Thrips: A tiny pest with big consequences

Thrips, specifically western flower thrips (Frankliniella occidentalis), are currently the most damaging thrips species in many greenhouse crops, including ornamental crops. Unlike in the past when thrips occurred seasonally, the pest is increasingly becoming an all-year-round pest.

Thrips cause damage to plants by pricking cells on the surface of leaves and flowers and sucking them dry. Their feed marks leave silver-grey spots on the leaves and brown marks on flower buds. This has the potential to cause significant yield losses, and the visual damage caused has huge negative economic consequences, especially for ornamental crops.

Unlike pests such as spider mites, whitefly, and aphids, which have all the developmental stages on the leaves, thrips have a unique lifecycle that includes a resting pupa stage that resides in the media or is hidden under the crop canopy.

The changing dynamics in the environment, such as higher temperatures, which exacerbate thrips populations, increase the risk for growers. Growers take different approaches to tackle this dynamic pest. Some growers attempt to control thrips with the use of a lot of chemical insecticides, while others employ IPM, which includes the use of various natural enemies, supported by compatible pesticides.

Regardless of the approach, what is clear, is that thrips always require a well-considered plan of action for the entire season. Recent global developments have led to restrictions on certain chemical actives, narrowing the range of insecticides that growers rely on for effective control of thrips. This further makes it difficult to rely entirely on chemical insecticides to control thrips.

When timely control measures are not taken, a thrips population can develop explosively in the greenhouse. In warm conditions, some species e.g. the western flower thrips, doubles population in just ten days! Thus, quick response to new outbreaks and prevention measures from the build-up of resident thrips are the keys to success.

Solutions inspired by nature

For over 50 years, Koppert has invested in research and developing effective integrated pest control systems for various crops. "We believe that an effective approach to thrips management should be a holistic plan that proactively integrates cultural, mechanical, biological, and safe chemical options," the Koppert team says. "The investment in our IPM solutions is offset by sustainable incomes from a crop with higher productivity of better quality."

Koppert has, over time, developed a wide range of solutions for Thrips that target the insect at different stages of its life cycle.

Boveril: A new solution

Koppert is introducing Boveril to Kenyan growers. Boveril contains a unique strain (PL 63) of the insect pathogenic fungus Beauveria bassiana formulated as a wettable powder. The formulation has high solubility and suspensibility giving it excellent dispersion in water and under field application conditions.

"It comes as a great addition to our range of solutions that offer effective and sustainable control of Thrips and whitefly, among other insect pests, which are increasingly difficult to control with the available chemical insecticides."

Mode of action

The mode of action of the active agent Beauveria bassiana is an entomo-pathogenic fungus that infects the target insect pests through adhesion proteins and enzymatic activity through the production of mucilage at the site of contact.

The fungus acts on different stages of host development, such as larvae, pupae, and adults.

The evasion of the immune system is mediated by the expression of Mcl1 proteins, the secretion of destruxins A and E, the production of trehalase, and the expression of faith genes involved in the cycle cell, allowing rapid multiplication and differentiation of hyphae in the host's hemolymph, leading to host mummification of the affected insect. The fungus completely colonizes the insect after 72 hours, leading to death.

Application

Boveril can be applied via soil drenching or aerial spraying. The application must provide direct contact between the product and the target pests. Apply in the late afternoon or on cloudy days, with temperatures between 25 and 35 degrees Celsius and a minimum relative humidity of 60%. Perform prior cleaning of the spraying equipment and avoid using a ready mixture.

"For best results, we recommend an application rate of 2g/L of water. Boveril is available in a variety of pack sizes ranging from 75gms to 1KG to cater to large and small-scale growers."