Compound models describing the relationship between dosage of (Z)- or (E)-isomers of 1,3-dichloropropene and hatching behaviour of Globodera rostochiensis
Authors: Schomaker Corrie , Been Thomas 
Published: March 2012

Batches of increasing numbers of Globodera rostochiensis cysts were exposed
to a range of concentrations of the (E)- and (Z)-isomers of
1,3-dichloropropene. The cysts were of identical origin. Temperature during
treatment was 10 degrees C, humidity 100%, and time of exposure 8 days. The
integrals of concentration time products (CT) created were 0, 3, 7, 14, 31,
60, 125, 242, and 437 mug/ml day for the (E)-isomer and 0, 3, 16, 59, 240,
and 419 mug/ml day for the (Z)-isomer. Survival was estimated by hatching
tests 1.5, 3, and 7 months after treatment. The relationship between dosage
of (E)-isomer and numbers of hatchable nematodes followed a log-logistic
equation at all hatching dates. Hatchability, and therefore lethal dosages,
increased at the later dates of the hatching tests: 7 months after
treatment, practically all treated nematodes had recovered and hatchability
of treated and untreated nematodes was the same. A log-logistic relationship
was also found for dosage (Z)-isomer and numbers of hatchable nematodes 1.5
months after treatment. When hatching tests of nematodes treated with the
(Z)-isomer were made 3 and 7 months after treatment, the results were better
explained by a compound model assuming two independent log-logistic effects,
one stimulating hatch at low dosages and one reducing hatch at all dosages.
Only the (Z)-isomer of 1,3-dichloropropene was effective as a nematicide.
Modeles composites decrivant la relation entre dose des isomeres (Z) ou (E)
du 1,3-dichloropropene et le comportement d'eclosion de Globodera
rostochiensis - Des lots comprenant un nombre croissant de kystes de
Globodera rostochiensis ont ete exposes a une serie de concentrations des
isomeres (Z) ou (E) du 1,3-dichloropropene. Ces kystes avaient la meme
origine. Le traitement, d'une duree de 8 jours, etait effectue a 10 degrees
C et a une humidite relative de 100%. Les integrales des produits
concentration / temps (CT) ainsi creees etaient de 0, 3, 7, 14, 31, 60, 125,
242 et 437 mug/ml jours pour l'isomere (E) et de 0, 3, 16, 59, 240 et 419
pour l'isomere (Z). La survie a ete estimee par des tests d'eclosion apres
1, 5, 3 et 7 mois. La relation entre dose de l'isomere (E) et le nombre de
nematodes eclos suit une equation log-logistique pour toutes les durees. La
capacite d'eclosion, et donc les doses letales, augmentent si les tests
d'eclosion sont differes. Sept mois apres le traitement, pratiquement tous
les nematodes ont recupere et l'eclosion est identique chez les nematodes
traites et non traites. Une relation log-logistique a egalement ete mise en
evidence entre les doses de l'isomere (Z) et le nombre de nematodes eclos
apres 1,5 mois. Lorsque les tests d'eclosion sur les nematodes traites avec
l'isomere (Z) etaient differes jusqu'a 3 et 7 mois apres le traitement, les
resultats s'expliquaient mieux a l'aide d'un modele composite prenant en
compte deux effets log-logistiques independants, l'un stimulant l'eclosion
aux faibles doses, l'autre reduisant celle-ci pour toutes les doses. Seul
l'isomere (Z) du 1,3-dichloropropene est efficace en tant que
nematicide.