Nematodes against
BIOLOGICAL POTATO BEETLE CONTROL
The Colorado potato beetle, scientifically known Leptinotarsa decemlineata, is one of the best known and economically most important pests in potato cultivation. Originally native to North America, it has spread across large parts of the world over time. Its voracious behaviour and ability to develop resistance to chemical pesticides make it a major challenge for farmers.
LIFE CYCLE OF THE POTATO BEETLE
The life cycle of the Colorado potato beetle comprises several stages of development, which vary greatly in their appearance and function. Depending on the weather conditions
it can form one to two generations per year. It prefers dry and warm weather conditions. The adult beetles overwinter in the soil and crawl out of the soil of the previous year's potato fields when the potatoes emerge (from a soil temperature of 15° C). After ten to 14 days of maturation feeding, the females begin to lay their eggs.
1. egg deposition
The females lay their bright orange-coloured eggs in groups of 20 to 60 on the underside of potato leaves. Over the course of two months, a female can lay up to 400 eggs.
2. larval stage
The larvae hatch after 4-14 days. At first they are small and dark brown, later they develop a striking red colour with black spots. The larvae go through four larval stages and feed tirelessly on the leaves of the host plant. A larva can feed on up to 40cm2 of leaf area in four weeks, with the majority of this being accounted for by larval stages L3 and L4.
3. pupation
After three to four weeks, the fully-grown larvae burrow into the soil and pupate at a depth of approx. 10 cm. The pupae are yellowish-brown in colour and remain in the soil for 10 - 14 days until the young beetles hatch from them.
4. adult stage
The adult Colorado potato beetles, with their distinctive yellow and black striped wings, emerge from the pupa and begin to reproduce soon afterwards. Under favourable conditions, they can produce several generations per year.
From egg to beetle: Development stages of the colorado potato beetle
DAMAGE CAUSED BY POTATO BEETLE
The Colorado potato beetle mainly attacks plants of the nightshade family (Solanaceae), especially potatoes, aubergines and tomatoes.
The main damage is caused by the larvae and adult beetles feeding on the leaves. In cases of severe infestation, the plants can be completely defoliated, resulting in considerable yield losses. In extreme cases, the entire harvest can be destroyed. Infestation during the flowering period and tuber formation is particularly critical, as the plant requires the most energy during this phase. The greatest damage is caused by the larvae in the 3rd and 4th larval stage.
Leaves stripped bare by the larvae of the Colorado potato beetle
POTATO BEETLE CONTROL WITH NEMATODES
Nematodes of the species Steinernema carpocapsae can be used against the pupae and larvae of the Colorado potato beetle, but are most effective against larvae in the developmental stages L1-L3. The product nemastar® contains Sc-nematodes and is an effective and biological solution against the colorado potato beetle.
nemastar® can be used in against the larvae in summer. Field trials against the larvae have shown a control effect of 60%.
The application rate is 1.5 million nematodes per litre of spray mixture or 250,000 nematodes per m2 or 2.5 billion per hectare. The nematodes are stored in a natural carrier material and are simply mixed with water and applied to the leaves with 500 - 800 litres of water per hectare. As nematodes dry out quickly and are UV-sensitive, they should be applied in damp weather conditions and/or in the evening. For optimum control success, the treatment should be repeated after two weeks.
The nematodes can be mixed with many other active ingredients. A detailed overview of the miscibility of nematodes can be found here.
Nematodes of the species Steinernema carpocapsae