Crawling was determined to be an important dispersal mechanism for spider mites leaving border vegetation and entering corn fields early in the season. This dispersal did not appear important in peanut fields. Large populations of spider mites in field corn were found responsible for subsequent infestations in peanuts. As corn plants senesced, mites began crawling to the periphery of the corn plant and grouping in masses on leaf tips, tassels and silks. During this period of mite movement, large numbers of mites were dispersed from the corn on wind currents and carried to nearby host plants. Aerial trapping verified this dispersal of mites and their subsequent colonization of previously uninfested peanut fields. Mites labelled in corn with a fluorescent powder were later found on peanut plants confirming the interhost movement. RÉSUMÉ Dispersion des tétranyches et relations entre champs voisins de maïs et d'arachide Dans le S. E. des U.S.A. Tetranychus urticae Koch est un ennemi sévère de nombreuses cultures. Il attaque souvent le mais le N. E. de la Caroline du Nord en juin et juillet: cependant les pullulations sur arachide se produisent généralement en aoǔt et septembre. Les tétranyches peuplent la végétation sauvage sur les bords des champs chaque printemps, quelle que soit la nature de la culture. Ces acariens pénètrent dans le champ à partir de cette végétation limitrophe et commencent à consommer le maïs. Les dégǎts sont plus sévères le long des bords. A cette époque, pour des raisons inconnues, très peu d'acariens ont émigré dans les champs d'arachide. Quand les acariens attaquent les arachides (aoǔt — septembre), il y a rarement cet effet de bordure. L'absence d'effet de bordure est dǔ au fai que les acariens se déplacent dans la culture d'arachide de différentes façons. L'éloignement des acariens de la plante a été observé quand le maïs se dessèche en juillet. Pendant ce déplacement, de nombreux acariens sont dispersés par le vent. La capture de tétranyches sur des lames de microscope engluées suspendues au‐dessus du maïs et des arachides, confirme cette dispersion aérienne. Ces acariens abandonnent un hǒté dépérissant (le maïs) pour coloniser les champs antérieurement sains d'arachide. L'utilisation de poudre fluorescente pour marquer les acariens sur le maïs permet de les récupérer sur les champs adjacents d'arachide, ce qui confirme le changement d'hǒtes. 86% des acariens capturés sur les lames engluées sont des femelles; ceci montre l'utilisation maximale du comportement de dispersion pour libérer les éléments reproducteurs.

ABSTRACTyield, improve some market grade characteristics, and decrease incidence of tomato spotted wilt tospovirus Experiments were conducted from 1999 through 2002 in North(TSWV) (Baldwin and Williams, 2002;Hurt et al., 2003). Interactions of planting pattern and seeding rate with irrigation have been reported for several crops. Irrigation increased corn (Zea mays L.) yield when higher A ltering plant population and row pattern can afplant populations were established compared with lower fect crop yield, quality factors, and pest developplant populations when row pattern was held constant ment in peanut. Pod yield of bunch-type peanut was (Liang et al., 1992). In contrast, corn yield did not in-16% higher when peanut was seeded in rows spaced crease when plant population was increased in absence 46 cm apart compared with 91 cm (Norden and Lipsof irrigation (Liang et al., 1992). In soybean [Glycine comb, 1974). Duke and Alexander (1964) reported pod max (L.) Merr.], increasing plant populations and deyield that was 14% higher in narrow row plantings comcreasing row width increased yield (Lehman and Lampared with traditional wider row patterns using largebert, 1960). In cotton (Gossypium hirsutum L.), yield seeded Virginia bunch-type peanut. Spanish market increases were noted when seeding rate was increased type peanut planted in 46-cm rows yielded higher than and row spacing was decreased (Briggs et al., 1967; Heitpeanut planted in rows spaced 61, 76, 91, or 107 cm apart holt et al., 1992;Hoskinson et al., 1974). at similar in-row plant populations (Parham, 1942). Cox Determining interactions of seeding rate and planting and Reid (1965) reported that increasing plant populapattern with variables such as cultivar selection and tions by increasing in-row seeding rate or by decreasing irrigation will assist growers and their advisors in develrow width increased pod yield.oping efficient production and pest management sysAlthough the majority of peanut in the USA is seeded tems for peanut. Therefore, research was conducted to in single rows spaced 91 to 102 cm apart, research sugcompare peanut pod yield, market grade characteristics, gests that seeding peanut in standard twin row patterns and TSWV severity when peanut was seeded in various (rows spaced approximately 18 cm apart with centers planting patterns, seeding rates, and cultural practices. of these rows spaced 91 to 102 cm apart) can increase MATERIALS AND METHODS

Several restriction sites in the cytochrome oxidase I gene of fall armyworm, Spodoptera frugiperda (J.E. Smith), were identified by sequence analysis as potentially being specific to one of the two host strains. Strain specificity was demonstrated for populations in Florida, Texas, Mississippi, Georgia, and North Carolina, with an AciI and SacI site specific to the rice (Oryjza spp.)-strain and a BsmI and HinfI site joining an already characterized MspI site as diagnostic of the corn (Zea mays L.)-strain. All four of these sites can be detected by digestion of a single 568-bp polymerase chain reaction-amplified fragment, but the use of two enzymes in separate digests was found to provide accurate and rapid determination of strain identity. The effectiveness of this method was demonstrated by the analysis of almost 200 adult and larval specimens from the Mississippi delta region. The results indicated that the corn-strain is likely to be the primary strain infesting cotton (Gossypium spp.) and that an unexpected outbreak of fall armyworm on the ornamental tree Paulownia tomentosa (Thunb.) Sieb. & Zucc. ex Steud. was due almost entirely to the rice-strain.

No abstract

Several restriction sites in the cytochrome oxidase I gene of fall armyworm, Spodoptera frugiperda (J.E. Smith), were identified by sequence analysis as potentially being specific to one of the two host strains. Strain specificity was demonstrated for populations in Florida, Texas, Mississippi, Georgia, and North Carolina, with an AciI and SacI site specific to the rice (Oryjza spp.)-strain and a BsmI and HinfI site joining an already characterized MspI site as diagnostic of the corn (Zea mays L.)-strain. All four of these sites can be detected by digestion of a single 568-bp polymerase chain reaction-amplified fragment, but the use of two enzymes in separate digests was found to provide accurate and rapid determination of strain identity. The effectiveness of this method was demonstrated by the analysis of almost 200 adult and larval specimens from the Mississippi delta region. The results indicated that the corn-strain is likely to be the primary strain infesting cotton (Gossypium spp.) and that an unexpected outbreak of fall armyworm on the ornamental tree Paulownia tomentosa (Thunb.) Sieb. & Zucc. ex Steud. was due almost entirely to the rice-strain.