Developmental rates of post-diapause eggs of Diabrotica virgifera virgifera LeConte were compared in the laboratory at six constant temperatures, 12, 16, 20, 24, 28, and 32°C. Linear and nonlinear models were fitted to temperature versus developmental data and were used to predict egg hatch in the field. A four-parameter model fitted to median developmental rates (r2 = 0.99) indicated that development was linear between 16 and 28°C, optimal at 28°C, and decreased at 32°C. The lower development threshold (± SE) (10.5 ± 0.1°C) was determined by linear regression and the x-intercept method. Completion of post-diapause egg development required 258 ± 3 degree-days (± SE) above the base temperature. This compared well with the mean degree-days accumulated to 50% hatch (± SE) of 265 ± 24 which we observed in the field at several locations over 3 years using a degree-day model incorporating an 11°C developmental threshold and soil temperatures at 5- and 10-cm depths. A stochastic simulation model, incorporating a nonlinear developmental function dependant on soil temperatures taken every 2 h also predicted 50% hatch within 2 days. This model was validated in the field with 19 independent records of soil temperatures for several locations at two depths in the soil over 3 years. The simulation model accurately predicted time of 5 and 95% hatch, which indicates that this model has broad application in predicting the pattern of egg hatch for pest management.

When carrot rust fly, Psila rosae (Fab.), collected as mature third-instar larvae on three dates in each fall of 3 years from carrots from the Holland Marsh, Ont., pupated in the laboratory at 10°C, the intensity of the diapause induced was lower in the samples collected latest in the season. Similarly, the latest pupating cohorts of pupae formed in the field exhibited less intense diapause and developed more rapidly at 20°C in the fall or the following spring. When larvae were kept at 1 or −2°C for varying periods before pupation at 10°C, the incidence and intensity of the pupal diapause decreased with increasing duration of exposure to the low temperatures. Larvae held at 5°C pupated in less than 60 days and entered diapause. Transfer of puparia from 20 to 10°C at various stages of pupation showed that diapause was induced if pupae were transferred less than 48 h after formation of the pupa was first evident.

Adults of Bandakia hoffmannae sp.nov., Bandakia mexicana sp.nov., Chappuisides notialis sp.nov., and Neoacarus adocetus sp.nov., all collected in the mountains west of Mexico City, are described. These are the first reports of species of these three essentially holarctic genera from south of the United States border in North America. These discoveries provide new insight concerning the extent of refugial areas for freshwater arthropods in southern North America during the Pleistocene.

Relationships among catches of corn earworm moths, Helicoverpa (= Heliothis) zea (Boddie), in pheromone traps, numbers of corn earworm eggs, and corn ears with fresh silks were investigated in eight corn fields during a 2-year period in Brazos River Valley, Texas. Cross-correlation analysis indicated that the catches of corn earworm moths in pheromone traps were closely associated with egg numbers in seven of eight fields with a time differential varying between −1 to +2 days. Cross-correlation peaks for new silks versus eggs occurred with time differentials being mostly positive, indicating that corn earworm egg numbers reached a maximum after corn produced large numbers of fresh silks on ears.

There was a weak but significant linear relationship between egg numbers and corn earworm catches in pheromone traps when corn was in the whorl stage of growth. A stepwise regression model of the form: log (eggs/ha + 1) = 3.71 + 0.22*log(S + 1)*log(T + 1) − 0.3*log(S + 1), where S = numbers of corn ears with new silks per hectare, and T = mean corn earworm moths per trap, explained 52.5% of the variance. These results emphasize the mediating effects of fresh silks on corn earworm oviposition on corn.

An improved method for rearing horn flies, Haematobia irritans irritans (L.), on bovine hosts is reported in which adult flies were confined in cages fastened to the backs of stanchioned cattle. Survival of females was 75% per day and longevity averaged 3.5 days. Oviposition began when females were 2 days old. The number of eggs produced per female entering the population averaged 20.1, and a single female could produce up to 112 eggs in her lifetime. Immature survival averaged 48.9%. The generation growth rate was 4.91 females per female. Generation time was 20 days at 25°C. Approximately 1–3.8 g of manure per egg is recommended for larval rearing. Pupae can be stored at 10°C for up to 18 days with little loss in viability. Methods for using the life history information for optimizing rearing are discussed.

Adult females of Rutripalpus canadensis sp.nov. (family Rutripalpidae) from Cape Breton Island, Nova Scotia, Canada, adults of both sexes of Scutolebertia trinitensis gen.nov., sp.nov. (family Lebertiidae) from the Coast Range in northern California, USA, and adults of both sexes of Pseudotorrenticola chiricahua sp.nov. (family Torrenticolidae) from Arizona, USA, are described. The three new species represent the first members of their respective genera to be reported from North America, and their discovery provides new perspectives on the phylogeny and biogeography of mites in these genera.

Larvae of one pyralid, five noctuid, and one geometrid species were exposed to six species/strains of steinernematid and two species of heterorhabditid nematodes applied to soil surface in the laboratory. The most parasitic nematodes were Steinernema bibionis Bovien for the wax moth (Galleria mellonella L.) and the bertha armyworm (Mamestra configurata Wlk.), Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) for the cereal armyworm [Pseudaletia unipuncta (Haw)], S. feltiae Filipjev Mexican for the variegated cutworm [Peridroma saucia (Hbn.)], and S. feltiae All for the red-backed cutworm [Euxoa ochrogaster (Gwen)] and the spring cankerworm [Paleacrita vernata (Peck.)]. When both LD50 values and rates of parasitism of the hosts were considered together, the most promising nematode for soil applications was S. feltiae against the bertha armyworm.

Fourteen new species of the family Pauropodidae are described from central Japan: Allopauropus (Allopauropus) loligoformis. A. (Decapauropus) fortisus, A. (D.) ibarakiensis, A. (D.) infurcatus, A. (D.) ligulosus, A. (D.) pseudokoreanus, A. (D.) tetraramosus, A. (D.) toshiyukii, A. (D.) yamizo, Pauropus tamurai, Stylopauropus (Stylopauropus) canaliculatus, S. (Donzelotauropus) peniculatus, S. (D.) undulatus, and Colinauropus schelleri. Among them, two genera, Stylopauropus and Colinauropus, are recorded for the first time from Japan.

Five species of Aphis Linnaeus from Leguminosae in North America which have large dorsal sclerotized areas on apterous viviparous females are known: A. craccae Linnaeus, A. craccivora Koch, A. cytisorum Hartig, A. astragalina Hille Ris Lambers, and A. gallowayi sp.nov., described from Astragalus pectinatus Douglas, Bow Valley Provincial Park, Alberta.

Bumble bees rely on stored nectar to maintain high colony temperatures. This study examines some of the costs associated with exhausting stored nectar for a day in confined colonies of Bombus occidentalis Greene and B. melanopygus Nylander. Workers from energy-deprived colonies ceased incubating and allowed brood temperatures to drop to ambient levels. Workers from energy-rich colonies responded to a simulated vertebrate predator by actively moving about and buzzing loudly (apparently searching for the source of disturbance), but those from energy-depleted colonies mostly remained stationary on the comb. Workers from energy-rich colonies responded to an intruding social parasite (a Psithyrus insularis Smith queen) by chasing and attacking it, whereas those from energy-depleted colonies adopted stationary threat postures. In both cases, the more successful defensive strategy of simultaneous attack by several workers was not employed by nectar-depleted colonies. Cooling of final-instar larvae and pupae added to their development times (disproportionately so in the case of pupae), but low temperature per se did not affect their probability of survival. Hence, the costs of short-term energy shortfall include increased susceptibility to predators and parasites and a lengthened period of development. These costs probably relate to energy stores in a nonlinear manner, providing the foundation upon which risk-sensitive foraging decisions can be based.

Moths of the genus Pseudexentera are early-season fliers that include three species of economic importance: P. spoliana (Clemens) on oak (Quercus), P. oregonana (Walsingham) on aspen (Populus), and P. mali Freeman on apple (Malus). GC and GC/MS analysis, EAG and behavioral bioassays, and field tests confirmed that Z10-16:Ac is an attractive sex pheromone component of female P. spoliana. Capillary GC analysis supported by GC/MS also indicated the presence of 16:Ac, Z10-16:OH, and 16:OH in pheromone extracts and there was tentative GC evidence for Z12-16:Ac. However, addition of these compounds to Z10-16:Ac in various blends did not enhance male attraction. The major sex pheromone component of female P. oregonana is Z8-14:Ac. There was also GC and GC/MS evidence for Z8-14:OH and tentative GC evidence for 14:Ac in the pheromone of this species. Their addition to Z8-14:Ac failed to increase moth catches in baited traps. Pseudexentera mali males were attracted by Z,Z-8,10-16:Ac, a previously reported sex pheromone of this species. Pheromone lures targeted for each species were not cross-attractive.

All larval instars of Compsilura concinnata (Meigan) (Diptera: Tachinidae) develop in the midgut of the gypsy moth [Lymantria dispar (L.) (Lepidoptera: Lymantriidae)] between the peritrophic membrane and gut wall. Parasitoid larvae placed artificially in the host haemocoel quickly moved to this characteristic position. There was a positive relationship between parasitoid size, as measured by the weight of the puparium, and the potential fecundity of female flies. When C. concinnata parasitized third-instar larval hosts, there were fewer successful multiple emergences, parasitoid larvae took longer to develop, and puparia were significantly smaller than those of parasitoids attacking fifth-instar hosts.

Gypsy moth larvae grew more slowly on diets supplemented with 0.5 and 2.5% tannic acid than on non-supplemented diets. Similarly, C. concinnata females were smaller (with associated reduction in fecundity) when emerging from hosts feeding on the tannin diets than when hosts were feeding on control diets. The effect of tannic acid on the parasitoid was indirect and was the result of a reduction in host quality on the tannin diets. Reduction in parasitoid fecundity associated with tritropic interactions (among the host plant, the gypsy moth, and the parasitoid) may provide a possible explanation for the irregular impact of C. concinnata on gypsy moth populations.

A simulation model was developed for the population dynamics of a carrot weevil, Listronotus oregonensis (LeConte), population on muck-grown carrots. The model includes mortality rates of eggs, larvae, and pupae for different sowing dates of carrots. It also incorporates the overwintered adult density, the temperature-dependent growth rates of the above-mentioned life stages, the age-, temperature-, and phenology-dependent oviposition rates, and the impact of an egg parasitoid, Anaphes sordidatus (Girault), on egg mortality rates. Model output was evaluated by comparing simulated results with observed results on the seasonal totals and time of population peaks of the egg and larval populations. The mean percentage differences between the simulated and observed seasonal egg totals were 3.1 ± 0.66 (SE) in 1987 and 1988, and 4.2 ± 0.05 in 1989. They were not statistically different. The mean percentage differences between the simulated and observed seasonal larval totals were 10 ± 3.33 in 1987 and 1988 and 29.8 ± 0.66 in 1989. Independent data sets (i.e. field data in 1989) showed a significant increase in the simulation error of the larval population. Sensitivity analysis indicated that A. sordidatus had a large influence on the population dynamics of L. oregonensis.

Enzymes were investigated, by electrophoresis, in a population of Glossina fuscipes fuscipes Newstead collected from Rusinga Island in Lake Victoria, Western Kenya.

The following enzymes were tested: glucose phosphate isomerase, glucose-6-phosphate dehydrogenase (G6PDH), hexokinase. isocitrate dehydrogenase (IDH), malate-dehydrogenase (MDH), phosphoglucomutase, and xanthine dehydrogenase (XDH).

Single monomorphic bands were stained by the following enzymes apparently under the control of single loci: G6PDH, MDH, and XDH. The enzyme IDH showed two bands with very close mobilities and no variation among individuals in the population. Hence IDH was considered as representing a single locus. Glucose phosphate isomerase manifested three alleles and apparently six genotypes. Phosphoglucomutase manifested a double-banded pattern representing an autosomal locus.

Dilemmas in weed biocontrol are wide ranging. Even the term biological control is confusing as meanings may be restricted to the use of parasites and predators or extend to the use of all non-chemical means of control. Another problem is that two-thirds of the agents released do not become numerous enough to inflict major damage to the weed population, although this statistic is misleading as it includes agents costing little in pre-release studies where failure is of little consequence and those costing about two scientist years each, or currently about $400,000. Many of the suggestions for improvement are costly and time consuming. Delay is unacceptable where agent release is seen by sponsors as a mark of progress in a program likely to require 20 years and funding is difficult. Analysis of previous biocontrol attempts for attributes of "success" have been disappointing, partly because there are a number of steps involved, each with its own attributes. This paper recognizes four graded "success" steps and discusses many agent selection methods.

There are public demands for a change in emphasis from chemical to biological control; but in the absence of effective enabling legislation, the practice of biocontrol can be legally and politically hazardous; biocontrol should be carried out by a multidisciplinary team but it is usually assigned to a single scientist; it needs to branch in new directions to remain scientifically stimulating, but this increases the risk of failure. Possible solutions for these dilemmas are discussed.

Morphological and distributional data are presented for the North American species of the genera Phreatobrachypoda Cook, 1963 and Bharatalbia Cook, 1967. These mites live in gravel deposits associated with riffle areas and the hyporheic zone of streams. Female adults of Phreatobrachypoda multlpora Cook are redescribed, and males of this species are described for the first time. Adults of P. robusta Cook and P. acuta Habeeb are redescribed, and males and females of these two species are correctly correlated for the first time. Male and female adults of two new species of Phreatobrachypoda are described. The male mite described as Japonaxonopsis nuiakiensis Imamura is reassigned to Phreatobrachypoda, and the name Japonaxonopsis becomes a junior synonym of Phreatobrachypoda. Two subgenera, Phreatobrachypoda (s.s.) and Ameribrachypoda subgen.nov., are proposed and diagnosed based on the morphology of the dorsal shield, genital field, and fourth pair of legs of males. A key to known species of die genus is presented. Male and female adults of two new species of Bharatalbia (Japnnalbia) are described, and the deutonymph of one of these species is correlated with adults and described. This is the first reported occurrence of this genus in North America.

All North American species of Phreatobrachypoda and Bharatalbia inhabit coastal areas in Oregon and California. The highly disjunct distributions of these genera suggest that species of both were widespread throughout western North America and eastern Eurasia during the Tertiary Era, but survived the Pleistocene only in isolated temperate refugia well beyond the southern limit of glaciers.

In laboratory tests, many miticides affected more than one life stage of the European red mite but most showed greater toxicity to one specific stage. Most were more toxic to nymphs and adults than to eggs. Cyhexatin was more toxic to nymphs whereas fenbutatin-oxide was more toxic to adults than to nymphs. Propargite, formetanate HCl, and dinocap were more toxic to nymphs than to adults. Dicofol and oxythioquinox were more toxic to adults than to nymphs. Dienochlor was the least toxic miticide tested, and was more toxic to nymphs and adults than to eggs. Amitraz, permethrin, and fenpropathrin were repellent to motile stages at low concentrations, but amitraz was also highly ovicidal. Clofentezine and hexythiazox were toxic to eggs and nymphs but not to adults. Affected nymphs developed into the deutochrysalis or teleiochrysalis stages but were unable to eclose from these quiescent stages.

In field trials, applications timed to coincide with a predominance of sensitive stages were successful. Early season applications suppressed mite numbers for much of the growing season. Populations exhibiting considerable synchrony occurred into August suggesting that susceptible stages could be targeted for control throughout the season.

Three field tests were conducted in which fresh lodgepole pine (Pinus contorta Douglas var. latifolia Engl.) material, namely bolts with and without bark, bark only, and freshly tapped resin, were placed in beetle-excluding “greenhouse” cages; empty cages served as controls. Two “window” flight traps per cage, at right angles to each other, caught mountain pine beetles (Dendroctonus ponderosae Hopkins) arriving at the cages. Significantly more mountain pine beetles were trapped at cages baited with bolts and wood only than at empty control cages. Primary attraction in the mountain pine beetle is thus established, in the absence of pheromones and normal visual cues (tree stem silhouette). More beetles were trapped at cages baited with bark only and with resin than at empty control cages, but differences were not significant at p = 0.05. The sex ratio of trapped beetles (4.83 females: 1 male) was more than twice as high as the reported sex ratios of free-flying and emerging beetles.

The impact of canopy dieback on the activity and diversity of epigeal Carabidae was studied during the summers of 1987 and 1988 in 18 maple stands in southeastern Québec, using pitfall traps. A canopy thinning index (CTI) based on severity and incidence of dieback, and on tree basal area was calculated for each of the 72 stations sampled. An analysis of variance shows that canopy dieback had a significant effect on carabid beetle activity in 1988. The CTI was negatively correlated with the carabid species richness and diversity in 1988. The number of individuals caught per station was negatively correlated with the CTI for all species combined, except for the dominant Pterostichus coracinus Newm. in 1988. These results indicate a negative response of carabid beetles to canopy dieback in 1988; the climate may have tempered the effects of dieback in 1987.

The within-cone distribution of Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), the Douglas-fir seed chalcid, infesting Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] cones from north-central France was compared with that in samples from California. Results indicate that the mid-region of cones was more intensively utilized by seed chalcids in France than in California, whereas in the northwestern United States the mid-region is characteristically occupied by dipteran and lepidopteran species. This difference in distribution may explain the large discrepancy in infestation rates on the two continents. The potential impact of this finding on pest management strategies is discussed.

Cones were measured and dissected or X-rayed to determine seed chalcid infestation levels. Analysis of covariance performed on data from cones that were collected in 1986 and dissected showed cone diameter at maturity to be a highly significant factor in attack rate, although slopes were different among clones. Between-tree variation was also significant, but clonal source was not. Cone diameter, clonal source, and between-tree variation constituted 87.1% of the variation in rate of attack by the seed chalcid. Although clone was not a significant factor in data from dissected cones, X-rayed cones showed significant differences in attack rates for some clones.