In-field results showing Thrips management and bee health
Onion thrips (Thrips tabaci) occur worldwide and reportedly feed on over 300 plant species while being recognised as the most abundant thrips species on vegetable crops (Visser, 2015). It attacks nearly all vegetables, with the most prominent problems occurring in onions, cabbages, and beans (Visser, 2015). Severe scarring on onions due to onion thrips damage can reduce the photosynthetic area and create entry points for foliar diseases. High numbers of T. tabaci in onions can reduce both the yield and storage quality of onions. On onions grown for seed, onion thrips can reduce both the yield and quality of seed production during seed set.
When the Bee-Tech group approached realIPM to trial their Dr Bee dispensers as a way to control thrips, it made perfect sense to combine our biologicals with their bees. Not only would we learn if the dispensers worked to transfer the biological to the plants, but we would showcase the effect of the biologicals on the bees.
The Dr Bee dispenser is a South African developed dispenser which loads bees with biocontrol agents to use for pest management during pollination season. The dispenser is highly effective as the bees carry the biocontrol agent and target the plant’s flowers directly, thus reducing water requirements, fuel and labour when compared to foliar spray application.
A number of studies have been conducted all over the world which have experimented with bee vectoring and shown successful outcomes (Smagghe et al. 2012). Thrips can be difficult to control with foliar sprays alone, and bees as transporters into ‘hard-to-reach’ areas in the flowering plant, make them ideal undercover agents for biologicals.
Bee-Tech and realIPM conducted a trial on onion seed production, aimed at controlling Thrips tabaci (Thysanoptera: Thripidae) on onion thrips, at a seed production research farm in Oudtshoorn, using REAL METARHIZIUM 69. A contact biopesticide containing Metarhizium anisopliae Strain ICIPE 69, REAL METARHIZIUM 69 does not need to be ingested for effective action, and once the spores come into contact with the cuticle of the target pest, they germinate, secreting enzymes, which are specific in their ability to weaken the insect cuticle.
Throughout the four week trial there was a considerable (32.2%) decrease in thrips numbers in the treatment tunnel compared to the untreated control tunnels.
Bee vectoring of REAL METARHIZIUM 69 proved very successful for the control of thrips during onion pollination and is a useful tool for farmers to keep thrips populations below economic threshold during pollination.
When realIPM’s biologicals, REAL METARHIZIUM 69 and REAL TRICHODERMA TRC900 were tested for bee health, both were found to have no negative effect on the bees or the hives, and in both cases, the hives grew with healthy young brood present and good pollen and nectar stores.
realIPM are very excited to be a part of this initial research and look forward to working with Bee-Tech in the future.
Please contact realIPM or Bee-Tech for further information.
References:
Smagghe, G., Mommaerts, V., Hokkanen, H. & Menzler-Hokkanen, I. 2012.
Multitrophic interactions: the entomovector technology. In Smagghe G., Diaz I. (Eds.)
Arthropod-Plant Interactions. 127-157. Springer, Dordrecht.
Visser, D. 2015. Vegetables: Onion, leek, garlic and chives. In Prinsloo, G. L. & Uys, V. M., eds. Insects of cultivated plants and natural pastures in Southern Africa. Cape Town, South Africa: Kadimah Print. pp. 44–47.