Observations on periodicity of hatching of eggs of the potato cyst nematode, Heterodera rostochiensis Woll.

Abstract

Soil containing new-generation cysts of Heterodera rostochiensis was taken from the field at monthly intervals during late summer and autumn and kept in various conditions for up to a year. The number of eggs that hatched in the stored cysts was compared each month with the number that hatched in cysts taken directly from the field. Eggs did not hatch readily when stimulated during the late autumn and early winter, although more did so in cysts taken from the field before August than after. A few more eggs hatched in cysts stored in air-dried soil than in cysts stored in moist soil. Some cysts were kept at 15 or 20 "C continuously and others at 5 , 15 or 30 "C for 6 weeks followed by 20 "C continuously. Storage at 30 "C caused eggs to hatch sooner, but otherwise the temperature of storage had little effect on hatch at any time of the year. Warmth also increased the hatch of H . cruciferae sooner, and some synthetic hatching agents did so with both of these species. When freed from new cysts, more eggs of H. rostochiensis hatched than in intact cysts and hatch was further increased when the fragments of tanned cystwall were left with the freed eggs. Puncturing the cyst-wall of new brown cysts had little effect on the hatch in potato root diffusate. Like eggs in new cysts, those in I-year-old cysts stored out of doors ceased to hatch during the autumn and winter. The term 'dormancy' is inadequate to describe the inability of eggs of H. rostochiensis and other Heterodera spp. to hatch in the appropriate stimulant and the term 'facultative diapause', as applied to insects, better fits the phenomenon.

Protease inhibition by Heterodera glycines cyst content: evidence for effects on the Meloidogyne incognita proteasome

“…Although interest in the physiological role of the cyst, particularly with regard to its effects on hatching, goes back 50 years (Kaul, 1962;Shepherd & Cox, 1967), published reports have been sporadic. However, a consistent feature of most reports is that soluble cyst content contributes to hatch effects (Okada, 1972(Okada, , 1974Charlson & Tylka, 2003;Pridannikov et al, 2007;Masler & Rogers, 2011).…”

Effects of catechins and low temperature on embryonic development and hatching in Heterodera glycines and Meloidogyne incognita

“…A polyphenol similar to the condensed tannin catechin that accumulated in G. ro.nochiensis cysts during cold months (Kaul, 1962) accounted for 2% of cyst wall content by weight (Clarke, 1968). Kaul (1962) suggested that the catechin might repress hatching and Shepherd & Cox (1967) directly tested the effects of cyst wall on hatching in G. rostochiensis. They reported mixed results, with a slight decrease in hatch in the presence of yellow cyst walls but an increase in hatch in the presence of brown cyst walls.…”

Diapause in the nematodeGlobodera pallida

“…This trend may suggest that, because diapause lasts for a long period in the 'new' cysts, it may require a much longer storage period before the diapause can be broken. Alternatively, G. pallida may have multiple diapause as suggested previously for G. rostochiensis [Oostenbrink, 1967;Shepherd and Cox, 1967].…”

“…Various suggestions have been made to explain why some encysted eggs do not hatch, including the presence of inhibiting substances produced as a result of metabolic activities of the juveniles within the eggs during process of hatching [Ellenby, 1946], oxygen deficiency in the hatching medium [Wallace, 1959], seasonal variation [Calam et al, 1949] and genetic inheritance [E1-Shatoury, 1978]. Shepherd and Cox [1967] and Oostenbrink [1967] considered that G. rostochiensis eggs which failed to hatch under optimum conditions were in diapause, and they compared the phenomenon with that found in insects. However, their evidence was confusing due to lack of fundamental information on (a) history of cysts, (b) species involved (prior to the work of Stone [1972] G. pallida was not distinguished as a separate species from G. rostochiensis), (c) storage conditions of cysts, (d) hatching conditions of cysts, (e) hatching medium used, (f) how the hatching medium was produced and (g) host plants on which cysts were raised.…”