Evidence for competitive deplacement of Panonychus ulmi (ERM) from apple trees via Aculus schlechtendali (ARM) by what is thought to be a foliage conditioning mechanism is presented. Previous feeding of ARMs at high and moderate density levels near or below the economic threshold for this phytophagous mite on apple reduced the build-up of the ERM in 3 years of field experiments on Red Delicious trees and during a single season on McIntosh apple foliage. Comparative tests measuring oviposition rates of the ERM on excised apple leaves which had sustained high and low levels of previous rust mite feeding gave results similar to field experiments. The applied aspect of how this interspecific relationship can be managed in the context of an integrated mite management program for apples is discussed.

The North American Diparinae (Pteromalidae: Chalcidoidea) consists of six genera and 11 species, of which eight species are described as new. These are Trimicrops bilineatus, T. trilineatus, Dipara pedunculata, Netomocera nearctica, Lelaps floridensis, L. beckeri, L. melinus, and L. striatus. Illustrated keys to genera and species are provided.

The effect of density on host–parasite interactions between Hypera postica (Gyllenhal) and Bathyplectes anurus (Thomson) was studied in a caged system in the laboratory. There was no significant relationship between proportion of hosts parasitized and host density. The frequency distribution of the parasite’s eggs approximated the Poisson distribution in 83% of the cases. There was a quadratic relationship between number of superparasitized hosts and parasite density. However, no significant correlation between proportion superparasitized and host density was detected. The Nicholsonian area of discovery was inversely related to parasite density with a strong mutual interference constant of −.467.

Five controlled-release granular formulations were developed that eluted 3-methyl-2-cyclohexen-1-one (MCH) in the laboratory at a rate ≥ 0.5µg/h for 60 days. Elution rate was determined by trapping gaseous radioactive MCH followed by scintillation counting. The inert components of these formulations consisted either of a wax-coated molecular sieve, polyethylene emulsion-coated ground corncob, or dimer acid polyamide beads. These formulations and a liquid standard were applied 9 May just prior to Douglas-fir beetle (Dendroctonus pseudotsugae Hopk.) flight to plots containing single, freshly felled Douglas-fir (Pseudotsuga menziesii var. glauca) trees. Three months later, infestation by Douglas-fir beetle and other insects was evaluated. All treatments except coated corncobs and certain applications of the molecular sieve significantly reduced Douglas-fir beetle attacks. Douglas-fir beetle brood in three treatments was significantly less than in controls. Abundance of entomophagous insects was proportional to density of host beetle attacks. Douglas-fir beetle attack density was negatively correlated with degree of infestation by the scolytid Pseudohylesinus nebulosus (Lee).

Within-tree models of Dendroctonus frontalis generation survival from attacking adults to emerging adults and survivorship from eggs to emergence were developed for five regions of the infested tree bole of Pinus taeda L. The generation survival model (GS) describes the number of D. frontalis/attacking adult as a function of time at a specific height. The form of the model is

YGS = 1.0 + C(1–e–20.0X)eA(1.0–X)B + ɛ.

The survival model (S) describes the number of D. frontalis/100 eggs as a function of time at a specific height. The form of this model is

YS = CeA(1.0–X)B + ɛ.

The generation survival model indicated that the rate of survival was primarily a function of generation development time, rather than position on the infested tree bole. The rates also varied in different sections of the tree depending on the initial egg/attacking adult population of D. frontalis. The emergence/attack ratios for the tree sections were slightly greater at the top and bottom than in the middle of the infested bole.

The survivorship curves, based on an initial cohort of 100 eggs, were similar for the various sections of the tree bole. Again, the rate of population change was primarily a function of developmental time, rather than position on the tree. The curves for the various tree sections were essentially the same.

The combined action of the various biotic and abiotic mortality agents acting in the different sections of the tree resulted in essentially uniform survivorship throughout the infested portion of the tree bole.

Apple orchard tests in 1974, 1975, and 1976 showed that applications of granulosis virus reduced deep-entry damage by larvae of the codling moth, Laspeyresia pomonella (L.), to apple fruit at harvest by 55 to 96% compared with damage to fruit on nontreated check trees. Sting or shallow-entry injury was usually higher on virus-sprayed trees than on check trees presumably because larvae were killed by the virus soon after entry into the apple.

Pupal diapause in Athrycia cinerea (Coq.), a larval parasite of bertha armyworm, Mamestra configurata Walk., was usually prevented if the parasite larvae were reared at 25°C, but not if they were reared at 20°C. Mature larvae of the parasite were more sensitive than younger larvae to this temperature effect. Diapause incidence in A. cinerea at 20°C was not reduced by using only young parent females for oviposition; by rearing the parent females at a high temperature (25°C) and long day (16 h) prior to and during oviposition; by using host larvae that had been light-programmed for non-diapause; or by increasing the photoperiod, to which the parasite larvae were exposed, from 12 to 16 h. Termination of pupal diapause was accelerated by low temperature; at least 24 weeks at 2 °C were required to synchronize adult emergence.

Studies on the flue-cured tobacco losses caused by the natural tomato hornworm, Manduca quinquemaculata (Haworth), were conducted in the field at Delhi, Ont., during 1973, 1974, and 1975. The feeding habits of the larval stage were observed and data on the subsequent damage to tobacco were recorded Two to six leaves per plant, depending on leaf size, were unmarketable due to damage caused by one hornworm larva. The most severe damage by the larva was due to destruction of terminal buds.

The tobacco yield was significantly related, negatively, to the tomato hornworm infestation levels. All infestation levels influenced quantitative tobacco losses, but no qualitative differences were apparent when compared with the yield in the insect-free plots. Maximum yield losses occurred at the highest level of infestation. There were no significant differences in yield losses per larva among the infestation levels or among the years. The average yield reduction per larva for all of the population densities and years was 0.70 oz of cured leaves. A prediction equation to establish the relationship between hornworm infestation levels and tobacco yield losses was calculated. A theoretical economic-injury level for the tomato hornworm on tobacco in Ontario was established.

Adults of Phytoptus oculatus n. sp. are described. These are unusual among Eriophyoidea in possessing eye-like structures lateral to the prodorsal shield. Diagnoses for the genus Phytoptus and two provisional species groups within the genus are included.

A new genus, Fallocampus, with type-species Camponiscus americanus Marlatt is described to accommodate the Nearctic species formerly assigned to Platycampus Schiødte. The adults and larvae of the new genus resemble Platycampus and Anoplonyx Marlatt respectively. Diagnostic characters separating the adults and larvae of these genera are noted and illustrated. Biological notes and a key to the larvae of Fallocampus are presented.

The effectiveness of 16 experimental compounds as soil insecticides was assessed under laboratory conditions. Chlorpyrifos, carbofuran, and dieldrin were included as standard insecticides. Spectrum of activity as contact insecticides was determined using 24–48 h nymphs of the field cricket, Acheta pennsylvanicus (Burmeister), 24–48 h onion maggot adults, Hylemya antiqua (Meigen), third stage darksided cutworms, Euxoa messoria (Harris), northern corn rootworm adults, Diabrotica longicornis (Say), and honeybees, Apis mellifera L. First stage crickets were used to assess the biological activity of experimental compounds relative to soil type, moisture, and temperature and also their volatility in moist sand and persistence of biological activity over a 48 week period. All of the insecticides showed broad spectrum contact activity. Twelve showed fair to very good potential in soil. Four insecticides, Shell WL 24794 (O,O-dimethyl-S-1-[3-(5-methyl-1,2,4-oxadiazolyl)] ethyl phosphorodithioate), Shell WL 25735 (O-[2-chloro-1-(2,5-dichlorophenyl) vinyl] O-methyl methylphosphonothioate), Shell WL 26738 (O-[1-(2,4-dichlorophenyl) vinyl] O-methyl ethylphosphonothioate), and chlorpyrifos-methyl showed good potential. Two others, Counter® (S-[(tert-butylthio) methyl] O,O-diethyl phosphorodithioate) and Shell WL 24073 (O-[2-chloro-1-(2,5-dichlorophenyl) vinyl] O-methyl ethylphosphonothioate) were considered to have very good potential as soil insecticides.

The potential of chlorpyrifos-methyl and Counter® (S-[tert-butylthio) methyl] O, O-diethyl phosphorodithioate) as soil insecticides was assessed in the laboratory. Two established soil insecticides, chlorpyrifos and phorate, which are similar in chemical structure to chlorpyrifos-methyl and Counter respectively were included for comparative purposes. Spectrum of activity was determined using 24–48 h crickets, Acheta pennsylvanicus (Burmeister), 24–48 h adults, Chaetopsis spp., third stage darksided cutworms, Euxoa messoria (Harris), northern corn rootworm adults, Diabrotica longicornis (Say), and honeybees, Apis mellifera L. Chlorpyrifos-methyl and chlorpyrifos showed the broadest spectrum of activity being toxic to all five species of insects; Counter and phorate were toxic to four of the five. Initial activity in soil was assessed relative to soil type, moisture, and temperature using crickets as the indicator species. Chlorpyrifos-methyl was as effective and more consistent in activity than chlorpyrifos. Counter was more effective and consistent in soil than phorate other than under conditions of low soil moisture. No clear relationship between chemical structure and either direct contact or initial toxicity in soil was apparent. Tests on persistence of biological activity in mineral soil indicated that, as is generally the case with dimethyl and diethyl forms of organophosphorus insecticides, chlorpyrifos-methyl was even less persistent than chlorpyrifos. Counter was slightly more persistent than phorate. Although very active the potential of chlorpyrifos-methyl as a soil insecticide would be restricted by its limited persistence. Counter was considered to have good potential.

Preserved material from 1962 field studies provided information on the habits and morphology of the tachinid parasitoid Chaetophlepsis nasellensis Reinhard. Parasitization of the larvae of the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst), continues over a 30- to 40-day period. Maggots issue from the host larvae and drop to the ground to pupate. The pupae normally overwinter, with adults emerging the following spring or summer. The early first-instar larva differs markedly from the late first-instar. The three instars can be distinguished on the basis of body length and the structure and form of the buccopharyngeal apparatus. The first and third larval instars and the puparium are distinctive enough to permit easy identification during studies of the western hemlock looper and associated loopers.

There was no evidence that the corn leaf aphid, Rhopalosiphum maidis (Fitch), can overwinter in southwestern Ontario. An alate with a small colony of nymphs was found on 26 April, indicating that migration from the south starts early in the spring. Early migrants colonized winter barley, but not winter oats, rye, or wheat. Colonization on field corn did not occur until over a month after plant emergence. Only small numbers of alatae initiated infestations on corn and the large variation in size of aphid infestations observed at pollination was due to differences in the longevity and fecundity of these few early attackers. The whorl leaves which enclosed the tassel before pollination provided a very favorable environment for rapid development of the aphids. Trapping of alatae in yellow pans of water at the periphery of a corn field in the fall showed that a minimum temperature of 13°C was required for flight. At a constant temperature of 25.5°C and a light:dark photoperiod of 14:10 h, the average prereproductive, reproductive, and postreproductive periods for 29 aphids were 5.9, 15.8, and 9.6 days, respectively. The average number of nymphs produced/female was 68.2.

Morphological features of the eggs of Euxoa campestris, E. declarata, and E. rockburnei, the “declarata group”, were diagnostic for the species; the esterase zymograms of the eggs of campestris and declarata support the morphological findings. Chorionic features and the esterase zymograms of a hybrid resembled those of the female parent.

The important species of predacious ants in Europe and North America belonging to the Formica rufa L. group, and their association with forest insects, is discussed. The absence of desirable species in Quebec is stated, and a brief description of an aggressive western North American species (F. obscuripes Forel) is given. The method used in collecting large colonies of this species in Manitoba, of transportation to Quebec, and of the eventual release and establishment is described. It is concluded that F. obscuripes is increasing in number in Quebec, and should be considered as permanently established.

A method was developed to terminate pupal diapause in Rheumaptera hastata through experimentation using controlled abiotic factors. Male and female pupae exposed to 0 °C at 75–100% moisture content for 90–120 days terminated diapause within 8–19 days following treatment. This method reduces diapause by 4 months compared with natural conditions. Light had a minimum effect on diapause termination; therefore, pupae should be exposed to constant darkness during the treatment period, followed by exposure to a 20L:4D photoperiod to obtain a high percentage of adult emergence.