The range of sunflower moth is from Mexico and Cuba to Canada. It is usually found in all regions where wild or domesticated sunflowers ( Helianthus ) grow.
There is some variation in researchers reports of egg counts from the moth. One said "a single female laid 91 eggs, mostly in a single day". Another said "females lay 30 or more eggs either singly or in groups of 4-5 within or among corolla tubes of individual florets". Also "most oviposition takes place on the 3rd day after the head opens and 75% of eggs are laid by 6th day" and "lab moths laid 337 eggs in a 2 week period". In our 1986 study at Ames, IA, we observed that 107 females laid 11,100 eggs in 8 days for an average of 103.7 eggs/female.
Adults have been observed in N. Dakota and Canada from early to mid-July. They migrate from the south central U.S. Published records note first observations in the following states: Iowa (early July), Missouri (late June), Georgia (July), Texas (late April), California (early June), and Mexico (November to April).
The basic life cycle of the sunflower moth is as follows: Egg - hatch within 3-5 days; Larva (4-5 instars) with the 1st being ˇ 4 days, the 2nd = 3-5 days, the 3rd = 5 days, the 4th = 1-3 days, and the 5th = 10-12 days; Pupa pupate in soil for 6-7 days, and the Adult lives a couple of weeks.
Diapause depends on both temperature and photoperiod and is induced more readily at 21o C with less than 10 hrs light. Diapausing prepupae cannot survive 5o C for 7 or more consecutive days so are absent north of roughly 40o N. latitude. Nondiapausing larvae died after 1 day at 10o C but 33% of diapausing larvae survived to pupate after 7 days at 10o C. This suggests that SM is capable of overwintering much farther north than was previously thought.
Egg: pearly white, elliptical, finely reticulated, from 0.63-0.80 mm long and 0.23-0.27 mm diameter; Larva: brown head capsule, purplish or reddish brown body with alternate dark and light stripes running longitudinally; from 19-25 mm long; Pupa: reddish-yellow to brown, 10 mm long; Adult: buff to gray moth with wing span of 19-20 mm and body length of 9-11 mm.
Pest damage is described in the literature as follows: "larvae laid a delicate silk over surface giving a trashy appearance - early instars feed on florets rather than achenes", "a single larva damaged 9 achenes in a 3 week period", "single larva feeds on 3-12 seeds", "severe infestations can cause 30-60% loss", and "a two year study found sunflower moth larva consumed 0.29g and 0.23 g seed, respectively".
Researchers have found that "From 12 - 24 larvae per head causes serious seed loss" and "the economic threshold is 1 to 2 adults per 5 plants at onset of bloom".
The field is sampled using an X - Pattern, beginning at least 75-100 ft from the field margins. Sunflower moths are counted on 20 heads per sample. Five samples are taken for a total of 100 heads per field.
Primary sex pheromone is Z-9, E-12-tetradecadien-1-ol (Z9,E12-14:OH). Also Z-9-tetradecen-1-ol (Z9-14:OH) may be important when acting in combination with the primary sex pheromone.
In the interaction of sunflower moths with the sunflower plant, there appear to be important chemicals present in the pollen. An ethanol extract of pollen was shown to be an oviposition stimulant. Presence of pollen caused females to initiate calling behavior at a younger age and they spent more time calling. This resulted in an increased rate of egg maturation.
Few diseases have been identified that attack sunflower moth. A nosema fungi has been identified that attacks the European sunflower moth. This fungus attacks other Pyralids (e.g., European corn borer) so it could potentially be a control method for the sunflower moth. In Missouri, researchers found a fungus on sunflower moth called Metarrhizum anisopliae . They didn't mention whether or not this would be a useful "potential" control agent.
The rearing diet began with the basic wheat germ diet developed by Adkisson et al. and later modified by Vanderzant. Rogers modified the diet by substituting B-vitamin (with inositol) and ascorbic acid for vitamin mix. He added two anti-fungal compounds (potassium sorbate and methyl p-hydroxybenzoate). Wilson modified the diet by using vitamin fortification mix (ICN National Biochemicals) and also added an antifungal compound. He also used a microwave oven for heating agar which helps prevent burning the agar during the cooking process.
Our rearing procedure starts with one gallon size oviposition jars in which the bottoms are covered with about 5 cm of fine white sand. The sand is lightly dampened with water and covered with 15 cm filter paper. A 30 ml cup with a cotton wick and 5% sucrose solution is added to feed the adults. Oviposition pads (8 cm2) are suspended inside jar. The rearing room is kept at 24-27o C, with 60% RH, and 14:10 (light:dark). About 250 pupae, hand picked from the diet 2-3 days after pupation, are placed in a 9 cm petri dish and placed into the adult oviposition container.
Egg are collected by lifting the oviposition pad gently from jar, and shaking off any moths that may cling. Most eggs are obtained from day 3-5. Wilson and McClurg found the eggs can be stored in 5o C for up to one week without significantly reducing egg hatch. When we need larvae for testing, the eggs are moved to a 27o room where they will hatch in 2-4 days. The larvae are reared in either a 26 cm diameter (large) or 30 ml capacity (small) plastic container. The diet is scored (scratched with a sharp object) before introducing larvae. We place about 600 larvae in the large containers, but the small containers hold 6-8. It takes about 3 weeks for late instar pupae to develop.
The sunflower moth has been found on many plant families but mostly on the Compositae (Asteraceae). The list includes, but is not all inclusive, of some of the following plants: Rosering gaillardia, Golden crownhead, Goldenmane, Lanceleaf gaillardia, Englemann daisy, Twoleaf senna, Big flower, Gumweed, African marigold, French marigold, Golden wave, Tickseed, Orange coneflower, Yellow chamomile, Romerillo blance, Citrus, Safflower, Sweetclover, Corn, Globemallow, Musk thistle, and many species of Helianthus .
Beregovoy recovered 17 species of Hymenoptera and Diptera parasites from sunflower moth larvae. In a Missouri study, they found 12 parasites: Lixophaga variabilis, Erynnia tortricis, Leskiomima tenera, Clausicella floridensis, Bracon mellitor, Bracon nuperus, Chelonus altitudinus, Apanteles homoeosomae, Agathis buttricki, Macrocentrus ancylivorus, Creamastus epagoges , and Perilampus epagoges . Three were found in a Texas study: Chelonus altitudinus, Apanteles epinotiae , and Clausicella neomexicana . In California, four were found: Mesotimes gracilis, Pristomerus pacificus, Apanteles homoeosomae , and Euxesta anna . And in North Dakota two others were listed: Lixophaga plumbea , and Erymnia tortricis . Some of the parasites are found in more than one location.
Searching for plant resistance in 1966, Kinman found a single sunflower plant with 10% damage and it was incorporated into the pedigree of hybrid T56002. In 1971, Teetes et al. showed differences in susceptibility to selected varieties. The Russian varieties armavirec' and kubanec' were less damaged than was inbred HA 6. Carlson and Witt identified resistance and tolerance in cultivars H2131 and H2135 and others in 1974. And in 1980, Jarvis evaluated 350 National Plant Germplasm System sunflowers at Ames, IA and found three resistant H. annuus accessions (PI 172906, PI 204578, PI 380569).
In 1984, Seiler et al. looked at 50 species of wild sunflower and found the resistance factor, phytomelanin, in pericarp of them all. Then in 1993, Dozet et al. tested populations of 23 species for presence of phytomelanin layer. The species with the highest percent phytomelanin layers include: Helianthus salicifolius (85%), H. laevigatus (80.5%), H. strumosus (73%), H. resinosus (75%), H. giganteus (67.5%), and H. grosseserratus (66%).
The literature cites other possible sources of sunflower moth resistance: H. ciliaris, H. decapetalus, H. maximiliani, H. occidentalis ssp. occidentalis, H. pumilus, H. silphioides, H. strumosus, H. tuberosus, and H. petiolaris ssp. petiolaris.
Some biochemical compounds are involved in host-plant resistance of sunflower to the sunflower moth. In 1985, Gershenzon et al. found high levels of sesquiterpene lactones and diterpenes in glandular hairs on wild species of Helianthus. Rogers et al. tested 30 perennial and 11 annual species of Helianthus in 1989 and noted that plants were resistant when terpenes were found in floral parts and phytomelanin in seed pericarp.
At the North Central Regional Plant Introduction Station, we evaluate domesticated sunflower for sunflower moth resistance by the following technique: (1) select test accessions from the sunflower collection and include the checks 894' and Arrowhead', (2) plant each accession in 2 row plots, 25 ft long, (3) infest the accession when 20 plants are at the R5.2 stage, (4) 10 plants are labeled and infested with sunflower moth eggs, (5) another 10 plants are sprayed with Asana after one week, (6) 1-2 days after spraying, all 20 plants are covered with muslin bags. By waiting one week, this allows natural pollination to occur before bagging. (7) the heads are harvested at physiological maturity, (8) head diameters are measured, the seed are removed by hand, and the seed are cleaned, weighed and counted, (9) gm seed/cm2 and no. seed/cm2 are calculated, (10) % of control is calculated by dividing infested head data by check head data, (11) accessions with % of control values˛ 100 are considered resistant.
Some results from 1994: 48 accessions were tested, 8 had both % of control values for no. seed/cm2 and gm seed/cm2 > 100%. The resistant accessions are: PI 162453, PI 170389, PI 170401, PI 170420, PI 170428, PI 176975, PI 250853, and PI 301060.
Released germplasm: In 1984, Rogers et al. released 3 germplasm lines for resistance to sunflower moth; SFM 1 is an interspecific cross of PI 181954 X PI 423011 [H. petiolaris], SFM 3 is a cross of PI 181956 X PI 423011 and SFM 2 is a cross of PI 356301 X HA 89. All of the germplasm lines have genes that encode production of phytomelanin in their pericarp.
Planting date studies in Nebraska, Texas, and Georgia showed that early planted sunflowers had smaller infestations of sunflower moth. A Kansas study found that delaying planting until the middle of June reduced sunflower moth infestations and with no significant loss in yield.
The currently registered chemicals for control of sunflower moth are:
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Beregovoy, V. H. 1985. Parasitism of the sunflower moth, Homoeosoma electellum (Hulst) (Lepidoptera: Pyralidae) in the central United States. J. Kan. Entomol. Soc. 58: 732-736.
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Gershenzon, J., M. Rossiter, T. J. Mabry, C. E. Rogers, M. H. Blust, and T. E. Hopkins. 1985. Insect antifeedant terpenoids in wild sunflower: a possible source of resistance to the sunflower moth. Am. Chem. Soc. Symposium Series 276, Am. Chem. Soc., Washington, D. C., p. 433-446.
Jarvis, J. L. 1977. Evaluation of sunflower introductions for resistance to sunflower moth in 1976. North Central Regional Plant Intro. Sta. A-2, Ames, IA, p. 2-16.
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McBride, D. 1994. Sunflower pest management. In: Sunflower Production. (ed. D. R. Berglund). Ext. Bull. 25, North Dakota Agric. Exp. Sta. and Extension Serv., NDSU, Fargo. p. 22-43.
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Rogers, C. E., Archer, T., and E. D. Bynum, Jr. 1984. Bacillus thuringiensis for controlling larvae of Homoeosoma electellum on sunflower. J. Agric. Entomol. 1: 323-329.
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Teetes, G. L. and N. M. Randolph. 1969. Chemical and cultural control of the sunflower moth in Texas. J. Econ. Entomol. 62:1444-1447.
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