Efficacy of Baculovirus heliothis against larvae of the tobacco budworm was studied under laboratory, greenhouse, and field conditions. Dosage-mortality studies using a diet surface inoculation technique resulted in LC₅₀ values of less than 2 PIB/mm² for 1- to 5-day-old larvae. Onset of mortality was delayed in older larvae, and a greater quantity of inoculum was needed to produce the same mortality level as larvae matured. Length of the incubation period was shortened by increasing the dose. In laboratory and greenhouse studies, mortality of neonates was enhanced by the addition of commercial feeding stimulants. A cottonseed-base adjuvant was more effective than either virus alone or virus mixed with soybean flour. The value of the bait was particularly apparent when larvae were held for short durations on virus-treated terminals. Water extracts of fresh and dried garbanzo beans were shown to be highly attractive to tobacco budworm larvae, suggesting their potential for use as a feeding stimulant. Both bean treatments performed as well as the commercial cottonseed adjuvant. Virus-water extracts of garbanzo bean leaves and pods were no more effective in producing larval mortality than virus in water alone. Although addition of a feeding stimulant significantly extended activity of virus residues on cotton terminals bioassayed with H. virescens in the laboratory, the combination did not improve efficacy when larvae were allowed to feed on treated plants in the field. It may be that the effect of bait on young larvae was overridden by high temperatures or light intensities in the upper plant canopy. Time of application studies directed at the egg-stage showed that larvae are capable of ingesting lethal quantities of the pathogen while chewing out of treated eggs. Applications should coincide as closely as possible with egg hatch to maximize infection. Following hatching, there was a consistent decline in effectiveness as treatments were delayed. No significant effects on longevity or fecundity resulted from the feeding of virus to adults in a sucrose solution. Transovum transmission of virus to progeny was inefficient, regardless of the dose administered.

No description available.

A laboratory selected strain of Heliothis virescens demonstrating a 400-fold resistance to permethrin exhibited no differences in penetration and only a slight enhancement of metabolism when compared with a susceptible strain. Synergism with piperonyl butoxide and DEF produced similar synergist ratios for the resistant and susceptible strains, but the resistant strain showed a much larger synergist difference. Thin layer chromatography of extracts from larvae dosed with 14C-labelled permethrin demonstrated a small increase in metabolism of the cis-isomer by the resistant strain, but no differences in metabolism of the trans-isomer. The synergism study and the 14C-labelled permethrin experiment both indicate that there is a small increase in metabolism of permethrin in the resistant strain, but not enough to account for the greatly increased LD50 value. Cross-resistance to DDT indicated that target site insensitivity may play a major role in resistance to pyrethroids in this strain.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

No description available.

No description available.

Thesis (Ph. D.)--Auburn University. / Abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Some text in Spanish. Typescript. Vita. Includes bibliographical references (leaves 103-114). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Some text in Spanish. Typescript. Vita. Includes bibliographical references (leaves 103-114). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 75-84). Also available on the Internet.