Nematoda, Tylenchida, Heteroderidae .
Description, Biology, Life Cycle, Damage, Common Names, Images
- Host plants: this genus exclusively parasitizes the Solanaceae, especially potato, tomato, egg plant and a few volunteer plants such as bittersweet (Solanum dulcamara) and henbane (Hyoscyamus niger).
- Hatching, which is favoured by humidity and a substance secreted by the roots of the host plant, is never complete, certain eggs remaining in a latent state for many years.
- Young juveniles pierce the cuticle of the host plant's radicles, penetrate the tissues and make their way between cells, causing the formation of giant cells which hold up sap circulation. After some time, males vacate the roots while females move to the surface, break out of the epidermis, but with their head remaining fixed to the host.
Mating occurs, eggs develop and cause the body of females to swell. Females then become cysts and die. These become detached and remain in the soil. The complete cycle lasts 50-70 days.
- There is 1 generation per year.
- Hatching begins as soon as temperatures reach 12°C and takes place gradually. The 1st cysts are few in June but appear in considerable numbers in July and August, formation ceasing in October. Eggs usually do not all hatch in one season: the emergence of the juveniles is spread out over several years. In the absence of suitable hosts plants, nematode populations decrease by 30% per year, and it may take 20-30 years before heavy infestations disappear.
- Nematode secretions lead to a modification of plant tissues and a reduction of sap circulation. Moreover, roots turn brown, ramify and become shrubby. Growth of potato is slowed down, lower leaves wither and die; upper leaves become discoloured, the edge of leaflets exhibiting brown spots. Affected plants are stunted and yield poorly.
- Attacks in fields tipically occur in patches (*) .
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.