Use of neem-based insecticides against southern armyworm,
Spodoptera eridania (Stoll) (Lepidoptera: Noctuidae)
Laboratory bioassays were carried out to study the
insecticidal, antifeedant, developmental, and
reproductive effects of three commercial neem
oil-based formulations (Pure Neem Oil, Azatrol,
and Triple Action Neem) on Spodoptera eridania
when used at recommended concentrations. Neem-
derived insecticides significantly reduced the food
intake of all instars tested, often limiting the
feeding activity on neem-treated leaf areas to a
fraction of that occurring on controls, in both
choice and no-choice bioassay tests. Pure neem
oil, followed by Azatrol, demonstrated up to 96%
antifeedant activity against larvae; consequently,
both biopesticides are effective antifeedants.
A two-day feeding period on leaves treated
independently with pure neem oil and Azatrol
induced the prolongation of the second larval
instars by 4.5 and 2.7 days, and by 2.4 and 1.3 days
for fourth larval instars, respectively. Mortality
and pupal ecdysis of S. eridania were also negatively
impaired by neem-based biopesticides, with the
greatest efficacy attributable for pure neem oil.
When administered orally, commercial formulations
induced significant reduction in longevity by
0.8-4.1 days, and fecundity of adults was
significantly reduced compared to those fed on
KEYWORDS: southern armyworm, Spodoptera
eridania, biopesticide, neem oil, antifeedant
One of the principal constraints in increasing crop
productivity in the world is infestation by pestiferous
insects. Southern armyworm, Spodoptera eridania
(Stoll), is an example of such destructive pests. It
attacks a very broad range of hosts, including
vegetable, fruit, and ornamental crops.
As a consequence of the lack of knowledge and
the absence of alternative plant protection strategies
in many countries, the most frequent method used
by growers to protect their crops from pest attack
is the use of traditional chemical pesticides.
In view of the well-known detrimental effects of
synthetic insecticides , development of sustainable
and non-polluting plant protection strategies has
become important for the global populations’ food
supply, and ecosystem conservation. Thus,
some producers are progressively adopting more
environment friendly integrated pest management
and organic farming approaches, which are
increasingly considered to be core practices in
plant protection .
Many pesticides of botanical origin are characterized
by their relatively low toxicity, biodegradability
and other factors that make them acceptable in
the environment, and which would favor their
incorporation into integrated pest management
programs . With the robust growth of safer
insecticides in the global pesticide market,
azadirachtin, a steroid-like tetranortriterpenoid derived
from the Indian neem tree (Azadirachta indica),
1Jordan University of Science and Technology, Faculty of Agriculture, Department of Plant Production,
P. O. Box (3030), Irbid 22110, Jordan. 2University of Florida, Institute of Food and Agricultural Sciences,
Department of Entomology and Nematology, P. O. Box 110620, 1881 Natural Area Drive, Gainesville,
Florida 32611, USA
Hail K. Shannag1, John L. Capinera2 and Nawaf M. Freihat1
Vol. 9, 2013
46 Hail K. Shannag et al.
mortality, fecundity and longevity. Use of such
innovative, effective, and practical options could
offer the opportunity for further use of sustainable
pest management systems for many other crops,
particularly where traditional pesticide inputs are
undesirable or restricted.
MATERIAL AND METHODS
Plant and southern armyworm rearing
The experiments were carried out at Department
of Entomology and Nematology, University of
Florida, Gainesville, Florida, USA. A stock culture
of S. eridania was established from larvae collected
from a farm near Gainesville, Florida, immediately
before the research, and the progeny used
subsequently throughout the studies. They were
moved from their natural plant diet to synthetic
bean-based diet  shortly before studies
commenced, and maintained on this diet for the
duration of the investigations.
Adults of southern armyworm were kept in screen
mating cages (50 cm x 50 cm x 70 cm) and nourished
on a 20% honey solution as a source of energy
that was offered in a small plastic bottle with screw
plastic cap. An absorbing wick (1 cm in diameter
x 7.5 cm long) was inserted through a hole punctured
in the lid of feeding bottle. The artificial diet used
to feed adults was replaced as appropriate. Pieces
of folded wax paper were placed in the rearing cage
for egg-laying. Oviposition substrates occupied
with eggs were removed daily and maintained
independently in a plastic container. After hatching,
neonate larvae were reared on the artificial bean-
based food until they pupated. A thick layer of
vermiculite furnished at the bottom of a cylindrical
plastic container (25 cm diameter x 10 cm height)
was provided for pupation. Insect rearing and all
bioassays were conducted in the same experimental
conditions, in a controlled room at 25 ± 1 °C and
long-day photoperiod of 16:8 h (L:D).
Commercially formulated Azatrol (1.2% azadirachtin)
manufactured by Pbi/Gordon Corporation, Kansas
City, Missouri, USA; Triple Action Neem Oil
(70% neem oil) from Southern Agricultural
Insecticides Inc, Palmetto, Florida, USA; and Pure
Neem Oil (100% neem oil) produced by Dyna-Gro,
is uniquely positioned as a key insecticide in the
botanical market segment . Based on its
advantages, there is increasing interest in the use
of azadirachtin to suppress phytophagous insects,
particularly in cropping systems that rely on natural
enemies as a major component of integrated pest
management. In spite of there being commercial
neem-based products labeled for many insect
species, their efficacy under field and greenhouse
conditions has been proven to be variable .
Evaluation of azadirachtin is confounded by the
insect growth regulator actions of neem products
. Similarly, the impacts of neem-based pesticides
on many other aspects of insect biology, including
feeding behavior, reproduction, growth, fitness
and mobility of the insects seem to vary among
insects, as well as challenging to assess. The
variable effects of azadirachtin could be attributed
to the insect species tested, the application dose,
and application . Other components in neem
extracts, along with the methods of extraction,
storage conditions, origin of neem, or contamination
with mycotoxins, can also influence performance .
Even with the several advantages of neem-based
insecticides, their use may be limited by their
susceptibility to environmental variability, particularly
by photodegradation. As neem extracts are mainly
applied as spray treatments onto the crop canopy,
they are subject to environmental influences,
sometimes resulting in erratic levels of success on
a variety of arthropod pests . Therefore, there
are many efforts underway to stabilize such
biopesticides by using photostabilizers to achieve
persistence as desired for specific control situation.
Insecticidal adjuvant formulations such as stilbene-
derived optical brighteners, particularly Tinopal
LPW, has been used over the past decade in some
bio-pesticide formulations, mainly with baculoviruses
[9, 10, 11]. Soil treatment making use of the
systemic properties of azadirachtin is another option
that may lessen instability and prolong persistency
of the neem-derived insecticides, although this
approach is accompanied by higher costs [12, 13].
Therefore, this study was performed to evaluate
the response of the southern armyworm to three
commercially formulated biopesticides, namely
Azatrol (EC), Triple Action Neem Oil, and Pure
Neem Oil, under laboratory conditions. We assessed
their potential effects on feeding, development,
Effect of neem-derived insecticides on Spodoptera eridania 47
Larvicidal and pupicidal activity
Water-based solutions of Triple Action Neem Oil,
Azatrol, and Pure Neem Oil were applied at
recommended concentrations using a leaf dip
method. Treated cucumber leaves were presented
to 25 insects in the second or fourth instar after a
12 h period of starvation. A feeding period of two
days was chosen to ensure that all larvae were fed.
Afterwards, the larvae were transferred into new
plastic containers and provided continuously with
plain artificial diet until they fully developed.
Once larvae molted to the pupal stage, pupae were
kept in new containers with a layer of vermiculite
as a pupation substrate until they reach the
adulthood. Six replicates were used for each
treatment with 25 larvae per replicate (150 larvae/
treatment). Larval mortality, length of larval
development, and proportion of pupae developing
into adults were recorded. Percent mortality was
calculated according to Abbott’s formula (Abbott,
1925): corrected mortality = [(% mortality in
treatment - % mortality in control)/(100 - % mortality
in control)] x 100. Pupicidal activity was computed
by subtracting the number of emerging adults from
the total number of pupae.
Fecundity and longevity of S. eridania adults
Effects of ingestion of commercially formulated
neem products on the fecundity and life span were
studied by allowing recently emerged adults (24 h
old) to feed on 20% honey solution containing
either Triple Action Neem Oil, Azatrol, or Pure
Neem Oil at concentrations of 7.8 ml, 31.2 ml,
and 7.8 ml per liter, respectively. Control insects
were offered plain 20% honey solution. Groups of
five pairs of adults (5 females and 5 males) were
confined in an aluminum screen cage (20 cm x
20 cm x 20 cm) containing folded wax paper as
oviposition substrate. Insecticide solutions were
offered continuously to adults in a small plastic
bottle with screw cap (5 cm diameter x 5 height)
provided with a piece of absorbant wick through
the lid. Diet solutions were replaced every two
days to prevent fungal growth. Three replicates,
each replicate consisting of one screen cage with
five pairs of adults, were used per neem product,
plus a control. Longevity was determined by
checking adult moths daily until death occurred,
and the number of eggs they produced was
recorded daily until the death of all adults.
San Pablo, California, USA, were used in all
experiments as water-based solutions at recommended
field concentrations: 31.2 ml/l for Azatrol, 7.8 ml/l
for Triple Action Neem Oil, and 7.8 ml/l for Pure
Feeding responses of S. eridania larvae to either
treated or untreated leaf disks were examined by
no-choice, choice, and multiple choice methods.
Fresh cucumber leaf disks measuring 28.3 cm2
were punched immediately before application of
treatment solutions to minimize changes in leaf
quality and then dipped for a minute into the
prepared solutions of formulated neem-derived
chemicals. Leaf disks immersed only into water
were used as a control. All treated leaf disks were
left dry at room temperature.
Plastic Petri dishes (9 cm x 1.5 cm) lined at the
bottom with wet filter paper were used for no-
choice tests, whereas cylindrical plastic containers
(25 cm x 10 cm) with moist tissue at the bottom
were applied for choice and multiple-choice tests
in order to maintain high humidity and to avoid
early drying of the leaf disks. In no-choice tests,
one leaf disk and a single, second, third, or fourth
instar larvae were transferred individually into Petri
dish after a 12 h period of starvation and allowed
to feed freely for 24 h. Leaf area consumed by
each larva in both treated and control leaves was
measured using a leaf area meter (LI-3000A,
LI-COR, Lincoln, Nebraska, USA).
In choice tests, one treated and one control disk
were placed in each container containing either a
single, second or fourth instar larva. The distance
between the two disks was approximately 10 cm.
In order to determine the neem-based product with
the most effective antifeedant activity, multiple-
choice bioassays that included all the four
treatments in the same container were carried out
for 24 h for all bioassays. For every chemical
substance evaluated and each instar larva, 10 larvae
with three replicates were used. The consumed
area in all tests was obtained by subtracting the
remaining area from the initial area of each leaf
disk. The percentage of antifeedant activity was
calculated using the formula: antifeedant index =
[(leaf area consumed in control - leaf area consumed
in treatment)/leaf area consumed in control] x 100.
48 Hail K. Shannag et al.
showed the least inhibition of food intake (19.8%)
with the antifeedant index estimated as 14.8%.
Pure Neem Oil and Azatrol were much more
effective antifeedants, displaying antifeedant
activity of 94.8% and 80.9% (Table 2), with
larvae consuming only 0.5% and 3.2% of leaf
area, respectively (Table 1).
The same trends, but at a lower magnitude, were
observed by the fourth instars, which were less
sensitive to Triple Action Neem Oil behaviorally,
displaying a slight inhibition of leaf consumption
(3.8% antifeedancy), whereas Pure Neem Oil and
Azatrol markedly reduced food consumption by
S. eradania larvae by 78.4 and 65.6%, respectively.
Feeding activity in choice tests
On average, the second and fourth instars of
S. eridania preferred significantly more untreated
leaf disk material when presented simultaneously
with treated, but at the same time they did not
reject the neem-treated food completely (Table 3).
Data were subjected to analysis of variance by
means of SAS software version 9.2  and means
were compared using the Least Significance
Differences (LSD) test at P ≤ 0.05. Mortality counts
of S. eradania were evaluated by using Abbot’s
formula . Values of antifeedant activity were
transformed to log10(X -100).
Feeding activity in no-choice test
There is strong evidence that neem-based
products inhibited food intake in the different
instars evaluated using no-choice tests (Table 1).
On an average, 8.3% of untreated leaf disks of
cucumber plants were consumed by the second
instars, whereas the larvae consumed only 0.3-6.5%
of treated leaf disks, depending on the chemical
tested. The antifeedant index was 16.6% for
Triple Action Neem Oil, 96.3% for Pure Neem
Oil and 89% for Azatrol (Table 2).
Neem-based products also significantly reduced
feeding by third instars. Triple Action Neem Oil
Table 1. Average leaf area (cm2) and proportion of cucumber disks consumed by S. eridania
larvae in no-choice bioassays.
Treatments 2nd instar 3rd instar 4th instar
Control 2.34 a (8.3%) 6.67 a (23.6%) 20.13 a (71.1%)
Triple Action Oil 1.84 b (6.5%) 5.60 b (19.8%) 19.36 a (68.4%)
Azatrol 0.26 c (0.9%) 0.91 c (3.2%) 7.67 b (27.1%)
Pure Neem Oil 0.08 c (0.3%) 0.14 d (0.5%) 4.18 c (14.8%)
DF 3, F 178.33
DF 3, F 336.1
DF 3, F 221.7
Mean values of leaf consumption within column for each instar followed by the same letter are not
significantly different at P ≤ 0.05.
Table 2. Antifeedant indexes and their proportional feeding reduction for the three neem-based
pesticides when evaluated on different instars of S. eridania.
Treatments 2nd instar 3rd instar 4th instar
Triple Action Oil 4.67 a (17.4%) 4.72 a (14.4%) 4.62 a (2.4%)
Azatrol 5.23 a (89.0%) 5.22 b (84.6%) 5.10 b (64.0%)
Pure Neem Oil 5.28 b (96.3%) 5.29 c (98.2%) 5.18 c (78.3%)
DF 2, F 30.18
DF 2, F 236.2
DF 2, F 297.5
Mean antifeedant indexes within column for each instar followed by the same letter are not significantly
different at P ≤ 0.05. Data are transformed to log10(X -100).
Effect of neem-derived insecticides on Spodoptera eridania 49
insecticides exerted a deleterious effect on feeding
behavior that was statistically superior to that of
the Triple Action Neem Oil and control treatments.
In comparison to the control, the average leaf
consumption of treated leaf disks by second
instars was reduced by 85.2% for Triple Action
Neem Oil, 95.6% for Pure Neem Oil, and 94.8%
for Azatrol. The second and fourth instar larvae
behaved similarly with respect to the treatments.
For trials with fourth instars, leaf consumption of
treated disks was reduced by 72.9% for Triple
Action Neem Oil, 97.5% for Pure Neem Oil, and
96.2% for Azatrol in comparison with the control.
However, the amount of leaf material consumed
by larvae exposed to leaves treated with Triple
Action Neem Oil did not differ significantly from
those of untreated leaves. In contrast, Pure Neem
Oil and Azatrol induced significant inhibition of
food intake, with about 20 times as much leaf area
consumed in untreated foliage as compared to
Feeding activity in multiple-choice test
The multiple-choice bioassays demonstrated that
Pure Neem Oil and Azatrol were the most effective
feeding deterrents for the second and fourth
instars of southern armyworm (Table 4). Both
Table 3. Total area of consumed cucumber leaf (cm2) and proportion
consumed by S. eridania in choice bioassays.
Treatment 2nd instar 4th instar
Triple Action Oil
0.86 a (3.0%)
1.01 a (3.5%)
12.63 a (44.6%)
9.69 a (34.2%)
DF 1, F 1.01
DF 1, F 1.24
2.16 a (7.6%)
0.10 b (0.3%)
21.95 a (77.6%)
1.25 b (4.4%)
DF 1, F 203.10
DF 1, F 236.7
Pure Neem Oil
1.62 a (5.7%)
0.06 b (0.7%)
17.51 a (61.9%)
0.72 b (2.5%)
DF 1, F 245.0
DF 1, F 372.2
Means within column for each paired control and treatment values for each
instar followed by the same letter are not significantly different at P ≤ 0.05.
Table 4. Total leaf area (cm2) consumed by S. eridania larvae in multiple-
Treatment 2nd instar 4th instar
Control 2.32 a 15.53 a
Triple Neem oil 0.34 b 4.63 b
Azatrol 0.12 b 0.65 c
Pure Neem oil 0.11 b 0.43 c
DF 3, F 114.2
DF 3, F 60.2
Means within column followed by the same letter are not significantly different
at P ≤ 0.05.
50 Hail K. Shannag et al.
lesser effects, also leading to significant decreases in
the number of adults emerging from the pupal stage.
The effects of neem-derived insecticides on the
development time of S. eridiana are presented in
Table 6. Increased larval development periods were
observed among second instars fed with neem-
treated food for 48 h when compared to those kept
on untreated food, although the degree of delayed
development varied among treatments. The Pure
Neem Oil and Azatrol treatments induced significant
prolongation of larval development time relative
to the control, extending mean development time
by 4.74 and 2.69 days, respectively. On an average,
Triple Action Neem Oil delayed mean larval
development for less than a day, which did not
significantly differ from control treatment.
In contrast, the development time of the fourth
instars did not differ significantly between the control,
Triple Action Neem Oil, and Azatrol. However, Pure
Mortality, development and pupal ecdysis
When larvae were fed cucumber leaves dipped in
commercial neem-based products at recommended
concentrations, some treatments induced mortality
(Table 5). Mean mortality of second instar S. eridania
was 12.2% for Azatrol and 35.5% for Pure Neem
Oil, whereas larval mortality was negligible for
both Triple Action Neem Oil and control treatments.
The same trend, but at higher levels, was observed
for both neem products fed to fourth instars, with
mean mortality of 26.8% for Azatrol and 45.2% for
Pure Neem Oil.
Pupal ecdysis was affected in second instars fed
with neem-treated diet for 24 h and reared to the
pupal stage. However, the effect varied among
products. The greatest reduction in the number of
pupae reaching adulthood was observed for
S. eridania fed on foliage treated with Pure Neem Oil.
The other neem-based products induced similar but
Table 5. Mean S. eridania mortality (%) and successful adult emergence (%) caused by
feeding of second or fourth instars for 24 hours on cucumber leaves treated with different
Treatment 2nd instar 4th instar Adult emergence
Control 2.67 a 2.67 a 82.88 a
Triple Action Oil 1.94 a 2.67 a 74.78 b
Azatrol 14.67 b 28.77 b 74.82 b
Pure Neem Oil 37.33 c 46.67 c 63.13 c
DF 3, F 57.1
DF 3, F 61.0
DF 3, F 18.84
Means within each column followed by the same letter are not significantly different at P ≤ 0.05.
Table 6. Mean development times (days + SE) for second and fourth instars of S. eridania to
complete larval development when fed for 48 hours on diet treated with different neem-
Treatment 2nd instar (days) 4th instar (days)
Control 14.54 ± 0.14 a 8.66 ± 0.08 a
Triple Action Oil 15.01 ± 0.12 b 9.24 ± 0.08 b
Azatrol 17.07 ± 0.13 c 9.94 ± 0.10 c
Pure Neem Oil 19.20 ± 0.14 d 11.10 ± 0.11 d
Critical T value 1.96
Critical T value 1.96
Means ± SE within column followed by the same letter are not significantly different at P ≤ 0.05.
Effect of neem-derived insecticides on Spodoptera eridania 51
active ingredients of neem compounds are non-
volatile substances and the insect must taste them
in order to respond to their presence . Previous
studies revealed that the antifeedant effects caused
by formulated neem-based products appear to
vary with insect species and the formulated neem
product tested. However, similar reductions in
food uptake has been documented for S. lituralis
, Salix exigua , Mamestra brassicae ,
and Heliothis viridescens  during one- or two-
day feeding periods on leaves treated with
different neem products. The feeding inhibition
has been credited to a direct action of neem
products on the centers of control that regulate
feeding and metabolism  and/or the inhibition
of feeding behavior by stimulation of deterrent
chemoreceptors on the mouthparts, or blockage of
input receptors for phagostimulants . However,
azadirachtin and other neem extracts have been
reported not to exhibit antifeedant activity in
Manduca sexta  and Peridroma saucia .
In addition to having generalized antifeedant
properties, neem-based preparations induce a
variety of disruptive developmental phenomena in
lepidopteran larvae. In the present study, the
second and fourth instars of S. eridania exposed
to Pure Neem Oil and Azatrol took considerably
longer time to reach the pupal stage when
compared to control insects. Such prolonged time
of larval development may be as a result of a
reduction of food intake and lack of converting
food into biomass, as reported for S. littoralis
. Prolonged larval periods were associated
with increased larval mortality in S. eridania, but
Neem Oil significantly prolonged the duration of
larval development for 2.44 days relative to those
maintained on untreated food.
Fecundity and longevity of adults
Fecundity and longevity of S. eridania adults
were significantly affected by prolonged ingestion
of the neem-based products (Table 7). However,
as with other aspects of insect biology, the
magnitude of the effect varied among the products.
Young adults fed with honey solutions containing
neem-derived insecticides at recommended
concentrations produced significantly fewer eggs
over their life span, with egg production decreased
to as little as one-tenth the egg production of
insects fed with untreated foliage, though Triple
Action Neem Oil was not as effective as Azatrol
and Pure Neem Oil. Except in the case of Triple
Action Neem Oil, ingestion of the neem products
significantly decreased adult longevity. Longevity
was reduced by 3.66 d and 4.10 days by Azatrol
and Pure Neem Oil, respectively.
Commercially available neem seed extracts have
shown a wide range of bioactivity against insects,
affecting reproductive fitness, hatchability,
molting, development rates, and feeding behavior
[17, 18]. Our results provide clear evidence that
commercially formulated Pure Neem Oil and
Azatrol applied to cucumber leaf disks induce
potent feeding deterrent activity against S. eridania,
though not entirely preventing insect feeding even
in choice tests where the larvae have an alternative
neem-free food source. This is likely because the
Table 7. Effects of neem-derived insecticides on fecundity and mean longevity of
S. eridania adults continuously provided with 20% honey solution mixed with neem-
based products at recommended concentrations.
Treatment Fecundity (5 pairs) Longevity (d)
Control 6621.66 a 9.73 a
Triple Action Oil 2311.67 b 8.93 a
Azatrol 810.33 b 6.07 b
Pure Neem oil 646.33 b 5.63 b
DF 3, F 27.5
DF 3, F 16.7
Means within each column followed by the same letter are not significantly different at P ≤ 0.05.
52 Hail K. Shannag et al.
Of particular interest would be combinations with
stilbene-derived optical brighteners in order to
improve persistence of azadirichtin and/or other
additives. Also, the differing effectiveness of the
various commercial formulations is of considerable
importance, as their effects on insect biology and
survival can be markedly different.
1. Neem-based products evaluated were not able
to completely inhibit food intake of Spodoptera
eridania larvae, but they limited effectively the
feeding activity at different magnitudes depending
on the product.
2. A short-term exposure of S. eridanian larvae to
diet treated with neem-based products prolonged
significantly the duration of larval development.
3. The magnitude of the negative effect on the
larval mortality and pupal ecdysis varied
considerably among neem-drived insecticides tested.
4. A reduction in the fecundity and longevity
followed by the ingestion of commercial neem
oil-based formulations by adult females clearly
indicate that neem-containing products may have
potential for being utilized in food-based traps to
disrupt the biology of some insects.
5. Insecticides based on neem oil seem to have
potential to protect plants from S. eridania, although
additional studies are needed to evaluate their
efficacy under field conditions.
6. Caution in making assumptions on neem products
is advised, as their effects on insect biology and
survival can be markedly different.
I would like to thank Jordan University of Science
and Technology and Fulbright for their financial
support. My gratitude and appreciation are also
extended to Prof. John Capinera at Department of
Entomology and Nematology, University of Florida,
USA for hosting me at his institution and
providing me with all research facilities during
CONFLICT OF INTEREST STATEMENT
There are no conflicts of interest.
death was delayed a week or longer. Similar effects
were found in S. exigua  and Cnaphalocrocis
medinalis treated with different neem-derived
Adults of several important lepidopteran pests
have been reported previously to respond in different
ways to exposure to neem-based products, either
through topical application or by ingestion. As
was observed in other studies, our results clearly
indicate that neem-based products adversely
affected not only the larvae, but the longevity and
the reproductive potential of adults treated orally.
Similar to these results, other commercially
available neem seed extracts adversely affected
the fecundity of several insect pests of significant
importance such as S. littoralis , S. exempta
, Pieris brassicae , and Plutella xylostella
. These consequences could be induced by
interference of neem-based biopesticides with
vitellogenin synthesis or uptake in developing
oocytes, along with the accumulation of proteins
in the eggs that is required for maturation of insect
eggs [31, 34]. Moreover,  attributed this effect
to the incorporation of the neem compound into
the eggs during copulation, through sperm transport,
transovarial transport, or both together. Although
our results provide no insight into the mechanism
of disruption, they clearly indicate that neem-
containing products have potential for being
utilized in food-based traps to disrupt the biology
of some insects.
In a recent study, azadirachtin demonstrated a
significant effect on the longevity of S. littoralis
adults only at the higher concentrations , whereas
in other investigations, longevity of Phthorimaea
operculella , Trichoplusia ni, Peridroma
saucia, and S. litura  were not influenced by
azadirachtin. Such disparate outcomes may be
caused by differences in azadirachtin content of
the various parts of the neem tree , as well as
inherent differences in the insect species tested.
Adult susceptibility to neem products is not well
understood; the biochemical target sites for neem
are not yet identified.
Commercial formulations of neem-based insecticides
seem to have considerable potential to protect plants
from S. eridania, though additional studies are needed
to evaluate their efficacy under field conditions.
Effect of neem-derived insecticides on Spodoptera eridania 53
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