No abstract

We studied imidacloprid application methods and timing to control the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), in forests. The methods compared were 1) soil injection near the trunk; 2) soil injection dispersed throughout the area under the canopy; 3) soil drench near the base of the trunk; and trunk injection with the 4) Arborjet, 5) Wedgle, and 6) Mauget systems. The applications were made in the fall and the following spring. Adelgid populations on the hemlocks (Tsuga spp.) were assessed in the fall of two successive years after the treatments. Relative to the untreated control trees, all the soil applications resulted in population reductions, but none of the trunk injections resulted in reductions. Fall and spring treatment efÞcacy did not differ. Reductions by the soil treatments were between 50 and 100% (avg 80%) by the Þrst fall and 83Ð100% (avg 98.5%) by the second fall. Analysis of imidacloprid residues using enzyme-linked immunosorbent assay found residues in sap, needles, and twigs 1 mo to 3-yr after application. A laboratory doseÐresponse bioassay using excised, adelgid-infested hemlock branches with cut ends immersed in serial dilutions of imidacloprid determined the LC 50 value to be 300 ppb, based on an exposure of 20 d. A high degree of suppression of the adelgid on forest trees was associated with residues in hemlock tissue Ͼ120 ppb 2 yr after soil treatment. Although precise relationships between residues and efÞcacy are elusive, it is clear that soil application of imidacloprid resulted in chronic residues of imidacloprid in tissues and suppression of adelgid populations for Ͼ2 yr.

A manual colorimetric method for analyzing ammonia or total Kjeldahl nitrogen is described that eliminates irreproducibility due to variability in time between additions of reagents. Variability is negligible when trisodium phosphate is substituted in the buffer in place of the usual disodium phosphate and sodium hydroxide. The resulting procedure is very simple and reliable and uses salicylate, which is the most environmentally acceptable of the alternative colorimetric reagents. Only two reagents are used, the first containing trisodium phosphate, salicylate, and sodium nitroprusside and the second containing hypochlorite. The accuracy of the method was verified in two ways:  first, by analyzing the digestate of three NBS standards and comparing the results to the NBS certified value; second, by analyzing the digestate of in-house samples and comparing the results using this procedure to the results using two other colorimetric procedures. Keywords: Total Kjeldahl nitrogen; ammonia; salicylate; NBS Standard tomato leaves; NBS Standard bovine liver; NBS Standard pine needles

Ethanol, methanol, acetone, and acetaldehyde-chemicals identified in the inner bark of living trees-were used to bait vane traps placed in crowns of oak trees in Connecticut. Ethanol-baited traps caught more cerambycid, scolytid, and clerid beetles than unbaited traps. Buprestidae were not attracted to ethanol. Acetaldehyde and acetone were not attractive to any family. A mixture of ethanol, methanol, and acetaldehyde was no more attractive than ethanol alone. The vane traps were very effective at catching Cerambycidae and Scolytidae, but ineffective compared to sticky panels at catching Buprestidae.

North American gypsy moths disperse as newly hatched larvae on wind currents in a behavior called ballooning. Because ballooning occurs before neonates begin to feed, resources used in dispersal are limited to those carried over from the egg. We show that nutritional experience of the maternal parent can influence the tendency of offspring to disperse, and that resource provisioning of eggs by the maternal parent affects the duration of the window for disperal. Offspring of females from defoliated sites had a lower tendency to balloon in a wind tunnel than larvae from females which had not experienced nutritional stress associated with host defoliation. The number of eggs in an egg mass, a reflection of the maternal parent's nutritional experience, also contributed to the predictive model for dispersal that included defoliation level. Egg weight and the levels of two yolk proteins, vitellin (Vt) and glycine-rich protein (GRP), however, had no influence of the proportion of ballooning larvae. The length of survival without food, and thus the maximum period of time for dispersal, was correlated with levels of Vt and GRP, but not with egg weight. The level of defoliation at the site from which the maternal parent was collected was not related to the longevity of offspring, nor did it have a significant effect on the levels of Vt, GRP or egg weight. Levels of hemolymph proteins arylphorin and vitellogenin in the maternal parent during the prepupal stage had no influence on levels of yolk proteins, larval longevity, or tendency to balloon.