Abstract:
The paper presents the
efficacy of the some biopesticides used in
the experiments to control fall webworm
(Hyphantria cunea), comparatively to some
plant secondary metabolites from
autochthonous flora. From the first category
there were used: spinosad, a secondary
metabolite produces by the fermentation
from Saccharopolyspora spinosa mushroom
and is the active principle of the commercial
products of the Naturalyte class;
azadyrachtines – a group of limonoids,
obtained from the seeds of the Neem tree
(Azadirachta indica), and milbecmectin, a
product obtained from a metabolite of the
Streptomyces hygroscopicus subsp.
aureolacrimans bacteria. The results
revealed the efficacy of all bio insecticides
against fall webworm in 2-7 days period
after treatment. Spinosad presented a quick
action, comparatively to the other bio
pesticides. The secondary metabolites, used
into fall webworm control, were extracted
from autochthonous plants: the common
ladyfern (Drioperis filix mas), the perennial
sage (Salvia nemorosa), the wormwood
(Artemisia dracunculus, A. vulgaris, A.
absinthium) the European birthwort
(Aristolochia clematidis), Cow parsnip
(Heracleum spondylium), the hedge nettle
(Stachis sylvatica), the speedwell
(Tanacetum vulgare), the nettle (Urtica
dioica), the danewort (Sambucus ebulus)
and the yew tree (Taxus baccata) to fall
webworm. Plants extracts were obtained
from dried ground plants, using 25 g/ 1 litter
of cold water, stirred for 24 hours. The
extracts in ethylic alcohol were made using
the same method, 25 g dried plants in 200
ml alcohol and completed up to 1 litter with
water. The experiments were carried out
under laboratory conditions, treatments
being applied on shoots with leaves affected
by fall webworm, placed in growth boxes.
Each variant had three replications and each
replication contained three infested shoots.
The treatments were applied with manual
small pumps. Efficacy (E%) was calculated
after Săvescu-Iacob formula. The majority
of alcoholic plant extracts influenced the
decrease of leafs consumption as extracts
with water. Extracts of metabolites influenced the eating with repellent effects
against larvae, no palatable etc. The future
experiments must use more chemical
analyses to discriminate the main
metabolites, which influence the worm
activities.
