Banded Sunflower Moth Research Articles

Registration of oilseed sunflower maintainer germplasm HA 489 with resistance to the banded sunflower moth

AbstractThe banded sunflower moth is one of the most pervasive insect pests of sunflower (Helianthus annuus L.) in North America, in large part due to its ability to overwinter in cold climates. The goal of this research is to provide germplasm containing resistance to infestation by the banded sunflower moth while retaining valuable traits, such as imidazolinone herbicide tolerance and high oleic acid content in the seed oil, along with suitable agronomic performance for the northern Great Plains climate and other similar climates where the banded sunflower moth is prevalent. HA 489 (Reg. no. GP‐370, PI 691858) is a maintainer inbred germplasm developed by pedigree selection and testcross evaluation that can fill this need. HA 489 has high oleic acid composition, exhibits tolerance to imidazolinones, and provides resistance to banded sunflower moth infestation. This line was released by the USDA‐ARS, Fargo, ND, to fill the need for sources of host‐plant resistance to important insect pests.

Capitate Glandular Trichomes Fail to Provide Significant Resistance to Banded Sunflower Moth (Lepidoptera: Tortricidae)

Extracts from capitate glandular trichomes (CGT) of wild and cultivated sunflowers, Helianthus spp., have repellent or toxic effects on sunflower specialists and generalist herbivores less closely associated with sunflower. Though CGT have been primarily examined for their potential to provide partial resistance to the sunflower moth, Homoeosoma electellum Hulst (Lepidoptera: Pyralidae), a floret- and seed-feeding pest, the banded sunflower moth (Cochylis hospes Walsingham [Lepidoptera: Tortricidae]) is a similar species more common in the primary sunflower-producing states of North Dakota and South Dakota. Replicated field trials using partially inbred lines with low or high CGT densities were used to evaluate possible reductions to seed damage by C. hospes larvae in 2016-2017. Results failed to support the idea that CGT are a useful defense against larvae of C. hospes; the putative plant defense of high trichome density corresponded to slightly more, rather than less, insect damage. A test of a secondary explanation, that strength of sunflower hulls could help determine patterns of seed damage among tested lines, produced similarly negative results. Though timing of bloom differed between groups of most- and least-damaged lines, prior research and pheromone-trapping data suggest differences in plant maturity also cannot adequately explain the observed results. While the specific mechanisms remain unclear, significant differences in susceptibility to C. hospes exist for cultivated sunflower and limit losses from this primary insect pest.

Cochylis hospes (Lepidoptera: Tortricidae) damage to male lines varies significantly and inbred susceptibility predicts damage to hybrids

AbstractLarvae of Cochylis hospes (Walsingham) (Lepidoptera: Tortricidae) (banded sunflower moth) are a primary source of insect damage to seeds of cultivated sunflower, Helianthus annuus Linnaeus (Asteraceae), in North America. Field trials were used to evaluate seed damage under natural infestations for panels of publicly released male lines, publicly derived hybrids (females crossed to one common male parent), and commercial hybrids over a total of four years. For trials in 2013–2014 including 17 male lines, seed damage ranged from 3% to 19%. The least damaged male, RHA 266, was statistically similar to one other male, RHA 455. Three commercial hybrids used as checks also received very little seed damage (< 5%). In trials during 2016–2017, hybrids created by pollinating 15 different female lines with RHA 266 showed 4–14% damage. Data from female parents explained about 28% of variation in seed damage for the hybrids. Results confirm cultivated sunflower has greater variation in susceptibility to C. hospes than previously believed, and that seed damage to inbred lines provides some predictive power for hybrids. Though breeding for resistance to C. hospes seems possible, it may be too labour-intensive without relating resistance to more easily measurable traits or genetic markers.

Concentrations of sunflower phenolics appear insufficient to explain resistance to floret- and seed-feeding caterpillars

Cultivated sunflowers, Helianthus annuus L., show significant variation in susceptibility to insect pests, though specific mechanisms of resistance are not clear. Plant secondary compounds, including phenolics, are often associated with resistance to insects and pathogens. Because several phenolics are present in sunflower florets, wild sunflowers and cultivated inbred lines were sampled to document natural variation in free phenolics and evaluate their potential effects on floret-feeding pests. Four di-O-caffeoylquinic acid isomers were the largest contributors to total phenolic content of disc florets. When identified phenolics were combined with unidentified flavonoid glycosides, total phenolic concentration in inbred lines varied fourfold (≈ 18–72 mg/g), and was significantly greater than that in wild sunflowers. Two lab assays with 50 or 100 mg/g chlorogenic acid showed inconsistent reductions in mass or increases in mortality of sunflower moth (Homoeosoma electellum Hulst) larvae after 9 days, and tests using floret tissue with low or high levels of total phenolics did not show an effect of tissue type on H. electellum development. Tests for correlation between total phenolics and field data on susceptibility of sunflowers to another floret-feeding pest, banded sunflower moth (Cochylis hospes Walsingham), did not show any significant association. Cumulatively, results suggest there may be minor effects of phenolic compounds on floret-feeding insects, but these alone are insufficient for plant defense. However, variation in concentration of phenolic compounds may remain valuable, both as a component of plant defense and a source of oxidative stability in sunflower oil.

Effect of female and male age on copulation of the banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera : Tortricidae)

Effect of female and male age on copulation of the banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera : Tortricidae)

Relative susceptibility of sunflower maintainer lines and resistance sources to natural infestations of the banded sunflower moth (Lepidoptera: Tortricidae)

AbstractThe banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Tortricidae), is a significant seed-feeding pest of sunflowers (Helianthus Linnaeus; Asteraceae) in North America. Though some wild Helianthus, interspecific crosses, and H. annuus Linnaeus cultivars (which precede hybrid sunflower breeding) have low susceptibility to banded sunflower moth, no apparent effort has been made to evaluate modern inbred lines as a source of resistance for hybrids. In field trials from 2013 to 2015, inbred maintainer (HA) lines, resistant accessions (PI), and unreleased, partially inbred (F6) lines were evaluated in field trials using natural infestations of banded sunflower moth. Results show greater seed damage to maintainer lines than the other groups, but also significant variability among lines within groups. The best maintainer, HA 207, had ≈75% fewer damaged seed than the most susceptible HA lines. Among the resistant PI and unreleased inbred lines, only one entry had significantly less damage than HA 207. While PI 494859 showed banded moth resistance superior to the best inbred lines, its other agronomic liabilities make breeding with the least susceptible maintainer lines appear more practical. A key unknown for any attempts to breed hybrids resistant to banded sunflower moth is how closely damage is correlated between inbred lines and their hybrids.

Effects from Early Planting of Late-Maturing Sunflowers on Damage from Primary Insect Pests in the United States

AbstractDelayed planting is recommended to reduce damage from sunflower insect pests in the United States, including the sunflower moth, Homoeosoma electellum (Hulst) and banded sunflower moth, Cochylis hospes Walsingham. However, in some locations, planting earlier or growing later-maturing hybrids could improve yield or oil content of sunflowers which would partially offset any added costs from insect pests or their management. Because the abundance and distribution of some sunflower insects have changed since recommendations for delayed planting were developed, experimental plots were grown in 2012 and 2013 at sites in North Dakota, Nebraska, Iowa, and Illinois. Sunflowers were planted two to four weeks earlier than normal, including hybrids that flower two to three weeks later than elite commercial hybrids. The sum of seed damaged by sunflower moth, banded sunflower moth, and red sunflower seed weevil, Smicronyx fulvus LeConte, (i. e., total percentage) was influenced by location, but not the relative maturity of tested entries. However, when damage attributed solely to the red sunflower seed weevil was analyzed, more damaged seed were found for late-maturing entries in North Dakota and Nebraska. In addition to the trial data, current pest populations are lower than when delayed planting was first recommended and insecticide use during sunflower bloom is both common and effective. Together, these observations suggest factoring insect pests into planting time decisions may be unnecessary, except for areas with a history of problems with severe pests that cannot be managed using insecticides (e. g., sunflower midge, Contarinia schulzi Gagné).

Ovipositional Preference and Larval Performance of the Banded Sunflower Moth (Lepidoptera: Tortricidae) and Its Larval Parasitoids on Resistant and Susceptible Lines of Sunflower (Asterales: Asteraceae)

Banded sunflower moth, Cochylis hospes Walsingham, is one of the most destructive seed-feeding insect pests of sunflowers, causing significant economic yield losses in the northern Great Plains. In an attempt to understand host-plant resistance mechanisms for this pest, we field-tested, over several years, the effects of seven sunflower accessions, rated as resistant to C. hospes in previous screening trials, and a susceptible control (Par 1673-2), on the ovipositional preference and larval performance of C. hospes and its larval parasitoids. Of the resistant accessions, PI 494859 was the most preferred for oviposition, receiving a significantly greater number of eggs per head than did the susceptible Par 1673-2 in 2 of 3 yr. However, the numbers of larvae, and consequently the rate of seed infestation, found in PI 494859 heads were significantly lower than those in Par 1673-2 heads over all 3 yr. Female moths laid relatively few eggs on accessions PI 170385, 291403, and 251902, compared with on Par 1673-2, resulting in lower numbers of larvae per head and lower percentages of seed damaged. No association was observed between the concentrations of two diterpenoid alcohols or two diterpenoid acids in sunflower bracts and the numbers of eggs laid on the heads of the accessions. The number of banded sunflower moth larvae and the proportion of seeds damaged were positively correlated with kaurenoic acid concentrations and negatively correlated with kauranol concentrations. A positive association between resistance to larval feeding and parasitism was found in years 2006 and 2008, with resistant accessions having significantly greater proportions of parasitized larvae than did the susceptible Par 1673-2.

The role of chemical cues in host-plant selection by adult female Homoeosoma electellum (Hulst) (Lepidoptera: Pyralidae) and Cochylis hospes Walsingham (Lepidoptera: Tortricidae)

The sunflower moth, Homoeosoma electellum (Hulst), and banded sunflower moth, Cochylis hospes Walsingham, are important insect pests of cultivated sunflower, Helianthus annuus L., in North America. We tested whether females and larvae of the two species were able to different iate between different phenological stages of sunflower heads, as well as whether females of the two species could detect the presence of conspecific larvae in heads. Sunflower moth adult females laid more eggs on R5-stage than R2-stage sunflower heads, and also on covered R5-stage heads as compared to covered R2-stage heads. In contrast, C. hospes laid more eggs on R2-stage heads than R5-stage heads, but there was no differentiation between the two when the heads were covered. In a bioassay testing, the preferences of neonate larvae of H. electellum and C. hospes to R2-stage and R-5-stage head tissues of both species exhibited preferences to the head stage they typically feed on (that is, H. electellum larvae preferred R5 florets to R2 involucral bracts, whereas, C. hospes larvae preferred R2 involucral bracts to R5 florets). Finally, both H. electellum and C. hospes females exhibited ovipositional preferences to uninfested sunflower heads over heads infested with conspecific larvae, suggesting that females could detect infested heads, possibly by a change in chemical signal. This study demonstrates the importance of chemical stimuli in the preferences of these two species to sunflower phenological stages.

Resistance among cultivated sunflower germplasm to the banded sunflower moth (Lepidoptera: Tortricidae) in the Northern great plains

A five year field trial evaluated 71 oilseed sunflower, Helianthus annuus L., accessions, 32 breeding lines, and 25 interspecific crosses for resistance to infestation by naturally occurring populations of the banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Tortricidae), in North Dakota. Germplasm with resistance to attack by the banded sunflower moth and subsequent larval feeding damage in the seeds was identified. PI 251902 had less than 10% feeding damage per head in all five years of testing and less than 6% in three of the five years. PI 372259 and PI 170401 exhibited 12% or less seed damage in three years of evaluation and PI 253776 had only 3% damage in two of the three years and was the least damaged in 2004. Four other accessions (PI 170385, PI 291403, PI 494859, and PI 505651) revealed resistance in three of five years. A number of the interspecific crosses which were retested based on earlier results showed reduced seed damage in 2003, but subsequently exhibited much greater damage the following year due to higher populations of banded sunflower moth. Hybrid 894 was earlier used by others as a susceptible check; however, in the current investigation, this hybrid consistently had the lowest average seed damage from C. hospes feeding among the germplasm evaluated. Results from this investigation indicate that there is potential for developing resistant genotypes with reduced feeding injury that will help sunflower producers reduce yield loss due to the banded sunflower moth. In addition, plant resistance can effectively be combined with delayed planting to decrease densities of C. hospes, thus reducing crop losses without disrupting the control of the larvae by parasitoids.

Isolation of Three Diterpenoid Acids from Sunflowers, as Oviposition Stimulants for the Banded Sunflower Moth, Cochylis hospes

The banded sunflower moth (BSFM), Cochylis hospes Walshingham (Lepidoptera: Cochylidae) is a specialist insect, the larvae of which feed on sunflowers, Helianthus spp., and a few other species of Compositae. It is one of the most important pests of sunflower in the USA. Previous work on H. annuus, the cultivated sunflower, revealed two diterpenoids that function as oviposition stimulants for female BSFM, and that other, more polar compounds also stimulated oviposition. Using a bioassay-guided approach, we isolated three additional diterpenoids, grandifloric acid (1), 15beta-hydroxy-ent-trachyloban-19-oic acid (2), and 17-hydroxy-16alpha-ent-kauran-19-oic acid (3), from polar fractions of pre-bloom sunflower head extracts. In laboratory bioassays, purified natural samples of each of these compounds stimulated oviposition by female BSFM. Structure-activity relationships of the five diterpenoids known to stimulate oviposition by female BSFM are discussed.

Using Banded Sunflower Moth (Lepidoptera: Tortricidae) Egg Density to Estimate Damage and Economic Distance in Oilseed Sunflower

The banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Tortricidae), is an important economic pest of sunflower in the Upper Great Plains of North America. Economic losses due to reductions in seed number, weight, and quality can be significant. Previously, the potential for economic losses were estimated by sampling for adult moths. However, sampling for moths can be difficult and inaccurate. An alternative is to sample for banded sunflower moth eggs, which can be accurately counted in the field by using a binocular 3.5 headband magnifier. The egg counts are used to calculate the economic injury level (EIL) (EIL = C/VWPK), where C is the cost of treatment per unit area, V is the crop market value per unit of weight, W is the slope of the regression between banded sunflower moth egg densities and weight loss per plant, P is a term for plant population per unit area, and K is the control treatment efficacy. Estimates of populations of banded sunflower moth eggs are taken from the center of 400-m spans along all field sides. From these samples and the calculated EIL, a map of the extent of the economically damaging banded sunflower moth population throughout the field is made using economic distance; ED = e ( ( (EIL/E)-1.458)/-0.262). Economic distance estimates the distance an economic population extends into the field interior along a transect from the sampling site. By using egg samples to calculate the EIL and mapping the distribution of economic populations throughout a field, producers can then make more effective pest management decisions.

Using Banded Sunflower Moth (Lepidoptera: Tortricidae) Egg Density to Estimate Damage and Economic Distance in Oilseed Sunflower

The banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Tortricidae), is an important economic pest of sunflower in the Upper Great Plains of North America. Economic losses due to reductions in seed number, weight, and quality can be significant. Previously, the potential for economic losses were estimated by sampling for adult moths. However, sampling for moths can be difficult and inaccurate. An alternative is to sample for banded sunflower moth eggs, which can be accurately counted in the field by using a binocular 3.5 headband magnifier. The egg counts are used to calculate the economic injury level (EIL) (EIL = C/VWPK), where C is the cost of treatment per unit area, V is the crop market value per unit of weight, W is the slope of the regression between banded sunflower moth egg densities and weight loss per plant, P is a term for plant population per unit area, and K is the control treatment efficacy. Estimates of populations of banded sunflower moth eggs are taken from the center of 400-m spans along all field sides. From these samples and the calculated EIL, a map of the extent of the economically damaging banded sunflower moth population throughout the field is made using economic distance; ED = e(((EIL/E) − 1.458)/−0.262). Economic distance estimates the distance an economic population extends into the field interior along a transect from the sampling site. By using egg samples to calculate the EIL and mapping the distribution of economic populations throughout a field, producers can then make more effective pest management decisions.

ISOLATION OF THE DITERPENOIDS, ENT-KAURAN-16?-OL AND ENT-ATISAN-16?-OL, FROM SUNFLOWERS, AS OVIPOSITION STIMULANTS FOR THE BANDED SUNFLOWER MOTH, Cochylis hospes

Two diterpenoid alcohols, ent-kauran-16alpha-ol (1) and ent-atisan-16alpha-ol (2), were isolated from pre bloom (R3-R4 stage) sunflower heads as oviposition stimulants for the banded sunflower moth, Cochylis hospes. Fractionation of a sunflower head extract, by normal-phase flash column chromatography, resulted in an early eluting fraction exhibiting significant activity in an egg-laying bioassay. Compounds 1 and 2, along with ent-trachyloban-19-oic acid (3) and ent-kaur-16-en-19-oic acid (4), were isolated as the major components of this fraction and identified by their NMR and mass spectra. The purified compounds were individually tested for ovipositional activity in dose-response bioassays. In these bioassays, compounds 1 and 2 gave linear dose responses, with increasing numbers of eggs laid as the dosage of either increased. Compounds 3 and 4 failed to stimulate significant egglaying at any of the dosages tested. A factorial design bioassay, using compounds 1 and 2, showed that 1 was relatively more stimulatory than 2, and that there was no synergistic effect on oviposition when the two compounds were combined.

Identification of the sex pheromone of Cochylis arthuri (Lepidoptera: Cochylidae)

AbstractThe sex pheromone of Cochylis arthuri Dang was identified as a 80:20 mixture of (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (E)-11-tetradecenyl acetate (E11-14:OAc). Cochylis arthuri is a congener of the banded sunflower moth, Cochylis hospes Walsingham, which is a major pest of sunflower, Helianthus spp. (Compositae), in the Great Plains region of North America. Both are found sympatrically on sunflower in this region, although C. arthuri appears to be less common. Field testing of various blends, in sticky traps, showed that a loading of 80 µg Z11-14:OAc and 20 µg E11-14:OAc on a red rubber septum gave the best catches. In field trials in sunflower plots, traps baited with either the C. hospes blend or the best blend tested for C. arthuri only caught significant numbers, relative to blank traps, of males of the respective species, suggesting that the sex pheromones of the two species are specific under those conditions. The identification of an attractive blend of the sex pheromone of C. arthuri will give researchers another tool to investigate the pest status of C. arthuri on sunflowers.

FERMENTATION OF A NEW Bacillus thuringiensis STRAIN / FERMENTACION DE LA VARIEDAD NUEVA Bacillus thuringiensis / FERMENTATION DE LA NOUVELLE RACE Bacillus thuringiensis

SUMMARYA new Bacillus thuringiensis strain, 00-50-5, exhibited an unusually high activity against banded sunflower moth (BSM) Cochylis hospes, which is an economically important pest of cultivated sunflowers in North America. The strain was fermented with a modified commercial medium in a bioreactor. This was a successful trial for production of 00-50-5 on a larger scale. After fermentation, the yield of dried powder was 5.8 g/l broth. In the laboratory assays, the LC50 (lethal concentration required to kill 50% of targets) of the dried powder was 0.5 μg/ml 3 d after exposure against four instars of BSM. Some practically useful conditions and parameters for the fermentation operating procedure and methods for harvesting were determined.

Biology and Seasonal Abundance of Parasitoids of the Banded Sunflower Moth (Lepidoptera: Tortricidae) in Sunflower

Mortality, parasitization, and overwintering development through pupation of the banded sunflower moth, Cochylis hospes Walsingham, larvae and two of its endoparasitoids, Glypta prognatha Dasch and Chelonus phaloniae Mason, were followed over a 2-year period (1987 to 1989). Development of parasitoids in the field was determined for each species by examination of moth eggs and larvae during the 1989 season. Parasitoids of C. hospes, recovered from cultivated sunflower, Helianthus annuus L., from North and South Dakota and Minnesota in 1994 and 1995, parasitized 24 and 17% of larvae, respectively. Species of Hymenoptera collected included G. prognatha and Trathala sp. (Ichneumonidae), C. phaloniae and Macrocentrus ancylivorus Rohwer (Braconidae), and Perilampus robertsoni Crawford (Pteromalidae). The most abundant parasitoid was G. prognatha. In 1994 and 1995, C. phaloniae, an egg-larval parasitoid, emerged earlier but was less abundant than the later occurring larval parasitoid G. prognatha. Species of parasitoids collected from cultivated sunflower and five species of native sunflowers were similar. An additional parasitoid, Mastrus sp. (Ichneumonidae), was recovered only from the native sunflowers H. annuus and H. tuberosus L. Results from 1994 and 1995 showed that parasitization rates for the total season by the two most abundant parasitoids were similar in fields using three planting dates. These results suggest that altering planting date could be successfully used as a pest management strategy without disrupting the biological control of the banded sunflower moth. Conservation of these parasitoids in the sunflower agroecosystem is needed since they play an important role in the management of C. hospes.

Honey Bees (Hymenoptera: Apidae) as Vectors ofBacillus thuringiensisfor Control of Banded Sunflower Moth (Lepidoptera: Tortricidae)

A study was conducted in 1996 and 1997 to determine if honey bees, Apis mellifera L., could vector Bacillus thuringiensis Berliner variety kurstaki from hives equipped with a pathogen applicator to sunflower capitula and if the amount of B. thuringiensis deposited on the capitula would be sufficient to control the banded sunflower moth, Cochylis hospes Walsingham. The study dem- onstrated that honey bees became contaminated with B. thuringiensis as they exited hives equipped with filled pathogen applicators and deposited enough B. thuringiensis on the capitula to cause banded sunflower moth larval mortality. When 2 methods of applying B. thuringiensis were com- pared, the honey bee vectoring method gave better or equivalent control of the banded sunflower moth larvae than manual sprays, resulting in higher seed yields than manual sprays. The presence of honey bees also increased seed set which contributed to greater yield.

Median Lethal Concentration and Efficacy of Bacillus Thuringiensis Against Banded Sunflower Moth (Lepidoptera: Tortricidae)

This study was conducted to determine dose-mortality response of the banded sunflower moth, Cochylis hospes Walsingham, to Bacillus thuringiensis Berliner and its effect on sunflower seed damage and yield. Of B. thuringiensis products tested, Cutlass AF and Javelin WG had the lowest LC50 values and highest slopes and relative potencies for C. hospes. Javelin WG was superior to the other B. thuringiensis materials tested and to Asana XL in preventing seed damage. Sunflower heads sprayed with Javelin WG had higher yields than sunflower heads sprayed with Asana XL or the other B. thuringiensis products tested. Asana XL is a standard chemical insecticide and is considered to give good control of banded sunflower moth. As an alternative to Asana XL, any of the B. thuringiensis products tested could be employed for control of C. hospes larvae and to reduce the impact on beneficials in sunflower fields.

Resistance in sunflower and interaction with Bacillus thuringiensis for control of banded sunflower moth (Lepidoptera: Tortricidae).

Four sunflower accessions were compared with a susceptible check, hybrid '894', in the greenhouse to determine their resistance to the banded sunflower moth, Cochylis hospes Walsingham, and their interaction with Bacillus thuringiensis Berliner variety kurstaki. Antibiosis, expressed as lower larval weight, was detected in all of the accessions. In addition to being antibiotic, sunflower accession Ames 3291 was antixenotic to banded sunflower moth oviposition and exhibited an additional impact on larval weight when B. thuringiensis was applied. By itself, B. thuringiensis provided better control of banded sunflower moth than the resistance tested. However, banded sunflower moth-resistant sunflower would be a good option when B. thuringiensis or another insecticide is not applied, and it may prevent the economic threshold from being reached.