flonicamid or spirotetramat.
The current situation, in which registrations of some of the commonly used substances have been cancelled and other products have generated resistance and / or loss of efficacy due to abuse of their use, the alternation of active substances with different modes of action is necessary.
If we alsoconsidert the demands of the market and consumers as well as new European projects which are focused on achieving more sustainable productions, reducing the use of substances of chemical origin and increasing the supply of fruits and vegetables free of residues, the inclusion of biorational products such as Breaker Max (a product formulated based on natural pyrethrin) and Botanigard in our crop prodtection programs is increasingly essential.
Drawing together all these points, Certis' proposal to growers is to achieve control by combining the use of active ingredients of chemical origin with biorational products such as Botanigard. The objective of these programs (Figure 1) is to achieve all the objectives noted above whicle avoiding the appearance of more resistance that could greatly complicate the management of crop pests.
When developing active ingredients of natural origin, Certis considers the growing need to offer solutions for organic production systems and is developing programs alternating Biorational products with different modes of action such as Breaker Max and Botanigard.
Between 2016 and 2018 Certis carried out 10 trials on stone fruit for the control of Myzus persicae in different areas of Spain and Italy. In these trials, four applications of Botanigard were carried out every seven days. The mean efficacy of Botanigard at the recommended doses of 1.5 – 2 L/ha in these trials 7seven days after the last application was 84% and after 14 days it was 93%. This level of efficacy justifies the intention to include Botanigard in programs for the control of Myzus persicae in stone fruit.
The trials results also show the high efficacy of the product, both alone and in programs. The first trial reported here took place in Valencia during 2017 and was carried out on peach, Carioca variety. In this trial, four applications were carried out, the maximum allowed by the current label, every 7 days. The incidence of infestation was evaluated before each treatment and 14 days after the last application.
In Figure 2 it can be seen that Botanigard shows a level of efficacy for the control of Myzus persicae close to 100%. This efficacy remained constant throughout the trial and is similar to pymetrozine (the chemical reference) and superior to the efficacy observed after the same applications and similar handling of another reference product on the market with a formulation based on a different strain of Beauveria bassiana.
During 2019 and 2020, the team at Certis carried out two commercial trials in Lleida, the first year in nectarines and the second in Paraguayan. On this occasion, Botanigard was introduced using two different strategies, compared to a standard strategy in which only applications of active substances of chemical origin were made. It began with a preventive application of an active substance of chemical origin to the "fall of petals" stage and it was followed with two more treatments at the time of the appearance of the infestation.
After two consecutive years, the trials demonstrated that with good application, in line with the label instructions, it is possible to obtain the same level of efficacy in a program in which Biorational products are integrated as in one based only on chemical products. It is important to highlight the additional benefits of obtaining residue-free production in fruits, avoiding the development of resistance and, of course, obtaining more sustainable and safe food production.
The trial results support the conclusion that Botanigard is an effective and important tool for the control of Myzus persicae in stone fruit, as has already been demonstrated for the control of the same pest in horticultural crops. The product has also shown very good efficacy for the control of mites in citrus and Psylla in pear.
In order to continue offering effective and sustainable solutions, work will continue on the development of Botanigard in more crops and against different pests such as thrips (the secondary effect it has on the control of this pest has already been noted).
1 Beauveria bassiana strain GHA (10.7% - 2.26X1013 conidia/L; w/v; OD) authorised by the European Union according to Regulation (EC) No. 1107/2009 of the European Parliament and of the Council.