@article{ellsworth_bradley_1992, title={COMPARATIVE DAMAGE POTENTIAL AND FEEDING DYNAMICS OF THE EUROPEAN CORN-BORER (LEPIDOPTERA, PYRALIDAE) AND COTTON BOLLWORM (LEPIDOPTERA, NOCTUIDAE) ON COTTON BOLLS}, volume={85}, ISSN={["0022-0493"]}, DOI={10.1093/jee/85.2.402}, abstractNote={European corn borer, Ostrinia nubilalis (Hubner), larvae are more likely to bore into 7-, 14-, 21-, and 28-d-old cotton bolls, Gossypium hirsutum L., when offered a no-choice situation than are cotton bollworm, Helicoverpa zea (Boddie) larvae. None of these four boll ages was safe from European corn borer entry for any instar tested. Cotton bollworm larvae were less able to penetrate larger bolls (21 and 28 d old) and did so appreciably only in the fourth and fifth instars. Early instar cotton bollwonns did not appreciably penetrate younger bolls (i.e., first ins tars in 7- and 14-d-old bolls and second instars in 14-d-old bolls). Given adult and larval behaviors, bolls ≥21 d old probably escape cotton bollworm entry; however, European corn borers can enter cotton bolls of any age. The character of the feeding damage is less severe and Jess cryptic in the cotton bollworm compared with the European corn borer. Bollworm entry holes were larger in surface area, which allowed drying of the wound. European corn borers removed only enough boll wall tissue to gain entry into the carpels and left the wound watery and ideal for growth of boll rot organisms. The relatively few times that the cotton bollwonn gained entry into the boll, it entered from the top two-thirds of the boll. However, European corn borers usually entered the boll in the bottom third, often through or from within the axial surface of the calyx. The ramifications of the feeding dynamics of these two species for pest scouting and management are discussed, and a model for predicting the probability that these larvae will enter boll tissue is presented.}, number={2}, journal={JOURNAL OF ECONOMIC ENTOMOLOGY}, author={ELLSWORTH, PC and BRADLEY, JR}, year={1992}, month={Apr}, pages={402–410} }
 @article{ellsworth_bradley_kennedy_patterson_stinner_1992, title={Irrigation effects on European corn borer ‐ maize water relations}, volume={64}, ISSN={0013-8703 1570-7458}, url={http://dx.doi.org/10.1111/j.1570-7458.1992.tb01589.x}, DOI={10.1111/j.1570-7458.1992.tb01589.x}, abstractNote={AbstractThis study examined the impact of irrigation water on certain aspects of an insect‐plant relationship in the field including the assessment of plant‐mediated water effects on an herbivore's development, survival, and behavior, and plant damage parameters and host tissue water status. Maize (Zea mays L.) plants were arranged in a randomized complete block design in the field over two years in North Carolina (NC). Four blocks were subjected to three different irrigation treatments initiated ca. one week before anthesis: optimal, intermediate, deficit water supply. Each plant was infested with one (1986) or two (1987) black head stage, E‐race European corn borer [Ostrinia nubilalis (Hübn.)] (ECB) egg masses at tasselling. ECB development, tunnelling site, and survival as well as plant tissue water status (tissue % water contents [θ] & leaf water potentials [Ψ]) were recorded through July. The irrigation effect on ECB parameters was slight and variable. Internal stalk temperatures of optimal plants were consistently cooler than their deficit counterparts (1 day‐degree/day). With degree‐days included as an explanatory variable in the analyses, there were no significant irrigation effects on the ECB parameters, except for total proportion of ECB's bored into maize plant parts. More ECB's bored into drier plants than in optimal plants; however, this trend was not significant in 1987.Plant water indices showed that though responded to irrigation, there were only minor changes in tissue θ, particularly in view of the larger diurnal tissue changes observed and the relatively high, sustained stalk θ levels seen over all treatments. Examination of ECB pupal θ confirmed that dietary water changes were minor or non‐limiting to the insects' developmental physiology, because pupal θ was not sensitive to the irrigation treatments.Though water supply changes have drastic developmental and agronomic consequences for the maize plant, little or no changes were seen in the ECB feeding environment. Furthermore, a plant damage model was developed whereby the total % of ECB's tunnelled into maize was related to the mean larval age. The implications of this model on the understanding of ECB tunnelling behavior, damage potential, and pest management is noted.}, number={1}, journal={Entomologia Experimentalis et Applicata}, publisher={Wiley}, author={Ellsworth, P. C. and Bradley, J. R., Jr. and Kennedy, G. G. and Patterson, R. P. and Stinner, R. E.}, year={1992}, month={Jul}, pages={11–21} }
 @article{ellsworth_patterson_bradley_kennedy_stinner_1989, title={Developmental consequences of water and temperature in the European corn borer – maize interaction}, volume={53}, ISSN={0013-8703 1570-7458}, url={http://dx.doi.org/10.1111/j.1570-7458.1989.tb03576.x}, DOI={10.1111/j.1570-7458.1989.tb03576.x}, abstractNote={AbstractMaize plants were grown under four moisture regimes (wet to extreme deficit) and three constant temperatures (20°, 25 ° & 30 ° C) in a phytotron. Each plant was infested with one E‐race European corn borer [Ostrinia nubilalis (Hubn.)] (ECB) egg mass at pollen shed. ECB development, location, and establishment were recorded over the course of 12 destructive sample dates (4/temperature). ECB developmental rates were not significantly affected by soil moisture treatments, but were significantly affected by temperature. In spite of successful establishment of four distinctly different soil moisture regimes, the maize stalk tissue water levels were not significantly different among soil water treatments. Instead, the maize plants exhibited accelerated leaf senescence in response to the water deficit conditions. Among the soil water treatments, differences were found in larval establishment, vertical distribution and dispersion, and feeding site selection; however, those effects were slight and could not explain the similarity in ECB developmental rates observed in these treatments.In maize, the larval environment within the stalk was effectively insulated from changes in the external environment by the plant's ability to maintain a relatively high and stable stalk tissue water content. Thus, large changes to the soil environment had essentially no effect on ECB development, though drastic consequences for the plant. This study indicates that ECB rates of development are relatively insensitive to changes in the soil water environment as well as the associated changes in the maize plant that accompany severe drought stress. The significance of these findings to insect modelling, crop physiology, and insect‐crop interactions is discussed.RÉSUMÉInfluences de l'eau et de la température sur le développement d'Ostrinia nubilalis dans le système pyrale‐maïsDes plants de maïs se développent dans un phytotron dans 4 conditions d'humidité du sol (de la saturation à la dessication) et à 3 températures constantes (20°, 25° & 30° C). Chaque pied est contaminé au moment de l'émission du pollen, par une ooplaque d'O. nubilalis Hübn. (ECB) de race européenne E. L'installation, la colonisation et le développement des chenilles sont notés lors de 12 périodes de prélèvements destructifs (4 par température). La vitesse de développement d'O. nubilalis est affectée par la température, main non par l'humidité du sol. Les 4 niveaux d'humidité du sol n'ont aucun effet sur la teneur en eau des tiges de maïs. En fait, les feuilles de maïs présentent une senescence précoce lorsqu'il y a déficit en eau dans le sol. La teneur en eau du sol agit sur l'installation, sur la distribution verticale, la dispersion et le lieu d'alimentation des chenilles; mais ces effets sont légers et ne modifient pas la vitesse de développement.L'environnement larvaire dans la tige de maïs est efficacement isolé des variations externes par l'aptitude de la plante à maintenir la teneur en eau des tiges relativement élevée et stable. Ainsi, des changements importants au niveau du sol n'ont pratiquement pas d'effets sur le développement d'O. nubilalis, malgré les conséquences brutales pour la plante. Cette étude montre que la vitesse de développement d'O. nubilalis est relativement insensible aux modifications de la teneur en eau du sol ainsi qu'aux effets de ce stress de sécheresse sévère sur le pied de maïs. La discussion porte sur l'importance de ces résultats pour la modélisation de la dynamique de l'insecte, la physiologie de la culture et les interactions entre insecte et plante.}, number={3}, journal={Entomologia Experimentalis et Applicata}, publisher={Wiley}, author={Ellsworth, P.C. and Patterson, R.P. and Bradley, J.R., Jr. and Kennedy, G.G. and Stinner, R.E.}, year={1989}, month={Dec}, pages={287–296} }
 @article{ellsworth_umeozor_kennedy_bradley_van duyn_1989, title={Population consequences of diapause in a model system: the European corn borer}, volume={53}, ISSN={0013-8703 1570-7458}, url={http://dx.doi.org/10.1111/j.1570-7458.1989.tb01284.x}, DOI={10.1111/j.1570-7458.1989.tb01284.x}, abstractNote={AbstractThe diapause biology of the European corn borer (ECB), Ostrinia nubilalis (Hübn.), is described based on natural and controlled environment studies of feral and lab‐reared ECB's in North Carolina (NC). The diapause response is described as a function of photophase (h of light/day) as well as a function of larval age (instar) at onset of diapause‐inducing conditions. A critical photophase of 14.4 h and a critical mean larval instar of 3.3 is found in the lab studies and supported by three years of insectary studies. Seven years of black light trapping of ECB moths in Goldsboro, NC, revealed the likelihood of up to four moth flights/year.Information about the diapause biology of this insect is used to explain both the number of flights and the relative magnitude of the final moth flights. On average, the majority of ECB lineages pass through three generations/year with early maturing ECB's producing a significant and predictable fourth generation. The timing and magnitude of the fourth flight can be partly explained on the basis of the critical photophase and the timing and age structure of previous ECB generations. In most years, the fourth flight is smaller than the third due to the majority of the fourth generation's predisposition towards diapause. However, in at least one case (1977), the fourth flight was unusually large and could be predicted by slight temporal shifts in the previous three flights resulting in the majority of the fourth generation larvae averting diapause. The value of the ECB‐diapause interaction as a model system for the explanation and prediction of dynamic phenological events is discussed.RésuméLes conséquences populationelles de la diapause sur le modèle biologique: Ostrinia nubilalisLa diapause d'O. nubilalis Hubn. est décrite d'après des études en conditions naturelles et programmées de souches sauvages ou élevées au laboratoire en Caroline du Nord. La diapause est décrite comme une fonction de la photophase (heures de jour/24 heures) et du stade larvaire au début des conditions inductrices de la diapause. Une photophase critique de 14,4 h et un stade critique larvaire de 3,3 ont été établis au laboratoire après 3 ans d'études en insectarium. 7 ans de piégeage à la lumière noire à Goldsboro, ont montré la vraisemblance de l'existence de 4 vols par an. Les données sur la diapause de cet insecte sont utilisées pour expliquer tant le nombre de vols que l'importance relative des derniers vols. En moyenne, la majorité des lignées ont 3 générations par an, O. nubilalis précoces produisant une quatrième génération conséquente et prédictible. La date et l'importance du 4ème vol peuvent être partiellement expliquées d'après la photophase critique, et la date et la structure en âge des générations précédentes. La plupart des années, le 4ème vol est moins important que le 3ème par suite de la prédisposition à la diapause de la majorité de la 4ème génération. Cependant, dans un cas au moins, en 1977, le 4ème était anormalement important et pouvait être prédit par de faibles changements temporels dans les 3 précédents vols, détournant de la diapause la majorité des chenilles de 4ème génération. La discussion porte sur la valeur du modèle fourni par la diapause de O. nubilalis pour expliquer et prédire la dynamique des événements phénologiques.}, number={1}, journal={Entomologia Experimentalis et Applicata}, publisher={Wiley}, author={Ellsworth, P.C. and Umeozor, O.C. and Kennedy, G.G. and Bradley, J.R., Jr. and Van Duyn, J.W.}, year={1989}, month={Nov}, pages={45–55} }