Tag Archives: Bemisia tabaci

Whitefly: Tecnova trial unveils Nakar’s potential

The new Seipasa natural formulation to control whitefly equals the chemical reference’s effectiveness, plus it does not leave any residue and it is suitable for integrated and organic production

María del Mar Téllez, IFAPA researcher, at the conference on whitefly.

María del Mar Téllez, IFAPA researcher, at the conference on whitefly.

At Tecnova’s headquarter, in Almería’s Technology Park, its researchers presented the results of a test conducted on integrated control of whitefly in greenhouse tomatoes developed in an experimental farm that belongs to the research entity. Next to María del Mar Téllez, researcher at the Institute of Research and Formation on Agriculture and Fisheries of the Government of Andalusia (IFAPA), technicians and producers introduced the most effective tools to deal with this insect, Bemisia tabaci, through preventive measures as well as plant health and biological control.

As explained by Tecnova’s R&D Director, Carolina Martínez, and integrated production technician Carolina Sánchez, this research has proven the high effectiveness of treatments that employ SEIPASA’s biopesticides on whitefly immature and adult populations.

NAKAR, Zero Residues and no safety term

NAKAR (registry # ES-00123) is a bioinsecticide taken as a reference, which show its great capacity to eradicate whitefly populations while shutting of its biological reproduction.

During the trial developed from March to June, we evaluated the insecticidal effectiveness in three experimental treatments compared to an untreated control: control (T0), NAKAR 10 ml/l (T1), NAKAR 6 ml/l + Pirecris 2 ml/l (T2) and Acetamiprid 0.5 g/l (T3).

The Tecnova researchers highlighted the successful process of whitefly pest control with natural products such as Nakar and Pirecris, as well as chemical reference Acetamiprid. The findings of the trial showed that “in all three treatments the insecticidal effect was similar and statistically indistinguishable from each other”, which confirms the effectiveness of Seipasa’s natural formulations equals the chemical reference, with added value too – it doesn’t leave behind residues in the crop and that makes it suitable for integrated and organic production.

Evolución de la severidad - Adultos Bemisia tabaci

Thus, the insecticide potential of the newly formulated NAKAR that was stated in this trial adds up to the advantage of being a zero residue product, which does not require safety periods. Similarly, its synergy with Pirecris, another botanical-based bioinsecticide, has proven a tight control of Bemisia tabaci.

As the conclusions stated in, both solutions cause direct and immediate effects on pests: “They have produced desiccation in immature stages and a loss of cohesiveness in the adult stage. In both cases, direct contact of these products has led to the death of insects”.

Fases inmaduras de la mosca blanca antes y despúes de los tratamientos, y efectos de los tratamientos sobre la fase adulta

In this line, Seipasa’s technical director, Xavier Nácher, emphasized the accomplished goal of this new solution hitting the market: “NAKAR achieves the eradication of the pest penetrating the insect’s cell membranes and causing its dehydration, by disruption of the waxy layer, and death”.

Xavier Nácher, Seipasa’s Technical Department Director.

Xavier Nácher, Seipasa’s Technical Department Director.

As Nácher stated, NAKAR’s action causes cytolysis of the insect cells, in other words, the breakdown or decomposition of the membrane, so it loses cell material and vital processes stop. Furthermore, it blocks the insect’s spiracles, which leads to its suffocation.

The NAKAR’s natural base makes it a privileged tool for Integrated Pest Management (IPM) strategies, as well as resistance management programs, to which it shows optimum results.


NAKAR use strategies

As Nácher explained, NAKAR can be used as a solution against whitefly in crops:

1) Intended for zero residues production, it must be applied as soon as the pest appears in order to shorten its life cycle and consequently its spread. Similarly, it can be used in the crop’s final stage to guarantee residues free harvests.

2) In order to set Integrated Pest Management (IPM) strategies and resistance management, NAKAR can be used with other insecticides that do have a security term in the middle period of the cycle.

3) Similarly, its effective insecticidal action, substantiated by recent trials, make it an alternative for the most demanding organic production.

Sandía virus venas amarillas

Cucumber vein yellowing virus CVYV

This disease, transmitted by the white fly, Bemisia Tabaci, affects cucurbitaceae such as the cucumber, courgette, melon or watermelon

The disease known as “Cucumber vein yellowing virus” (CVYV) is transmitted through the adult individuals of the whitefly (Bemisia tabaci) and affects cucurbitaceae species such as the cucumber, courgette, melon or water melon.

It was located for the first time in 1960 in cucurbitaceae cultivated in Israel. It appears to be related to the sweet potato mild mottle virus (SPMMV). It is wide-spread in Western Mediterranean countries, and since 2001 it affects the fields of Andalusia.

Symptoms of the vein yellowing virus

In cucumber and melos:
Yellowing of the veins is observed in the leaves of the shoot, a characteristic whence the virus derives its name, although, depending on the moment of infection, this yellowing can also occur in a generalised manner in the entire plant.  The plant development is also less.

In cucumber fruit, a light green, dark green, mosaic occurs, whilst no symptoms occur in melon fruit.

Virus venas amarillas en sandíaIt seems that this virus, associated with the cucurbit yellow stunting disorder  virus (CYSDV), produces a synergism that boosts the symptoms of both virus

In courgette:
The symptoms observed on the leaves are a slight yellowing of the veins.

In watermelon: In leaves where it has been detected, the chlorosis symptoms are very mild and may go unnoticed. At times, they are even symptom-free. A strong internal necrosis has been observed in the fruit, as well as splitting of this fruit, which is attributed to the virus, although whether this is a unique and/or direct consequence has not been entirely demonstrated.

Transmission of the vein yellowing disease

The virus is transmitted by the vector insect, Bemisia Tabaci (Homoptera: Aleyrodidae). The adults of this whitefly can be observed on the backs of the leaves like small insects that measure somewhat more than 1 millimetre long with a yellowish body and white wings due to the secretion of waxes that covers them.

A virus acquisition period of at least 30 minutes is needed, and at least 15 minutes feeding on the plant is required to inoculate it. The insect retains the virus for 6 hours and has a latent period of 75 minutes. Low transmission effectiveness by the Bemisia Tabaci has been indicated, and at least 15 to 20 insects are required per plant for its transmission.

Methods to combat Bemisia Tabaci

The management methods are based mainly on controlling the Bemisia Tabaci vector by means of prevention and culture practices (use of meshes, elimination of plant waste, use of resistant varieties, use of certified virus-free material, …), as well as plant health and integrated management practices.

The Regional Ministry of Agriculture and Fishery of the Junta of Andalusia, advises a series of specific measures:

  • Placement of double mesh on the edges and ridges of the greenhouses and placement of double door or mesh at the entrance.
  • When the climate conditions (especially humidity) permit adequate ventilation of the greenhouse, placement of anti-trip meshes.
  • Use of yellow chromotropic traps.
  • Surveillance and control of the white fly in early cultivation stages and seed beds.
  • Set up the measures relating to cleaning plant remains and weeds in the greenhouse and surrounding areas. Pull out and immediately eliminate plants affected by the virus during cultivation.
  • Not abandoning the crops and carrying out treatment against Bemisia Tabaci before pulling them out is compulsory as a management method, as well as correctly eliminating the plant remains.
  • Leave a rest period of at least one month between one cucurbitaceae crop and the next one to break the cycle of whitefly.

To control the whitefly in the framework of the integrated management of pests, natural specialised plant health products that have proved to be very effective in eradicating Bemisia Tabaci can be resorted to, as is the case of Pirecris.

Source: Consejería de Agricultura y Pesca. Andalucía.
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