A mark–recapture study examined the spring flight dispersal of the ambrosia beetle, Trypodendron lineatum (Olivier), in an even-aged second-growth coastal forest in British Columbia. Pheromone-baited traps were placed in circular traplines at distances from 5 to 500 m from a central release location to (1) examine the relationship between wind direction and beetle catches in traps arranged around the release point, and (2) evaluate beetle catch characteristics when distances to baited traps were varied. A total of 29 800 marked beetles were released in three experiments. Upwind flight was most strongly exhibited at 5 m, with an upwind trend at 25 m, and no consistent flight pattern at 100 m, when wind movement was significantly directed. When the closest attraction was 100 m from the release point, beetles were caught uniformly in all directions indicating that flight was non-directional with respect to wind, for light wind speeds. Catches at 500-m traps tended to be downwind, thus beetles capable of flying that distance were ones that were flying with the wind. Equal numbers of beetles were captured at 5, 25, and 100 m despite increased intertrap spacings of 8, 20, and 32 m, respectively. A higher proportion of beetles were captured at 100 m when close-range traps at 5 and 25 m were not present.

Fenvalerate resistance was monitored in Psylla pyricola Foerster populations at 51 sites in Washington, Oregon, California, and British Columbia during early 1988. Resistance levels ranged from susceptible in an organic orchard in the Willamette Valley, OR, and at several other sites in Oregon and California, to highly resistant (> 100-fold compared with a susceptible strain) at several sites in central Washington. Generally, resistance levels were greater in the north than the south. In the Wenatchee and Yakima/Ellensburg, WA, areas, pyrethroid resistance was areawide, showing similar levels in both heavily treated and untreated orchards. In the Willamette Valley, OR, pyrethroid resistance was local and more consistent with the treatment histories of individual orchards. Factors influencing regional resistance appeared to be the species pool size of resistant and susceptible pear psylla, the intensity of spraying, and the unique host plant, life cycle, and dispersal attributes of this pest. Reasons for high regional resistance in central Washington and not in southerly areas are unknown, but this pattern is consistent with earlier patterns of insecticide resistance in pear psylla. The observed trends in fenvalerate resistance are discussed in relation to limiting resistance in pear psylla.

Relationships between temperature and immature developmental rates of apterous and alate Rhopalosiphum padi (L.) were determined in laboratory experiments conducted at constant and fluctuating temperatures. Lower and upper thresholds for development were 5.78 and 25.09 °C, respectively. Studies at fluctuating temperatures which simulated average and extreme low and high temperatures occurring during late-spring in eastern South Dakota were conducted to determine developmental rates and age-specific life table statistics. Developmental rates for cohorts exposed to variable temperatures were similar to expected developmental rates determined from constant temperature studies. Age-specific life table statistics differed among alate and apterous R. padi exposed to identical temperature regimes. On a day time scale, population growth rates of either morph increased with increasing temperature. When data were expressed on a degree-day time scale, population growth rates were similar for cohorts of either morph exposed to low and average temperature regimes. Population growth rates declined for cohorts of both morphs exposed to high temperatures. Equations were provided that estimate age-specific survival and natality for fluctuating temperatures. Stable nymphal instar distributions for apterous R. padi were similar at all temperatures; for populations with stable age structures, approximately 55, 15, 10, 7, and 10% of individuals would be first, second, third, and fourth nymphal instars, and adults, respectively.

The relative diapause intensity of a French univoltine and Saskatchewan commercial strain of the alfalfa leafcutting bee, Megachile rotundata (Fab.), was evaluated over a 3-year period. Prepupae from both strains underwent diapause development at 10 °C for different time periods. Diapause intensity was estimated by scoring days to emergence after initiating incubation at three different times in each of the 3 years: fall incubation (immediate post harvest); winter incubation; and spring incubation. In all comparisons made, the univoltine strain had a significantly increased diapause intensity compared with the commercial strain. We concluded that diapause intensity was heritable and that this stable difference between strains could provide the basis for a selected line with increased univoltinism under field conditions.

Phenology, fecundity, development, and mortality were studied for co-occurring, declining populations of Dendroctonus ponderosae Hopkins in limber pine and lodgepole pine at two sites in the Porcupine Hills of southwestern Alberta in 1985–1986. Beetles reared in lodgepole pine emerged and attacked new hosts 7–8 days earlier than those in limber pine in 1985. Beetles were able to utilize over two-thirds of the length of each limber pine bole but only about one-third of the length of each lodgepole pine bole. Also, beetles infesting limber pine had significantly higher fecundity, produced more eggs per centimetre of gallery length, and their progeny developed faster and survived better than beetles infesting lodgepole pine. There was no apparent phenological or other barrier that might inhibit gene flow between D. ponderosae populations in limber pine and lodgepole pine. In the area studied, limber pine was a better host for D. ponderosae reproduction, development, and survival than was lodgepole pine. Thus, beetle populations may be able to increase much more quickly in limber pine, arguing for regular monitoring of these populations.

Sticky stovepipe traps, flight interception traps, and Lindgren multiple-funnel traps were baited with conifer monoterpenes and ethanol to capture conifer-feeding beetles and their associates. Of the more than 6000 beetles captured, 74.6% were caught by stovepipe traps, 14.8% by interception traps, and 10.7% by multiple-funnel traps. Dominant families were the Scolytidae (14.5% of all beetles captured), Elateridae (14.4%), Lampyridae (12.1%), Cerambycidae (12.0%), Cleridae (10.5%), Curculionidae (9.3%), Staphylinidae (4.0%), and Buprestidae (3.4%), with other families accounting for 19.8% of specimens captured. Conifer-feeding species in the families Buprestidae, Melandryidae, Cerambycidae, Scolytidae, and Curculionidae and their predators (Cleridae) were captured in greatest numbers by the sticky stovepipe traps; the interception traps generally captured the fewest specimens. The sticky stovepipe traps may be superior because they offer a distinct vertical silhouette to approaching insects.

Based on field and laboratory research, a simulation model was developed that describes the within-season population dynamics and oviposition of adult northern corn rootworm beetles, Diabrotica barberi Smith and Lawrence, in field corn, Zea mays L. Particular emphasis was placed on the role of host plant phenology. Overall goals were to examine the contribution of insect dispersal to the dynamics of single fields, and provide a means of examining the factors influencing insect/plant synchrony and the relationship between adult abundance, oviposition, and crop phenology. The model is process-oriented and integrates component models for corn phenology, and adult emergence, mortality, dispersal, reproductive development, and oviposition.

Comparison of field data with simulations excluding dispersal generally indicated a net emigration of beetles from corn fields on a season-long basis; however, the timing and magnitude of dispersal from fields were strongly influenced by the relative timing of corn flowering, beetle sex, and the reproductive maturity of females. Simulation and field data were used to describe and estimate the parameters of a component model for dispersal incorporating these features. Various component models and the overall system model were validated against independent field data. The model provided adequate prediction of adult emergence and crop phenology for three varieties on which it was based, but consistently underpredicted total oviposition and poorly predicted the phenology of two different corn varieties. Overall, the model accurately predicted seasonal population trends, the relative abundance of mature females, and the relationship between adult abundance and oviposition.

Analyses were performed on a simulation model describing the population dynamics of adult Diabrotica barberi Smith and Lawrence in field corn. Overall goals were to gain a better understanding of the dynamics of this insect/plant system and explore possibilities for improved population management. Parametric sensitivity analyses revealed that model behavior was moderately sensitive to changes in the timing of female emergence, rates of immature female dispersal at peak flower, fecundity, and rates of reproductive development. Model behavior was highly sensitive to changes in age-specific oviposition rates, and to factors determining the seasonal timing and duration of the flowering period of corn. Alteration of planting dates, variations in seasonal temperature patterns, and year-to-year variation in beetle dispersal patterns greatly affected the simulated relationship between adult abundance, oviposition, and crop phenology, and the synchronization of beetle populations with flowering corn. Factorial analyses indicated that manipulation of planting dates, variety, and the duration of the flowering period represent equivalent alternatives for reducing site-specific oviposition. Factorial analyses further suggested that the timing of emergence and dispersal, relative to flowering, are the major factors contributing to the presence of beetles during the flowering period, but their relative contributions depend on the seasonal time of flowering. The timing of emergence is more important in early-flowering fields but dispersal becomes more important for fields flowering later in the season. Simulation was used to examine the relationship between adult abundance, oviposition, and crop phenology and to formalize hypothetical improvements in current action thresholds for making recommendations for corn rootworm control based on adult sampling. Overall, analyses have allowed important insights into the behavior of this insect/plant system.