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152 Rodr�guez-Navarro et al. 2008
Table 1. Monthly temperature and humidity in the
glasshouse.
ments with nine replications were evaluated. In the first
three treatments, mites were transferred manually (50,
150 and 200 individuals) to the stems of field bindweed
(McClay et al., 1999); in another three treatments infested
stems with 3, 5 or 7 galls were twisted around healthy
stems of field bindweed (Rodr�guez et al., 2004; Lauriault
et al., 2002). For the final treatment, no plants were infested
as the controls.
Fifteen days after infestations a random sample was
taken to check for the presence of symptoms on the
treated plants. Mite specimens were mounted on slides using
Hoyer’s medium and identified by comparison with
A. malherbae characteristics (Nuzzaci et al., 1985).
Sampling - The number of galls and the number of
stems with galls were counted from all samples taken at
15 day intervals from each of the pots. Mean temperature
and humidity data for the duration of the trial were obtained
from sensors connected to a Hobo H21-001
climatologic station.
Statistical analyses - To corroborate the normal
distribution of data, the Kolmogorov-Smirnov; Cramervon
Mises and Anderson-Darling (SAS, 2001) methods
were used. Subsequently differences between sample
means were tested by ANOVA and a regression analysis
was done.
RESULTS AND DISCUSSION
Because sample data did not represent a normal distribution
despite transformation, the analysis of variance
was not applied to the mean values, and instead the
non-parametric Kruskal-Wallis (Zar, 1996) method was
applied. According to Fig. 1, the selected ranges of the
samples used in the comparison representing the various
infested stems were not statistically different. Nevertheless
a positive response was observed with all the treatments
except for the controls and the treatment with infested
stems with three galls each. The treatment with 150
mites, overall, produced the highest number of infested
stems (Fig. 2).
The non-parametric tests used for the variation of
galls per plant, again, did not indicate any statistical differences
between the treatments. Similarly, as mentioned
before, the number of galls per plant in the controls and in
the treatment using 3 galls per stem showed no response.
The treatment with 150 mites again presented the highest
number of galls per plant. As was the case in the controls,
the absence of any response to the treatment using three
galls per stem could have been the result of the low survival
of A. malherbae.
The regression analysis (Fig. 3) to determine the relation
between the number of infested stems and the num-
Fig. 1. Infested stems for the various treatments (mean values). Bars with the same letter indicate no statistical differences
between treatments.