Adult Bollworms Research Articles

Study on Spatial Distribution and Occurrence of Pink Boll Worm on Cotton

An investigation was carried out to “Study on spatial distribution and occurrence of pink boll worm on cotton” under Agricultural Research Station (ARS), Adilabad, Professor Jayashankar Telangana State Agricultural University during Kharif, 2018 and 2019. The main objective of this study was to determine distance and migration of pink boll worm adults from ginning mill to cropping area of different location through GIS tools and the results revealed that spatial distribution of pink bollworm was found to be low in the villages which are 15 kms away from the ginning mill i.e. pheromone catches (1515 and 1267) and PBW larvae/20 bolls (13.76 % and 15.00%) and villages which are 5kms away from the ginning mill was found to be high incidence i.e. pheromone catches (2185 and 1929) and PBW larvae/20 bolls (38.14 % and 28.10%) during Kharif 2018 and 2019, respectively.

Suitability of Satellite Imagery for Surveillance of Maize Ear Damage by Cotton Bollworm (Helicoverpa armigera) Larvae

The cotton bollworm (Helicoverpa armigera, Lepidoptera: Noctuidae) poses significant risks to maize. Changes in the maize plant, such as its phenology, influence the short-distance movement and oviposition of cotton bollworm adults and, thus, the distribution of the subsequent larval damage. We aim to provide an overview of future approaches to the surveillance of maize ear damage by cotton bollworm larvae based on remote sensing. We focus on finding a near-optimal combination of Landsat 8 or Sentinel-2 spectral bands, vegetation indices, and maize phenology to achieve the best predictions. The study areas were 21 sweet and grain maze fields in Hungary in 2017, 2020, and 2021. Correlations among the percentage of damage and the time series of satellite images were explored. Based on our results, Sentinel-2 satellite imagery is suggested for damage surveillance, as 82% of all the extremes of the correlation coefficients were stronger, and this satellite provided 20–64% more cloud-free images. We identified that the maturity groups of maize are an essential factor in cotton bollworm surveillance. No correlations were found before canopy closure (BBCH 18). Visible bands were the most suitable for damage surveillance in mid–late grain maize (|rmedian| = 0.49–0.51), while the SWIR bands, NDWI, NDVI, and PSRI were suitable in mid–late grain maize fields (|rmedian| = 0.25–0.49) and sweet maize fields (|rmedian| = 0.24–0.41). Our findings aim to support prediction tools for cotton bollworm damage, providing information for the pest management decisions of advisors and farmers.

Technical efficiency of insecticides against Helicoverpa armigera Hübner caterpillars in corn crops

Goal. To establish the effectiveness of the use of modern insecticides in corn crops against the cotton bollworm.
 Methods. Determination of the technical efficiency of insecticides was carried out in field conditions. Treatment with chemical insecticides was carried out on the 3rd day after the mass flight of H. armigera once, with biological preparations — twice, during the period of mass revival of caterpillars. Observation of the pest after treatment with drugs was carried out on the 3rd, 7th and 14th day at the rate of ex./100 plants in four repetitions, by counting them on cobs, panicles and leaves. For the experiments, the Paradiz corn hybrid (mid-early) was used, the seeds of which were pre-treated at the plant with a fungicide Maksym XL 035 FS (fludioxonil, 25 g/l, metalaxyl-M, 10 g/l) — 1 l/t. The beginning and intensity of the flight of cotton bollworm adults was determined using pheromone traps. The collection of male imagos was carried out every three days after the start of the flight. Data on crop losses were based on the actually calculated indicators of each variant of the experiment. The reliability of the obtained results was determined using the mathematical and statistical method.
 Results. In 2021—2022, when testing insecticides against cotton bollworm caterpillars on corn crops, the highest technical efficiency was provided by: Koragen 20 KS (chlorantraniliprole, 200 g/l) — 82.1% and Ampliho 150 ZC, FC (chlorantraniliprole 150 g/l, lambda-cyhalothrin 50 g/l) — 77.7%. The biological preparations of Lepidotsyd-BTU, r. (Bacillus thuringiensis var. Kurstaki, serotype 3, titer 1.0 ќ 10 9 CFU/cm3) had the lowest technical efficiency — 48.2% and Bitoksybatsylin-BTU, r. (Bacilius thuringiensis var Thuringiensis, endospores — titer 1.0 ќ 10 9 CFU/ cm3) — 53.7%. When using the tested insecticides, the productivity of the Paradiz hybrid was higher compared to the control. When treated with Koragen 20 KS and Ampligo 150 ZC, FC, the yield increased by 0.480 and 0.320 t/ha. When treated with Radiant, CS (spinetoram, 120 g/l) and Belt 480 SC, CS (flubendiamide, 480 g∕l), — by 0.250 and 0.280 t/ha, respectively more. With the use of Liufoks 105 ES, e.c. (75 g/l fenoxycarb, 30 g/l lufenuron), Lepidotsyd-BTU, r. and Bitoksybatsylin-BTU, r., the amount of preserved corn grain yield was 0.190, 0.110 and 0.140 t/ha, respectively.
 Conclusions. It was found that Koragen 20 KS (82.1%) and Ampligo 150 ZC, FK (7.7%) were the most effective insecticides against cotton bollworm caterpillars in the Left Bank Forest Steppe of Ukraine. The specified drugs are used in low concentrations, and with the help of phytosanitary and instrumental monitoring in corn crops, treatment is recommended to be carried out once, which in turn allows to reduce the pesticide load on the ecosystem and prevents the development of resistance in phytophagous plants.

Development and Dispersal of Helicoverpa zea (Lepidoptera: Noctuidae) on Non-Bt and Bt Pyramided Cotton.

Bollworm (Helicoverpa zea Boddie) (Lepidoptera: Noctuidae) can cause economic losses in both non-Bt and Bt cotton. Larvae modify their behavior in the presence of Bt by moving away from terminals faster in Bt cotton compared to non-Bt cotton and avoiding Bt-treated diets. Our objectives were to understand differences in bollworm egg and larvae populations within, and dispersal away from, non-Bt and Bt pyramided-toxin cotton. We conducted small plot experiments in 2016 and 2017 to monitor on-plant egg and larval numbers, and off-plant dispersal of larvae, from non-Bt and different Bt toxin pyramided cotton. Bollworm adults preferred to oviposit in most Bt toxin pyramids compared to non-Bt; this was likely unrelated to detection of Bt by adults, but rather density-dependent aversion from high larval populations. First instar numbers were similar in all non-Bt/Bt toxin pyramids and dispersed at a similar rate. Second through fifth instar numbers were higher in non-Bt than Bt toxin pyramids but dispersed equally from all non-Bt/Bt toxin pyramids, regardless of Bt pyramid type. Development times of larvae were often slower in Bt toxin pyramids compared to non-Bt. Fifth instars were found in, and dispersing from, Bt toxin pyramids containing Vip3A, raising concerns of resistance development. Furthermore, differences in oviposition rate among non-Bt/Bt toxin pyramids and slowed development rate of larvae on Bt varieties could create inconsistencies in generation times emerging from Bt and non-Bt hosts, which could contribute to resistance development.

Determining the major Bt refuge crops for cotton bollworm in North China.

Evaluation of the effectiveness of refuge strategies involved in cotton bollworm Bt resistance management would be aided by technologies that allow monitoring and quantification of key factors that affect the process under field conditions. We hypothesized that characterization of stable carbon and nitrogen isotopes in adult bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) moths may aid in determining the larval host that they developed upon. We found moths reared from larvae fed on peanut, soybean or cotton, respectively, could be differentiated using isotopic analyses that also corresponded to their respective larval host origins. These techniques were then used to classify feral second-generation bollworm moths caught in Bt cotton (Gossypium hirsutum) fields into different populations based on their isotopic signatures. In 2006-2007 feral moths captured in Bt cotton fields predominantly correlated with the peanut (Arachis hypogea) having served as their larval host, indicating this is the most important refuge crop for Bt-susceptible bollworm individuals (providing 58%-64% individuals) during independent moth peaks for the second generation in North China. The remaining feral moths correlated with soybean (Glycine max) (0-10%); other C3 plant (20%-22%) and non-C3 plant (12%-14%) host types also provided some Bt-sensitive moths. Field observations showed that peanut constitutes the primary refuge crop contributing to sustaining Bt-susceptible moths dispersing into cotton in North China. These results suggest that peanut may be a more effective refuge to sustain Bt-susceptible bollworm individuals and reduce the risk of development of a Bt-resistant biotype.

Field Longevity of a Fluorescent Protein Marker in an Engineered Strain of the Pink Bollworm, Pectinophora gossypiella (Saunders)

The cotton pest, pink bollworm (Pectinophora gossypiella (Saunders)), is a significant pest in most cotton-growing areas around the world. In southwestern USA and northern Mexico, pink bollworm is the target of the sterile insect technique (SIT), which relies on the mass-release of sterile pink bollworm adults to over-flood the wild population and thereby reduce it over time. Sterile moths reared for release are currently marked with a dye provided in their larval diet. There are concerns, however, that this marker fails from time to time, leading to sterile moths being misidentified in monitoring traps as wild moths. This can lead to expensive reactionary releases of sterile moths. We have developed a genetically marked strain that is engineered to express a fluorescent protein, DsRed2, which is easily screened under a specialised microscope. In order to test this marker under field conditions, we placed wild-type and genetically marked moths on traps and placed them in field cages. The moths were then screened, in a double-blind fashion, for DsRed2 fluorescence at regular intervals to determine marker reliability over time. The marker was shown to be robust in very high temperatures and generally proved reliable for a week or longer. More importantly, genotyping of moths on traps by PCR screening of the moths was 100% correct. Our findings indicate that this strain - and fluorescent protein markers in general - could make a valuable contribution to SIT.

Mortality and reproductive effects of ingested spinosad on adult bollworms

Upon emergence from their pupal cells, bollworm, Helicoverpa zea (Boddie), adults actively seek and feed on plant exudates before they disperse and reproduce on suitable host plants. This nocturnal behavior of the bollworm may be exploited as a pest management strategy for suppression of the insect by using an attractant/stimulant mixed with an insecticide to induce feeding to cause adult mortality or reproductive reduction/inhibition. This study aimed to determine in the laboratory whether or not spinosad when mixed with sucrose solution as a feeding stimulant and ingested by bollworm could influence mortality and reproduction of the insect. Sublethal concentrations of spinosad fed to laboratory-reared females confined with males significantly reduced percentage hatch of eggs at 0.1 mg L(-1), and it was reduced to near zero at 2.5 mg L(-1) when compared with females fed 2.5 M sucrose solutions only. The lethal concentration (LC(99)) for males captured from the field in sex-pheromone-baited traps was 73 mg L(-1) for 24 h response. Proboscis extension response was not inhibited significantly even at 10 g L(-1). In spite of a 137-fold increase in lethal dose concentration, spinosad did not inhibit feeding. A detailed study of laboratory-reared and field-collected bollworm adults relative to mortality and reproduction after ingestion of spinosad indicates that spinosad would be useful in an attract-and-kill strategy to control the insect when mixed with a feeding attractant/stimulant. Field validation of the data is warranted.

Role of juvenile hormone esterase and epoxide hydrolase in reproduction of the cotton bollworm, Helicoverpa zea

The role of juvenile hormone (JH) esterase (JHE) and epoxide hydrolase (EH) in reproduction of the cotton bollworm, Helicoverpa zea, was investigated. Peak emergence of male and female bollworm adults occurred early in the scotophase. Female adults were added to males in a 1:2 ratio, respectively, at the beginning of the first photophase after emergence (d0). The highest oviposition rates for mated females were noted on d 2–4. The in vitro JH III esterase and JH III EH activity was measured in whole body homogenates of virgin and mated females from d0 to d8 post-emergence. Maximal JHE activity for virgin females occurred on d2 (1.09±0.14(±1 SEM) nmol of JH III degraded/min/mg protein), which was approximately twice that of mated females on the same day. The same results were observed for EH where the activity peaked on d2 at 0.053±0.003 as compared to 0.033±0.003 nmol of JH III degraded/min/mg protein, respectively. By d4, both JHE and JH EH activities declined significantly in virgin and mated females and were the same through d7. The developmental changes and effects of mating on JH degradation were similar when measured per insect. The highest levels of JHE and JH EH activity/min/mg protein in d2 virgin and mated females was found in ovaries followed by the carcass and then haemolymph; no EH activity was found in haemolymph as expected. For ovary, the JHE and JH EH activity was highest in virgin compared to mated females. The role of both enzymes in the regulation of reproduction is discussed.

Comparative Production of <I>Helicoverpa zea</I> (Lepidoptera: Noctuidae) from Transgenic Cotton Expressing Either One or Two <I>Bacillus thuringiensis</I> Proteins with and without Insecticide Oversprays

Transgenic cotton, Gossypium hirsutum (L.), expressing either one or two Bacillus thuringiensis ssp. kurstaki Berliner (Bt) proteins was compared with the conventional sister line in field experiments with regard to production of bollworm, Helicoverpa zea (Boddie), and bolls damaged by bollworm. The relative numbers of bollworms that developed on Bollgard (Monsanto Co., St. Louis, MO), Bollgard II (Monsanto Co.), and conventional cotton were estimated under nontreated conditions in 2000 and both insecticide-treated and nontreated conditions in 2001-2002 in North Carolina tests. Averaged across seven field studies under nontreated conditions, Bollgard cotton generated statistically similar numbers of large (L4-L5) bollworm larvae compared with the conventional variety; however, Bollgard cotton produced significantly fewer damaged bolls and bollworm adults than the conventional variety. Production of large larvae, damaged bolls, and adults was decreased dramatically by Bollgard II cotton as compared with Bollgard and conventional varieties. When comparing insecticide-treated and nontreated cotton genotypes, both Bt cotton sustained less boll damage than the conventional variety averaged across insecticide regimes; furthermore, Bollgard II cotton had fewer damaged bolls than the Bollgard variety. When averaged across cotton genotypes, pyrethroid oversprays reduced the numbers of damaged bolls compared with the nontreated cotton. Insecticide-treated Bollgard cotton, along with insecticide-treated and nontreated Bollgard II cotton reduced production of bollworm larvae, pupae, and adults. However, the addition of pyrethroid oversprays to Bollgard II cotton seemed to be the best resistance management strategy available for bollworm because no bollworms were capable of completing development under these conditions.

Carryover mechanism of pink bollworm Pectinophora gossypiella (Saunders) in Andhra Pradesh

Investigations on the carryover mechanism of pink bollworm from season to season were undertaken during 1998-99 at the Regional Agricultural Research Station, Lam, Guntur, Andhra Pradesh. The studies revealed that pink bollworm adults were continuously emerging in the local ginning mills from the seed cotton received regularly from different regions of the state. The damaged and discarded kapas, blo lint and seed in ginning mills were found as the major sources for regular build up of pink bollworm on cotton in this region. Further, the pink bollworm damage was very high in unpickable and discarded bollsmo present on the cotton stubbles and about 1/3 of the damaged bolls harboured live larvae indicating that the cotton stubbles even after harvesting supported high larval population and formed an important link in the old carryover of the pest.

Automated Pheromone Traps Show Male Pink Bollworm (Lepidoptera: Gelechiidae) Mating Response Is Dependent on Weather Conditions

The mating response of male pink bollworm, Pectinophora gossypiella (Saunders), based on time of capture, was monitored in cotton (Gossypium hirsutum) with an automated pheromone trap. Weather parameters were recorded automatically at the same trapping site. Data were accumulated and transmitted via an infrared telemetry link to a base-station computer located on farm property. The collected data were accessed and downloaded via a telephone modem. As the growing season progressed, the time of peak trap catch gradually shifted from early in the evening to late in the evening. The time interval of male fight activity was defined widely both early and late in the season and was defined more narrowly in midseason. The major factors affecting the number of males caught and the time of peak catch were temperature, wind speed, and time of sunset. As previously reported, wind speeds >2.5 m/s and temperatures below 20°C suppressed flight activity. The number of male moths captured was suppressed after insecticide applications and rain. A model predicting peak flight times was validated, and modifications were suggested. The results suggest that the use of automated traps that incorporate weather information would be invaluable in predicting optimal times of insecticide application for control of pink bollworm adults and, more importantly, would prevent applications at times that would be ineffective.

Mating Response Behavior of Sterile Pink Bollworms (Lepidoptera: Gelechiidae) Compared with Natives

A timing pheromone trap was invented to capture male pink bollworm adults Pectinophora gossypiella (Saunders) for specific time intervals as they entered a commercial pheromone trap. The device was used to compare the window of male pheromone response of two different strains of released sterile pink bollworm populations with responses of native adult males. In all trials in cotton fields in Phoenix, AZ, and in Palo Verde, CA, the released sterile male adults entered commercial pheromone traps during the same time interval as native adult males. Native and sterile females were comparable in attracting and successfully mating with natives when confined in field stations. Thus, the quality of behavioral responses (male-pheromone response window) of laboratory-reared male pink bollworms was comparable to native adults infesting cotton fields in Arizona and California.

Reversion of Permethrin Resistance in Field Strains and Selection for Azinphosmethyl and Permethrin Resistance in Pink Bollworm (Lepidoptera: Gelechiidae)

Rearing of two fields strain (Marana, Yuma) of pink bollworm, Pectinophora gossyptella (Saunders), from Arizona under conditions free of insecticidesresulted in reversion of resistance (in adults) in four and five generations, respectively, to levelsclose to that found in the susceptible laboratory strain. Permethrin resistance in these field strains is unstable and is apparently in its early phase of development. Results suggest that monitoring of pink bollworm resistance in field strains reared in the laboratory should be performed in the F1 generation. Subsequent selection studies were performed on both larval and adult stages to investigate the capacity of the pink bollworm to develop resistance in both life stages. Fourteen generations of selection of larvae and adults with azinphosmethyl produced 1.9- and 1.6- fold tolerance, respectively, in the adult stage. Sixteen generations of larval selection with permethrin produced 9.7-fold resistance in adults; 14 generations of adult selection produced 8.8-fold resistance in adults. Azinphosmethyl evidently possessesa low degree of selectivity for development of resistance in pink bollworm adults. Selection of larvae with both azinphosmethyl and permethrin seemed to cause higher levels of tolerance in larvae than in adults.

Resistance to Cypermethrin in First Generation Adult Bollworm and Tobacco Budworm (Lepidoptera: Noctuidae) Populations Collected as Larvae on Wild Geranium, and in the Second and Third Larval Generations

First generation (G1) larvae of the overwintered (parent) population of bollworm, Heliothis zea (Boddie), and of the tobacco budworm, H. virescens (F.), were collected in wild geranium, Geranium dissectum L. and G. carolinianum L., and then reared on artifical diet. These first generation (G1) adults were tested with a vial bioassay for resistance to cypermethrin. Survival, at the 10 p. g per vial rate, of the (G1) adult male and female bollworm was 2.9 and 5.6% and of the (G1) tobacco budworm-26 and 41.5%, respectively. First generation (G1) male and female tobacco bud worm moths that survived the 10 p.g per vial rate were mated, and the resulting second generation (G2) larvae were divided into two groups. One group was tested as third instars for resistance in a cotton terminal bud bioassay. The second group was reared to the adult stage, mated, and the resulting third generation (G3) larvae were treated as third instars with topical application of cypermethrin. In the cotton terminal bud bioassay, 65% of the (G2) larvae tested survived an application of Cymbush (cypermethrin) at its highest recommended field rate (0.09 kg [AI]/ha). LD50’s and LD50’s obtained from the topical treatment of (G3) larvae with cypermethrin were intermediate to those reported by others for tobacco budworm larvae collected from fields with control problems in the Mississippidelta. These data indicate that if the (G1) adult and (G2) larval populations in cotton in June were treated with pyrethroids, control problems would be more likely to occur later in the growing season.

Pattern of Emergence of Adult Heliothis1 from Fields Planted to Cotton, Corn, Tobacco, and Soybeans 23

Adult bollworms, Heliothis zea Boddie, and tobacco budworms, H. virescens (F.) emerging from overwintering populations were difficult to detect when covers were placed over the soil in fields planted the previous year in corn, cotton, soybeans, or tobacco, but later generations were easily detected. Counts of larvae taken weekly in these fields and subsequent identification of the larvae indicated that blacklight traps detected the presence of bollworm moths but not budworm moths.

Heliothis zea and H. virescens: moth activity as measured by blacklight and pheromone traps.

Activity of adult bollworms, Heliothis zea (Boddie) and tobacco budworms, H. virescens (F.), was monitored with BL and pheromone traps. Light traps captured far more of both sexes of bollworms than of tobacco budworms; pheromone traps seemed more effective in early season when populations were low. When both species were combined as attractants in the same pheromone traps, significantly fewer moths of each species were captured than when traps contained only 1 species.

A Model to Describe the Uniform Buildup of Populations of Adult Bollworms and Cabbage Loopers 12

Linear regression equations for the number of Heliothis zea (Boddie) collected in light traps at Stoneville, Miss., showed an essentially consistent rate of increase from spring to fall for 6 years. Also, in 1969 the rates of increase of H. zea at locations in 5 states were similar. Likewise, light trap catches of Trichoplusia ni (Hubner) at Waco, Tex., for 14 years showed a relatively consistant rate of increase although they were somewhat higher in 2 years and somewhat lower in 3 years. Equations such as these may be useful for comparison with the output of more dynamic models or could provide a simplified input of insect populations into crop or economic models. The inherent stability of populations of these economic pests despite an unstable agronomic ecosystem has implications for integrated pest management programs.

Spectral Sensitivity of the Compound Eyes of Field-Collected Adult Bollworms and Tobacco Budworms1,2

When the electroretinogram was used to measure the spectral sensitivity of the compound eye of the bollworm moth, Heliothis zea (Boddie), and the tobacco budworm moth, Heliothis virescens (F.), the compound eyes of both species responded to light stimuli over a range of wavelengths of 350 to 700 nm and were most sensitive to wavelengths of 365 and 480-575 nm. Also, with both species, receptors in the compound eyes failed to respond to infrared wavelengths from 800 to 1520 nm, though the levels of radiation intensity were 22-35 µw/cm2, 100 times those required to elicit a response at 700 nm and 10,000 times those required at 500 nm. Wavelengths of 365 nm and 480-575 nm may be the most effective light stimuli for these moths.

Bollworms and Tobacco Budworms: Mating of Adults at Three Locations in the Mississippi Delta12

When adult bollworms, Heliothis zea (Boddie), and tobacco budworms, H. virescens (F.), were collected over a 2-year period in insect traps equipped with blacklight lamps at 3 locations (north, central, and south) in the Mississippi Delta, a high percentage of the bollworm catch at each location was males. A higher percentage of mated females occurred at the locations that had a higher percentage of males. An average of one or more spermatophores per female bollworm usually was found when the monthly collections consisted 55% or more males. Many of the females collected at each location were young unmated moths, but of those that had mated, the larger percentage had mated only and Similarly, the percentage of male tobacco budworm moths and the average number of spermatophores per mated female tobacco budworm moth were highest at the north location and decreased at the more southern locations.

Bollworms and Tobacco Budworms: Mortality of Adults Exposed to Insecticides on Cotton12

Adult bollworms, Heliothis zea (Boddie), and tobacco budworms, H. virescens (F.), were confined in small field cages on terminals of field-grown cotton that had bee sprayed (high clearance sprayer) with monocrotophos, carbaryl, carbaryl + molasses, toxaphene + methyl parathion, or toxaphene + DDT either immediateely after the treatment or 53 hours later, mortality was determined after 24 and 48 hours of each exposure. When moths were caged on the treated cotton immediately after treatment, mortality was significantly greater than in the untreated check after either 24 or 48 hours of exposure to all treatments except toxaphene + DDT. When moths were caged on the treated cotton 53 hours after treatment, mortality was significantly greater than in the untreated check after 48 hours of exposure to carbaryl + molasses, or monocrotophos. Thus, the addition of molasses to the carbaryl formulation increased kill and extended tended residual activity.