Synergistic interaction between sublethal doses of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> and <Emphasis Type="Italic">Campoletis chlorideae</Emphasis> in managing <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) is an important solitary larval endoparasitoid of the tomato fruit borer Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in India. The interaction between Bacillus thuringiensis subspecies kurstaki (Btk) HD-1 and C. chlorideae was studied under laboratory condition to explore their compatibility in managing H. armigera. The results had indicated that the growth and development of H. armigera was affected in a dose-dependent manner upon feeding on sublethal doses of Btk HD-1-treated diets. There were no larval survivors in lethal doses of Btk HD-1 (LC₇₀ and LC₉₀). The growth and survival of the parasitoid were normal when the host larvae were fed with sublethal doses or subjected to short time exposure to lethal doses of Btk HD-1. However, the parasitoid offsprings developed slowly and pupal as well as adult period, adult weight and adult emergence rate were reduced significantly if the parasitoid was developing inside a severely Bt intoxicated host larvae. There were no evident differences in longevity of parasitoid adults that were fed on honey solution containing different concentrations of Btk HD-1 as compared to adults fed only on honey solution. This indicates no direct adverse effect of Btk HD-1 on C. chlorideae. Further, the gravid female parasitoid did not discriminate Btk HD-1 intoxicated and normal H. armigera larvae for oviposition. The result implies that spore crystal formulation of Btk HD-1 can be effectively used in a synergistic manner along with existing natural or prereleased population of C. chlorideae in organic farming or as components in biointensive IPM module for managing H. armigera.     

Morphology and development of <Emphasis Type="Italic">Pteromalus cerealellae</Emphasis> (Ashmead) (Hymenoptera: Pteromalidae) on <Emphasis Type="Italic">Callosobruchus maculatus</Emphasis> (F.) (Coleoptera: Chrysomelidae)

Pteromalus cerealellae (Ashmead) (Hymenoptera: Pteromalidae) is an ectoparasitoid of several stored-product insect pests. Very little information has been published on its biology and development in host larvae, which typically are concealed within seeds. We documented the development of P. cerealellae within fourth instar larvae of its concealed host, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) infesting cowpea seeds. The preimaginal life stages of the parasitoid were characterized for the first time using morphological structures revealed by microscopic techniques including scanning electron microscopy. Pteromalus cerealellae produces hymenopteriform eggs and larvae. Eggs hatch into 13-segmented first instar larvae with peripneustic condition of spiracles. The larvae have simple, tusk-like mandibles, whereas the mandibles of the pupae and the adults are of the conventional toothed types. Using statistical analyses of the sizes of the larval mandibles and head capsules in conjunction with reliable characters such as the number of exuviae on the body of parasitoid larvae, cuticular folding, and excretion of the meconium, we recorded four larval instars for P. cerealellae. The data showed significant positive correlations between larval mandible lengths and widths of larval head capsules, as well as between mandible lengths and larval instars, suggesting that mandible length is a good predictor of the number of instars in P. cerealellae. Developmental time from egg to adult emergence was ∼12 d for females and ∼11 days for males at 30 ± 1°C, 70 ± 5% r.h. and 12L:12D photoperiod.     

Close-Range Host Searching Behavior of the Stemborer Parasitoids <Emphasis Type="Italic">Cotesia sesamiae</Emphasis> and <Emphasis Type="Italic">Dentichasmias busseolae</Emphasis>: Influence of a Non-Host Plant <Emphasis Type="Italic">Melinis minutiflora</Emphasis>

Studies were conducted on the host searching behavior of the larval parasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and the pupal parasitoid Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae), both of which attack lepidopteran (Crambidae, Noctuidae) cereal stemborers. The behavior of D. busseolae was observed in a diversified habitat that consisted of stemborer host plants (maize, Zea mays L. and sorghum, Sorghum bicolor (L). Moench (Poaceae)) and a non-host plant (molasses grass, Melinis minutiflora Beauv. (Poaceae)), while C. sesamiae was observed separately on host plants and molasses grass. In previous olfactometer studies, C. sesamiae was attracted to molasses grass volatiles while hboxD. busseolae was repelled. The aim of the present study was to investigate the influence of molasses grass on close-range foraging behavior of the parasitoids in an arena that included infested and uninfested host plants. Dentichasmias busseolae strongly discriminated between host and non-host plants, with female wasps spending most of the time on infested host plants and least time on molasses grass. Likewise, C. sesamiae spent more time on uninfested and infested host plants than it did on molasses grass in single choice bioassays. While on infested plants, the wasps spent more time foraging on the stem, the site of damage, than on other areas of the plant. Overall, the results indicate that presence of the non-host plant does not hinder close range foraging activities of either parasitoid.     

Toxicity and kinetics of spinosad in different developmental stages of the endoparasitoid <Emphasis Type="Italic">Hyposoter didymator</Emphasis> (Hymenoptera: Ichneumonidae) and its host <Emphasis Type="Italic">Spodoptera littoralis</Emphasis> larvae (Lepidoptera: Noctuidae)

The toxicity of spinosad was evaluated using the RaPID Assay^® Spinosad immunosorbent assay in different developmental stages of the parasitoid, Hyposoter didymator, and in its host, fourth-instar larvae of the cotton leafworm Spodoptera littoralis. Spinosad was applied directly to pupae and adults of H. didymator (ingestion or topical application) or to the immature stages of the parasitoid via the host larvae. Low amounts of spinosad were recovered from S. littoralis host larvae after topical treatment, and the compound was mainly retained in the hemolymph. Amounts of spinosad detected in third-instar larvae of H. didymator, pulled out from the hemolymph of parasitized S. littoralis larvae, were 85 pg (3.57 ng a.i./g body weight) in dead larvae, and 82 pg (3.42 ng a.i./g body weight) in alive individuals. After topical treatment of H. didymator cocoons, most of the compound was retained in the silken cocoon, preventing contamination of the pupa. Also in the parasitoid adults, relatively low amounts of spinosad were accumulated in the body overall, but half of all the insecticide recovered was found in the ovaries. The kinetic results obtained help to better understand the toxicity of spinosad in the complex S. littoralis–H. didymator, and to ascertain the compatibility between spinosad and the parasitoid for optimizing the control of lepidopteran pests.     

Fecundity and feeding of <Emphasis Type="Italic">Galerucella calmariensis</Emphasis> and <Emphasis Type="Italic">G. pusilla</Emphasis> on <Emphasis Type="Italic">Lythrum salicaria</Emphasis>

Fecundity and feeding of two introduced sibling biological control species, Galerucella calmariensis and G. pusilla (Coleoptera: Chrysomelidae) on purple loosestrife, Lythrum salicaria L. (Lythraceae) were compared at constant temperatures of 12.5, 15, 20, 25, and 27.5 °C. Larval feeding was also carried out at 30 °C, but at this temperature, larvae developed only to the L2 stage and none pupated. Thus, data for this temperature were not used in the analysis. There were significant species × temperature interactions in fecundity. Of the two species, Galerucella pusilla laid more eggs. Although egg production of both species was lowest at 12.5 °C and increased to 20 °C, at higher temperatures, the two species reacted differently. From 25 to 27.5 °C, egg production decreased for G. pusilla, but G. calmariensis fecundity peaked at 27.5 °C. Significant temperature × species × life-stage interactions were also observed in feeding. For each species, the amount of feeding varied with temperature and stage of development. Galerucella pusilla adults consumed more foliage at 15, 20, and 27.5 °C. However, at 12.5 °C G. calmariensis adults fed more than G. pusilla. G. pusilla larvae consumed an average of 25% less foliage than G. calmariensis. The lower larval consumption of G. pusilla suggests that when food is limited, G. pusilla larvae may have a higher survival rate because of its ability to complete larval development with less food and produce more progeny due to its greater fecundity. When food is not limited neither species would have a competitive advantage and both species could coexist temporally and spatially. However, since G. calmariensis larvae consumed more leaf material, the larval stage of this species would have a greater impact on purple loosestrife than G. pusilla.     

Potential for lab rearing of <Emphasis Type="Italic">Apanteles taragamae</Emphasis>, the larval endoparasitoid of coconut pest <Emphasis Type="Italic">Opisina arenosella</Emphasis>, on the rice moth <Emphasis Type="Italic">Corcyra cephalonica</Emphasis>

A lab rearing technique was standardised for Apanteles taragamae Viereck (Hymenoptera: Braconidae), the early larval parasitoid of the coconut leaf-eating caterpillar, Opisina arenosella Walker on the alternate host Corcyra cephalonica Stainton (Lepidoptera: Pyralidae). The parasitoid took 23.3 ± 3.2 days to complete the egg to adult period. Adult longevity for males and females was 15.3 ± 4.6 and 13.8 ± 4.6 days respectively. Fecundity was 14.8 ± 4.3 eggs per female. The percentage parasitism was 60.6 ± 5.7 on the alternative host C. cephalonica and 64.6 ± 5.5 on the natural host O. arenosella. Eight- to ten-day-old caterpillars were the ideal stage of C. cephalonica for rearing A. taragamae. The results indicated the amenability of rearing A. taragamae on C. cephalonica in the laboratory.     

First report of <Emphasis Type="Italic">Harmonia axyridis</Emphasis> Pallas being attacked by <Emphasis Type="Italic">Dinocampus coccinellae</Emphasis> Schrank in Canada

Field parasitism of two lady beetles, a recently introduced species, Harmonia axyridis Pallas, and an indigenous species, Coleomegilla maculata lengi Timberlake, by Dinocampus coccinellae Schrank (Hymenoptera: Braconidae) was investigated in southwestern Québec. Adult coccinellids were sampled from June to September 2001 in alfalfa and corn fields. Parasitism rates were recorded by dissection and rearing of coccinellids in controlled condition. The average proportions of coccinellids with a parasitoid larva were 4.6%for H. axyridis and 32%for C. maculata but 0%of the H. axyridis and 5.9%of theC. maculatawere successfully parasitized. In July, more C. maculata than H. axyridiswere found to be parasitized and among all individuals dissected, C. maculata were more frequently found superparasitized than H. axyridis. Our results suggest that D. coccinellae is not well adapted to H. axyridis in Quebec. This is the first mention of H. axyridis being attacked by D. coccinellae in Canada.     

Rearing temperature and parasitoid load determine host and parasitoid performance in Manduca sexta and Cotesia congregata

1. Temperature strongly influences the rates of physiological processes in insects, including the herbivore Manduca sexta and its larval endoparasitoid Cotesia congregata. Parasitisation by C. congregata decreases the growth and consumption of food by larval M. sexta. However, the effects of temperature on parasitised caterpillars and the developing wasp larvae are largely unknown. 2. In this study, parasitised and unparasitised caterpillars were reared at three constant temperatures (20, 25 and 30 °C) throughout larval development. Caterpillar mass gain and consumption were monitored daily until wandering (unparasitised control group) or wasp emergence (parasitised group) was observed. Development time and survival to emergence were measured as metrics of parasitoid performance. 3. Parasitised M. sexta developed more slowly than unparasitised controls, but had similar cumulative consumption until the terminal instar. Parasitised caterpillars with relatively large parasitoid loads had higher rates of consumption and growth than those with smaller loads. Both temperature and parasitoid load strongly affected wasp success. Mean development time to wasp emergence increased with low temperatures and with large loads. The combination of warm temperature and large parasitoid loads greatly reduced wasp survival. 4. These results demonstrate the interactive effects of rearing temperature and parasitisation on host consumption and growth rates throughout larval development. In addition, wasp performance was affected by the interaction of temperature and parasitoid load size. High temperatures alter the dynamics of the interaction between the parasitoid and its caterpillar host, which could have far-reaching impacts as the global temperatures continue to rise.     

<Emphasis Type="Italic">Toxoneuron nigriceps</Emphasis> parasitization delays midgut replacement in fifth-instar <Emphasis Type="Italic">Heliothis virescens</Emphasis> larvae

We have analyzed the effects of Toxoneuron nigriceps parasitization on the midgut development of its host Heliothis virescens. In parasitized H. virescens larvae, the midgut epithelium undergoes a complete replacement, which is qualitatively not different to that observed in synchronous unparasitized larvae, with similar temporal profiles of cell death and metabolic activity. However, the whole gut replacement process is significantly delayed in parasitized larvae, with complete differentiation of the new gut epithelium being observed 4 days later than in unparasitized controls. The administration of juvenile hormone before commitment and of 20-hydroxyecdysone (20E) after commitment delays and fosters, respectively, the replacement process of the midgut epithelium; moreover, the injection of 20E into developmentally arrested and 20E-deficient host last-instar larvae parasitized by T. nigriceps immediately triggers regular gut development. These hormone-based experiments suggest that endocrine alterations in the larval host, induced by T. nigriceps parasitism, are responsible for the temporal alterations in the gut replacement process. The role of this parasitoid-induced developmental change in the host regulation process is discussed. This work was partially supported by FAR 2006–2007 (University of Insubria) to G.T., by MIUR-FIRB-COFIN (grant no. RBNE01YXA8/2004077251), and by the Centro Grandi Attrezzature (University of Insubria).     

Influence of parasitism byEucelatoria bryani [Dip.: Tachinidae] on the consumption and utilisation of chickpea flour diet byHeliothis armigera [Lep.: Noctuidae]

Fourth and 5th instar larvae ofHeliothis armigera (Hübner) parasitised byEucelatoria bryani Sabrosky consumed significantly less chickpea flour diet than unparasitised larvae of the same age in the laboratory. Significant reduction in diet consumption, larval weight gain and frass produced at 24 and 48 h following parasitisation was observed in 5th instar host larvae. Parasitised larvae retained a greater percentage of food ingested (AD) than did the unparasitised ones. Unparasitised 5th instar larvae ofH. armigera were more efficient in converting the ingested food (ECI) and digested food (ECD) into body substance than larvae of similar age parasitised byE. bryani.     

Supplementary host specificity testing of the sawfly <Emphasis Type="Italic">Heteroperryia hubrichi</Emphasis>, a candidate for classical biological control of Brazilian peppertree, <Emphasis Type="Italic">Schinus terebinthifolius</Emphasis>, in the USA

Supplementary host specificity tests were conducted with the defoliating sawfly Heteroperreyia hubrichi (Hymenoptera: Pergidae), a candidate for classical biological control of Brazilian peppertree, Schinus terebinthifolius (Sapindales: Anacardiaceae), in the United States. These tests were conducted as part of the environmental assessment required by the National Environmental Policy Act (NEPA). The suitability of the federally listed endangered native plant Rhus michauxii (Anacardiaceae) and the economically important Litchi chinensis (Sapindaceae) as potential host plants for H. hubrichi was evaluated in a series of no-choice larval development tests conducted in a Florida quarantine laboratory. Neonate larvae transferred to individual test plants failed to develop to the pupal stage on R. michauxii or L. sinensis, whereas Brazilian peppertree supported development of the sawfly to pupation. The results of the additional host specificity tests indicated these critical non-target plants are not at risk from attack by H. hubrichi if it were released in Florida, USA.     

Dispersal and Burial Behavior in Larvae of <Emphasis Type="Italic">Chrysomya megacephala</Emphasis> and <Emphasis Type="Italic">Chrysomya albiceps</Emphasis> (Diptera,Calliphoridae)

Blowflies use discrete and ephemeral substrates to feed their larva. After they run out of food, the larvae begin to disperse in order to find adequate places for pupation or additional food sources, a process named post-feeding larval dispersal. Briefly state the aspects and why they are important were studied in a circular arena of 25 cm in diameter and covered with wood shavings to a height of 40 cm allowing post-feeding dispersal from the center of the arena. Larvae of both Chrysomya albiceps and C. megacephala were used in five experiments for each species. For each pupa location, determined as distance from the center, depth, and weight were evaluated. Statistical tests were done to verify the relation between weight, depth and distance for pupation and for larvae of two species shows that the media distance is significantly different for two species and for C. megacephala this distance is greater than the distance for C. albiceps. The depth too is different for each species, as the larvae of C. megacephala buries deeper than C. albiceps. With relation of weight, there is no statistic evidence that have any difference between weights for pupation for each species.     

Body size variation in <Emphasis Type="Italic">Gryon gallardoi</Emphasis> related to age and size of the host

This study aimed to evaluate the influence of Spartocera dentiventris (Berg) (Hemiptera: Coreidae) egg quality (regarding age, size and superparasitism) on male and female body size of Gryon gallardoi Brèthes (Hymenoptera: Scelionidae). It was also analysed host size influence on offspring sex choice and female oviposition order (within egg groups). Groups of 12 eggs, 2, 3, 4, 5, 6, 7, 8, and 12 days old were individually exposed to a female parasitoid for 2 h, and the order of each egg parasitisation was recorded. Size of adult parasitoids (head width and tibia length of the second leg pair), and parasitised and superparasitised host eggs were measured. Sexual dimorphism related to size (SDs), was estimated through a model II linear regression. Females have a larger head width but a smaller tibia length. Parasitoid adult size is significantly related to host age and size. Within an egg group, females did not exhibit preference for any egg size category either to start oviposition or to oviposit male or female eggs. The body size of both sexes diminished with host aging. There was a positive response in both sexes to host size increasing. Estimated SDs diminished with host aging and increased with host volume augmentation. The results suggest that adult body size of G. gallardoi, as well as size differences between males and females, are strongly associated to host quality.     

Effect of parasitism byAscogaster reticulatus [Hym.: Braconidae] on growth of the host,Adoxophyes sp. [Lep.: Tortricidae]

The developmental interaction between the egg/larval parasitoid,Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae) and its host,Adoxophyes sp. (Lepidoptera: Tortricidae) was examined. Prior to the egress of a final-instar parasitoid larva from the 4^th-instar host larva, host weight decreased by 22% from the maximum weight. The final body weight of a host larva was 27% of the maximum weight of a healthy 5^th-instar host. Food consumption was significantly reduced in both 3^rd-and 4^th-instar parasitized larvae compared with healthy ones. In the 4^th instar, a parasitized larva consumed 28% less artificial diet and produced less frass than a healthy larva. The growth rate of the endoparasitoid larvae greatly increased after their host's molt to the 4^th instar. Parasitoid larval volume increased 40 fold in the 4^th-instar host.      

Additive interaction of <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> Nucleopolyhedrovirus and Azadirachtin

Mortality of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) was higher in the combined treatment of Nucleopolyhedrovirus (NPV) and Azadirachtin (AZA) and mortality was increased when AZA concentration was doubled. Larval mortality decreased as the age of the larvae increased in all the treatments. The time for 100% kill of third instar larvae was significantly reduced to 72 h when AZA (0.1 ppm) was combined with NPV (10³ PIB/ml) when compared to 168 and 120 h for the same dose NPV and AZA individual treatments, respectively. The average leaf disc consumption, consumption index (CI), relative growth rate (RGR), the efficiency of conversion of ingested (ECI) and digested (ECD) food values were drastically reduced in the combined treatment of NPV and AZA than in the individual treatments. Larval as well as pupal durations were significantly extended and the adult longevity and fecundity were significantly reduced in the combined treatment of NPV and AZA. Weight of 14 day old control larvae was 420 mg and it was reduced to 299 and 248 mg after NPV (5 × 10² PIB/ml) and AZA (0.025 ppm) treatments, respectively. The larval weight was drastically decreased to 99 mg after the combined treatment at the same dose. The additive interaction between both the treatments, AZA and NPV, was found to be in a dose dependent manner and were highly compatible in disrupting the survival, feeding and biology of H. armigera.     

Larval sex identification in the paper wasp <Emphasis Type="Italic">Polistes dominulus</Emphasis> (Vespidae,Hymenoptera)

Identifying the sex of larvae is important in social Hymenoptera. Until now for Polistes wasps it has been necessary to genotype larvae at microsatellite loci, and assign their sex based on homozygosity at these loci. In our study on the paper wasp Polistes dominulus we have found morphological differences between larval sexes that can be used for larvae from the 3^rd instar on to easily and cheaply identify larval sex: the external gonopore and the shape and size of larval gonads. The robustness of these indicators was supported by genotype data at four microsatellite loci. Using gonopore and gonad features for sex assignment will assign diploid males as males, unlike techniques based on genetic loci or chromosomes. Received 12 July 2006; revised 4 January 2007; accepted 5 February 2007.     

Growth,development, and behaviour of the parasitised and unparasitised larvae of a shelter‐building moth and consequences for the resulting koinobiont parasitoid

Most attention to size‐time trade‐offs of insects has focused on herbivore risk, with considerably less attention paid to parasitoids. Here, we focus on parasitoid risk, comparing the fates of unparasitised herbivore hosts and parasitised hosts that protect the parasitoids. Success of a koinobiont parasitoid (host grows after parasitisation) depends on maintaining a delicate balance with its host, thereby ensuring its own survival while the host grows. To evaluate growth rate–mortality rate relationships of host and parasitoid, we compared several aspects of the growth, phenology, and behaviour of unparasitised fern moth [Herpetogramma theseusalis (Walker) (Lepidoptera: Crambidae)] larvae and larvae parasitised by Alabagrus texanus (Cresson) (Hymenoptera: Braconidae), a solitary koinobiont (one parasitoid per host) wasp. Host larvae feed and construct shelters on sensitive fern, Onoclea sensibilis L. (Dryopteridaceae). Alabagrus texanus parasitise early‐instar moths in late summer, which overwinter in their host, emerging in mid‐summer to pupate and eclose. During the autumn following hatching and the immediately following spring, parasitised and unparasitised moth larvae did not differ in size, took similar time to choose between satisfactory and unsatisfactory foods, and built similar shelters. Prior to any other changes noted, more parasitised than unparasitised larvae also died when severely starved. Parasitised larvae subsequently grew less and pupated later than unparasitised ones (small size, slow growth), but consumed similar amounts of food. Although the numerically dominant parasitoid of fern moths, we concluded that A. texanus do not efficiently exploit their hosts.     

Host specificity of <Emphasis Type="Italic">Anagrus epos</Emphasis>: a potential biological control agent of <Emphasis Type="Italic">Homalodisca vitripennis</Emphasis>

Anagrus epos Girault (Hymenoptera: Mymaridae) is a candidate for a classical biological control program targeting the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), in California. Because mass production of GWSS is expensive and labor-intensive, a factitious host that is more economical to produce is desirable to mass produce A. epos for colonization and augmentation efforts. Here, we report the results of host specificity tests and potential rearing techniques for A. epos under laboratory conditions. Females discriminated and oviposited into eggs of seven cicadellid species: H. vitripennis, Circulifer tenellus (Baker), Erythroneura variabilis Beamer, Amblysellus grex (Oman), Graphocephala atropunctata (Signoret), Macrosteles severini Hamilton, and H. liturata Ball, and two cerambycid species: Phoracantha recurva Newman and P. semipunctata (F.). Anagrus epos successfully completed development in the eggs of H. vitripennis, C. tenellus, E. variabilis, A. grex, G. atropunctata, M. severini, and H. liturata. The use of a factitious host and potential nontarget effects of this generalist parasitoid are discussed.     

Inhibitory activity of probiotics <Emphasis Type="Italic">Streptococcus phocae</Emphasis> PI80 and <Emphasis Type="Italic">Enterococcus faecium</Emphasis> MC13 against Vibriosis in shrimp <Emphasis Type="Italic">Penaeus monodon</Emphasis>

Occurrence of widespread epizootics among larval and cultured shrimp has put on viable preventive approaches such as application of probiotics on a high priority in aquaculture. In the present study, four probiotics bacteria were isolated from marine fish and shrimp intestine based on the antagonistic activity and nonpathogenic to the host. The isolates of probiotics strains Streptococcus phocae PI80, Enterococcus faecium MC13, Lactococcus garvieae LC149, B49 and one commercial probiotics (ECOFORCE) were fed to post larvae of Penaeus monodon obtained from two different hatcheries to analyze the growth and protection against Vibrio harveyi and V. parahaemolyticus. Growth of P. monodon post larvae fed with probiotic strain S. phocae PI80 was significantly (P < 0.001) higher when compared with control and other three strains in both experiments. The treatment of post larvae with B49 reduced the growth as well as Specific growth rate. Among the three probiotic strains S. phocae PI80 and E. faecium MC13 have effectively inhibited the pathogens. In experiment I high survival (92%) were observed in S. phocae PI80 treated post larvae when challenged with Vibrio harveyi followed by E. faecium MC13 (84%), B49 (76%) and ECOFORCE (68%) but PI80 did not protect the post larvae in the same experiment when they were exposed to V. parahaemolyticus. The probiotic isolate of MC13 has protected the post larvae against V. parahaemolyticus when compared to other probiotics and control. Similarly in the second experiment feeding of S. phocae enhanced the survival of larvae when challenged with V. harveyi. The laboratory studies proved that bacterial probionts S. phocae and E. faecium isolated from shrimp and brackishwater fish has potential applications for controlling pathogenic vibriosis in shrimp culture.