The spatial and statistical distribution of eggs and larvae of the wheat midge, Sitodiplosis mosellana (Géhin), in wheat in northeastern Saskatchewan were investigated. The highest number of each stage occurred in the top third of the head and the lowest in the bottom third. Because of this the entire wheat head is considered an adequate sample unit for density estimates of the two life stages. Sample sizes required to estimate egg and larval populations with given levels of precision were determined. A sequential sampling plan for larval populations was derived using Green’s and Iwao’s methods. Both methods gave similar results; however, the number of samples required to reach a decision was higher using Green’s method than using Iwao’s.

Three methods—tube chambers (ventilated and unventilated), petri dish chambers, and field cages—were used to evaluate the toxicity of deltamethrin, trichlorfon, and methoxychlor deposits on alfalfa, Medicago sativa L., to 1- to 7-day-old alfalfa leafcutter bees, Megachile rotundata (F.), 24 and 48 h after exposure. In unventilated tube chambers, all three insecticides were significantly toxic to male bees after 24 and 48 h, but only deltamethrin and trichlorfon were significantly toxic to female bees after 24 h. In ventilated tube chambers, only deltamethrin was significantly toxic by contact and then only to male bees at 24 h. Significant vapor action was observed only for trichlorfon and only in unventilated tube chambers. By the petri dish method, only deltamethrin caused significant mortality to male and female bees. However, bee mortality increased significantly between 24 and 48 h. By the field cage method, there was no significant difference in mortality among treatments and controls within the 24- and 48-h evaluations. Bee mortality in the controls was much higher in the petri dish and field cage methods than in either of the two variations of the tube chamber method. The three evaluation methods are compared and the need for a standardized laboratory evaluation procedure is discussed.

Wild codling moth, Cydia pomonella (L.), females were trapped from May through September in the upper (Yakima) and lower (White Swan) Yakima River Basin, WA, using 10 bait traps and 4 and 19 blacklight traps, respectively, for 2 and 5 years in abandoned apple orchards. The average spermatophore count per female at Yakima was 1.08; at White Swan it was 1.76. The spermatophore count was similar in both first (0.97 and 1.79) and second (1.00 and 1.70) generations at both locations. Regression analysis of field data and laboratory tests showed that cool temperatures reduced the number of spermatophores, which reflect reduced mating. There was a high correlation between the number of small spermatophores and females with multiple spermatophores. Usually females with a large spermatophore mated only once. Females usually mated on the 1st day following emergence. Once mated, even females with small spermatophores seldom mated again on subsequent days.

Evaluations of individually collected wheat heads and whole plants indicated that several factors may influence the efficacy of aerial sprays against the wheat midge, Sitodiplosis mosellana (Géhin). These factors related to methods of assessing midge damage, condition of wheat heads during spraying, and methods of spray application. Location- and distribution-related influences also were important.

Efficacy assessments were based on reductions in midge larvae, midge-damaged kernels, and percentage kernel damage. The latter data were confounded by differences in kernel numbers within wheat heads. In head and plant samples, sprays were more effective at reducing numbers of midge larvae than reducing the incidence of midge-damaged kernels. Evaluations of individual heads overestimated the efficacy of sprays in whole plants which contained one primary and two tiller heads. Sprays provided more effective midge control and kernel protection in the primary heads, which emerged before spraying, than tiller heads, which emerged mainly after spraying. Protection was usually better in apical than basal regions of each head type. In whole plants, efficacy declined as tillering increased.

Plant evaluations indicated that the high-volume (37.4 L water per hectare) chlorpyrifos spray provided the best midge control and kernel protection (95% and 87%, respectively), followed by the low-volume (18.7 L water per hectare) chlorpyrifos spray (87% and 76%, respectively), and low-volume dimethoate spray (66% and 53%, respectively). When improvements in both yield and grade were considered and calculations based on 1987/1988 wheat prices, net returns from the three aerial sprays ranged from $62 to $113 Canadian per hectare. Long-term benefits of the sprays probably were less favourable. Reduction in wheat midge after spraying would negate the benefits of an egg–larval parasite, Pirene penetrans (Kirby), which was present in low numbers.

A model of predation by Podisus maculiventris (Say) on Mexican bean beetle, Epilachna varivestis Mulsant, larvae in soybeans is presented. The attack equation described the number of prey attacked as a function of the number of prey, soybean leaf area, and the search behavior of the predator. The area searched by P. maculiventris was related to the amount of leaf area and the number of prey. Predictions of the number of Mexican bean beetles attacked per predator were compared with an independent field data set. The relevance of the predation model to studies of predation in other agricultural systems is discussed.

A combination of laboratory and field trials, from 1983 to 1985, were used to determine mortality factors affecting all life stages of Alberta populations of the European corn borer, Ostrinia nubilalis (Hübner), feeding on corn. The resulting life table demonstrated that greatest mortality occurred during the first and second larval instars (62.2%), when mature larvae are in diapause (69.5%), and from moth migration and loss in reproductive potential (70.3%). Stages where mortality was slight included the egg stage (11.7%), non-diapausing third- to fifth-instar larvae (2%), and pupae (10.4%).

Laboratory trials showed that greater egg mortality occurred at relative humidities (RH) of 35 and 55% than at a RH of 75%. In the field, egg parasitism was nil, predation of early-instar larvae (5.2%) and diapausing larvae (6%) was low, and parasitoids were scarce (emerging from ca. 2% of pupae). Sustained periods of hot, dry weather with high moisture stress were related to mortality of both eggs and early-instar larvae. Death of early-instar larvae also was related to periods of rainy weather with low evaporation. The 64% non-diapause larval mortality was much lower than that reported elsewhere. The dramatic increase in the corn borer since its recent introduction to Alberta may be due to a lack of natural enemies, and because only non-resistant corn hybrids are grown.

The purpose of this study was to determine spider species composition and their temporal and vertical distributions in corn in southern Quebec. We sampled 30 corn plants weekly for 12 weeks from 9 July to 23 September in 1985. We found nine families, 14 genera, and 12 identifiable species. Web-building spiders were more abundant than hunting spiders. The dominant species was Tetragnatha laboriosa Hentz (Tetragnathidae). Web-builders were generally found under the ear of the plant, whereas the vertical distribution of hunting spiders was more even.

Field tests, using bolts of American elm trees either uninfested or infested with laboratory-reared or feral Hylurgopinus rufipes (Eichhoff), the native elm bark beetle, were conducted to evaluate colonization behavior of the beetle. The data confirm that (1) colonization of elm by H. rufipes can be accounted for by host attractants alone; (2) overwintered adult H. rufipes are attracted to broodwood (moribund or recently cut elm) in the spring, but summer-emergent adults are attracted to healthy elm; and (3) H. rufipes attacks broodwood primarily during evening beetle flights, and females initiate the gallery. A beetle-produced sex pheromone may be involved in the male–female pairing on broodwood.

The temperature-dependent rate of development of the post-diapause larval and pupal stages of the spruce budworm parasitoid, Apanteles fumiferanae Vier., was estimated under controlled conditions. Parasitoid larvae required 289.0 degree-days (DD) above a threshold of 8.1 °C to complete development and the pupae required 106.2 DD above a threshold of 9.6 °C to complete development. Longevity of the adult wasp at several temperatures also was examined. Female wasps lived longer than male wasps at all temperatures. Wasps tended to mate more readily under natural than under artificial light conditions.

Newly emerged female A. fumiferanae had few, if any, mature eggs in their ovaries. The number of mature eggs increased to a peak of 40–75 eggs, 4–12 days after eclosion of the adult. The pattern in number of ovipositions was similar to this pattern of egg availability. The daily rate of oviposition, however, was only about one-quarter the number of eggs available.

These biological measurements are discussed in view of the development of a mass-rearing technique for this parasitoid.

Based on data collected at seven constant temperatures, a temperature- and age-dependent model for reproductive development and oviposition by Diabrotica barberi Smith and Lawrence was developed. The model couples temperature-dependent rate and temperature-independent distribution models to represent the observed variability in developmental times for pre-reproductive, reproductive, and post-reproductive females. Using a cohort approach to maintain a physiological age structure, development was coupled with a temperature- and age-dependent model of oviposition. The model was validated at one constant-temperature and three variable-temperature regimes in the laboratory. The time spent in the pre-reproductive stage was slightly underestimated by the model, but the development of mature females and both the timing and magnitude of oviposition under fluctuating-temperature regimes were accurately predicted. The model was relatively insensitive to errors in estimation of the rate of development in the pre-reproductive stage but sensitive to errors in estimation of developmental rate of the reproductive stage and fecundity. Errors in input temperatures were found to be very important, stressing the need for accurately measuring temperature, The major driving variable. The model should be a valuable aid toward understanding oviposition by D. barberi in the field.

The toxicities of two commonly used soil insecticides, fonofos and phorate, were compared among one larval population of the corn wireworm, Melanotus communis (Gyllenhal), from sugarcane fields and three populations from potato fields in southern Florida. Fonofos toxicity did not differ among most populations; however, phorate toxicity did. Phorate was consistently less toxic to one population from potato fields. The toxicities of these two compounds to the population from sugarcane fields did not differ from those from potato fields, despite differences in insecticide pressure between the two crops.

A new penicillate diplopod, Polyxenus koreanus sp. nov., is described from Korea. This is the first record of penicillate diplopods in Korea.

Mandibles of four species and three subspecies of penicillate diplopods inhabiting Japan, and two species from outside Japan, were studied to clarify their taxonomic significance. The mandibular structure showed distinct differences both between genera and between species, indicating its usefulness in the taxonomy of penicillate diplopods.

The genus Parabarrovia Gibson, with one included species, P. keelei Gibson, was previously known from the original type material collected in the MacKenzie Mountains, Northwest Territories, in northern Canada. The known range of P. keelei is extended to include other areas in Beringia, namely, Yukon (British Mountains), Alaska (Brooks Range and Seward Peninsula), and the USSR (Wrangel Island). The immature stages are described for the first time. A second species of Parabarrovia, P. ogilviensis Lafontaine, also known only from the Beringian area, is described from the Ogilvie Mountains, Yukon, Canada. The position of Parabarrovia within the Noctuidae is reviewed and the genus is tentatively retained within the subfamily Noctuinae. Adults, including genital characters, and the immature stages are described and illustrated for both species.

The Phoridae chapter in the "Manual of Nearctic Diptera, Volume 2" is updated to include newly collected material. Genera new to North America are as follows: Dacnophora Borgmeier, represented by D. pectinatus nov. sp. from Arizona; Ecitoptera Borgmeier and Schmitz, represented by a single badly damaged, undescribed, female specimen from Arizona; Kerophara gen. nov., represented by the type species K. ferruginea sp. nov. from Alberta, K. brunnea sp. nov. from Alberta, and K. sicula sp. nov. from Virginia; Mennoziola Schmitz, represented by a single, undescribed female specimen from Florida; and Styletta Borgmeier, represented by the widespread species S. camponoti sp. nov. The monobasic Borgmeieria Prado is shown to be congeneric with Neodohrniphora Borgmeier (syn. nov.) based on examination of the previously unknown female, and the names are synonymized. Also, the undescribed female of Abaristophora Schmitz is briefly diagnosed; species of the genus Bactropalpus Borgmeier are known to be the males of Trophodeinus Borgmeier; the genus Gymnophora Macquart has recently been revised; Lecanocerus Borgmeier probably does not belong to the Beckerinini; and Microselia Schmitz and Rhyncophoromyia Malloch are included in the Manual key. Corrections, additional couplets, and illustrations for the Manual key reflect this new knowledge.

Body size and mass variation of queen bumble bees (Bombus Latr. spp.) were analyzed in relationship to hibernation survival and optimal body size. Body mass and size (measured by radial cell length) were significantly correlated in six of eight species. Also, spring queens of B. occidentalis Greene were, on average, significantly larger yet lighter than young fall queens. These observations were consistent with weight loss known to occur during hibernation coupled with greater mortality of small queens over the winter. Thus large queens may be at an advantage for this and other reasons (e.g. foraging efficiency, usurpation). However, an optimality model showed that an intermediate body size was optimal if the reproductive success of a colony (foundress queen and workers) was considered. The assumptions were that fitness did not increase linearly with body size but was a convex function, and that colonies only had a fixed amount of energy to invest in reproductive offspring leading to a trade-off between size and number.

A survey of grasshopper populations in Saskatchewan and Alberta indicated that the fungal disease caused by Entomophaga grylli (Fresenius) pathotype II was present in melanopline grasshoppers in 1985 and 1986. The disease was more prevalent and widespread in 1986, being found at 44% of 128 survey sites in Saskatchewan compared with 11% of 190 sites in 1985. In Alberta a high incidence (≥ three per 100 m2) of infected grasshoppers was found at 6% of 1746 sites in 1986 as compared with less that 1% of 2055 sites in 1985. Levels of infection based on cadaver densities at sites with high incidence of disease in Saskatchewan were similar in both years ranging from 3 to 28% for the total population. Melanoplus bivittatus (Say) was the predominant host species for E. grylli pathotype II; M. sanguinipes (Fabricius) was less affected. Entomophaga grylli pathotype I was isolated from Camnula pellucida (Scudder) hosts from a few sites in both Saskatchewan and Alberta in 1986.

An emergence trap for bark-inhabiting insects was constructed out of a 22.7-L plastic pail. Screened windows in the sides of the bucket provided ventilation. A plastic funnel in the bottom of the bucket held one of three sizes of container for live- or dead-trapping of emerged insects. In laboratory and field tests with lodgepole pine bolts infested with mountain pine beetle and associated insects, the traps had a trapping efficiency of 97.5%.

The seasonal activity and infestation potential of the cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae), attacking rutabaga was studied at two Manitoba locations over 4 years based on captures of females in yellow water traps baited with alryl isothiocyanate. The activity peak for the overwintering generation occurred on 8 June ± 4.1 days (mean ± SD), with degree-day accumulations, base 5°C, of 159 ± 6.2 for soil at 5 cm and 387 ± 69.4 for air for both locations combined. The activity peak for the first generation occurred on 12 August ± 11.7 days with degree-day accumulations of 981 ± 229.3 and 1295 ± 175.7 for soil and air temperatures, respectively.

Correlations between numbers of females trapped per week and of eggs in soil samples from around rutabaga plants for individual seasons at the two locations generally were not significant. A regression of numbers of eggs on females trapped based on all data was significant but had a low coefficient of determination (r2 = 0.289). The water traps are adequate for monitoring seasonal activity of adult flies but the captures are unreliable as quantitative indicators of potential infestation.

Populations of larvae of the bertha armyworm, Mamestra configurata Wlk., in four physiographic regions of Manitoba showed similar trends over time: a decline from the outbreak of 1971–1972 to very low densities in 1975–1977, an increase to a peak during the years 1979–1981, and a subsequent decline. During the period of peak larval populations, brief (1 or 2 years) outbreaks [at least some fields with > 20 larvae per square metre) occurred at five locations in two regions, the Swan River Plain and the Valley River Plain, but not in the Western Uplands or the Manitoba Lowlands. In the first two regions, larval densities rose rapidly (from < 1.6 to > 13.8/m2) in 1 year. Although the general trend of population density was similar, there were differences in density among and within regions, and in the timing, severity, and duration of peak populations. Two parasitoids (Banchus flavescens Cress., Athrycia cinerea (Coq.)) and two pathogens (a nuclear polyhedrosis virus (NPV) and fungi of the Entomophthorales) occurred regularly in larval populations. Of these, B. flavescens had the highest constancy among collections and may help to keep bertha armyworm populations at low densities. NPV was rarely found among larvae from low-density populations but appeared in all populations that reached outbreak levels. No single biotic agent could be associated with the population declines because of multiple parasitism and the difficulty in partitioning mortality when only a single sample could be taken. The rapid increase of bertha armyworm larvae from very low to outbreak levels in 1 year will prevent predictions of outbreaks from being based on larval densities in the preceding year.