Cruise of the United States frigate Potomac round the world : during the years 1831-34 ; embracing the attack on Quallah-Battoo ... /

Mode of access: Internet.

The Intellectual observer.

Title from caption.

The Student and intellectual observer of science, literature and art

Vol. 5 also called New series, vol. 1

England and Germany. Republished from "The Observer."

Mode of access: Internet.

The theories of inspiration of the Rev. Daniel Wilson, Rev. Dr. Pye Smith, and the Rev. Dr. Dick, proved to be erroneous : with remarks on the Christian observer, & Eclectic review,

Mode of access: Internet.

Rating the susceptibility of stands to southern pine beetle attack.

"April 1985"--P. [2]

The African observer : a monthly journal, containing essays and documents illustrative of the general character, and moral and political effects of negro slavery.

Mode of access: Internet.

The South Australian system of conveyancing by registration of title, with instructions for the guidance of parties dealing, illustrated by copies of the books and forms in use in the Land Titles Office. To which is added the South Australian Real Property Act as amended in the sessions of 1858, with a copious index by Henry Gawler. Adelaide, Printed at the Register and Observer Printing Offices, 1859.

Mode of access: Internet.

Computed induced velocity, induced drag, and angle of attack distributions for a two-bladed rotor

Cover title.

Influence of Observer Presence on Pacific Damsel Bug Behavior: Who is Watching Whom?

When direct observations are used to study animal behavior the presence of the observer may alter the animal and hence influence the data being collected, yet few studies have quantified this effect. We conducted direct observation studies in the glasshouse to assess the relative influence of observer presence on the behavior of Pacific damsel bugs, Nabis kinbergii, a potentially important predator of crop pests. Comparisons of predator activity, predator distribution, prey (Helicoverpa armigera) mortality and prey distribution between frequently observed and minimally observed treatments, during diurnal and nocturnal observation sessions showed that the frequency of observer presence had no apparent impact on Pacific damsel bug behavior. This is the first documented test of the impact of observer presence in an insect system. To place our results in context, we reviewed 15 papers on the influence of observer presence in a range of animals. We established that just over half of these papers found evidence for an effect. Nevertheless, direct observations should be useful in further studies of Pacific damsel bug behavior, and researchers using direct observations to study the behavior of other animals should be cognizant of observer effects during design and interpretation of their study.

Helicoverpa armigera (Hubner): can wheat stubble protect cotton plants against attack?

When investigating strategies for Helicoverpa armigera (Hubner) control, it is important to understand oviposition behaviour. Cotton (Gossypium hirsutum) was sown into standing wheat (Triticum astivum L.) stubble in a closed arena to investigate the effect of stubble on H. armigera moth behaviour and oviposition. Infrared cameras were used to track moths and determine whether stubble acted as a physical barrier or provided camouflage to cotton plants, thereby reducing oviposition. Searching activity was observed to peak shortly before dawn (03:00 and 04:00 h) and remained high until just after dawn (4 h window). Moths spent more time resting on cotton plants than spiralling above them, and the least time flying across the arena. While female moths spent more time searching for cotton plants growing in wheat stubble, the difference in oviposition was not significant. As similar numbers of eggs were laid on cotton plants with stubble (3.5/plant SE +/- 0.87) and without stubble (2.5/plant SE +/- 0.91), wheat stubble does not appear to provide camouflage to cotton plants. There was no significant difference in the location of eggs deposited on cotton plants with and without stubble, although more eggs were laid on the tops of cotton leaves in wheat stubble. As the spatial and temporal distribution of eggs laid on the cotton plant is a crucial component of population stability, eggs laid on the upper side of leaves on cotton plants may be more prone to fatalities caused by environmental factors such as wind and rain. Therefore, although stubble did not influence the number of eggs laid, it did affect their distribution on the plant, which may result in increased mortality of eggs on cotton plants sown into standing wheat stubble.