Pest Management of Douglas-Fir Tussock Moth (Lepidoptera: Lymantriidae): A Sequential Sampling Method to Determine Egg Mass Density

Abstract

The sex pheromone of bertha armyworm, Mamestra conjigurata (Walker), was reported to be ( a -1 1-hexadecenyl acetate (Z11-16:Ac) and an unidentified tetradecenyl acetate. Electroantennogram responses of male antennae to synthetic isomeric tetradecenyl acetates and attractancy tests under field conditions showed that the highest number of males were captured with a blend of Z9-14:Ac : Z11-16:Ac in a ratio of 1:19 (Underhill et al. 1977). This blend has been useful for monitoring the relative abundances of bertha armyworm; however, in 162 monitor traps in southern Alberta from 1979 to 1982, the catches consisted of 18.4% Agroperina cogitata (Sm) .Recent advances in sex pheromone analyses, particularly the use of high resolution capillary gas chromatography (GC) with simultaneous flame ionization and electroantennographic detectors (GC-FID-EAD) or coupled directly to a mass spectrometer (GC-MS), have greatly facilitated the identification of minor pheromone components (Struble and Am, in press). Extracts from calling female moths were examined by these methods to confirm the presence of Z9-14:Ac and Z11-16:Ac, and to detect any other minor components that might be present. These components were then tested for their effects on the attraction of bertha armyworm males and common nontarget species.GC-FID-EAD and GC-MS conditions were as previously described (Struble 1983) except that glass capillary columns for GC-FID-EAD were 28 m Carbowax 20M TPA and Silar 10C, and a 55 m Carbowax 20M TPA column was used for GC-MS. Excised abdomen tips from 365 calling females were extracted with n-hexane, filtered, concentrated (N,) and analyzed without further clean-up.GC-MS analysis of the extract yielded complete EI and CI (isobutane) mass spectra of compounds having retention indices equivalent to 12:Ac, Z9-14:Ac, 16:Ac, Z9-16:Ac and Z11-16:Ac. Two other compounds, Z7-12:Ac and 14:Ac, were detected, but their spectra were incomplete due to a lack of sensitivity of the GC-MS.Male bertha armyworm antennae gave EAD responses only to Z9-14:Ac and Z11-16:Ac in the female extract. Antennae from males of other species, which had known specific EAD responses (Struble and Am, in press), were used as detector antennae to confirm the isomeric assignments of these two components and for the detection of 27-12:Ac, Z9-14:OH, 27-16:Ac, Z9-16:Ac and Z11-16:OH in the female extract (Table I). These isomeric assignments were based upon GC-FID-EAD retention times and cochromatography with authentic standards on both liquid phases. The estimated relative

DEVELOPMENT OF SAMPLING DESIGNS FOR EGG AND LARVAL POPULATIONS OF THE WHEAT MIDGE, SITODIPLOSIS MOSELLANA (GÉHIN) (DIPTERA: CECIDOMYIIDAE), IN WHEAT

“…Sequential sampling is used for a number of insect species as a tool in surveys for decision making in crop protection (Morris 1955;Waters 1955). It is also a reliable tool in pest management'to reduce sampling effort in monitoring a pest population if economic injury level of the pest species is known (Shepherd et al 1984;Turgeon and Regnibre 1987). Olfert et al (1985) reported that l , 2 , 3 , and 4 wheat midge larvae per kernel ( = 36, 72, 108, and 144 larvae per wheat head) damage 38, 58,78, and 96% of the kernels per head.…”

DEVELOPMENT OF SAMPLING TECHNIQUES FOR THE SPRUCE BUDMOTH, ZEIRAPHERA CANADENSIS MUT. AND FREE. (LEPIDOPTERA: TORTRICIDAE)

“…Iwao (1975) described a method of sequential sampling to help classify populations relative to a critical density, based on the mean crowding versus mean density relationship mentioned above. This method was used by several authors (Shaw et al 1983;Shepherd et al 1984;Shepherd 1985). Nyrop and Simmons (1984) discussed the errors associated with this method, and suggested that these errors be evaluated with every application.…”

DISTRIBUTION OF EGGS OF WESTERN BLACKHEADED BUDWORM, ACLERIS GLOVERANA (WALSINGHAM) (LEPIDOPTERA: TORTRICIDAE), AND OF FOLIAGE OVER THE CROWNS OF WESTERN HEMLOCK, TSUGA HETEROPHYLLA (RAF.) SARG.

“…Egg densities per branch were similar (6.26 and 6.49, respectively, t-testp = 0.79), but because foliage was reduced on the partially defoliated trees (3.69 and 6.70 g of needles per branch, respectively, p < 0.0001), egg density per gram of dry needle weight was significantly higher on the partially defoliated trees (2.63 and 1.20, respectively, p < 0.0001). Shepherd et al (1984) found that distribution of egg masses of Orgyiapseudotsugata (McDunnough) also changed depending on the basic unit selected. However, in contrast to A. gloverana, Condrashoff and Grant (1962) and Mason (1970) found egg mass density of 0. pseudotsugata became concentrated in the lower crowns when upper levels were defoliated.…”