BACKGROUND
according to the report of fao, due to the attack from pathogenic organisms and insect pests, 20–40% decrease in crop yield occurs which results in loss of  <dig> billion us $ worldwide  <cit> .
pest insects, being plant disease vectors reduce crop output by 10–30% either by reducing the quality and quantity of the crop production, or by serving as vectors of plant diseases  <cit> .
spodoptera litura  , a polyphagous insect of cosmopolitan distribution, has a large host range of more than  <dig> host species  <cit>  and is considered economically important in many countries including india, japan, china and southeast asia  <cit> .
this defoliating insect pest affects the yield of various cultivated crops, vegetables, weeds and ornamental plants by feeding gregariously on leaves and causes large economic losses of crop plants.
it was reported as a major pest in groundnut in andhra pradesh, india and caused 28–100% yield loss depending upon crop stage and its level of infestation  <cit> .
the management of s. litura to ensure the stable and high output of crops is a great challenge in agricultural field and therefore, insecticide use is most widely practiced for its control.
however, there is widespread concern over negative impact of insecticides on environmental and human health due to accumulation of insecticide residues as well as emergence of pesticide resistance in the pests  <cit> .
application of chemical pesticides also kills different varieties of pest predators and results in ecological imbalance, thereby causing pest resurgence and a greater outbreak of secondary pests  <cit> .
therefore, there is a need for developing safe and eco-friendly alternatives to chemical insecticides for pest control.
biological control as a part of integrated pest management has gained interest among researchers as it is an environmentally friendly and a safe strategy for pest management  <cit> .
natural products obtained from plants and microorganisms have been used for insect control  <cit> .
azadirachtin , a natural compound isolated from indian neem tree, azadirachta indica a. juss , is known to have lethal effects on more than  <dig> insect species  <cit>  and many workers have used azadirachtin as positive control .
recently, microbial insecticides have attracted considerable attention  <cit>  because they are more specific, have low relative cost and are more eco-friendly .
among the biological control agents derived from different microbes, actinobacteria especially streptomyces spp.
are one of the most important microbial resources which can provide potential new bioactive compounds for use as insect-control agents  <cit> .
many reports indicated the important role played by actinobacteria in the management of spodopetra littoralis   <cit> , s. litura  <cit> , musca domestica   <cit> , culex quinquefasciatus   <cit> , drosophila melanogaster   <cit> , helicoverpa armigera   <cit> , anopheles mosquito larvae  <cit> .
bream et al.
<cit>  showed potent biological activity of secondary metabolites of actinobacteria such as streptomyces and streptoverticillum against s. littoralis which caused larval and pupal mortality.
several metabolites from genus streptomyces, such as avermectin, prasinons, doramectin, milbemycin, nanchangmycin, dianemycin and spinosad have been established as potential protective agents against a variety of pest insects and are friendly to environment  <cit> .
in light of this and inspired by the remarkable pharmaceutical and agricultural potential of bioactive metabolites of actinobacteria, kaur et al.
<cit>  screened actinobacterial isolates, recovered from different rhizospheric and non-rhizospheric soils, for antifungal activity against fungal phytopathogens and reported strong insecticidal activity against s. litura in one of the isolates, streptomyces hydrogenans dh <dig> which also exhibited potent antifungal activity  <cit> .
present study was aimed at further systematic evaluation of antifeedant, larvicidal, pupicidal and growth inhibitory effect of solvent extract from s. hydrogenans dh <dig> against s. litura.
RESULTS
there is a long history of utilizing natural products produced by microbes for pharmaceutical and agricultural purposes.
actinobacteria especially, streptomyces spp.
have provided wide variety of secondary metabolites of high commercial importance and continue to be routinely screened for new bioactive compounds.
present work further corroborates the earlier findings and reports that secondary metabolites from s. hydrogenans exhibit the potential to be used as insecticidal agents.
in this study, s. hydrogenans extract showed deleterious effects on growth and development of s. litura larvae that survived the toxic effects of highest concentration.
significant increase in larval development period was observed at all concentrations over the control .
at highest concentration , larval period prolonged by  <dig>  days in comparison to control group .
our result coincided with the findings of arasu et al.
<cit>  who reported larvicidal and growth inhibitory activities of a novel polyketide metabolite isolated from streptomyces sp.
ap- <dig> against h. armigera and s. litura.
the metabolite also prolonged the larval–pupal duration of the insects at all the tested concentrations as compared to control.
the delayed larval period observed in the present study could be due to low consumption of diet by the larvae of s. litura indicating the antifeedant effect of the extract.
pupal period decreased significantly with treatment  however, at highest concentration pupae formed from treated larvae remained in pupal stage till the termination of experiment.
the total development period from larva to adult of s. litura differed but remained non significant .
the lc <dig> and lc <dig> values were  <dig>  and  <dig>  μg/ml, respectively for s. litura .
no larval mortality was observed in lowest concentration as well as in control but when larvae were fed on highest concentrations of  <dig> and 1600 μg/ml, larval mortality of  <dig> and 70%, respectively was recorded and was statistically significant compared to control .
similar study on soil bacterium metabolite 12-epi-hapalindole j isonitrile isolated from cyanobacterium terium showed 100% larval mortality against dipteran chironomus riparius  at 26 μm concentration within 48 h of exposure  <cit> .
similarly, anti-insect activity of crude ethanolic extracts from streptomyces sp.
in terms of larval mortality had been reported by rishikesh et al.
<cit> .
the isolate showed a marked insecticidal activity against sitophilus oryzae in a dose dependent manner with 100% mortality at concentration of 24 mg/ml.
later, arasu et al.
<cit>  documented  <dig> % and  <dig> % larvicidal activities by polyketide metabolite from streptomyces sp.
ap- <dig> against h. armigera and s. litura, respectively at 1000 ppm.
azadirachtin showed a more toxic effect towards s. litura as compared to the crude extract of s. hydrogenans as 100% mortality was noticed at higher concentrations.table  <dig>
influence of ethyl acetate extract of
s. hydrogenans
on and azadirachtin on various developmental parameters of
s.litura
treatments
concentrations
larval period
pupal period
total developmental period
r2
r2
mean ± se followed by different letters  with in a column are significantly different.
tukey’s test p ≤  <dig> , n.s = non significant, r2 = coefficient of determination, *significant at 5% level, **significant at 1% level.
regression equation, lower as well as upper 95% confidence limits for lc
50
and lc
90
regression equation
95% confidence limit
lc
50
lc
90
lower
upper
<dig> c
alower and upper 95% confidence limits for lc <dig> for streptomyces ethyl acetate extract, blower and upper 95% confidence limits for lc90
streptomyces ethyl acetate extract, clower and upper 95% confidence limits for lc <dig> for azadirachtin, dlower and upper 95% confidence limits for lc <dig> for azadirachtin.
prepupal mortality  was also higher at the highest concentration  .
diet supplemented with extract of s. hydrogenans induced 48–100% pupal mortality.
as compared to control, significantly higher mortality of more than 50% was recorded at highest concentrations  .
similarly, dose dependent  pupal mortality  was reported by arasu et al.
<cit>  and documented that prolonged larval–pupal durations were directly proportional to the increase in pupicidal activities.
the adverse effect of solvent extract was also observed on emergence and performance of adults emerged from treated larvae.
adult emergence was significantly lower when larvae were reared on diet amended with extract  and the decrease was found to increase with increase in concentration .
maximum adverse effect was observed at highest concentration where no adult emergence occurred.
also, adults emerged at lower concentrations were small in size with varied abnormalities.
xiong et al.
<cit>  found that out of  <dig> isolates from marine micro-organisms, streptomyces sp.
<dig>  similar to avermectin b <dig> possessed strong insecticidal potential against h. armigera.
in another study, xiong et al.
<cit>  reported strong inhibitory activity of streptomyces avermitilis strain  <dig> isolated from marine source against heliothis zea , plutella xylostella , spodoptera exigua  and aphids.table  <dig>
effect of ethyl acetate extract of
s. hydrogenans
and azadirachtin on mortality rate of different developmental stages of
s.litura
treatments
concentrations
larval mortality
prepupal mortality
pupal mortality
corrected pupal mortality
r2
r2
mean ± se followed by different letters with in a column are significantly different.
tukey’s test p ≤  <dig> , r2 = coefficient of determination, **significant at 1% level.
effect of ethyl acetate extract of
s. hydrogenans
on % age emergence of
s.litura.
columns and bars represent the mean ± se.
different letters above the columns representing each concentration indicate significant differences at tukey’s test p ≤  <dig> .
adult survival time was also influenced by the s. hydrogenans as longevity of emerged adults declined significantly from  <dig>  days in control to  <dig>  days at 800 μg/ml  .
fecundity in emerged adults from treated larvae was also significantly inhibited.
it declined from  <dig> eggs/female  to  <dig>  eggs/female at 400 μg/ml concentration .
the viability of these eggs was also negatively affected as the eggs failed to hatch whereas in control  <dig> % hatching of eggs was observed .
no egg laying was recorded at 800 μg/ml concentration.
abouelghar et al.
<cit>  also demonstrated the negative effects of sublethal concentrations of spinosad on development, fecundity and food utilization in the cotton leafworm, s. littoralis .table  <dig>
effect of ethyl acetate extract
s. hydrogenans
on longevity, fecundity and percent hatching of
s.litura
adults
concentrations
longevity
fecundity
percent hatching
r2
mean ± se followed by different letters with in a column are significantly different.
tukey’s test p ≤  <dig> , r2 = coefficient of determination, **significant at 1% level.
morphological abnormalities
the inhibitory effect of extract was further manifested in the form of deformed adults which emerged from the larvae fed on s. hydrogenans extract supplemented diet.
the deformed adults had crumpled and underdeveloped wings as well as were half emerged from pupa.
these deformities in adults were recorded only at  <dig> and 800 μg/ml concentrations .figure  <dig>
developmental stages of
s.litura
reared on control diet  and abnormalities in different stages fed on diet supplemented with different concentrations of ethyl acetate extract of s. hydrogenans .
food utilization assay
the diet utilization experiments indicated significant effect of s. hydrogenans solvent extract on s. litura.
as is apparent from table  <dig>  there was significant decrease in relative growth and consumption rate of s. litura as well as efficiency of conversion of ingested and digested food.
diet supplemented with extract resulted in 13–49% reduction in rgr over the control .
food consumption rate reduced to half of that in control at highest concentration .table  <dig>
effect of ethyl acetate extract of
s. hydrogenans
and azadirachtin on food utilization and feeding of
s.litura
treatments
concentrations
rgr
rcr
ad
r2
r2
mean ± se followed by different letters with in a column are significantly different.
tukey’s test p ≤  <dig> , r2 = coefficient of determination, *significant at 5% level, **significant at 1% level.
a concentration dependent decrease in eci and ecd was observed in the larvae of s. litura .
the diet amended with extract caused 18–67% decline in eci and 17–72% decline in ecd over the control.
approximate digestibility increased by 43% at 1600 μg/ml in comparison to control as shown in table  <dig> .
the reduction in diet utilization suggests that reduced growth and development might have resulted from both behavioral and physiological effects.
it is likely that this decrease in consumption rate  could be due to the antifeedant nature of the extract and accounts for the majority of the decrease in growth rate .
the streptomyces extract also altered food utilization indices in s. litura and revealed less conversion of ingested  and digested  food to body biomass.
the extract also influenced ad of larvae fed on amended diet as it increased with increase in concentration but the increase in ad could not compensate for the decrease in ecd, which consequently led to reduced growth rate.
eci is an overall measure of an insect’s ability to utilize the food that it ingests for growth and development and ecd is a measure of the efficiency of conversion of digested food into growth  <cit> .
a drop in eci indicates more food is being metabolized for energy purpose and less for conversion to body substance.
ecd also decreases as the proportion of digested food metabolized for energy increases.
thus, decreased eci and ecd values in the present studies indicate that ingested crude extract of streptomyces does exhibit some chronic toxicity against s. litura  <cit> .figure  <dig>
effect of  ethyl acetate extract of
s. hydrogenans
and  azadirachtin on eci of
s.litura
.
columns and bars represent the mean ± se.
different letters above the columns representing each concentration indicate significant differences at tukey’s test p ≤  <dig> .
effect of  ethyl acetate extract of
s. hydrogenans
and  azadirachtin on ecd of
s.litura
.
columns and bars represent the mean ± se.
different letters above the columns representing each concentration indicate significant differences at tukey’s test p ≤  <dig> .
CONCLUSIONS
present study reports growth inhibitory activities of metabolites of s. hydrogenans on s. litura.
the metabolites in the extract showed strong antifeedant, larvicidal, pupicidal and toxic activities against major pest s. litura.
diet utilization experiments clearly revealed the growth inhibitory impact of extract.
however, the toxic effect of the extract was less as compared to the positive control, azadirachtin, which could be due to the purified nature of the plant compound.
these findings indicate that the extract has considerable potential to control insect pest populations and can further be used for development of novel insecticidal formulation as an alternative to toxic chemicals for the management of field pests.

 according to the report of fao, due to the attack from pathogenic organisms and insect pests, 20–40% decrease in crop yield occurs which results in loss of billion us $ worldwide. pest insects, being plant disease vectors reduce crop output by 10–30% either by reducing the quality and quantity of the crop production, or by serving as vectors of plant diseases. spodoptera litura, a polyphagous insect of cosmopolitan distribution, has a large host range of more than host species and is considered economically important in many countries including india, japan, china and southeast asia. this defoliating insect pest affects the yield of various cultivated crops, vegetables, weeds and ornamental plants by feeding gregariously on leaves and causes large economic losses of crop plants. it was reported as a major pest in groundnut in andhra pradesh, india and caused 28–100% yield loss depending upon crop stage and its level of infestation. the management of s. litura to ensure the stable and high output of crops is a great challenge in agricultural field and therefore, insecticide use is most widely practiced for its control. however, there is widespread concern over negative impact of insecticides on environmental and human health due to accumulation of insecticide residues as well as emergence of pesticide resistance in the pests. application of chemical pesticides also kills different varieties of pest predators and results in ecological imbalance, thereby causing pest resurgence and a greater outbreak of secondary pests. therefore, there is a need for developing safe and eco-friendly alternatives to chemical insecticides for pest control. biological control as a part of integrated pest management has gained interest among researchers as it is an environmentally friendly and a safe strategy for pest management. natural products obtained from plants and microorganisms have been used for insect control. azadirachtin, a natural compound isolated from indian neem tree, azadirachta indica a. juss, is known to have lethal effects on more than insect species and many workers have used azadirachtin as positive control. recently, microbial insecticides have attracted considerable attention because they are more specific, have low relative cost and are more eco-friendly. among the biological control agents derived from different microbes, actinobacteria especially streptomyces spp. are one of the most important microbial resources which can provide potential new bioactive compounds for use as insect-control agents. many reports indicated the important role played by actinobacteria in the management of spodopetra littoralis, s. litura, musca domestica, culex quinquefasciatus, drosophila melanogaster, helicoverpa armigera, anopheles mosquito larvae. bream et al. showed potent biological activity of secondary metabolites of actinobacteria such as streptomyces and streptoverticillum against s. littoralis which caused larval and pupal mortality. several metabolites from genus streptomyces, such as avermectin, prasinons, doramectin, milbemycin, nanchangmycin, dianemycin and spinosad have been established as potential protective agents against a variety of pest insects and are friendly to environment. in light of this and inspired by the remarkable pharmaceutical and agricultural potential of bioactive metabolites of actinobacteria, kaur et al. screened actinobacterial isolates, recovered from different rhizospheric and non-rhizospheric soils, for antifungal activity against fungal phytopathogens and reported strong insecticidal activity against s. litura in one of the isolates, streptomyces hydrogenans dh which also exhibited potent antifungal activity. present study was aimed at further systematic evaluation of antifeedant, larvicidal, pupicidal and growth inhibitory effect of solvent extract from s. hydrogenans dh against s. litura.  there is a long history of utilizing natural products produced by microbes for pharmaceutical and agricultural purposes. actinobacteria especially, streptomyces spp. have provided wide variety of secondary metabolites of high commercial importance and continue to be routinely screened for new bioactive compounds. present work further corroborates the earlier findings and reports that secondary metabolites from s. hydrogenans exhibit the potential to be used as insecticidal agents. in this study, s. hydrogenans extract showed deleterious effects on growth and development of s. litura larvae that survived the toxic effects of highest concentration. significant increase in larval development period was observed at all concentrations over the control. at highest concentration, larval period prolonged by  days in comparison to control group. our result coincided with the findings of arasu et al. who reported larvicidal and growth inhibitory activities of a novel polyketide metabolite isolated from streptomyces sp. ap- against h. armigera and s. litura. the metabolite also prolonged the larval–pupal duration of the insects at all the tested concentrations as compared to control. the delayed larval period observed in the present study could be due to low consumption of diet by the larvae of s. litura indicating the antifeedant effect of the extract. pupal period decreased significantly with treatment however, at highest concentration pupae formed from treated larvae remained in pupal stage till the termination of experiment. the total development period from larva to adult of s. litura differed but remained non significant. the lc and lc values were and  μg/ml, respectively for s. litura. no larval mortality was observed in lowest concentration as well as in control but when larvae were fed on highest concentrations of and 1600 μg/ml, larval mortality of and 70%, respectively was recorded and was statistically significant compared to control. similar study on soil bacterium metabolite 12-epi-hapalindole j isonitrile isolated from cyanobacterium terium showed 100% larval mortality against dipteran chironomus riparius at 26 μm concentration within 48 h of exposure. similarly, anti-insect activity of crude ethanolic extracts from streptomyces sp. in terms of larval mortality had been reported by rishikesh et al.. the isolate showed a marked insecticidal activity against sitophilus oryzae in a dose dependent manner with 100% mortality at concentration of 24 mg/ml. later, arasu et al. documented % and % larvicidal activities by polyketide metabolite from streptomyces sp. ap- against h. armigera and s. litura, respectively at 1000 ppm. azadirachtin showed a more toxic effect towards s. litura as compared to the crude extract of s. hydrogenans as 100% mortality was noticed at higher concentrations.table influence of ethyl acetate extract of s. hydrogenans on and azadirachtin on various developmental parameters of s.litura treatments concentrations larval period pupal period total developmental period r2 r2 mean ± se followed by different letters with in a column are significantly different. tukey’s test p ≤ , n.s = non significant, r2 = coefficient of determination, *significant at 5% level, **significant at 1% level. regression equation, lower as well as upper 95% confidence limits for lc 50 and lc 90 regression equation 95% confidence limit lc 50 lc 90 lower upper c alower and upper 95% confidence limits for lc for streptomyces ethyl acetate extract, blower and upper 95% confidence limits for lc90 streptomyces ethyl acetate extract, clower and upper 95% confidence limits for lc for azadirachtin, dlower and upper 95% confidence limits for lc for azadirachtin. prepupal mortality was also higher at the highest concentration. diet supplemented with extract of s. hydrogenans induced 48–100% pupal mortality. as compared to control, significantly higher mortality of more than 50% was recorded at highest concentrations. similarly, dose dependent pupal mortality was reported by arasu et al. and documented that prolonged larval–pupal durations were directly proportional to the increase in pupicidal activities. the adverse effect of solvent extract was also observed on emergence and performance of adults emerged from treated larvae. adult emergence was significantly lower when larvae were reared on diet amended with extract and the decrease was found to increase with increase in concentration. maximum adverse effect was observed at highest concentration where no adult emergence occurred. also, adults emerged at lower concentrations were small in size with varied abnormalities. xiong et al. found that out of isolates from marine micro-organisms, streptomyces sp. similar to avermectin b possessed strong insecticidal potential against h. armigera. in another study, xiong et al. reported strong inhibitory activity of streptomyces avermitilis strain isolated from marine source against heliothis zea, plutella xylostella, spodoptera exigua and aphids.table effect of ethyl acetate extract of s. hydrogenans and azadirachtin on mortality rate of different developmental stages of s.litura treatments concentrations larval mortality prepupal mortality pupal mortality corrected pupal mortality r2 r2 mean ± se followed by different letters with in a column are significantly different. tukey’s test p ≤ , r2 = coefficient of determination, **significant at 1% level. effect of ethyl acetate extract of s. hydrogenans on % age emergence of s.litura. columns and bars represent the mean ± se. different letters above the columns representing each concentration indicate significant differences at tukey’s test p ≤ . adult survival time was also influenced by the s. hydrogenans as longevity of emerged adults declined significantly from  days in control to  days at 800 μg/ml. fecundity in emerged adults from treated larvae was also significantly inhibited. it declined from eggs/female to eggs/female at 400 μg/ml concentration. the viability of these eggs was also negatively affected as the eggs failed to hatch whereas in control % hatching of eggs was observed. no egg laying was recorded at 800 μg/ml concentration. abouelghar et al. also demonstrated the negative effects of sublethal concentrations of spinosad on development, fecundity and food utilization in the cotton leafworm, s. littoralis.table effect of ethyl acetate extract s. hydrogenans on longevity, fecundity and percent hatching of s.litura adults concentrations longevity fecundity percent hatching r2 mean ± se followed by different letters with in a column are significantly different. tukey’s test p ≤ , r2 = coefficient of determination, **significant at 1% level. morphological abnormalities the inhibitory effect of extract was further manifested in the form of deformed adults which emerged from the larvae fed on s. hydrogenans extract supplemented diet. the deformed adults had crumpled and underdeveloped wings as well as were half emerged from pupa. these deformities in adults were recorded only at and 800 μg/ml concentrations.figure developmental stages of s.litura reared on control diet and abnormalities in different stages fed on diet supplemented with different concentrations of ethyl acetate extract of s. hydrogenans. food utilization assay the diet utilization experiments indicated significant effect of s. hydrogenans solvent extract on s. litura. as is apparent from table  there was significant decrease in relative growth and consumption rate of s. litura as well as efficiency of conversion of ingested and digested food. diet supplemented with extract resulted in 13–49% reduction in rgr over the control. food consumption rate reduced to half of that in control at highest concentration.table effect of ethyl acetate extract of s. hydrogenans and azadirachtin on food utilization and feeding of s.litura treatments concentrations rgr rcr ad r2 r2 mean ± se followed by different letters with in a column are significantly different. tukey’s test p ≤ , r2 = coefficient of determination, *significant at 5% level, **significant at 1% level. a concentration dependent decrease in eci and ecd was observed in the larvae of s. litura. the diet amended with extract caused 18–67% decline in eci and 17–72% decline in ecd over the control. approximate digestibility increased by 43% at 1600 μg/ml in comparison to control as shown in table . the reduction in diet utilization suggests that reduced growth and development might have resulted from both behavioral and physiological effects. it is likely that this decrease in consumption rate could be due to the antifeedant nature of the extract and accounts for the majority of the decrease in growth rate. the streptomyces extract also altered food utilization indices in s. litura and revealed less conversion of ingested and digested food to body biomass. the extract also influenced ad of larvae fed on amended diet as it increased with increase in concentration but the increase in ad could not compensate for the decrease in ecd, which consequently led to reduced growth rate. eci is an overall measure of an insect’s ability to utilize the food that it ingests for growth and development and ecd is a measure of the efficiency of conversion of digested food into growth. a drop in eci indicates more food is being metabolized for energy purpose and less for conversion to body substance. ecd also decreases as the proportion of digested food metabolized for energy increases. thus, decreased eci and ecd values in the present studies indicate that ingested crude extract of streptomyces does exhibit some chronic toxicity against s. litura.figure effect of ethyl acetate extract of s. hydrogenans and azadirachtin on eci of s.litura. columns and bars represent the mean ± se. different letters above the columns representing each concentration indicate significant differences at tukey’s test p ≤ . effect of ethyl acetate extract of s. hydrogenans and azadirachtin on ecd of s.litura. columns and bars represent the mean ± se. different letters above the columns representing each concentration indicate significant differences at tukey’s test p ≤ .  present study reports growth inhibitory activities of metabolites of s. hydrogenans on s. litura. the metabolites in the extract showed strong antifeedant, larvicidal, pupicidal and toxic activities against major pest s. litura. diet utilization experiments clearly revealed the growth inhibitory impact of extract. however, the toxic effect of the extract was less as compared to the positive control, azadirachtin, which could be due to the purified nature of the plant compound. these findings indicate that the extract has considerable potential to control insect pest populations and can further be used for development of novel insecticidal formulation as an alternative to toxic chemicals for the management of field pests. 
the results indicated that highest concentration of 1600 μg/ml was significantly effective as 70% larval, % prepupal and 100% pupal mortality was noticed. because of its potent biocontrol attributes, ethyl acetate extract of streptomyces hydrogenans dh a soil isolate, was tested to assess its anti-insect potential against polyphagous noctuid, spodoptera litura. the secondary metabolites in the ethyl acetate extract of s. hydrogenans dh exhibited larvicidal and growth inhibitory activities. significant decrease in relative growth and consumption rate, efficiency of ingested and digested food and increase in approximate digestibility in larvae reared on diet supplemented with ethyl acetate extract accounts for the toxic as well as anti-nutritive nature of extract. significant decline in adult emergence, adult longevity, fecundity and % hatching was recorded at higher concentrations along with morphological abnormalities as compared to control. negative effects of s. hydrogenans were also observed on development of the insect. secondary metabolites in the fermentation broth from s. hydrogenans were toxic to the larvae at higher concentrations whereas lower concentrations significantly reduced the reproductive potential of s. litura. therefore, these metabolites show considerable potential for incorporation in pest management programmes as new biopesticidal formulation. are rich source of bioactive secondary metabolites which may provide valuable alternatives to chemical insect-control agents as they can be less toxic and readily biodegradable. streptomyces hydrogenansspodoptera lituralarvicidalnutritional assaygrowth inhibitoryissue-copyright-statement© the author 2014
 destructive impacts of insecticides on non targeted populations necessitate the development of an eco friendly pest control method. streptomyces spp. are rich source of bioactive secondary metabolites which may provide valuable alternatives to chemical insect-control agents as they can be less toxic and readily biodegradable. because of its potent biocontrol attributes, ethyl acetate extract of streptomyces hydrogenans dh a soil isolate, was tested to assess its anti-insect potential against polyphagous noctuid, spodoptera litura.  the secondary metabolites in the ethyl acetate extract of s. hydrogenans dh exhibited larvicidal and growth inhibitory activities. the results indicated that highest concentration of 1600 μg/ml was significantly effective as 70% larval, % prepupal and 100% pupal mortality was noticed. the metabolites also prolonged the larval developmental period. the lc and lc values were and  μg/ml, respectively for the insect. negative effects of s. hydrogenans were also observed on development of the insect. significant decline in adult emergence, adult longevity, fecundity and % hatching was recorded at higher concentrations along with morphological abnormalities as compared to control. significant decrease in relative growth and consumption rate, efficiency of ingested and digested food and increase in approximate digestibility in larvae reared on diet supplemented with ethyl acetate extract accounts for the toxic as well as anti-nutritive nature of extract.  secondary metabolites in the fermentation broth from s. hydrogenans were toxic to the larvae at higher concentrations whereas lower concentrations significantly reduced the reproductive potential of s. litura. therefore, these metabolites show considerable potential for incorporation in pest management programmes as new biopesticidal formulation. keywords streptomyces hydrogenansspodoptera lituralarvicidalnutritional assaygrowth inhibitoryissue-copyright-statement© the author 2014 