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Jeffrey pine, Pinus jeffreyi Greville and Balfour, is a dominant yellow pine and important overstory component of forests growing on diverse sites from southwestern Oregon to Baja California to western Nevada. The Jeffrey pine beetle, Dendroctonus jeffreyi Hopkins (Coleoptera: Curculionidae: Scolytinae), is monophagous on Jeffrey pine and its primary insect pest. Despite the importance of P. jeffreyi, difficult terrain, environmental concerns, and lack of roads can constrain pest management activities. Semiochemicals are often easier to apply and more environmentally acceptable than other options, but they are lacking in this system. Attractants have been identified, but field bioassays have been limited because of infrequent or short duration outbreaks and a lack of beetles during nonoutbreak periods. Disruptant semiochemicals have not been assessed for D. jeffreyi during outbreak conditions; however, commercially available semiochemicals have been implicated as disruptants for this bark beetle. The objective of this study was to identify the most effective commercially available attractant and disruptant semiochemicals for D. jeffreyi. Our highest observed catch occurred with the blend of 5% 1-heptanol and 95% n-heptane. When this was used to challenge potential disruptant semiochemicals, the combination of S-(-)-verbenone and the green leaf volatile blend (cis-3-Hexenol and 1-Hexanol) reduced trap catch by ≈80%. However, frontalin was most effective, reducing the number of D. jeffreyi caught by >96%. Within each year of the study, the percentage female of D. jeffreyi caught with our attractant decreased from start to end of the experimental period. On average, our first collection in a year (mid-June to early July) was 59% female, whereas our last (mid-August) was 34%. Frontalin was equally or more effective against females (the pioneering sex) than males, providing optimism that semiochemieal disruption may be possible for protecting Jeffrey pines from D. jeffreyi. [ABSTRACT FROM AUTHOR]

Herbicide-resistant biotypes of weeds are an increasing threat to crop production. An understanding of the basic biology of resistant biotypes, including their growth and development relative to susceptible biotypes, may yield information helpful in the management of resistant biotypes. Greenhouse and growth chamber experiments were conducted to compare growth characteristics of biotypes of common cocklebur (Xanthium strumarium L.) that are resistant or susceptible to acetolactate synthase (ALS)-inhibiting herbicides. Averaged over two temperature regimes (24/18°C and 34/24°C day/night) under noncompetitive conditions, an ALS herbicide-susceptible (S) biotype produced more leaves, greater leaf area, and greater shoot dry biomass at 20 and 30 d after planting (DAP) than an ALS herbicide-resistant (R) biotype. By 40 DAP, leaf number, leaf area, leaf area ratio (LAR), leaf dry biomass, and shoot dry biomass were similar for R and S biotypes. Susceptible plants produced a greater root biomass, but R plants were taller at 40 DAP under noncompetitive conditions. Averaged across biotypes, relative growth rate (RGR) and photosynthetic net assimilation rate (NAR) were greater at the 24/18°C temperature regime. Averaged across temperature regimes, RGR and NAR were 11 and 17% greater for the R biotype than the S biotype under noncompetitive conditions. Under intertypic competitive conditions, the biotypes were similar in height, but the S biotype had a greater leaf number per plant. Evaluation of replacement series diagrams and relative crowding coefficient (RCC) estimates suggest that the two biotypes did not differ competitively in leaf production or plant height. The R biotype demonstrated a statistically significant, but probably trivial, competitive disadvantage in leaf dry biomass (tlof= -4.55, P = 0.01; RCCR:S = 0.73 ± 0.07) and shoot dry biomass production (tlof = -3.73, P = 0.02; RCCR:S = 0.73 ± 0.08). [ABSTRACT FROM AUTHOR]

The multicolored Asian lady beetle Harmonia axyridis (Pallas) is often a pest during autumn, when large numbers take flight and subsequently land on and enter buildings. Open field experiments were conducted during the autumn flight to examine the role of linear contrast in visually attracting beetles. White targets printed with 61 by 15-era stripes that varied in orientation and degree of contrast were covered in insect adhesive, attached to a white background panel, and erected in sites known to be attractive to flying beetles. Flights occurred when temperatures rose above 21°C. Diurnally, peak flight occurred between 1400 and 1600 hours but shifted progressively earlier within that framework as the flight season advanced. Beetles significantly chose targets with high contrast, black stripes; the number of beetles landing on all other contrast levels did not differ significantly from controls. Vertically positioned stripes attracted more beetles than horizontal ones, but not significantly. The effects of high contrast were absolute rather than relative. The number of beetles landing on targets with 50% contrast stripes did not increase when these were the highest contrast targets available. Results suggest that visual intensity contrast is key to understanding the behavior of H. axyridis in autumn and call into question some commonly accepted ideas regarding choice of overwintering sites. First, during migratory flight, H. axyridis is not visually attracted to the color white per se, and second, it is unlikely that, during flight, pheromones are involved in beetle orientation. [ABSTRACT FROM AUTHOR]