Habrobracon Hebetor Say Research Articles

Economic feasibility of an augmentative biological control industry in Niger

Farmers in Niger are vulnerable to high millet yield losses due to the millet head miner, Heliocheilus albipunctella De Joannis (Lepidoptera: Noctuidae), for which pest control options are limited. Researchers have developed a procedure to multiply and spread an augmentative biological control agent Habrobracon hebetor Say (Hymenoptera: Braconidae) which is effective in limiting millet yield losses due to the pest. This study assesses the economic viability of small businesses to produce and sell biological control agents. It analyzes the profitability of the businesses under alternative pricing regimes given estimated costs to produce and distribute biological control agents. The economic assessment provides budget analysis for potential businesses and discusses options for scaling, price setting, and organizing. Our study suggests that the small H. hebetor industry should turn a profit in Niger at relatively low prices for the biological control agents of $3.00-$4.00 per bag with 15 bags needed per village. Competitive wages are achievable for the businesses that sell to at least 13 villages. Each business would hire three workers from late May to late August. Commercialization of H. hebetor would generate opportunities for wide geographic distribution of the technology on a sustainable basis in Niger.

ИЗУЧЕНИЕ ТРОФИЧЕСКИХ СВЯЗЕЙ РАЗЛИЧНЫХ ГЕОГРАФИЧЕСКИХ ПОПУЛЯЦИЙ ЭКТОПАРАЗИТОИДА ГУСЕНИЦ HABROBRACON HEBETOR SAY

ИЗУЧЕНИЕ ТРОФИЧЕСКИХ СВЯЗЕЙ РАЗЛИЧНЫХ ГЕОГРАФИЧЕСКИХ ПОПУЛЯЦИЙ ЭКТОПАРАЗИТОИДА ГУСЕНИЦ HABROBRACON HEBETOR SAY

Effects of Palpita unionalis and Galleria mellonella larval densities on functional response, egg dispersion and progeny sex ratio of Habrobracon hebetor

ABSTRACTTo assess the potential of the hymenopteran ectoparasitoid, Habrobracon hebetor Say as a biological control agent, we evaluated its response to different larval densities of two pyralid hosts, Palpita unionalis Hbn. and Galleria mellonella L. The former host is a serious pest of olive trees, whereas the latter is used as a factitious host in parasitoid mass rearing. In order to study the functional response of the parasitoid, five host densities (1, 2, 3, 5, 7) of either late instar larva per Petri dish were used. The shape of the functional response curve was determined using logistic regression and could be described as a type II response for both hosts, characterised by a monotonic decelerating increase in the number of hosts attacked with increasing host density. Female parasitoids allocated more eggs to the first larva attacked than all the remaining larvae. Aggregated dispersion patterns for parasitoid egg distribution at different host densities were estimated using the Green index. Multiple visits and ovipositions by females did not significantly affect the total number of progeny produced or their sex ratio. This study has generated novel information on egg laying, egg distribution and sex ratio of H. hebetor when reared on G. mellonella and has the potential to be used in the development of sustainable biological control programmes aimed at P. unionalis in olive orchards.

Putative Host Volatiles Used by Habrobracon hebetor (Hymenoptera: Braconidae) to Locate Larvae of Plodia interpunctella (Lepidoptera: Pyralidae)

Indianmeal moth, Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae), is a post-harvest pest of grains, milled and processed food, processing plants, warehouses and bakeries. The parasitoid, Habrobracon hebetor (Say) is among the most important natural enemies of Pyralidae infesting stored grains and grain products. Many parasitoids use semiochemicals originating from their hosts, or host’s habitat as cues to locate hosts, hosts’ food or habitat. The authors used Y-tube and four-way olfactometers to assay responses to stimuli with the moth host and thereby understand the role of host-associated semiochemicals in host location by H. hebetor. Responses of mated parasitoid females were assayed to the following stimuli: P. interpunctella sex pheromone, female adults, larvae, or hexane extracts of residue of the rearing medium. Generally, host-related odor sources generated stimuli that elicited better responses than those to blank controls. Previous exposure to odor sources from the host shortened latency periods and response times compared to naive females. Odors emanating from live moth larvae elicited the strongest responses. When responses from the four odor sources were compared in a four-way olfactometer, it was confirmed that volatiles from larval moths elicited the strongest attraction to the parasitoid. The involvement of host-specific chemical cues in both long and short range host location by female parasitoid is discussed.

Field persistence of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) following augmentative releases against the millet head miner, Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae), in the Sahel

Biological control by augmentative releases of the parasitoid wasp Habrobracon hebetor Say (Hymenoptera: Braconidae) is a promising strategy for controlling the millet head miner (MHM), Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae). A current biological control program in the Sahel region involves inoculative releases of the parasitoid each growing season, but this is prohibitively expensive. The present study aimed to quantify residual parasitism of MHM in years after augmentative release. We also investigated the impact of two successive annual releases of H. hebetor on MHM parasitism. Two successive releases did not increase parasitism, but slightly reduced MHM damage in terms of number of mines and their length. Parasitism levels decreased in subsequent years if no additional parasitoids were released. Nevertheless, in the first year after release, parasitism levels in release villages remained significantly higher than in control villages. These findings suggest that augmentative releases could be carried out biennially instead of annually. Possible means of enhancing parasitoid survival between seasons are discussed.

Impact of carbohydrase inhibition on Habrobracon hebetor in a tritrophic diet‐host‐parasitoid system

AbstractHabrobracon hebetor Say (Hymenoptera: Braconidae) is a cosmopolitan idiobiont ectoparasitoid wasp and one of the most important biological control agents of lepidopteran larvae, especially of larvae of the family Pyralidae such as Indian meal moth, Plodia interpunctella (Hübner). Using biological control agents in combination with other pest management approaches may enhance the efficiency of pest management. Acarbose, a non‐proteinaceous inhibitor, is well known for its inhibitory effect on insect digestive carbohydrases, especially α‐amylase. In the present study the effect of the inhibitor on various physiological and biological parameters of the parasitoid H. hebetor was investigated in a diet‐host‐parasitoid tritrophic system. The inhibitor decreased α‐amylase activity in both in vitro and in vivo assays with the parasitoid; however, there was no significant impact on the biological characteristics studied. Quantification of energy reserves in host larvae and adult parasitoids revealed a dose‐dependent effect of the inhibitor on total protein, lipid, carbohydrate, and glycogen contents of the larval host, whereas total protein and carbohydrate of the parasitoid were only reduced at high inhibitor concentrations. In general, the inhibitor acarbose can interfere with some physiological processes in H. hebetor, although the parasitoid's fitness is not negatively affected. Therefore, enzyme inhibitors may be considered an effective tool for pest control in integrated pest management programs.

Parasitism Rate of Habrobracon hebetor to Ephestia kuehniella Larvae: Residual Effect of Deltamethrin, Fenvalerate and Azadirachtin

Sublethal concentrations of chemical insecticides may cause changes in some behavioral characteristics of natural enemies such as functional responses. The residual effect of three synthetic insecticides including deltamethrin, fenvalerate and azadirachtin were studied on functional response of Habrobracon hebetor Say to Ephestia kuehniella Zeller larvae. Seven host densities (2, 4, 8, 16, 32, 64 and 96) were used during a 24 h period. The resulting data were appropriately fit to Type II functional response models in all treatments: (1) control (0.0916 h−1; and T h = 0.2011 h); (2) deltamethrin (a = 0.0839 h−1; and T h = 0.3560 h); (3) fenvalerate (a = 0.0808 h−1 and T h = 0.3623 h); and (4) azadirachtin (a = 0.0900 h−1 and T h = 0.2042 h). Maximum theoretical parasitism rate (T/T h ) was 119.34 estimated for control wasps. There was no significant difference between the values of attack rates (a and a + D a ) in all treatments while the handling time was statistically affected in female wasps treated with fenvalerate. Our findings will be useful in safe application of these insecticides in pest management programmes.

A new suite of twenty-two polymorphic microsatellite loci in the parasitic wasp, Habrobracon hebetor (Hymenoptera: Braconidae): Promising molecular tools for studying the population genetics of several beneficial braconid species

Combining a biotin-enrichment protocol and 454GS-FLX titanium pyrosequencing technology, we characterised 22 polymorphic microsatellite loci from the parasitic wasp, Habrobracon hebetor (Say) (Hymenoptera: Braconidae), a cosmopolitan species commonly used in biological control against a wide range of both major lepidopterous pests of stored products and field crops in different parts of the world. Three multiplex PCR sets were optimised and characterised across 46 H. hebetor specimens from two samples collected from millet fields in Niger. Two to 11 alleles were found per locus and observed heterozygosity ranged from 0.289 to 0.826. Polymorphism was detected in both samples with a similar level of observed heterozygosity (0.482 vs. 0.502) and number of alleles (4.1 vs. 3.6). Deviation from Hardy-Weinberg equilibrium was detected at the same five loci in both samples and five or seven more loci in each sample but was not associated with heterozygote deficiencies. Even though evidence for linkage disequilibrium was found between a few alleles, these new loci segregated independently. The variability of the 22 loci will enable estimates of genetic diversity and structure patterns, as well as gene flow between H. hebetor populations at different spatial scales. Cross-species amplifications were successful among the six Bracon spp. tested and nine loci will be particularly appropriate for population genetic studies in B. brevicornis.

Temperature-dependent functional response and host preference of Habrobracon hebetor between fungus-infected and uninfected Ephestia kuehniella larvae

An ongoing question in biological control consists of whether antagonistic interaction between different agents can be reduced in pest biocontrol. This study investigated the behavioral performance of Habrobracon hebetor Say on Ephestia kuehniella Zeller larvae treated with Metarhizium anisopliae (Metsch.) Sorokin sensu lato (s.l.) (isolate M14) at two different temperatures (25 and 30 °C). A type II functional response was observed in female wasps of all treatments. Estimated handling time and attack rate values were not statistically different at two thermal conditions. Female wasps avoided the odor of fungus-infected host larvae when offered simultaneously with healthy ones at 30 °C revealed by olfactory choice test. The number of untreated larvae parasitized by H. hebetor females was significantly differed between temperatures (25 and 30 °C). Overall, this study suggests that application of M. anisopliae s.l. for biological control of E. kuehniella is compatible with concurrent use of H. hebetor at 30 °C.

Adaptation of Habrobracon hebetor (Hymenoptera: Braconidae) to Rearing on Ephestia kuehniella (Lepidoptera: Pyralidae) and Helicoverpa armigera (Lepidoptera: Noctuidae).

Food characteristics strongly regulate digestive enzymatic activity of insects through direct influences on their midgut mechanisms. Insect performance is better on diets that contain nutrients in proportions that fit its digestive enzymes. Little is known about the influences of rearing history on parasitism success of Habrobracon hebetor Say. This research focused on the effect of nutrient regulation on survival, development, and parasitism of H. hebetor. Life history and digestive enzyme activity of fourth-stage larvae of H. hebetor were studied when reared on Ephestia kuehniella Zeller. This parasitoid was then introduced to Helicoverpa armigera (Hübner), and above-mentioned parameters were also studied in the first and fourth generations after transfer. In term of parasitism success, H. hebetor preferred E. kuehniella over He. armigera. When the first and fourth generations of He. armigera-reared H. hebetor were compared, the rearing history affected the life history and enzymatic activity of the parasitoid. A better performance of H. hebetor was achieved after it was reared on He. armigera for the four generations. Because, digestive α-amylase and general protease of the parasitoid were matched with the new host, it used reserve energy for a better performance. Thus, a better performance of H. hebetor could be obtained when the parasitoid was reared on its original host for at least four generations.

Sublethal effects of Metarhizium anisopliae on life table parameters of Habrobracon hebetor parasitizing Helicoverpa armigera larvae at different time intervals

The ectoparasitoid wasp, Habrobracon hebetor Say and the entomopathogenic fungus, Metarhizium anisopliae (Metsch.) Sorokin are biocontrol agents attacking larval stages of Helicoverpa armigera (Hubner). Life table parameters of H. hebetor were studied on H. armigera third instar larvae previously (0, 24, 48, and 72 h) infected with a sublethal concentration (LC30) of M. anisopliae (isolate M14). Fungal infection adversely affected life table parameters of H. hebetor depending on the host post-inoculation time for parasitoid release. The entropy values showed the age-specific survivorship (l x ) curves of type 1 at ≤24 h treatments. The highest and lowest intrinsic rates of increase (r m ) were 0.223 and 0.109 for control and 72 h treatment, respectively. Statistically different variations were observed for r m values when post-exposure time was longer than 24 h. Our findings highlight appropriate introduction times of H. hebetor in combination with M. anisopliae (isolate M14) for successful integrated management of H. armigera.

Effects of pupal treatment with Proteus® and Metarhizium anisopliae sensu lato on functional response of Habrobracon hebetor parasitising Helicoverpa armigera in an enclosed experiment system

ABSTRACTThe ectoparasitoid wasp, Habrobracon hebetor Say (Hymenoptera: Braconidae) is a valuable biocontrol agent attacking larval stages of many lepidopteran pests including Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). The possibility of combined application of this parasitoid wasp with other biological control agents and chemical insecticides is necessary for the success of an Integrated Pest Management (IPM) programme. One of the most important behaviours of a parasitoid refers to the number of hosts attacked by per parasitoid as a function of host density. In this research, the single and joint effects of the insecticide, Proteus® and the entomopathogenic fungus, Metarhizium anisopliae sensu lato (Metsch.) Sorokin (Hypocreales: Clavicipitaceae) (isolate M14) were studied on the functional response of H. hebetor. Newly mated females (<24 h) from treated pupae of H. hebetor were used to study the functional response of this parasitoid wasp to different densities of H. armigera larvae. A type II functional response was observed in all treatments. The results revealed that control and Proteus® treatments developed the lowest (0.5599 ± 0.0373 h) and the highest (0.5709 ± 0.0443 h) handling time, respectively. The most and the least values of attack rate were observed in control (0.0996 ± 0.0164 h−1) and Proteus® (0.0776 ± 0.0119 h−1) treatments, respectively. The maximum theoretical parasitism rate (T/Th) was estimated to be 42.86 for female control wasps. After conducting field experiments on functional response along with life table parameters, M. anisopliae sensu lato (isolate M14) may be used as a compatible biocontrol agent with H. hebetor in IPM programmes of H. armigera.

Lethal and Demographic Impact of Chlorpyrifos and Spinosad on the Ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae).

The appropriate use of biological agents and chemical compounds is necessary to establish successful integrated pest management (IPM) programs. Thus, the off-target effects of pesticides on biological control agents are essential considerations of IPM. In this study, the effects of lethal and sublethal concentrations of chlorpyrifos and spinosad on the demographic parameters of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) were assessed. Bioassays were carried out on immature and adult stages by using dipping and contact exposure of dry pesticide residue on an inert material, respectively. The lethal concentration (LC)50 values of chlorpyrifos and spinosad were 3.69 and 151.37 ppm, respectively, on the larval stage and 1.75 and 117.37 ppm, respectively, on adults. Hazard quotient (HQ) values for chlorpyrifos and spinosad were 400 and 2.2, respectively, on the larval stage and 857.14 and 2.84, respectively, on adults. A low lethal concentration (LC30) was used to assess the sublethal effects of both pesticides on the surviving females. In each treatment, 25 survivors were randomly selected and transferred into 6-cm Petri dishes. Adults were provided daily with last instars of Anagasta kuehniella (Zeller) as a host until all of the females died. The number of eggs laid, percent of larvae hatched, longevity, and sex ratio were recorded. Stable population growth parameters were estimated by the Jackknife method. In control, chlorpyrifos, and spinosad treatments, the intrinsic rates of increase (r m) values were 0.23, 0.10, and 0.21, respectively. The results of this study suggest a relative compatibility between spinosad use and H. hebetor. Finally, further studies should be conducted under natural conditions to verify the compatibility of spinosad with H. hebetor in IPM programs.

Lethal and sublethal effects of azadirachtin and cypermethrin on Habrobracon hebetor (Hymenoptera: Braconidae).

Habrobracon hebetor Say is an ectoparasitoid of larval stage of various lepidopteran pests. Lethal and sublethal effects of azadirachtin and cypermethrin were evaluated on adult and preimaginal stages of H. hebetor under laboratory conditions. Contact exposure bioassays with adults indicated that the lethal concentration (LC50) of two commercial azadirachtin-containing formulations, NeemGuard and BioNeem, were 43.5 and 10.2 microg a.i./ml, respectively. The LC50 of cypermethrin was 5.4 microg a.i./ml. When larval stage of H. hebetor was exposed to these insecticides with a field recommended concentration of NeemGuard, BioNeem, or cypermethrin by a dip protocol, the emergence rate was reduced by 39.0, 36.6, and 97.6%, respectively. To assay the sublethal effects of these insecticides, adult wasps were exposed to an LC30 concentration of the insecticides, and then demographic parameters of the surviving wasps were determined. Fecundity, fertility, and parameters including the intrinsic rate of increase (r(m)) were affected negatively. The r(m) values following exposure to NeemGuard, BioNeem, cypermethrin, or mock treatment were 0.143, 0.149, 0.160, and 0.179, respectively, female offspring per female per day, respectively. The current study showed that cypermethrin had more acute toxicity on larval and adult stages of H. hebetor compared with azadirachin. The commercial formulations of azadirachtin and cypermethrin negatively affected most of the life table parameters of the parasitoid. Semifield and field studies are needed for obtaining more applicable results on combining H. hebetor and the tested insecticides for an integrated pest management-based strategy for crop protection.

Sublethal effect of chlorpyriphos and fenpropathrin on functional response of Habrobracon hebetor (Hym.: Braconidae)

One of the criteria for selecting a suitable natural enemy is its functional response to different densities of the host. Habrobracon hebetor (Say) is a larval ectoparasitoid of several species of lepidopteran. Functional response of H. hebetor, after treatment with LC25 of chlorpyrifos and fenpropathrin in three stages, was assessed to different densities of fifth instar of Ephestia kuehniella (2, 4, 8, 16, 32 and 64). LC25 values were estimated to be 0.043, 5.36 and 2.00 and 0.38, 13.9 and 4.45 mg a.i. l−1 for the larval, pupal and adult stages for chlorpyrifos and fenpropathrin, respectively. Host densities were offered to treated wasps for 24 h. Experiments were replicated 10 times. The results showed that the functional responses of wasps in control as well as immature stages treatments were Type III, whereas those of adult stage were Type II. a (Type II) or b (Type III) and Th parameters were evaluated with Roger’s equation. b and Th in control were assessed to be 0.0129 and 0.1723 h, respectively. These parameters were estimated in chlorpyrifos and fenpropathrin to be 0.0052, 0.00718 and 0.1945, 0.2492 h in larval stage; 0.00817, 0.00916 and 0.2736, 0.3108 h in pupal stage; and a and Th were 0.0064, 0.0137 h−1 and 0.2492, 0.2242 h in the adult stage, respectively. The insecticide had no significant effect on the searching efficiency of H. hebetor compared with those treated in control; however, they had significant effect on the handling time of the parasitoid and increased it, except in the larval stage treated with chlorpyrifos treatment.

FUNCTIONAL RESPONSE OF HABROBRACON HEBETOR SAY (HYM.: BRACONIDAE) TO MEDITERRANEAN FLOUR MOTH (ANAGASTA KUEHNIELLA ZELLER), IN RESPONSE TO PESTICIDES

Abstract The functional response is a behavioral phenomena defined as the relation between the parasitized host per each parasitoid and host density. This phenomenon can be useful in assessing parasitoid efficiency for the biological control of the host. Parasitoid wasps are most important insects and they play a significant role in the natural control of pests via their parasitism activities. In this study, the effects of diazinon and malathion were evaluated on the functional response of Habrobracon hebetor Say to different densities of last instar larvae of Anagasta kuehniella Zeller. Young adult females (&lt; 24 h old) of the parasitoid were exposed to LC30 values of pesticides. Host densities of 2, 4, 8, 16, 32, and 64 were offered, to treated young females for 24 h in 10 cm Petri dishes. At this point, the parasitism data were recorded. The experiments were conducted in eight replications. The functional response was type Ш in the control and insecticide treatments. Searching efficiency in the control, diazinon and malathion-treated wasps were 0.008±0.002, 0.003±0.002, and 0.004±0.002 h-1, handling times were 1.38±0.1, 7.95±0.91, and 6.4±0.81 h, respectively. Diazinon and malathion had the highest and the lowest effect on searching efficiency of H. hebetor, respectively. After conducting advanced field studies, it was found that malathion may be used as a compatible chemical material with biological control agent in IPM programs.

Effects of methoxyfenozide and pyridalyl on the larval ectoparasitoid Habrobracon hebetor

Habrobracon hebetor Say (Hymenoptera: Braconidae) is an ectoparasitoid that is used for inundative biological control of various lepidopteran insect pests. Lethal and sublethal effects of two biorational insecticides, methoxyfenozide and pyridalyl, were evaluated on H. hebetor under laboratory conditions. The adults were exposed to dry insecticide residues that were applied on glass plates. Bioassays showed that the LC50 values of methoxyfenozide and pyridalyl were 155 and 1,226 μg a.i./ml, respectively. The LT50 values of methoxyfenozide and pyridalyl were 2.1 and 3.3 days, respectively. The effects of methoxyfenozide and pyridalyl on larvae were tested using a dip method with field-recommended concentrations of either insecticide. The emergence rates were reduced by 24.4 and 29.3 % for methoxyfenozide and pyridalyl treatments, respectively. In order to assess the sublethal effects of low-lethal concentrations of methoxyfenozide and pyridalyl, adult wasps were exposed to the LC30 concentration of each insecticide, and demographic parameters of live wasps were recorded. Exposure of adults to low-lethal concentrations (LC30) negatively affected the fecundity, fertility, and sex ratio, and also the intrinsic rate of increase (rm), finite rate of increase (λ), generation time (T), and doubling time (DT). The longevity and net reproductive rate (R0) of H. hebetor were not affected by sublethal exposure to these insecticides. The results showed that despite low acute toxicities of both insecticides on larval and adult stages of H. hebetor, they may negatively affect the population of the parasitoid and interfere in IPM programs.

Effect of cold storage of pupae parasitoid wasp, Habrobracon hebetor (Say) (Hymenoptera: Braconidae), on its efficiency

Cold storage is an appropriate way to extend the life of natural enemies such as insect parasitoids. Identification of risk factors for use in biological control and replacing it instead of chemical control is important, and therefore wasp species of genus Bracon have been used for controlling various pests in the past and present. The aim of this study was to determine the optimum temperature and time of storage of parasitoids pupae, Habrobracon hebetor (Say) in cold conditions. After in vitro rearing of the insect, the pupae of H. hebetor at the temperatures of 12, 9 and 4 °C for a period of six weeks in five replicates were stored. After these times, the effect of storage on the percentage of emerged adults and the longevity of male and female adults was evaluated on a weekly basis. The results of the survey conducted at 12 °C showed that the percentage of adults emerged from the first week has dropped by almost half. H. hebetor pupae could be stored for a week at 9 °C. At 4 °C, a significant reduction was caused in the efficacy of the stored pupae and is not recommended.

Investigation of sex ratio and adult longevity of Habrobracon hebetor Say in relation to some conventional and biorational insecticides

Habrobracon hebetor Say (Hymenoptera: Braconidae) is one of the most important natural enemies that has been used for biological control of lepidopteran pests, so the sub-lethal effects of imidacloprid, abamactin and Bacillus thuringiensis Berliner (Bt) on progeny sex ratio (male/total) and adult longevity of H. hebetor were examined under laboratory conditions. It was found that the progeny sex ratio changed to male bias significantly by Bt treatment. Also, the adult longevity of the wasp was affected adversely by insecticides treatment and it was longest in Bt treatment. In conclusion, the current results indicated that the sub-lethal concentration of these insecticides affected the progeny sex ratio and adult longevity and the best strategies for reduction of hazard to the H. hebetor in combination with Bt is to avoid their application before Bt spraying.

Deleterious effects of Bacillus thuringiensis on biological parameters of Habrobracon hebetor parasitizing Helicoverpa armigera

The bacterium Bacillus thuringiensis (Bt) Berliner and the braconid wasp Habrobracon hebetor Say are valuable biocontrol agents attacking larval stages of Helicoverpa armigera (Hubner). Little information is available regarding combination of these biocontrol agents during integrated management of H. armigera. To address this knowledge gap, we document sublethal effects of Bacillus thuringiensis var. kurstaki (Btk) on the H. hebetor attacking H. armigera larvae infected with Btk. The results revealed that the duration of different life stages and fecundity of H. hebetor was significantly affected by sublethal treatments with Btk. We also present data supporting that sublethal concentrations of Btk could adversely affect life table parameters of H. hebetor. Sublethal treatments reduced the net reproductive rate (R0) and there were also significant differences among the values of this parameter at all treatments tested. The intrinsic (rm) and finite (λ) rates of increase were also significantly lower in parasitoid wasps reared on the treated larvae of H. armigera compared to control. These findings will be useful to develop appropriate strategies for assessing the risks of Btk to the parasitoids and safe deployment of both organisms in integrated pest management programs for sustainable crop production.