摘要:

Two concepts are presented concerning biology ofAgrotis ipsilon(Hufnagel) on corn: (1) the black cutworm larvae that damage seedling corn in May and early June, originate from eggs oviposited in the field in the spring before the corn is planted; and (2) agronomic practices that encourage the establishment of weeds, especially winter annual and perennial weeds, increase the potential for presence of the black cutworm.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.191

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Field corn plants grown with seasonal irrigations of 70 cb or less soil moisture tension, applied every furrow, supported fewer mites (Oligonychus pratensis(Banks) andTetranychus cinnabarinus(Boisduval)) and showed lower levels of plant stress than plants in plots kept dry (200 cb) at some time during the growing season. Mite densities remained low before tassel and began increasing rapidly prior to soft dough. Prolonged rain and thunder-storms at tassel caused reduced mite density. It was concluded that rain and/or instrument controlled irrigations of ≤ 50 cb can limit the growth and severity of spider mite populations on corn.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.196

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Both sexes of overwinteringLygus lineolaris(Palisot de Beauvois) adults visit apple buds and blossoms (where they feed and cause injury) as well as apple foliage, twigs, and small branches. With the ultimate aim of developing a visual monitoring trap, we compared responses of the adults to 15×20-cm sticky-coated rectangles of different hues and shades hung in apple trees. Non-UV reflecting Gloss White and Zn white, Zoecon Yellow, and clear Plexiglas rectangles captured equivalent numbers of adults, significantly more than other hues of yellow, green, orange, blue, red, black, UV-reflecting aluminum foil, or Pb white rectangles. The fact that captures on clear Plexiglas were as great or greater than captures on pigmented rectangles approximating the spectral reflectance pattern of apple buds, blossoms, foliage, or bark suggests that the adults are not specifically oriented to the hue of tree structures which they visit. Significant differences in captures between certain pigments do suggest, however, that visual stimuli play at least some (still undetermined) role in the orientation of adults within or to trees. Additional findings indicate that a sticky-coated, non-UV reflecting white or Zoecon Yellow rectangle, hung vertically at ca. 0.7 m above ground, is the most efficient method yet devised for detectingL. Lineolarisadults in apple trees.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.202

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Aqueous infusions of decayed paper birch,Betula papyrifera(Marsh), are shown to contain an oviposition attractant for the tree-hole mosquitoAedes triseriatus(Say) in laboratory experiments. The attractive material is proved to be volatile and soluble in pentane.p-Cresol is shown to be an active component of this extract. Further experiments demonstrate that contact of ovipositing mosquitoes withp-cresol odor alone suffices to induce significantly increased oviposition. Trapping experiments show thatp-cresol solutions attract significantly more mosquitoes, both male and female, than does distilled water alone.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.206

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Five species of mammals and 3 species of birds passed polyhedral inclusion bodies (PIB) of the gypsy moth nucleopolyhedrosis virus (NPV) through their alimentary tracts in amounts great enough to kill gypsy moth larvae in bioassays. Opossums and raccoons passed roughly 5% of the PIB administered by intubation while white-footed mice, a short-tailed shrew, and southern flying squirrels passed 2.3, 1.8, and 0.05%, respectively. House finches and a red-winged blackbird passed close to 15% of the PIB administered, whereas mourning doves passed 0.05%.All the birds, as well as the shrew and squirrels, passed the PIB within 6 h of intubation. The white-footed mice passed PIB within 18 h of intubation, while it took the raccoons 22, and the opossums 70 h to eliminate PIB from their alimentary tracts.It is concluded that both mammals and birds pass significant amounts of NPV, and that both groups have features which contribute to their ability to passively transport NPV within the environment.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.210

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

A study was conducted to determine if adult corn rootworm (Diabroticaspp.) population estimates were influenced by training and experience of the sampler and(or) if they were affected by inherent personal differences between individuals of equal training and experience. Two levels each of plant counts, ear-tip collections, and timed collections were used in replicated studies in 2 Iowa cornfields. One field was typical of cornfields grown for grain production. The other field was late planted and late maturing, simulating those fields that develop extreme corn rootworm problems because of their attractiveness to migrating beetles.The plant counts and ear-tip collections were not significantly influenced by the maturity of the field or the investigators' inherent abilities or level of experience. Corn rootworm population estimates produced by timed collections were influenced by both field maturity and investigator variability.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.215

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Captured native male moths of the lesser peachtree borer (LPTB),Synanthedon pictipes(Grote and Robinson) were released at the center of a circular 800-ha area containing evenly spaced (6.5/ha) large wing traps. The avg recovery at this trap density was 20.3%; however, 97% were recaptured in 15 traps located within a 0.6-km radius of the release point. On the basis of this recapture rate, an estimated 16.6% of the native male population were captured during the season. Of those captured, 77% were caught in traps located near or within peach orchards.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.218

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

Ceuthorhynchidius horridus(Panzer), an imported European weevil which feeds on thistle rosettes, first released in the U.S. in 1974, has become established in 3 counties of Virginia. Releases at 10 selected sites infested withCarduusthistles were made between 1974–76; 3 on musk thistle (Carduus nutansL.),26 on plumeless thistle (C. acanthoidesL.), and one on a mixed stand. Establishment has been confirmed in the 3 musk thistle sites, one plumeless thistle and one mixed thistle site. These are the 1st establishments ofC. horridusin North America.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.221

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

The influence of seasonal increases in plant-leaf surface area on the searching efficiency ofTrichogramma nubilaleErtle and Davis was investigated in field and laboratory studies. Parasitoids were released continuously in corn throughout the weeks of plant growth and their success in discovering European corn borer (Ostrinia nubilalis(Hbn.)) egg masses was measured. In the laboratory, single female parasitoids were placed with a host egg mass within different sized arenas to measure the effect of an increase in area on the searching efficiency of the parasitoid.Increases in the leaf surface area or in searching arena size showed an inverse response in percent discovery by the parasitoid ofO. nubilalis. Field and laboratory studies support Knipling and McGuire's (1968) theoretical model. where an Increase In searching area results in a decrease in host discovery, when the searching pattern of the parasitoid is random.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.224

出版商:Oxford University Press    

年代:1979

数据来源: OUP

摘要:

The major vector of Maize Streak Virus (MSV), the causal agent of a serious disease of corn in Africa, isCicadulina mbila(Naude), a leafhopper restricted to the tropics and subtropics but not found in the United States. Seven species of leafhoppers, 2 species of planthoppers, and 3 species of aphids were tested for their ability to transmit MSV with negative results. The inability of these domestic insects to transmit MSV would seemingly greatly reduce the threat of this disease to corn production in the United States should it become established in the tropical or subtropical areas of the Americas.

ISSN:1754-5692    

DOI:10.1093/ee/8.2.228

出版商:Oxford University Press    

年代:1979

数据来源: OUP