We compared the insect and arachnid species found in spring and summer samples of necrotic tissue of three species of columnar cacti, cardón [Pachycereus pringlei (S. Watson) Britten and Rose], organ-pipe (Stenocereus thurberi Buxb.), and senita [Lophocereus schottii (Engelm.) Britten and Rose] (all Cactaceae), endemic to the Sonoran Desert of North America. A total of 9380 arthropods belonging to 34 species, 23 families, 10 orders, and 2 classes were collected in 36 samples. Arthropod communities differed in composition among host cacti, as well as between seasons. These differences may be a function of variation in host characteristics, such as chemical composition and abiotic factors, such as water content or temperature.

Sexual size dimorphism occurs in many species. Differences between males and females, in size or other characteristics, may result from sexual selection, fecundity selection, natural selection, non-adaptive processes, or a combination of these pressures (Darwin 1874; Selander 1966; Trivers 1976; Slatkin 1984; Shine 1989). In insects, females with large body size often produce more eggs than smaller females, and femalebiased sexual size dimorphism is commonly attributed to such fecundity selection (e.g., Preziosi and Fairbairn 1997; but see Leather 1988). Water boatmen are detrivorous or zoophagous aquatic insects often inhabiting small ponds of the Northern Hemisphere (Hungerford 1948; Nosil and Reimchen 2001). Female water boatmen are generally larger than males. In this note, I quantify the nature and magnitude of a previously undescribed sexual size dimorphism in a natural population of the water boatman Callicorixa vulnerata Uhler (Hemiptera: Corixidae). I tested for differences between males and females in mean trait size (body length, body weight, mid-leg tarsal length, mid-leg tarsal spine number), and also tested for sexual dimorphism in allometric relationships between tarsal traits and body length.

The levels of ovarian growth and transcription of the vitellogenin gene were compared in Pissodes strobi Peck (Coleoptera: Curculionidae) feeding on severed leaders from susceptible and resistant Picea sitchensis (Bong) Carr (Pinaceae) and in weevils given a dose of an aqueous extract from the bark of such leaders. A force-feeding method was developed to deliver the extracts into the alimentary canal of the weevils. Weevils given one dose of the aqueous extract from resistant leaders, followed by feeding on sections of laterals from susceptible trees, exhibited a 60% inhibition of oocyte growth relative to insects given the extract from susceptible leaders. In similar experiments, transcription of the vitellogenin gene of the weevils was inhibited by about 48%. Transcription of the vitellogenin gene was reduced by about 60% in weevils feeding on the severed leaders from the resistant clone relative to those feeding on severed leaders from susceptible trees. Results indicate that these effects of resistance do not require an intact tree. Experiments using extracts show that the observed effects result from a post-ingestive effect of the extract.

In North America, the black carpet beetle, Attagenus unicolor (Brahm) (Coleoptera: Dermestidae), is a common household insect pest that feeds on many animal-origin and grain products. It overwinters as a larva, and the entire life cycle generally takes about 1 year. No information exists on its overwintering biology or cold hardiness (Fields 1992). In this experiment, the supercooling point (SCP) and survival rate of initially overwintering A. unicolor larvae collected in the nests of tree swallows, Tachycineta bicolor (Vieillot) (Aves: Hirundinidae), were measured. Changes in SCP and cold hardiness were determined for larvae held at 15 and –15°C. The cold hardiness of A. unicolor larvae collected from a feed mill in British Columbia was also measured.

Optical brighteners were recently discovered to function as UV protectants for baculoviruses of insects (Shapiro 1992) and, also, to enhance entomopathogenic activity of these viruses (Hamm and Shapiro 1992; Li and Otvos 1999a). Enhancement of viral activity by brighteners varied greatly from one virus–host system to another: for example, from 1500-fold in LdMNPV against Lymantria dispar (L.) (Lepidoptera: Lymantriidae) (Argauer and Shapiro 1997) to 2- to 13-fold in a multicapsid nuclear polyhedrosis virus of Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) (CfMNPV) against Choristoneura occidentalis Freeman (Li and Otvos 1999a). The reason for this variation in enhancement of viral activity is still unknown. In this study, we used CfMNPV to compare the levels of viral enhancement by an optical brightener between C. occidentalis and C. fumiferana.

Studies were conducted to document the oviposition biology of female white pine weevil, Pissodes strobi Peck. Data were recorded on female fecundity and daily feeding and oviposition activities. In addition, we compared fecundity of 1- and 2-year-old females. Female white pine weevils laid a mean ± SE total number of 132.3 ± 7.5 eggs (range 40–344 eggs) during an average oviposition period of 5.8 ± 0.4 weeks. It is during the first 5 weeks that white pine weevils lay the most eggs, with an egg-laying peak in the second week of the oviposition period. For a few females, egg production did not cease until the 22nd week. There was no difference between the number of eggs laid in the photophase and in the scotophase, but higher numbers of feeding punctures were observed during the night than during the day. The oviposition and feeding results for 2-year-old female white pine weevils were similar to those for 1-year-old females. This information contributes to the management of white pine weevils by providing a better understanding of some of the mechanisms of its population dynamics.

Host preference of the pine shoot beetle, Tomicus piniperda (L.), was investigated in two laboratory choice test studies using red pine (Pinus resinosa Ait.) (Pinaceae), jack pine (Pinus banksiana Lamb.), and Scotch pine (Pinus sylvestris L.). Host preference of parent adult beetles was evaluated using freshly cut, similarly sized logs in a wind tunnel. Parent beetles colonized Scotch pine logs significantly more often when given a choice of Scotch pine and either red pine or jack pine logs, but did not show a preference when presented with red pine and jack pine logs. Host preference of progeny adults was tested in a laboratory bioassay using current-year pine shoots. Shoot-feeding progeny adults initiated tunnels in jack pine shoots significantly more often than in Scotch pine and red pine shoots, and preferred Scotch pine over red pine shoots. Shoots with diameters of 0.4–0.5 cm were attacked most frequently, regardless of species. Results suggest that the two North American pines are suitable hosts, but T. piniperda may be most likely to colonize Scotch pine, a European species. Efforts to detect or monitor T. piniperda populations in the Great Lakes and northeastern regions should focus on areas with abundant Scotch pine brood material. Progeny that emerge from brood material, however, may be as likely to shoot-feed in jack pine as in Scotch pine.

We released marked mature male flies of the apple maggot, Rhagoletis pomonella (Walsh), inside and outside of square blocks of apple trees, Malus domestica Borkh. (Rosaceae), to test the effect of orchard structure on the interception of flies by odor-baited red-sphere traps. The blocks were composed of large trees planted at low density, medium-sized trees planted at medium density, or small trees planted at high density. The experiment was carried out in six commercial apple orchards during summer in 1997 and 1998. Released flies moving into blocks were intercepted in large proportions by baited perimeter traps, thus preventing fly penetration into sphere-protected blocks. In 1997, proportions of intercepted flies were higher for traps in blocks of small and medium-sized trees than for traps in blocks of large trees. In 1998, a year with an unusually low fruit load, interception remained high, but there were no differences in proportions of flies intercepted by perimeter traps among blocks of trees of different sizes. Overall we conclude that the tendency of apple growers in Massachusetts to replace large trees planted at low density with small or medium-sized trees planted at high or medium density will not adversely affect behavioral control programs for apple maggot flies. In fact, this practice may enhance the effectiveness of these programs through increased interception of immigrant adults.

The sex pheromone of the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), from the Niagara Peninsula, Ontario, was investigated using chemical analysis, GC–EAD, and field trapping experiments. The pheromone gland contained: (Z)-11-tetradecenyl acetate (Z11-14:Ac), (E)-11-tetradecenyl acetate (E11-14:Ac), (Z)-11-tetradecen-1-ol (Z11-14:OH), and (Z)-11-tetradecenal (Z11-14:Al). The average amounts of Z11-14:Ac, E11-14:Ac, Z11-14:OH, andZ11-14:Al were 40.40, 0.83, 0.47, and 0.13 ng/female, respectively. Eight other structurally related compounds, (E)-11-tetradecenal (E11-14:Al), (E)-11-tetradecen-1-ol (E11-14:OH), pentadecan-2-one (15-2kt), hexadecanal (16:Al), hexadecan-1-ol (16:OH), heptadecan-2-one (17-2kt), octadecanal (18:Al), and octadecyl acetate (18:Ac), were also identified. In a field trapping experiment, adding Z11-14:Al to lures containing a 100:3:5 blend of Z11-14:Ac, E11-14:Ac, and Z11-14:OH in an amount equal to 2% of the main component significantly increased the number of moths captured in apple, Malus domestica (Borkh.) (Rosaceae), orchards. The removal of Z11-14:Al from lures containing a 100:2:1.5:1 blend of Z11-14:Ac, E11-14:Ac, Z11-14:OH, and Z11-14:Al resulted in a > 50% reduction in the average total number of moths captured in a trap. This study provides the first evidence that Z11-14:Al is present in the pheromone of an eastern North American population of C. rosaceana.

Dendroctonus ponderosae (Hopkins) is widely distributed across western North America, feeding in at least 12 native species of Pinus L. (Pinaceae). We investigated the existence of heritable differences in two life-history parameters (adult size and development time) of D. ponderosae from a northern population (central Idaho, Pinus contorta Douglas ex Loudon) and a southern population (southern Utah, Pinus ponderosa Douglas ex P. and C. Lawson). We attempted to separate heritable from environmental effects by rearing individuals from both populations through two generations (F1 and F2) in a common standardized laboratory environment with a constant temperature. Two treatment effects were tested for in the F2 generation: (1) geographic location (source host) for F0D. ponderosae; and (2) the F2 brood host. We hypothesized that, if differences were observed and the F0 source host and region had a greater effect on F2 brood development time and adult size than did the host in which F2 brood were reared, a heritable factor related to the F0 parents was responsible. Time to emergence was significantly shorter for second-generation offspring of the northern population than for second-generation offspring of the southern population, regardless of the F2 brood host. Although both the F2 brood host and F0 source parents were significant in explaining differences observed in the developmental-time distribution of F2 brood, the F0 source effect was found to be much greater. Also, F2 males and females from southern source parents were significantly larger than F2 brood from northern source parents when reared in both F2 brood hosts. Geographic region and original host of F0 source parents had a significant effect on F2 offspring size, whereas the immediate food for F2 brood was not significant in explaining differences. These results suggest genetically based regional differences in D. ponderosae populations.

A previous investigation from our laboratory showed that the odor of live green peach aphids, Myzus persicae (Sulzer), highly attracts the convergent lady beetle, Hippodamia convergens Guérin-Méneville. In this study, we isolated the odor and identified it as (E)-β-farnesene (an aphid alarm pheromone) using gas chromatography – mass spectrometry. The olfactory response of the convergent lady beetle to (E)-β-farnesene was investigated using an eight-arm air-flow olfactometer and tracing the pathways of the lady beetles. The results clearly indicate that H. convergens can perceive and orient to (E)-β-farnesene released by green peach aphids. These findings suggest that this species of lady beetle has evolved a sensory system for detecting the green peach aphid alarm pheromone as a means of finding its prey.

Laboratory and field feeding tests with Leptoglossus occidentalis Heidemann demonstrated that both immature and mature seed bugs can use cones and foliage of whitebark pine, Pinus albicaulis Engelmann, as a food source for 1- to 2-week periods. Damage to unprotected whitebark pine cones by seed bugs ranged from 0.3 to 2.1% of seeds per cone. Total insect damage ranged from 0.4 to 7.1% of seeds per cone. A seed chalcid, Megastigmus Dalman. sp. (Hymenoptera: Torymidae), was documented for the first time on whitebark pine and was found in 4.7% of examined seeds at one site. The larch cone fly, Strobilomyia macalpinei Michelsen, was reared from cones of alpine larch, Larix lyallii Parl., from the Bitterroot Range of Montana. This is the first record of this species in the United States and the first since its description in 1988. Ninety-four percent of a sample of alpine larch cones were damaged by cone fly larvae and 64% contained larvae or puparia.

The pine engraver, Ips pini (Say), breeds in the phloem tissue of dead, dying, or downed pines, occasionally attacking standing live trees when populations build up to significant levels following logging activities or infestations by the mountain pine beetle, Dendroctonus ponderosae Hopkins (Furniss and Carolin 1980). In British Columbia, I. pini uses ipsdienol as an aggregation pheromone to facilitate large aggregations of mated beetles and breeding galleries (Miller et al. 1996). The aggregation pheromones, exo-brevicomin and cis- and trans-verbenol, used by D. ponderosae (Borden et al. 1987; Miller and Lafontaine 1991) interrupt attraction of I. pini to ipsdienol (Miller 1991). Another semiochemical, frontalin, is used by D. ponderosae as a multifunctional pheromone (Borden et al. 1987), enhancing attraction of beetles at low release rates and interrupting attraction at high release rates. I tested the effect of frontalin, over a broad range of release rates, on the attraction of I. pini to ipsdienol-baited traps.

The coffee white stem borer, Xylotrechus quadripes (Chevrolat) is a major pest of coffee, Coffea arabica (L.) (Rubiaceae), in South Africa, India, Thailand, and China (Duffy 1968; Schoeman 1990; Visitpanich 1994; Montavon 1997). Females lay eggs singly or in batches, generally under bark crevices of the stem. Neonatal larvae feed beneath the bark and, during development, bore deeply inside the stem. Stems are colonized by up to 60 larvae. Extensive damage by larvae causes mortality of coffee plants or reduction of fruit production (Duffy 1968; GK veeresh). Because larvae inside the stems of coffee plants are difficult to control, management tactics are aimed at preventing infestation, either by interfering with oviposition of females or by killing neonates before they bore into the stem. Our study tested insect and host plant derived stimuli that may affect the selection of oviposition sites by female X. quadripes.

The impact of multiple applications of the kaolin-based particle film M96-018 on the population density of selected pests of apple, Malus domestica (Borkh) (Rosaceae), and their natural enemy populations were measured in several Washington State orchards from 1997 to 1999. Densities of western tentiform leafminer, Phyllonorycter elmaella (Doganlar and Mutuura) (Lepidoptera: Gracillariidae), were significantly higher and percent parasitism was generally lower in treated plots than in untreated plots. The effect of M96-018 on green aphids (Aphis spp.) (Hemiptera: Aphididae) was variable between orchards; however, populations of rosy apple aphid, Dysaphis plantaginea Passerini (Hemiptera: Aphididae), were higher in treated plots than in untreated plots. M96-018 reduced the mean density of the white apple leafhopper, Typhlocyba pomaria (McAtee) (Hemiptera: Cicadellidae), and the density of spiders (Araneae) compared with untreated plots. Fruit injury by codling moth, Cydia pomonella (L.), and fruittree leafroller, Archips argyrospilus (Walker) (Lepidoptera: Tortricidae), was significantly reduced in the treated plots compared with the untreated plots. The effect of M96-018 on the mullein bug, Campylomma verbasci (Meyer) (Hemiptera: Miridae), was variable between orchards and years. Stink bug (Hemiptera: Pentatomidae) density and related fruit injury were unaffected by M96-018. Fruit infestation by San Jose scale, Quadraspidiotus perniciosus (Comstock) (Hemiptera: Diaspididae), was significantly higher in treated plots than in untreated plots. Discontinuing applications of M96-018 at mid-season reduced the number of aphid-infested leaves and increased fruit injury by leafroller compared with a full-season program. No differences in pest densities occurred in plots treated for one versus two consecutive years; however, the density of phytophagous mites (Acari: Tetranychidae) was significantly higher the subsequent year after plots were treated with M96-018. Further studies are needed to elucidate how these disruptive impacts of particle films can be minimized.

Fitness, defined as the per capita rate of increase of a genotype with reference to the population carrying the associated genes, is a concept used by biologists to describe how well an individual performs in a population. Fitness is rarely measured directly and biologists resort to proxies more easily measured but with varying connection to fitness. Size, progeny survival, and developmental rate are the most common proxies used in the literature to describe parasitoid fitness. The importance of the proxies varies between papers looking at evolutionary theories and those assessing ecological applications. The most direct measures of fitness for parasitoids are realised fecundity for females and mating ability for males, although these proxies are more difficult to measure under natural conditions. For practical purposes, measure of size, through body size or mass, is the proxy easiest to use while providing good comparative values; however, care must be taken when using a single proxy, as proxies can be affected differently by rearing conditions of the parasitoid.