The chemotaxis regulator <Emphasis Type="Italic">pilG</Emphasis> of <Emphasis Type="Italic">Xylella fastidiosa</Emphasis> is required for virulence in <Emphasis Type="Italic">Vitis vinifera</Emphasis> grapevines

Type IV pili of X. fastidiosa are regulated by pilG, a response regulator protein putatively involved in chemotaxis-like operon sensing stimuli through signal transduction pathways. To elucidate the roles of pilG in pathogenicity of X. fastidiosa, the pilG-deletion mutant XfΔpilG and complemented strain XfΔpilG-C were generated. While all strains had similar growth curves in vitro, XfΔpliG showed significant reduction in cell-matrix adherence and biofilm production compared with wild-type X. fastidiosa and XfΔpilG-C. The genes pilE, pilU, pilT, and pilS were down-regulated in XfΔpliG when compared with its complemented strain and wild-type X. fastidiosa. Finally, no Pierce’s disease symptoms were observed in grapevines inoculated with XfΔpilG, whereas grapevines inoculated with the wild-type X. fastidiosa and complemented strain of XfΔpilG-C developed typical Pierce’s Disease (PD) symptoms. The results indicate that pilG has a role in X. fastidiosa virulence in grapevines.     

Functional characterization of CgPBS<Subscript>2</Subscript>, a MAP kinase kinase in <Emphasis Type="Italic">Colletotrichum gloeosporioides,</Emphasis> using osmotic stress sensitivity as a selection marker

Colletotrichum leaf disease of Hever brasiliensis (rubber tree) caused by C. gloeosporioides is one of the major causes of declining rubber tree yields. Little is known about the fungal molecular characters that are important for pathogenicity on rubber tree and fungicide resistance. In this study, we cloned the CgPBS₂ gene, the key component of the Hog1 pathway which controls various aspects of osmoregulation and fungicide resistance in various fungal pathogens, including the causal agent of Colletotrichum leaf disease of rubber tree. We characterized the function of the CgPBS₂ gene by reverse genetics. Because the Hog1 pathway plays an important role in stress responses, we obtained a CgPBS₂ gene deletion mutant by PEG-mediated transformation of protoplasts after reducing the concentration of sucrose in the screening medium from 1.0 M to 0.2 M. Then, the complemented transformants and GFP-labelled CgPBS₂ gene transformants were selected directly under highly hyperosmotic medium (PDA?+?1.5 M sorbitol) without using other selectable gene markers. Phenotypic observations showed that the CgPBS₂ protein was mainly localized in the conidial cytoplasm of the CgPBS₂-GFP transformants. In addition, disruption of CgPBS₂ led to sensitivity to hyperosmosis and high salt concentration as well as resistance to the fungicide fludioxonil. No obvious difference in virulence was observed between the null mutant and the wild-type strain. These results provide insights into the role of the CgPBS₂ gene in osmotic stress, salt stress and fludioxonil resistance and suggest that osmotic stress sensitivity can be used as a selection marker.     

Nonhost resistance of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> against <Emphasis Type="Italic">Colletotrichum</Emphasis> species

Arabidopsis thaliana exhibits a durable resistance called nonhost resistance against nonadapted fungal pathogens. A. thaliana activates preinvasive resistance and terminates entry attempts by nonadapted fungi belonging to the genus Colletotrichum, which cause anthracnose disease in many plants. In the interaction between A. thaliana and nonadapted C. tropicale, the preinvasive resistance involves the PENETRATION 2-related antifungal secondary metabolite pathway and the ENHANCED DISEASE RESISTANCE 1-dependent antifungal peptide pathway. The development of invasive hyphae by C. tropicale owing to the reduction of preinvasive resistance then triggers the blockage of further hyphal expansion via the activation of the second layer of resistance, i.e., postinvasive resistance, which guarantees the robustness of the nonhost resistance of A. thaliana against Colletotrichum pathogens. Both the tryptophan-derived metabolic pathway and glutathione synthesis play critical roles in the postinvasive resistance against C. tropicale, although the molecular mechanism of postinvasive resistance remains to be elucidated. In this review, we describe the current understanding of the molecular background of the Arabidopsis nonhost resistance against Colletotrichum fungi and discuss perspectives for future research on this durable resistance.     

Disease suppressive activity of extracts from entomopathogenic fungus <Emphasis Type="Italic">Ophiocordyceps sobolifera</Emphasis> against chili anthracnose fungi <Emphasis Type="Italic">Colletotrichum</Emphasis> spp. in a pot experiment

This study evaluated the efficacy of the extracts of Ophiocordyceps sobolifera isolate Cod-NB1302 for the biological control of chili anthracnose disease caused by Colletotrichum capsici and C. gloeosporioides under pot conditions. Among the extracts, mycelial extract treatments provide the best reduction in disease severity. Interestingly, two bioactive constituents, adenosine and cordytropolone, from the mycelial extract, inhibited growth of the fungal pathogens. Moreover, these bioactive compounds had a synergistic effect against the fungal pathogens in a pot experiment. These results confirmed the disease suppressive activity of the mycelial extract.     

Molecular and phenotypic characterization revealed six <Emphasis Type="Italic">Colletotrichum</Emphasis> species responsible for anthracnose disease of small cardamom in South India

Small cardamom (Elettaria cardamomum Maton) is extensively cultivated in the Western Ghats of South India either as a monocrop under the forest trees or as an intercrop along with arecanut and coffee plantations. Colletotrichum species responsible for severe outbreaks of anthracnose on small cardamom in South India are reported. Small cardamom anthracnose, popularly known as “Chenthal”, manifests itself on the foliage as yellowish lesions, which later coalesce to form large blighted areas. In advanced stages, the affected leaves dry up giving a burnt appearance to the plant. Twenty-five isolates of Colletotrichum were isolated from leaves of small cardamom in Karnataka, Kerala and Tamil Nadu states of India. The isolates were characterized through morphological studies and multilocus phylogenetic analysis (ITS, ACT, CHS-1, GAPDH, TUB2, CYLH3, GS and ApMat gene regions) to test whether different species are present and identified: C. karstii (2 isolates), C. gloeosporioides (1), C. siamense (7), C. syzygicola (6), Colletotrichum sp (5), and C. guajavae (4), as the cause of anthracnose on small cardamom for the first time. Pathogenicity of the six species was confirmed. To our knowledge, this is the first detailed study of Colletotrichum species which cause anthracnose diseases on small cardamom.     

Markers to differentiate species of anthracnose fungi identify <Emphasis Type="Italic">Colletotrichum fructicola</Emphasis> as the predominant virulent species in strawberry plants in Chiba Prefecture of Japan

Colletotrichum fungi belonging to the Colletotrichum gloeosporioides species complex include a number of economically important postharvest pathogens that often cause anthracnose. Until now, different species within this group could only be distinguished from one another reliably using multigenic phylogenetic analyses. Using a comparative genomics approach, we developed a marker that can differentiate Colletotrichum fructicola, Colletotrichum aenigma and Colletotrichum siamense within the C. gloeosporioides species complex based on PCR amplicon size differences. When we used this marker to classify 115 isolates collected over 20 years from strawberries in Chiba Prefecture, Japan, the isolates were predominantly C. fructicola. To our knowledge, this is the first report characterizing different species of Colletotrichum infecting strawberries in Japan and contributes to our understanding on the diversity of anthracnose pathogens in Japan.     

Identification and characterization of <Emphasis Type="Italic">Colletotrichum</Emphasis> spp. associated with chili anthracnose in peninsular Malaysia

Anthracnose fruit rot caused by Colletotrichum spp. is a serious post-harvest disease of chili fruits (Capsicum spp.). One hundred-thirty isolates of Colletotrichum spp. were isolated from anthracnose of green and red cayenne pepper (Capsicum annuum) and bird’s eye chili (Capsicum frutescens). The isolates were morphologically identified as Colletotrichum acutatum sensu lato (62 isolates), Colletotrichum truncatum (54 isolates), and Colletotrichum gloeosporioides sensu lato (14 isolates). Molecular identification and phylogenetic analyses were based on internal transcribed spacer regions, β-tubulin, actin, and glyceraldehyde-3-phosphate dehydrogenase genes, and the isolates were re-identified as C. scovillei (58 isolates), C. truncatum (54 isolates), C. siamense (11 isolates), C. fioriniae (four isolates), and C. fructicola (3 isolates). Maximum likelihood trees using combined sequences showed that isolates of the same species grouped in the same main clade with the isolates used for comparison. Pathogenicity testing showed that the tested isolates from each species were pathogenic towards green and red Capsicum annuum and Capsicum frutescens upon treatment of wounded fruit, using both the mycelial plug and conidial suspension methods. Only five isolates of C. truncatum and seven isolates of C. scovillei were found to be pathogenic upon treatment of unwounded fruit. The occurrence of five Colletotrichum spp. (C. siamense, C. fructicola, C. scovillei, C. fioriniae, and C. truncatum) associated with chili anthracnose in Peninsular Malaysia indicates that correct species identification is important to formulate not only effective disease management, but also effective quarantine policy.     

Diversity of <Emphasis Type="Italic">Colletotrichum</Emphasis> species in coffee (<Emphasis Type="Italic">Coffea arabica</Emphasis>) plantations in Mexico

The aim of this study was to identify the Colletotrichum species associated with anthracnose symptoms in coffee (Coffea arabica L.) plantations in northern Puebla, Mexico. In 2013, five surveys were conducted in different production areas and at different altitudes. Symptomatic leaves, shoots, and ripe and unripe fruits of the coffee variety Red Caturra were collected. Isolates were obtained and the Colletotrichum species were identified morphologically and characterized by multilocus sequence analyses of the ACT, CAL, GAPDH, and TUB2 genes and the rDNA region. Additionally, pathogenicity tests were conducted using six isolates. We identified C. gigasporum, C. gloeosporioides, C. karstii (two isolates), C. siamense, and C. theobromicola. This is the first report of these five species infecting leaves of coffee. The symptoms caused by these species were characterized, but the species causing Coffee Berry Disease was not found. This is the first report of a complex of species affecting coffee plants in the same geographical area in Mexico, and suggests that other complexes of species may be important pathogens in coffee-producing areas elsewhere.     

Pathogenicity and characterization of <Emphasis Type="Italic">Colletotrichum lentis</Emphasis>: A causal agent of anthracnose in common vetch (<Emphasis Type="Italic">Vicia sativa</Emphasis>)

A series of studies were carried out on Colletotrichum lentis which had been been identified in 2015 based largely on the distinctive shape of conidia and ITS sequences, and which has been causing severe anthracnose disease symptoms on common vetch plants (Vicia sativa) in Gansu Province in the northwest region of China. A key focus of the present studies was to determine how vetch crops become infected. The addition of residues from harvested common vetch crops to land being prepared as a seedbed was shown to result in the highest levels of disease severity indicating that this management practice was the most likely way for crops to become severely infected. Seed transmission was unlikely to be the cause of severe outbreaks as less than 5% of seeds harvested from severely infected plants carried C. lentis. To verify that the species causing the severe outbreaks of anthracnose disease of vetch crops was C. lentis, sequence analysis of the ITS, TUB2, ACT, HIS3 and GAPDH genes was conducted. C. lentis isolates from common vetch and lentil (Lens culinaris) formed a distinctive group among Colletotrichum species, including those species that infect other forage and field crops. The unique shape of conidia of C. lentis, straight with only one end curved, was confirmed as being reliable for rapid identification of disease outbreaks caused by this damaging fungal pathogen.     

Rice <Emphasis Type="Italic">OsPBL1</Emphasis> (ORYZA SATIVA ARABIDOPSIS PBS1-LIKE 1) enhanced defense of <Emphasis Type="Italic">Arabidopsis</Emphasis> against <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> DC3000

The receptor-like cytoplasmic kinases (RLCK family VII) are required for plant defense against various pathogens. Previously, OsPBL1 (ORYZA SATIVA ARABIDOPSIS PBS1-LIKE 1) was isolated from rice as a potential RSV (rice stripe virus) resistant factor, but its physiological roles in plant defense are yet to be investigated. In this study, we demonstrated that OsPBL1increased defense against P. syringae in transgenic Arabidopsis. To ascertain the role of OsPBL1 gene in plant defense, OsPBL1 tagged with HA (i.e. Hemagglutinin) was overexpressed in Arabidopsis and examined for the resistance against Pseudomonas syringae pv. tomato DC3000 (i.e. Pst DC3000). At 3 dpi of Pst DC3000, transgenic Arabidopsis lines exhibited the reduced chlorotic lesion and propagation of P. syringae, compared to wild type. Elevated pathogen resistance of transgenic lines was correlated with increased H₂O₂ accumulation and callose deposition on the infected leaves. It was also revealed that expression levels of salicylic acid dependent genes such as PR1, PR2, and PR5, were induced higher in transgenic lines than wild type. Taken together, our data suggested that OsPBL1 exerted the role in defense against pathogen attacks in plant via mainly facilitating salicylic acid dependent pathway.     

AlgU contributes to the virulence of <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> pv. <Emphasis Type="Italic">tomato</Emphasis> DC3000 by regulating production of the phytotoxin coronatine

Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), which causes bacterial speck disease of tomato, has been used as a model pathogen to investigate the molecular basis of plant–pathogen interactions. The function of many potential virulence factors encoded in the Pst DC3000 genome and their modes of action are not fully understood. P. syringae is known to produce the exopolysaccharide alginate. Although AlgU, a sigma factor, is known to regulate the expression of genes such as algD related to alginate biosynthesis, the molecular mechanisms of AlgU in the virulence of Pst DC3000 is still unclear. To investigate the function of AlgU and alginate in plant–bacterial pathogen interactions, we generated ΔalgU and ΔalgD mutants. After inoculation with ΔalgU but not ΔalgD, host plants of Pst DC3000 including tomato and Arabidopsis had milder disease symptoms and reduced bacterial populations. Expression profiles of Pst DC3000 genes revealed that AlgU can regulate not only the expression of genes encoding alginate biosynthesis, but also the expression of genes related to type III effectors and the phytotoxin coronatine (COR). We also demonstrated that the ΔalgU mutant showed full virulence in the Arabidopsis fls2 efr1 double mutant, which is compromised in the recognition of PAMPs. Further, the application of COR was able to restore the phenotype of the ΔalgU mutant in the stomatal response. These results suggest that AlgU has an important role in the virulence of Pst DC3000 by regulating COR production.     

Postharvest anthracnose on Satsuma mandarin orange caused by <Emphasis Type="Italic">Colletotrichum fioriniae</Emphasis>

In early January 2015–2017, anthracnose was detected on Satsuma mandarin orange (SMO) (Citrus unshiu) fruits kept in farmers’ storage rooms in Saga Prefecture, Japan. Three single-spore isolates from rotten fruits reproduced the postharvest anthracnose symptoms in wound-inoculated SMO fruits and were re-isolated from lesions. The isolates were identified as Colletotrichum fioriniae based on conidial morphology, culture characteristics, rDNA-ITS, and beta-tubulin-2 gene sequences. This is the first report of postharvest anthracnose on SMO caused by C. fioriniae.     

<Emphasis Type="Italic">Fusarium ershadii</Emphasis> sp. nov., a Pathogen on <Emphasis Type="Italic">Asparagus officinalis</Emphasis> and <Emphasis Type="Italic">Musa acuminata</Emphasis>

Two Fusarium strains, isolated from Asparagus in Italy and Musa in Vietnam respectively, proved to be members of an undescribed clade within the Fusarium solani species complex based on phylogenetic species recognition on ITS, partial RPB2 and EF-1α gene fragments. Macro- and micro-morphological investigations followed with physiological studies done on this new species: Fusarium ershadii sp. nov can be distinguished by its conidial morphology. Both isolates of Fusarium ershadii were shown to be pathogenic to the monocot Asparagus officinalis when inoculated on roots and induced hollow root symptoms within two weeks in Asparagus officinalis seedlings. In comparison mild disease symptoms were observed by the same strains on Musa acuminata seedlings.     

Genetic structure of <Emphasis Type="Italic">Pyrenophora teres</Emphasis> f. <Emphasis Type="Italic">teres</Emphasis> and <Emphasis Type="Italic">P. teres</Emphasis> f. <Emphasis Type="Italic">maculata</Emphasis> populations from western Canada

Infection by Pyrenophora teres f. teres (Ptt) or P. teres f. maculata (Ptm), the causal agents of the net and spot forms of net blotch of barley, respectively, can result in significant yield losses. The genetic structure of a collection of 128 Ptt and 92 Ptm isolates from the western Canadian provinces of Alberta (55 Ptt, 27 Ptm), Saskatchewan (58 Ptt, 46 Ptm) and Manitoba (15 Ptt, 19 Ptm) were analyzed by simple sequence repeat (SSR) marker analysis. Thirteen SSR loci were examined and found to be polymorphic within both Ptt and Ptm populations. In total, 110 distinct alleles were identified, with 19 of these shared between Ptt and Ptm, 75 specific to Ptt, and 16 specific to Ptm. Genotypic diversity was relatively high, with a clonal fraction of approximately 10 % within Ptt and Ptm populations. Significant genetic differentiation (PhiPT = 0.230, P = 0.001) was found among all populations; 77 % of genetic variation occurred within populations and 23 % between populations. Lower, but still significant genetic differentiation (PhiPT = 0.038, P = 0.001) was detected in Ptt, with 96 % of genetic variation occurring within populations. No significant genetic differentiation (PhiPT = 0.010, P = 0.177) was observed among Ptm populations. Isolates clustered in two distinct groups conforming to Ptt or Ptm, with no intermediate cluster. The high number of haplotypes observed, combined with an equal mating type ratio for both forms of the fungus, suggests that P. teres goes through regular cycles of sexual recombination in western Canada.     

Infection of <Emphasis Type="Italic">Sorghum bicolor</Emphasis>, selected grass species and <Emphasis Type="Italic">Zea mays</Emphasis> by G<Emphasis Type="Italic">loeocercospora sorghi</Emphasis>, causal pathogen of zonate leaf spot

Zonate leaf spot (Gloeocercospora sorghi) is a common disease in Sorghum bicolor producing areas of the U.S., but little is known about its biology, virulence and severity on S. bicolor, Zea mays, and related crop grassweeds. Greenhouse studies were conducted to determine and compare the virulence and severity of G. sorghi on 10 commercially available sorghum hybrids, four Z. mays hybrids and selected grassweed species including Sorghum bicolor (grain sorghum and shattercane biotypes) and Sorghum halepense (Johnsongrass), two of the most problematic arable weeds. Plants from the respective species were inoculated with a local G. sorghi isolate and maintained in a dew-chamber at 24 °C for 24 h and then incubated under greenhouse conditions for 4 weeks. Plants were observed for lesion expression and rated using a modified Horsfall-Barrett scale (0–10). The first symptoms of infection were visible within 24 h following inoculation on shattercane and S. bicolor hybrids. Symptoms consisted of small, non-diagnostic purple lesions on the leaves. Results showed that S. bicolor, S. halepense and shattercane were susceptible to G. sorghi. All other species tested in this study were not infected. More particularly, disease severity, increased from a rating of 3 to 10 on sorghum and from 2 to 7 on S. halepense between 2 and 23 days after inoculation, respectively. However, disease severity on shattercane increased rapidly from 3.5 to 10 between 2 and 8 days after inoculation, respectively. Among the sorghum hybrids tested, FFR-322 appeared to be the most resistant to G. sorghi while Pioneer 83G66 appeared to be the most susceptible. Z. mays hybrids were not infected by the fungus used in this study. G. sorghi could be used effectively to manage shattercane and S. halepense infestations occurring in Z. mays and S. bicolor fields consisting of specific G. sorghi-resistant hybrids.     

Characterization of <Emphasis Type="Italic">Myoviridae</Emphasis> and <Emphasis Type="Italic">Podoviridae</Emphasis> family bacteriophages of <Emphasis Type="Italic">Erwinia amylovora</Emphasis> from Hungary - potential of application in biological control of fire blight

The virulence spectrum of 300 isolates of Xanthomonas oryzae pv. oryzae (Xoo), representing 17 districts of Punjab, Pakistan was elucidated through inoculation on a set of six rice IRRI-differentials. The virulence level was assessed by using principal component and cluster analysis. Among six principal components (PCs), PC-1 exhibited 59.3 % of the total variance. The highly virulent isolates clusters on the positive side of the ordination away from the point of intersection of PC1 and PC2 and classifies the Xoo isolates from slow disease to the highest disease causing entities. The 300 isolates were categorized into 29 pathotypes (Pt1-29) wherein the highly virulent pathotype (Pt-1), comprises of 39 Xoo isolates were widespread in 12 districts. The majority of Xoo isolates were moderately to least virulent (21.7–43 %) and average disease progress curves confirmed the field reactions of these pathotype clusters for an efficient recognition of Xoo isolates. Interaction of the pathogen with differentials harboring different resistant genes was well investigated in the current study for future management approaches for which the surveillance of the new Xoo pathotypes may expedite the disease resistant rice breeding programme in the country.     

Rapid diagnosis of soybean anthracnose caused by <Emphasis Type="Italic">Colletotrichum truncatum</Emphasis> using a loop-mediated isothermal amplification (LAMP) assay

A loop-mediated isothermal amplification (LAMP) assay that directly detects Colletotrichum truncatum in diseased soybean tissues is described, thus allowing rapid diagnosis of soybean anthracnose. Using the target gene Rpb1 (that codes for the large subunit of RNA polymerase II), we designed and screened a set of species-specific primers allowing amplification at 62 °C over 70 min. After addition of SYBR Green I to the LAMP reaction products, a yellow-green color (visible to the unaided eye) developed only in the presence of C. truncatum. The detection limit of the LAMP assay was 100 pg (per μL genomic DNA). The Rpb1-Ct-LAMP assay has been successfully used to diagnose soybean anthracnose in field samples collected from Jiangsu, Anhui and Hubei provinces of China, and to detect C. truncatum in soybean seeds from farmers’ markets. Our results show that the Rpb1-Ct-LAMP assay is a useful and convenient method for detecting C. truncatum, and thus for diagnosis of soybean anthracnose.     

Overexpression of <Emphasis Type="Italic">SlARG2</Emphasis> or <Emphasis Type="Italic">SlTD2</Emphasis> in Arabidopsis enhances resistance against <Emphasis Type="Italic">Plutella xylostella</Emphasis> L.

Tomato (Solanum lycopersicum L.) ARGINASE2 (ARG2) and THREONINE DEAMINASE2 (TD2) are involved in plant defense. These enzymes act in the midgut of herbivores fed on tomato plants to degrade the essential amino acids Arg and Thr, respectively. Although it has been demonstrated that overexpression of the SlARG2 gene in tomato enhanced its resistance against M. sexta larvae, knock-down the expression of SlTD2 reduced the resistance of tomato to lepidopteran herbivores; it remains unclear whether overexpression of SlTD2 could enhance the resistance of the host plants to herbivores, or whether combined overexpression of SlARG2 and SlTD2 could lead to synergistically enhanced resistance to insects. Here, we generated transgenic Arabidopsis plants overexpressing SlARG2 (SlARG2 OE) and SlTD2 (SlTD2 OE) individually as well as in combination (SlARG2-SlTD2 OE). Overexpression of these genes did not affect Arabidopsis development, seed yield, or Arg and Thr content. Insect-feeding bioassay was performed by feeding diamondback moth (Plutella xylostella L.) larvae on detached leaves of wild-type, SlARG2 OE, SlTD2 OE, and SlARG2-SlTD2 OE plants. Larvae fed on SlARG2 OE leaves showed approximately 31% to 35% reduction in weight and 6% to 10% reduction in survival rate compared to those fed on wild-type leaves. Although larvae fed on SlTD2 OE leaves showed no reduction in survival rate, they gained less weight. Whereas larvae fed on SlARG2-SlTD2 OE leaves showed neither reduction in weight nor reduction in survival rate. We further investigated the arginase enzymatic activity of the SlARG2 OE and SlARG2-SlTD2 OE transgenic plants. The SlARG2 OE line most resistant to diamondback moth larvae displayed the highest arginase activity. Our data indicate that overexpression of SlARG2 or SlTD2 in Arabidopsis can enhance its resistance against diamondback moth, whereas combined overexpression of SlARG2 and SlTD2 did not generate synergistically increased resistance to diamondback moth.     

Survival and development of spotted bollworm, <Emphasis Type="Italic">Earias vittella</Emphasis> (Fabricius) (Lepidoptera: Nolidae) on different transgenic <Emphasis Type="Italic">Bt</Emphasis> and isogenic non-<Emphasis Type="Italic">Bt</Emphasis> cotton genotypes

Four Bt cotton hybrids, each with one of four different events, viz., MRC 6301 Bt (cry1Ac gene), JKCH 1947 Bt (modified cry1Ac gene), NCEH 6R Bt (fusion cry1Ac/cry1Ab gene) and MRC 7017 Bollgard II (cry1Ac and cry2Ab genes) were compared for survival and development of Earias vittella (Fabricius) along with their isogenic non-Bt genotypes. None of the neonates were able to complete the larval period and reach pupal stage on squares of 90, 120 and 150 days old crop of all Bt hybrids. Likewise, on bolls also, zero per cent larval survival was observed in all Bt hybrids except JKCH 1947 Bt where 0.67 per cent larvae could manage to reach pre-pupal stage at 120 and 150 days old crop but failed to form cocoon and enter pupal stage. The surviving larva took more development time (3.7 to 5.4 days) as compared to larvae fed on bolls of JKCH 1947 non-Bt. The average survival period (ASP) of larvae was in order of 150 > 120 > 90 days old crop among the crop ages; JKCH 1947 Bt > MRC 6301 Bt > NCEH 6 R Bt > MRC 7017 Bollgard II among Bt hybrids; and bolls > squares between fruiting bodies. However, reverse was true for speed index of toxic effect. The concentration of Cry toxin varied significantly in squares and bolls and also among the crop ages. The amount of Cry toxin in squares and bolls had significant negative correlation with ASP of the E. vittella larvae.