Zea Moths Research Articles

Field Observations of Adult Emergence and Feeding Behavior of Helicoverpa zea (Lepidoptera: Noctuidae) on Dallisgrass Ergot Honeydew

Timing and magnitude of corn earworm, Helicoverpa zea (Boddie), emergence was measured in a corn, Zea mays (L.), field near College Station, TX. Approximately 15,500 H. zea per hectare were produced, with 85% of the moths emerging in a 10-d interval. Feeding H. zea moths were observed to be highly attracted to honeydew exudates of egrot, Claviceps paspali (F. L. Stevens & J. G. Hall) on infected florets of dallisgrass, Paspalum dilatatum (Poir.) in an adjacent pasture. Moths began feeding on the ergot at dusk. Feeding densities increased rapidly to peak at <1 h after sunset and then declined to relatively low levels by 2 h after sunset. Dissection analyses of sampled females showed that 95% were unmated, indicating that the characteristic age of the feeding moths was ≤1 d.

Taxonomy based on chemical constitution: Differentiation of new world from old world helicaverpa moths

Gas chromatography and pattern recognition methods were used to develop a potential method for differentiating Helicaverpa armigera from Helicaverpa zea moths. The test data consisted of 67 gas chromatograms of cuticular hydrocarbon extracts obtained from H. armigera and H. zea moths. Discriminants were developed that assigned a given gas chromatogram to its respective class ( H. armigera versus H. zea). The ability of these discriminants to predict the class of an unknown was tested successfully using a procedure known as internal validation.

Hemolymph lipids and flight activity in Helicoverpa zea (Boddie) (lepidoptera: Noctuidae)

AbstractIn this study the flight activity of female and male Helicoverpa zea (Boddie) moths was observed and compared to hemolymph lipid concentrations. The major male and female H. zea flight activity occurred between simulated dusk (1700) and dawn (0300). Male flight activity was up to 7 times greater than females through 6 days after eclosion except for the 1st day (0.8 times). Females had a unimodal pattern of flight activity, peaking between dusk and 2 h later. Males had a bimodal pattern; one between dusk and 2 h later, and another 3 h after dusk, continuing for h. Prior to dusk, total neutral hemolymph lipids (neutral) of H. zea day 4 moths was 64 μg/μl for males and 48 μg/μl for females. Typical lipid composition in day 4 males prior to flight was 1,2‐diacylglycerides (DG) (50% w/w), triacylglycerides (TG) (35%), cholesterol esters (2%), and less than 1% monoacylglycerides and cholesterol. The remainder consisted of free fatty acids (&lt;0.5 μg/μl), and various uncharacterized phospholipids and lipophilic compounds. Hemolymph DG concentration patterns were similar between day 4 males and females, were highest in both sexes prior to, during, and after flight (approximately 32 μg/μl), and then decreased steadily throughout the flight period to approximately 16 μg/ml as flight ceased. Hemolymph TG were lower than DG, but followed the same pattern except at 2100 and 2300. In day 4 males between 2100 and 2300, TG increased to 33 μg/μl which was when DG was lowest (15 μg/μl) and their flight activity was highest. Hemolymph DG decreased (26 to 20 μg/μl) in day 4 females between 2100 and 2300 as TG remained fairly constant (18 μg/μl).

Aldehyde oxidases and dehydrogenases in antennae of five moth species

Conversion of Z11–16:A1 to its corresponding carboxylic acid was examined in male antennal extracts from Heliothis subflexa, Heliothis virescens, Heliothis zea, Manduca sexta and Spodoptera frugiperda moths. Both aldehyde dehydrogenase (ALDH) and aldehyde oxidase (AO) activities were detected by radiochromatographic assays using [ 3H]Z11–16:A1 as the substrate and by spectroscopic assays using Z11–16:A1 as the substrate. AO activity in each of the five moths showed a broad substrate specificity which included C 4 to C 18 aliphatic aldehydes and benzaldehyde. ALDH and AO enzymes from the male and female antennal extracts were identified after electrophoretic protein separation. AO enzymes were visualized on native polyacrylamide gels with formazan- or horseradish peroxidase-mediated stain coupled to the AO-catalyzed oxidation of benzaldehyde. Both sexes of most species showed intense AO-stained bands of similar mobility. Molecular subunits of potential ALDH enzymes were visualized by fluorography of SDS-PAGE-separated proteins after covalent modification by [ 3H](Z)-1,11-hexadecadien-3-one, a selective affinity label for ALDH. ALDH subunits appeared at 51 ± 1 kDa in antennae from males of all five species and females of three species; female H. zea and M. sexta moths lacked these characteristic ALDH subunits. These results constitute the first biochemical comparisons of coexisting ALDH and AO enzymes in antennal extracts from lepidopteran species from two families.

Annual Contamination of Heliothis zea (Lepidoptera: Noctuidae) Moths with Aspergillus flavus and Incidence of Aflatoxin Contamination in Preharvest Corn in the Georgia Coastal Plain2

Annual Contamination of Heliothis zea (Lepidoptera: Noctuidae) Moths with Aspergillus flavus and Incidence of Aflatoxin Contamination in Preharvest Corn in the Georgia Coastal Plain2

Heliothis zea (Lepidoptera: Noctuidae): Effects of Radiation and Inherited Sterility on Mating Competitiveness

Normal and irradiated laboratory-reared Heliothis zea (Boddie) moths were released in screened field cages and in fields of tobacco and cotton. The nocturnal activities and incidence of mating of laboratory-reared and wild moths were observed. Laboratory-reared moths irradiated with 10 krad and released in field cages were competitive with nonirradiated laboratory-reared moths. The competitiveness of irradiated moths was not altered by the time interval (5 and 30 h) between irradiation and release, the mating status of the male, or by the time interval (24 and 48 h) between mating and release. Normal and irradiated, laboratory-reared males released in the field in either the presence or absence of laboratory-reared females were not significantly different in their nocturnal behavior and mating competitiveness. The interaction of wild and laboratory-reared moths was largely limited to wild males mating with laboratory-reared females.

COMPARATIVE RESPONSES OF FERAL AND LABORATORY TRICHOGRAMMA SPP. (HYMENOPTERA: TRICHOGRAMMATIDAE) TO HELIOTHIS SPP. (LEPIDOPTERA: NOCTUIDAE) MOTH SCALES AND INERT PARTICLES

A laboratory assay of the klinokinetic response of Trichogramma spp. to scales of Heliothis virescens (F.) and Heliothis zea (Boddie) was investigated. The assay indicated significant behavioral response to materials similar in size to lepidopteran scales (small glass beads, cotton fibers); however, response to these materials was significantly less than response to H. virescens scales. The assay did not distinguish any difference in response to H. zea scales betewen naturally occurring and laboratory-bred Trichogramma exiguum Pinto and Platner. Physiological status (freshly emerged, virgin vs. 3–4 day-old, mated) of the H. zea moths from which scales originated affected scale response, but anatomical origin (abdominal tip vs. abdominal venter vs. wing) of host scales did not.

INFLUENCE OF SNAP BEAN PHENOLOGY ON HELIOTHIS ZEA (BODDIE) (LEPIDOPTERA: NOCTUIDAE) OVIPOSITION

In greenhouse preference tests Heliothis zea (Boddie) moths oviposited significantly more eggs on blooming snap bean, Phaseolus vulgaris L., than on pre-blooming plants. When moths were held in cages containing only 1 plant stage (non-preference tests) significantly more eggs were laid on blooming snap beans than on either pre- or post-bloom plants. Furthermore, this ovipositional response to blooming plants was much more striking after moths were caged for 3 nights. During nights 4–6, oviposition continued at a similar rate on blooming plants, while pre- and post-bloom plants received very few eggs. Regardless of plant stage, most eggs were laid on the top and bottom of large snap bean leaves.

Kairomones and their use for management of entomophagous insects. XV.

Acids found in moth scales of laboratory-rearedHeliothis zea (Boddie) moths are hexanoic, heptanoic, octanoic, nonanoic, 2- (or 3-) furan carboxylic, phenylacetic, benzoic, sorbic, and 4-hydroxybenzoic acid. The last two of these acids are preservatives added to the artifical diet as sorbic acid and methyl-p-hydroxybenzoate. FemaleTrichogramma pretiosum Riley exhibited increased rates of parasitization ofH. zea eggs in the presence of some of these compounds in laboratory experiments. Exposure to a mixture of all of these compounds did not increase parasitization, and the elimination of acids from the crude moth-scale extract did not reduce parasitization by the wasps.

Behavioral responses of maleHeliothis zea moths in sustained-flight tunnel to combinations of 4 compounds identified from female sex pheromone gland

Each of the four compounds that have been identified from sex pheromone glands ofHeliothis zea female moths was examined for its ability to elicit sexual responses from male moths in a flight tunnel. Males flew upwind to (Z)-11-hexadecenal alone, but greater levels of behavioral activity were evoked with the addition of (Z)-9-hexadecenal to the treatment. Addition of hexadecanal or (Z)-7-hexadecenal to the initial two components had no effect in raising the behavioral response of the males in the flight tunnel whether added singularly at both the normal gland-emission ratio or at varying ratios or in combination at the normal ratio. Live, calling females elicited levels of sexual activity from males not significantly different from that elicited by the mixture of (Z)-11- and (Z)-9-hexadecenal on cotton wicks.

Kairomones and their use for management of entomophagous insects

Volatile chemicals emanating from an excretion (apparently meconium) and abdominal tips of femaleHeliothis zea (Boddie) moths mediated increased rates of parasitization ofH. zea eggs byTrichogramma pretiosum Riley. A blend of synthetic chemicals, consisting of hexadecanal, (Z)-7-hexadecenal, (Z)-9-hexadecenal, and (Z)-11-hexadecenal, which has been identified as the sex pheromone of and from the abdominal tip of femaleH. zea moths, also increased rates of parasitization ofH. zea eggs byT. pretiosum in greenhouse experiments. In addition, parasitization ofH. zea eggs by wildTrichogramma spp., in field plots of cotton,Gossypium hirsutum L., treated with a similar blend of chemicals, in Conrel fibers, was more than double that in untreated plots.

Disruption of Heliothis spp. 1 Mating Behavior with Chemical Sex Attractant Components 2

Three chemicals significantly reduced the mating success of female tobacco budworms (TBW), Heliothis virescens (F.) (Lepidoptera: Noctuidae), and disrupted courtship behavior of males when deployed separately or in paired combinations at the rate of 1 g/0.4 ha. These chemicals were ( Z )-11-hexadecenal, ( Z )-9-tetradecenal (Z-9-TDAL), and ( Z )-11-hexadecen-1-ol (Z-11-HDOL). Four other chemicals [( Z )-9-hexadecenal, ( Z )-7-hexadecenal, hexadecanal, and tetradecanal] were deployed separately at the same 1-g rate in the test plots but showed little or no effect on TBW courtship behavior, as indicated by catches in traps. Amounts of the chemicals that actually dissipated during 60-htreatment periods varied between chemicals from ca. 23 to 84%. Based upon actual quantities dispensed and relative biological effects, Z-11-HDOL was the most potent chemical assayed. Male H. zea (Boddie) moths were caught in traps baited with virgin TBW females when Z-9-TDAL was deployed at 1 g/0.4 ha in different 4-ha cotton fields in 1978 and 1979. Male H. zea were also captured in the traps in 1979 when Z-11-HDOL was deployed at 1 g/O.4 ha and again in 1981 when only 0.7 g was dispersed in 60 h. This interspecific response did not occur when the other five chemicals were deployed separately at the same rate, even though H. zea males were in the fields.

Labeling of Trichogramma pretiosum1 by Rearing on Eggs from 32P-fed Adults of Heliothis zea2,3,4

Heliothis zea (Boddie) female moths were labeled with /sup 32/P as orthophosphate using a feeding process and their eggs used as hosts in the rearing of Trichogramma pretiosum Riley. The percentage radioactive eggs oviposited by H. zea moths corresponded almost identically with the percentage radioactive parasites emerging from the eggs. The average counts per minute for the eggs and parasites were closely related with the high 1st day counts, declining progressively on following days of the study. Thus, Trichogramma can be reared on /sup 32/P-labeled H. zea eggs without affecting the parasite's ability to further parasitize H. zea eggs under laboratory conditions. There is no difference in the number of parasites emerging from control eggs and /sup 32/P-labeled eggs when used in the rearing of Trichogramma pretiosum. Greenhouse data suggest that this process might be used to monitor parasite activities in the field.

Kairomones and their use for management of entomophagous insects: III. Stimulation ofTrichogramma achaeae,T. pretiosum, andMicroplitis croceipes with host-seeking stimuli at time of release to improve their efficiency

Frass from larvae of the corn earworm,Heliothis zea (Boddie) and scales fromH. zea moths (that are known to contain the host-seeking stimulus, tricosane) stimulate and orient host-seeking activity in femaleMicroplitis croceipes (Cresson), a larval parasite ofH. zea, andTrichogramma spp., egg parasites ofH. zea. When larval frass, moth scales, and tricosane were used as sign stimuli (releasers) forM. croceipes, T. pretiosum (Riley), andT. achaeae Nagaraji and Nagarkatti, respectively, at time of their release from laboratory containers, parasite performance improved, resulting in significantly increased rates of parasitization over that of unstimulated parasites. Stimulation ofM. croceipes with larval frass had an overriding effect on this parasite's innate tendency to disperse upon release, thereby increasing the numbers remaining and prolonging their retention in the target area. Supplying the appropriate host-seeking stimuli to these 3 hymenopterous parasites ofH. zea at time of their release to improve their efficiency greatly increases the probability of their effective utilization in pest management systems.

Mortality Factors Affecting Cotton Insects: I. Resistance of Smooth and Nectariless Characters in Acala Cottons to Heliothis zea, Pectinophora gossypiella, and Trichoplusia ni

AbstractHost plant resistance to insects has become a major breeding objective in cotton (Gossypium hirsutum L.), since significant increases in resistance may result simultaneously in yield increases and reduced usage of insecticides. Nectariless ‘Acala’ cotton strains with reduced pubescence are being developed in an attempt to gain significant host plant resistance against harmful Lepidoptera. Extensive studies were undertaken to evaluate the first‐order effects that the nectariless and reduced pubescence plant modifications would have upon oviposition behavior of three key insects. Cage trials with pink bollworms (Pectinophora gossypiella) have been difficult to manage and results are inconclusive. It was found that cabbage loopers (Trichoplusia ni) showed a slight increase in oviposition on nectariless cottons with reduced pubescence. The increase was so small as to be of doubtful economic importance. Paired isolation cage studies conducted over a 4‐year period showed that similar numbers of Heliothis zea moths laid only 45% as many eggs on nectariless Acala strains as on their normally hairy, nectaried companion lines. There was a disturbing reversal in form in certain tests, due to variables not yet clearly understood. However, there was a clear trend indicating that the suppression of oviposition is greatest when environmental conditions are most favorable for a bollworm epidemic. This large reduction of egg numbers at peak oviposition is the strongest confirmation of the value of developing nectariless cottons to minimize Heliothis damage.

Influence of Near-Ultraviolet Output of Attractant Lamps on Catches of Insects by Light Traps1

Near-ultraviolet output of attractant lamps affected the catches of insects in traps more than any other single factor in field studies at College Station, Texas. The numbers of bollworm moths, Heliothis zea (Boddie), and cabbage looper moths, Trichoplusia ni (Hubner), caught in traps having lamps with total emission ranging from 122 to 8100 milliwatts of near-ultraviolet energy were almost directly proportional to the near-ultraviolet output of attractant lamps. Increased diameters of funnels used in the traps gave increased catches of insects.

Response of Acoustic Sense Cell of the Bollworm and Tobacco Budworm to Ultrasound12

The A-1 acoustic sense cell in the tympanic ears of bollworm moths, Heliothis zea (Boddie), and tobacco budworm moths, Heliothis virescens (F.), responded to sound pulses at frequencies ranging from 10 to 100 kilohertz (KHz), but was most sensitive to frequencies between 18 and 25 KHz. Free-flying moths of both species responded with similar evasive behavior when they were stimulated with pulses of ultrasound at frequencies of 21-22 KHz. However. in a preliminary field test, ultrasound at frequencies of 21-22 KHz and a rate of 10 pulses per second did not materially affect the populations of bollworms or tobacco budworms in cotton fields. Equipment failures were probably at least partially responsible for the lack of control.

Intermediate and Far Infrared Sensing of Nocturnal Insects. Part II. The Compound Eye of the Corn Earworm, Heliothis zea, and Other Moths as a Mosaic Optic-Electromagnetic Thermal Radiometer12

A histological description is given of the ommatidium of the corn earworm, Heliothis zea (Boddie). The cornea has the configuration of an achromatic doublet, and the crystalline cone of a field lens, which is coated in the night-adapted eye with a quarter-wave antireflection dielectric. All morphological units fit the theoretical configuration to be expected of a mosaic optic-electromagnetic thermal radiometer. There is a fast daylight-adaptation to ultraviolet and a lack of stimulated flight in an activity cage when moths are subjected to shortwave ultraviolet (2537 A). It is concluded that the compound eye is a high absorber of far infrared radiation and of such a configuration that it could orient to hot or warm spots of longwave infrared radiation in total darkness.