carried out in June 2001 and January 2002.
This comparison was executed by examin-
ing simultaneously, in the fecundity test
and the searching-ability test, individual
predators sampled from the same batch.
Results are presented in Table 16.5. Good
laboratory performers of June 2001 showed
a mean fecundity of 21.8 1.7 eggs per
female per 5 days, which is more than two
times higher than the product-control mini-
mum criterion of ten eggs per female per 5
days, and a survival rate of 85%, which is
higher than the minimum criterion of 80%
survivors at the end of the 5-day fecundity
test. Simultaneously, other female preda-
tors from the same batch have demon-
strated a 73% response in the
searching-ability test (response = predators
found on the target leaf within 24 h follow-
ing their release, and predator population
established on the target leaf at the end of
the trial (5 days after its start)). Both ‘fat’
and ‘flat’ (see section on Phytoseiulus in
Chapter 10) female predators from the
batch of 9 January 2002 showed poor fecun-
dity and high mortality in the laboratory,
and a searching ability rate of response
fluctuating between 37.5% and 57%, respec-
tively (Table 16.5). Another series of ‘fat’
females of P. persimilis, which was tested on
15 January 2002, yielded c. 11 eggs per
female per 5 days and 83% survival, but a
low response in the searching-ability test
(37.5%, Table 16.5).
Data are still insufficient to correlate
between bad/good performers in a labora-
tory fecundity test and their performance in
the greenhouse cage test (see discussion of
disease-infected predatory mites and
extreme dispersal behaviour in Chapter 10).
Such testing will be carried out in the near
future because of the problematic situation
with diseased predatory mites that may be
found in mass-rearing situations.Conclusions
The greenhouse-cage searching-ability test,
where dispersal of P. persimilisis possible,
is indeed halfway to field performance,
which is defined by van Lenteren and
Tommasini (1999) as: ‘Capacity to locate
and consume or parasitise prey/host in
crop under field conditions.’ Therefore, the
kind and strength of the correlation that
will be found between the laboratory prod-
uct-control test and the greenhouse-cage
test will apparently shed more light on the
relevance of a laboratory quality test as a
key product-control criterion that is prac-
tised by many natural-enemy producers
around the world.
As to the greenhouse-cage bioassay itself,
based on the limited data generated up till
now, we propose that 80% responding
predatory mites should be adopted as a min-
imum criterion. We suggest a minimum of 30
replicates per treatment for statistically
sound testing. This proposal has to be veri-
fied by ring testing, which will be conducted
in the near future.Dispersal Tests for Predatory Mites 229Table 16.5.Comparison between laboratory fecundity test and a greenhouse-cage searching-ability test
for the predatory mite Phytoseiulus persimilis.
Date/batch Fecundity SE* Survival (%) Response (%)**
June 2001 21.8 1.71 (n= 17) 85 73 (n= 11)
9 January 2002 (‘fat’ females) 6.41 1.21 (n= 22) 77 37.5 (n= 8)
9 January 2002 (‘flat’ females) Very low (n= 2) 47 57 (n= 7)
15 January 2002 (‘fat’ females)*** 10.96 1.33 (n= 26) 83 37.5 (n= 8)
Eggs per female per 5 days.
In the searching-ability test.
Sampled from the same batch of 9 January 2002.