Pink Bollworm Populations Research Articles

Pink Bollworm management in cotton: Challenges, innovations, and sustainable solutions

Pink bollworm (Pectinophora gossypiella) poses a significant threat to cotton production worldwide. Despite the initial success of Bt cotton, resistance has emerged, necessitating alternative management strategies. Integrated Pest Management (IPM) approaches, including mating disruption and the sterile insect technique (SIT), offer promising solutions. The SPLAT (Specialized Pheromone and Lure Application Technology) technique utilizes wax-based formulations to disrupt pink bollworm mating behaviour, reducing population growth and damage to cotton crops. Meanwhile, SIT utilizes radiation to induce sterility in pink bollworm populations, reducing reproductive rates and mitigating infestation levels. Embracing these innovative strategies collectively ensures sustainable cotton cultivation, safeguarding farmers' livelihoods and reinforcing resilience against the persistent threat of the pink bollworm. Keywords: Pectinophora gossypiella, Cotton, IPM, SPLAT, STI

Effect of weather parameters on pink bollworm damage and population of predators in Bt cotton in Central India

Effect of weather parameters on pink bollworm damage and population of predators in Bt cotton in Central India

Effect of Novel Insecticides on Sucking Pests and Pink Bollworm in Cotton Plants under Field Conditions

The study investigated that the effectiveness of various novel insecticides for controlling sucking pests and pink bollworm in cotton cultivation over a three-year period. The treatments were evaluated based on their impact on aphids, jassids, thrips, whiteflies and pink bollworm populations. During 2018-19, 2019-20 and 2020-21 years, among the tested novel insecticides, Fipronil + Imidacloprid @ 100g/ha has recorded lowest population of thrips, jassids. Similarly, Fipronil+ Acetamiprid @ 1000 ml/ha has recorded lowest aphid population whereas incidence of pink bollworm was least in Lamdacyhalothrin + Chlorantraniliprole @ 200 ml/ha.

Genetic diversity of cotton Pectinophora gossypiella (Saunders) (Lepidoptera, Gelechiidae) population in inferred from mitochondrial COI sequences

The objective was to identify different haplotypes network of pink bollworm and their distribution in south India using the partial mitochondrial COI sequence of pink bollworm populations. Genetic diversity analysis exhibited the presence of 5 haplotypes in COI gene sequences, and among them, Hap_1 was the most common and present in 17 populations. Distributions of pairwise differences obtained with partial COI data from the overall populations were unimodal, suggesting population expansion. A significant neutrality test based on Tajima’s D, Fu and Li’s D and F test presented a haplotype network with multiple haplotypes. The acceptance of the neutrality test with significant positive values validated the theory of demographic expansion in cotton pink bollworm populations with respect to COI. The pink bollworm has a population genetic diversity among the investigated populations collected from south India.

Evaluation and comparison of different refugia-in-bag (RIB) patterns against boll worm complex with special reference to pink boll worm in Bt cotton

Field study on evaluation and comparison of different refugia-in-bag patterns (RIB) against bollworm complex with special reference to pink bollworm was conducted at RARS, Nandyal during 2021 and 2022. Among different RIB patterns evaluated pooled results of two years indicated no significant difference in green boll and locule damage due to pink bollworm among different refugia patterns. Highest yield of 1002 kg/ha was recorded in 20% structured refugia which is statistically at par with all other refugia patterns except in 100% non Bt which recorded lowest yield of 762 kg/ha. Based on foregoing results it clearly states that refugia is longer effective against pink bollworm population which had already developed resistance therefore further development of resistance can be managed in pink bollworm and can be effectively utilized for other bollworm in slowing down the building up of resistance in Bt cotton.

Segregation of Cry Genes in the Seeds Produced by F1 Bollgard® II Cotton Differs between Hybrids: Could This Be Linked to the Observed Field Resistance in the Pink Bollworm?

Indian populations of the Pink Bollworm (PBW) are resistant to Bt (Bacillus thuringiensis) cotton hybrids containing Cry1Ac and Cry2Ab genes. Segregation of these Cry genes in F1 hybrids could subject PBW to sublethal concentrations. Moreover, planting hybrids with varying zygosities of Cry genes could produce diverse segregation patterns and expose PBW populations to highly variable toxin concentrations. This could potentially promote the rate of resistance development. Therefore, we studied the segregation patterns of Cry genes in different commercial Bt hybrids cultivated in India. Results showed that two hybrids segregated according to the Mendelian mono-hybrid ratio, three segregated according to the Mendelian di-hybrid ratio, and one showed a mixed segregation pattern. The assortment of seeds containing Cry genes varied between bolls of the same hybrid. In India, different Bt cotton hybrids are cultivated in small patches next to each other, exposing PBW populations to sublethal doses and wide variations in the occurrence of Cry genes. It is necessary to avoid segregation of Cry genes in the seeds produced by F1 hybrids. This study recommends using Bt parents homozygous for Cry genes in commercial Bt cotton hybrid development. This breeding strategy could be effective for similar transgenic crop hybrids as well.

Heterologous expression of cry3Bb1 and cry3 genes for enhanced resistance against insect pests in cotton

Transgenic technology played a crucial role in developing insect-resistant plants resulting in the reduced application of pesticides. This article reports the expression of two cry proteins (Cry3Bb1 and Cry3) in cotton for enhanced resistance against chewing insect pests. The aforementioned genes were synthetically developed and were cloned under appropriate regulatory sequences followed by transformation into Eagle-2 genotype (Gossypium hirsutum) of cotton through shoot apex-cut Agro-infiltration. The transgene integration was validated by polymerase chain reaction using primers flanking the aforementioned cry genes. Transgene expression was assessed by qRT-PCR using GADPH as a reference gene. The relative fold expression analyses revealed the highest expression of the transgene(s) in M1 plants, which is a 4.5-fold expression (Cry3 + Cry3Bb1) followed by M3 (fold expression, 3.0) (Cry3Bb1) and M2 (fold expression, 2.5) (Cry3) transformants of cotton. The confirmed transgenic plants were exposed to insect pests, pink bollworm (Pectinophora gossypiella), and army bollworm (Helicoverpa armigera). Bioassay results revealed that 60% mortality was observed against pink bollworm, and 75% mortality was observed against army bollworm in transgenic plants containing both Cry3Bb1 and Cry3 genes (M1 transgenic plants). In M2 transgenic plants containing only the Cry3Bb1 gene, the mortality was observed to be 40% in the pink bollworm population, whereas 45% mortality was observed in the army bollworm population. In the case of M3 transgenic plants containing single gene-Cry3, the mortality was 20% in the pink bollworm population, whereas 30% mortality was observed in the army bollworm population. Almost no mortality was observed in non-transgenic Eagle-2 control plants. Hence, the developed cotton transformants have improved resistance against chewing insect pests.

Extension Interventions for Enlightening Tribal Farmers for Enhancing Cotton Production in Nalgonda District, Telangana

Cluster Frontline Demonstrations using IPM technologies were conducted on farmer fields’ during two consecutive years of both kharif (June-November 2017 and 2018) by Krishi Vigyan Kendra, Kampasagar, Telangana State, India. The results revealed that, 16.9% increased cotton yield was observed in demonstration plot (2234.0 kg ha-1) against farmers practice (1910.5 kg ha-1). The average gross returns, net returns, and benefit-cost ratios were higher in the demonstration plot as compared to the farmers’ practice. The average cost reduction was (Rs. 41402.0 ha-1) in the demonstration plot when compared to farmers’ practice (Rs. 46190.0 ha-1). Incidence of sucking pests and pink bollworm was low in demonstrations plots and adoption of IPM practices i.e. stem application in cotton at 30 and 45 days after sowing with Monocrotophos and water (1:4) ratio and 60 days after sowing with Imidacloprid and water (1:20) ratio minimize the sucking pests. Further erection of pheromone traps @ 10 ha-1 at 45 DAS to monitor pink bollworm population and spraying of need-based plant protection chemicals i.e. Azadirachtin 0.15% EC @ 2.5 l ha-1 and Thiodicarb 75% WP @ 1.5 g l-1 at early stages and Emamectin benzoate 5% SG @ 0.5 g l-1 at later stages effectively controlled pink bollworm. The average extension gap, technology gap, and technology index were 323.25 kg ha-1, 266.25 kg ha-1 and 10.65%, respectively. Hence, adoption of IPM technologies play a major role for controlling the pest complex and need arises to adopt and popularize this technology in the cotton farming to mitigate the wider extension gap between improved and farmers’ practices.

Detoxifying Enzymatic Activity and Insecticide-Resistance Gene Expression in Field Populations of Pink Bollworm (Pectinophora Gossypiella (Saund.))

Detoxifying Enzymatic Activity and Insecticide-Resistance Gene Expression in Field Populations of Pink Bollworm (Pectinophora Gossypiella (Saund.))

Pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) survival on transgenic cotton in India

BackgroundInsecticidal proteins from the Bacillus thuringiensis (Bt) marks the genetically modified cotton crop that was commercialized in India in March 2002 for the control of lepidopteron bollworms. Despite organized initial control, the pink bollworm (PBW), Pectinophora gossypiella (Saunders), adapted itself to cry toxins resulted in field control failures in 2016 and 2017. The present study was designed to understand the survival and development of PBW populations differing in susceptibility to Cry toxins on Bt and non-Bt plants. ResultsFor assessment of infestation, populations were collected from different cotton growing states. Per cent infestation of flowers and green bolls in the study areas were in the range of 3.09–29.26 and 36–91.20% for flowers and green bolls, respectively. Among different locations highest magnitude of resistance to Cry1Ac (371.8-fold) and Cry2Ab (4214.3-fold) was spotted in late season populations of Rajkot collected from bolls. Further, in order to confirm field level resistance of surviving larvae on high and low concentrations of Cry toxins, larvae were pooled and subjected to boll bioassays. Results revealed that, none of the larvae from susceptible populations survived on BGII bolls. Although, the same populations showed a survival of 38 and 32%, which led to 80% locule damage on non-Bt cotton. Maximum survival (32%) and locule damage (70%) was observed for Maharashtra (F-H) Cry2Ab and Gujarat (B-H) Cry2Ab populations recorded 36% survival and 70% mortality, respectively, on BGII cotton and 58.33% survival and 60% locule damage on non-Bt cotton, respectively. Populations derived from survivals on low concentrations produced the lowest survival and locule damage on Bt cotton. Maximum number of mines on epicarp (2.4 mines/boll) was recorded by susceptible population on NBt cotton. Green bolls of Bt and NBt cotton did not differ in the number of mines.ConclusionIt was concluded that none of the larvae from susceptible populations survived on BGII bolls. Although, the same populations showed a survival of 38 and 32%, which led to 80% locule damage on non-Bt cotton

Degree day-based model predicts pink bollworm phenology across geographical locations of subtropics and semi-arid tropics of India

There is a global concern about the effects of climate change driven shifts in species phenology on crop pests. Using geographically and temporally extensive data set of moth trap catches and temperatures across the cotton growing states of India, we predicted the phenology of cotton pink bollworm Pectinophora gossypiella (Saunders). Our approach was centered on growing degree days (GDD), a measure of thermal accumulation that provides a mechanistic link between climate change and species’ phenology. The phenology change was predicted by calculating absolute error associated with DD and ordinal date, an alternative predictor of phenology, for peak moth abundance. Our results show that GDD outperformed the ordinal dates in predicting peak moth abundance in 6 out of 10 selected locations. Using established thresholds of 13.0/34.0 °C, mean DD accumulated between the consecutive moth peaks across different years were estimated at 504.05 ± 4.84. Seven generations were determined for pink bollworm in a cropping season, the length of which varied between 35 and 73 days in response to temperature. Pink bollworm population reached its peak during third generation which can be the target for management actions. The study provides essential information for developing pink bollworm management strategies under climate change.

Evidence for population expansion of Cotton pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) in India

Pink bollworm, Pectinophora gossypiella (Saunders) infestation on Bt cotton is a major concern to cotton production in India. The genetic diversity and phylogeographic structure of the insect in light of PBW resistance needs to be revisited. The objective of this study was to identify different haplotypes of pink bollworm and their distribution in India. To achieve this we studied the population structure in 44 cotton growing districts of India. The partial mitochondrial COI sequence analyses of 214 pink bollworm populations collected from 44 geographical locations representing 9 cotton growing states of India were analysed. Genetic diversity analysis exhibited presence of 27 haplotypes, among them Pg_H1 and Pg_H2 were the most common and were present in 143 and 32 populations, respectively. Distributions of pairwise differences obtained with partial COI gene data from the overall Indian populations are unimodal, suggesting population expansion in India. Significant neutrality test on the basis of Tajima’ D and Fu’s Fs presented a star-shaped haplotype network together with multiple haplotypes. The unimodal mismatch distribution, rejection of neutrality test with significant negative values supported the theory of demographic expansion in cotton pink bollworm populations in India. Genetic data not only provides us with a perspective of population genetics, but also that the two populations of pink bollworm, those occurring early in the season are genetically close to the late season populations with respect to their partial CO1 region. Resistance to Cry toxins does not seem to have had an impact on this region of the mt DNA in populations of pink bollworm.

Bt resistance alleles in field populations of pink bollworm from China: Similarities with the United States and decreased frequency from 2012 to 2015.

Although most monitoring of pest resistance to widely cultivated transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) relies on bioassays, DNA screening for alleles associated with resistance has some advantages, particularly for rare, recessively inherited resistance. In China's Yangtze River Valley, where farmers first planted transgenic cotton producing Bt toxin Cry1Ac in 2000, bioassays have been used to monitor the recessive resistance of pink bollworm (Pectinophora gossypiella). Previous bioassay results show a small but significant increase in resistance to Cry1Ac during 2008-2010, followed by a significant decrease in resistance during 2011-2015 associated with extensive planting of second-generation hybrid cotton seeds that boosted the percentage of non-Bt cotton. Here we screened DNA from 19 748 pink bollworm collected during 2012-2015 from the Yangtze River Valley for seven alleles associated with resistance to Cry1Ac. These alleles were previously identified from lab-selected strains; three from the U.S. and four from China. The most common resistance allele was first identified from the U.S. and accounted for over 71% of all resistance alleles detected. Resistance was rare, with the total frequency of the seven resistance alleles showing a significant, 2.3-fold decrease from 0.0105 (95% CI: 0.0084-0.0132) in 2012 to 0.0046 (0.0031-0.0067) in 2015. The DNA screening data confirm results from bioassays showing pink bollworm resistance to Cry1Ac remained rare in the Yangtze River Valley from 2012-2015. The prevalence in China of the resistance allele identified from the U.S. implies a shared genetic basis of resistance that could facilitate molecular monitoring of resistance. © 2019 Society of Chemical Industry.

Widespread infestation of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechidae) on Bt cotton in Central India: a new threat and concerns for cotton production

The pink bollworm Pectinophora gossypiella (Saundars) (Lepidoptera: Gelechidae) has recently emerged as a serious menace on Bt cotton in India. Extensive roving surveys were conducted in 83 locations spread across 16 major cotton growing districts of Maharashtra State, India to assess the level of pink bollworm infestation in Bt cotton. The dynamics and severity of pink bollworm damage during the different stages of boll development (90–130 days of crop age) were assessed based on random sampling of green bolls, opened bolls and picked bolls per plant and number of locules damaged per boll. Survey results revealed a widespread infestation of pink bollworm on Bt cotton across the surveyed sites in a range of 40–95% which accounts for anticipated yield losses between 20 and 30%. A typical pattern of progressive increase in the level of pink bollworm infestation and intensification of locular damage with the advancement of the crop season was observed. The pink bollworm hitherto was supposed to be under control since the introduction of Bt cotton in India, now it appears to be widespread, especially on Bt cotton throughout the cotton growing areas of Maharashtra State which shares approximately 36% and 25% of the country’s cotton area and production, respectively. This article discusses the implications of serious outbreak of pink bollworm infestations in Bt cotton and also suggest measures necessary to mitigate its potential threat to Indian cotton production. The modulation of management practices aimed at manipulation of cotton cropping pattern being followed in the country in general and Maharashtra in particular could strengthen the management of pink bollworm populations effectively. We discuss the practicality of several management options aimed at achieving this goal.

A new observation on feeding behaviour of pink bollworm and its application in screening Bt-resistant population.

The pink bollworm (PBW), Pectinophora gossypiella (Saund.) does not feed on leaves in natural circumstances. We made an attempt with the first instar larva (5days old) and found it eats the leaf in the absence of other foods. Utilizing this new feeding behaviour, a simple methodology was developed for screening of resistance in PBW against Bt cotton plants. The PBW collected from BGII Bt cotton fields (BGII-resistant population) and NBAIR culture (susceptible population) were reared under laboratory conditions for two generations. Laboratory reared 5-day old larvae of PBW were released on cotton leaf discs individually for screening. The BGII-resistant and susceptible larvae fed an average leaf area of 75.52 ± 16.68 and 5.95 ± 0.93 mm2 with survival rate of 90 and 4% respectively, in BGII Bt cotton leaves. Whereas in case of non-Bt cotton (MCU13), the BGII-resistant and susceptible larvae consumed average leaf area of 114.84 ± 23.70 and 116.80 ± 24.14 mm2 with survival rate of 93.34 and 95.33%, respectively. In addition to the screening process, the larval survivors were transferred to an artificial diet after 7days of experiment and observed up to their emergence as adults. To confirm the development of resistance in PBW, sequencing of larval DNA amplicons was carried out and it revealed mutation in the cadherin gene of the BGII-resistant PBW population. Hence, the detached leaf bit feeding assay described here could be used in a simple manner for screening of resistance developed by PBW against Bt cotton and also for evaluating Bt cotton plants for their inherent resistance to PBW. This method could also be used for studying toxicity of Bt isolates by coating spore-crystal mixture on non-transgenic cotton leaf discs.

Population genetic structure of cotton pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) using mitochondrial cytochrome oxidase I (COI) gene sequences from India

Pink bollworm (PBW), Pectinophora gossypiella is one of the most destructive pest’s globally inflicting huge economic losses in cotton even during later stages of crop growth. In the present investigation, the population genetic structure, distribution, and genetic diversity of P. gossypiella in cotton growing zones of India using partial mitochondrial DNA cytochrome oxidase-I (COI) gene was addressed. The overall haplotype (Hd), number of nucleotide differences (K), and nucleotide diversity (π) were 0.3028, 0.327, and 0.00047, respectively which suggest that entire population exhibited low level of genetic diversity. Zone-wise clustering of population revealed that central zone recorded low level of Hd (0.2730) as compared to north (0.3619) and south (0.3028) zones. The most common haplotype (H1) reported in all 19 locations could be proposed as ancestral/original haplotype. This haplotype with one mutational step formed star-like phylogeny connected with 11 other haplotypes. The phylogenetic relationship studies revealed that most haplotypes of populations are closely related to each other. Haplotype 5 was exclusively present in Dharwad (South zone) shared with populations of Hanumangarh and Bathinda (North zone). The result indicated that there is no isolation by distance effect among the Indian populations of PBW. The present study reports a low genetic diversity among PBW populations of India and H1, as ancestral haplotype from which other haplotypes have evolved suggests that the migration and dispersal over long distance and invasiveness are major factors.

Inheritance of field-relevant resistance to the Bacillus thuringiensis protein Cry1Ac in Pectinophora gossypiella (Lepidoptera: Gelechiidae) collected from India.

The inheritance and phenotypic expression of resistance to Bacillus thuringiensis Cry1Ac insecticidal protein were studied in selected populations of pink bollworm, Pectinophora gossypiella (Saunders), that were collected from Bollgard cotton in India. The individual populations in the pool were Cry1Ac resistant and sourced from Cry1Ac-containing Bt cotton (Bollgard) hybrids in 2010. Laboratory selection on diet with 1.0 µg Cry1Ac protein mL(-1) increased the percentage reaching at least third instar from 7% in the F3 generation to 94% in the F15 generation, a 257-fold increase in median lethal concentration relative to the susceptible strain. Analysis of reciprocal genetic crosses between the Cry1Ac-resistant strain NKJ and a susceptible laboratory strain MRC showed a dominance of 0.22, indicating that the inheritance of Cry1Ac resistance is partially recessive at Cry1Ac concentrations comparable with those in Bollgard. Analyses of backcrosses of F1 hybrid moths with NKJ and MRC indicated that resistance is autosomal. The Cry1Ac-resistant strain exhibited little or no cross-resistance to the Cry2Ab2 protein. This is the first study of the dominance of Cry1Ac field resistance in P. gossypiella. The results provide the basis for refining resistance management strategies for Bt cotton.

Analysis of resistance to Cry1Ac in field-collected pink bollworm, Pectinophora gossypiella (Lepidoptera:Gelechiidae), populations

High survivorship of pink bollworrm, Pectinophora gossypiella in bolls of Bollgard® cotton hybrids and resistance to Cry1Ac protein, expressed in Bollgard cotton were reported in field-populations collected from the state of Gujarat (western India) in 2010. We have found Cry1Ac-resistance in pink bollworm populations sourced from Bollgard and non-Bt cotton fields in the adjoining states of Maharashtra and Madhya Pradesh in Central India. Further, we observed reduced binding of labeled Cry1Ac protein to receptors localized on the brush-border membrane of pink bollworm larval strains with high tolerance to Cry1Ac. These strains were sourced from Bollgard and conventional cotton fields. A pooled Cry1Ac-resistant strain, further selected on Cry1Ac diet also showed significantly reduced binding to Cry1Ac protein. The reduced binding of Cry1Ac to receptors could be an underlying mechanism for the observed resistance in pink bollworm populations feeding on Bollgard hybrids.

Diminishing Returns from Increased Percent Bt Cotton: The Case of Pink Bollworm

Regional suppression of pests by transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) has been reported in several cropping systems, but little is known about the functional relationship between the ultimate pest population density and the pervasiveness of Bt crops. Here we address this issue by analyzing 16 years of field data on pink bollworm (Pectinophora gossypiella) population density and percentage of Bt cotton in the Yangtze River Valley of China. In this region, the percentage of cotton hectares planted with Bt cotton increased from 9% in 2000 to 94% in 2009 and 2010. We find that as the percent Bt cotton increased over the years, the cross-year growth rate of pink bollworm from the last generation of one year to the first generation of the next year decreased. However, as the percent Bt cotton increased, the within-year growth rate of pink bollworm from the first to last generation of the same year increased, with a slope approximately opposite to that of the cross-year rates. As a result, we did not find a statistically significant decline in the annual growth rate of pink bollworm as the percent Bt cotton increased over time. Consistent with the data, our modeling analyses predict that the regional average density of pink bollworm declines as the percent Bt cotton increases, but the higher the percent Bt cotton, the slower the decline in pest density. Specifically, we find that 95% Bt cotton is predicted to cause only 3% more reduction in larval density than 80% Bt cotton. The results here suggest that density dependence can act against the decline in pest density and diminish the net effects of Bt cotton on suppression of pink bollworm in the study region. The findings call for more studies of the interactions between pest density-dependence and Bt crops.

Field‐evolved resistance to Bt toxin Cry1Ac in the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), from India

The pink bollworm is one of the most destructive pests of cotton. Transgenic cotton producing Bt toxin Cry1Ac or a combination of Cry1Ac and Cry2Ab2 has been used effectively against this pest. However, some other insects have evolved resistance to Bt toxins in the field. During the 2007-2008 and 2008-2009 seasons, pink bollworm populations in India were surveyed to evaluate their responses to Cry1Ac and seed powder containing Cry1Ac and Cry2Ab2. The results provide evidence that resistance to Cry1Ac had evolved by 2008 in a population sampled from non-Bt cotton in the Amreli district of Gujarat in western India. The median lethal concentration of Cry1Ac for five-day-old larvae (LC50 ) was significantly higher for insects derived in 2008 from Amreli than for any of the other field populations tested from four locations in India. For Cry1Ac, the mean LC50 for the strain derived from Amreli in 2008 was 44 times higher than for the most susceptible population. However, for seed powder of Bollgard II containing primarily Cry2Ab2, the 2008 Amreli population was only slightly less susceptible than the most susceptible population. The data reported here constitute the first evidence of field-evolved resistance of pink bollworm to Cry1Ac. This initial evidence spurred more extensive evaluations during the 2009-2010 growing season, which confirmed field-evolved resistance to Cry1Ac in Amreli. The lack of cross-resistance to Cry2Ab2 suggests that plants producing this toxin are likely to be more effective against resistant populations than plants producing only Cry1Ac.