Dosage–response relationships of seven insect growth regulators (IGRs) to last instar western spruce budworm, Choristoneura occidentalis Freeman, were determined by topical application, spray application, and diet incorporation bioassays. Mortality was defined as failure to emerge as a viable adult. In spray application experiments, four IGRs—ZR-512, ZR-619, ZR-1662, and Ro 10-3108—had LD50s of less than 70 g/ha (1 oz/acre). Relative lethal effectiveness, based on a simple model combining data from the three bioassays, was ZR-1662 > ZR-619 > ZR-512 > Ro 10-3108 > ZR-777 > ZR-587 > ZR-515. We concluded that several IGRs, applied to a population consisting primarily of last instars, would induce lethal effects at dosages comparable to dosages of several conventional insecticides.

The variicornis-group of Gryon is proposed for 15 Neotropical species of which 12 are new to science: atrocoxalis (Ashmead) / Grenada & Trinidad, W.I., Brazil, Colombia/; cultratus n. sp. /Brazil/; david n. sp. /Panama/; goliath n. sp. /Panama/; helavai n. sp. /Panama/; hercules n. sp. /Brazil/; masoni n. sp. /Trinidad, W.I./; neotropicus n. sp. /Colombia, Ecuador/; peckorum n. sp. /Ecuador/; rothi n. sp. /USA/; scutellatus n. sp. /Brazil/; sinop n. sp. /Brazil/; titan n. sp. /Brazil/; tridentatus n. sp. /Ecuador/; and variicornis (Fouts) /Guyana, Panama, Nicaragua, Brazil, Colombia/. The systematic position of the group within Gryon is discussed.

A generic diagnosis of Microthoron Masner is completed, and the male antenna is figured. Data on distribution and variability of M. baeoides Masner are presented. M. miricornis n. sp. ♀ is described from South India. A key to the known species of Microthoron is given. Thoronidea taino n. gen., n. sp. ♀ is described from the Dominican Republic. Thoron longicornis n. sp. ♀ is described from Arizona, and a key to the known species of Thoron Haliday is given.

Worker-male conflict in different bumble bee species is strongly associated with tendency, toward inbreeding. It is hypothesized that the major cost imposed by inbreeding arises from the production of diploid males in place of workers, during the early phases of colony development. The consequent dilution of the labour force slows down colony growth and leads to ultimate reduction in reproductive success. An experiment to test this hypothesis is described, using consanguineously mated queens of B. atratus Fkln. Colonies yielding a 1:1 mixture of males and workers grew significantly more slowly than normal all-worker producing colonies, providing support for the hypothesis.

Selected primary (Z)-alkenals and (Z)-alkenyl acetates (odd-numbered unsaturation positions, even-numbered carbon chains C10–C16) were field tested in three groups for ability to attract male moths into traps. Within each group all possible combinations (1:1:1) of components were examined. From 441 combinations, consistent attractants for 47 species were found. In one case three components were required for attractancy, while in others two or one were minimally sufficient. Possible trapping inhibitors were revealed for most of the species taken. Of the captured species 44 were noctuids, two were tortricids, and one was a gelechiid.

This paper presents results of a multidisciplinary optimization study on the impact of Lygus hesperus Knight on cotton in the Great Central Valley of California. The results of the empirical studies indicate that lygus bug is not a serious pest of cotton under most circumstances and, furthermore, illustrate why cotton yield enhancements have occurred when their populations have not been controlled. An economic analysis of these results sheds some light on the concept of economic threshold. In particular it is shown how in this case an economic threshold exists even if the costs of pesticides are zero. The theoretical implications of these results are quite general.

Apple maggot eggs, Rhagoletis pomonella (Walsh), hatched equally well in apples on the tree and in picked fruit. Many larvae completed development in all different maturities of picked fruit and development and survival were similar in different cultivars. In contrast, larval mortality was high in apples remaining on the tree, particularly in fruit infested in late June and July. More larvae survived in the unpicked fruit of the earlier ripening, softer cultivars, Wealthy and McIntosh, than in the later ripening Rhode Island Greening and Rome apples.

Relationships of egg niches and eggs per unit (cm) of gallery were studied. On average egg niches were found to overestimate eggs by 36%. The rate of egg deposition in the mid-portion of the infested bole was found to be less than the upper and lower portion.

The biological and ecological relationships of the hickory timber beetle, Xyleborus celsus Eichoff (Coleoptera: Scolytidae), and black hickory, Carya texana (Buckley), were studied for 2 years in south-central Missouri. X. celsus was bivoltine and overwintered as an adult. Development from egg to adult required ca. 35 days. There were three larval instars. Brood adults either extended the galleries in which they completed immature development or emerged to seek new hosts. Most attacks occurred within 1.5 m above ground level The most heavily attacked height interval in the basal 1 m of 10–17 cm D.B.H. trees varied. This variability is correlated to the temporal relation of girdling of the tree and beetle attack. Aspect of beetle attack varied at random. Conditions for X. celsus development were not uniform in the basal 1 m of infested trees.

The six larval instars of Stegopterna mutata (Malloch) and seven larval instars of Simulium vittatum Zetterstedt can be definitively separated by differences in postgenal length, body length, and number of primary cephalic fan rays. Counts of the number of rows of hooks and hooks/row in the anal circlet were inconclusive in separating all instars of either species.

The fecundity and fertility of parent adult western spruce budworm, Choristoneura occidentalis Freeman, which survived treatment with IGRs in their last larval stage was assessed. With few exceptions, IGR treatment significantly reduced both reproductive factors regardless of whether the male or female parent had been treated. A simple model estimating population reduction in the F1-generation based on lethal and reproductive effects on the parents is described. If IGRs were applied at a dosage of 154 g/ha (ca. 2 oz/acre), the estimated percentages of F1 reduction which would result ranged from 74.6 (ZR-515) to 99+ (ZR-512 and Ro 10-3108 (oil)).

Sex pheromone traps to control codling moth by male removal was evaluated in three orchards in the Okanagan Valley. The program was successful in only one of the three orchards. This orchard is completely isolated and codling moth control has been obtained for 5 years. In a second orchard, codling moth populations were reduced by sprays prior to the male removal program. The program was successful in 1977, as the per cent injured fruit was only 0.6. In 1978, the codling moth capture rose sharply and at harvest the per cent injured fruit was 8.0. There was a high infestation in the third orchard when the program was initiated, and in 1976, the per cent injured fruit dropped to 10.4% from 60.0 in 1975. The per cent fruit injured by codling moth rose to 37.4 in 1977 and to 60.2 in 1978 under the male removal program. Our data show that this method of control is effective only under special circumstances, where codling moth populations are low and where isolation precludes reinfestation.

The host specificity of Lema cyanella (L.) (Coleoptera: Chrysomelidae) and its suitability as a biological control agent were investigated. The females lay an average of 1564 eggs and development from egg to adult takes 17.6 days at 25°C during the day and 20°C during the night (average about 23°C). Feeding of adults and larvae is confined to Cirsium, Carduus, and Silybum species, and according to literature records, Cirsium arvense (L.) Scop. is the main host. No economic plants are attacked. A colony of field collected beetles imported from Germany was infected with a Nosema disease. It is recommended that disease free L. cyanella should be released against the weed C. arvense in North America.

An electroantennogram (EAG) technique, which indicates electrochemical activity in a whole antenna, was used to study sex pheromone reception in spruce budworm moth antennae. For both males and females the EAG exhibited a phasic depolarization, reaching maximum near the end of a puff stimulation, followed immediately by repolarization which was prolonged by increasing amounts as the source concentration of the pheromone was increased. The dose–response curves for both sexes were sigmoid in shape, but they indicated that female antennae have a higher threshold and a lower peak response than that of males. Antennal response changed with age, being a regular increase and decrease for females and irregular for males.

Foraging honey bees were offered various sucrose–herbicide solutions. Despite the visual attractiveness of the feeding dishes to foragers, six of seven herbicides significantly reduced the incidence of feeding and were judged to be olfactory and gustatory repellents. The most repellent herbicide was 2,4,5-T, which totally inhibited feeding at concentrations as tow as 1000 ppm. The next most repellent was 2,4-DB, followed by linuron, picloram, 2,4-D, and monuron. Paraquat was the only herbicide that did not exhibit marked repellency at concentrations up to 4000 ppm.

The implications of these findings are discussed in terms of the impact of herbicide applications on honey bee foraging behaviour, brood development, pollination, and honey production.

A significant number of subordinates of the paper wasp Polistes metricus Say are former single foundresses that have had their position usurped by a more dominant foundress. Such a displaced foundress sometimes remains with the usurper as a subordinate. Some usurpers desert larger nests where they were single foundresses to usurp a smaller colony.

In early foundress associations (< 14 days old), queens frequently exhibit behaviors that are characteristic of subordinates in mature hierarchies. Early queens spend large proportions of their nest time inactive, adjacent to the nest. They also commonly retreat from approaching subordinates. In contrast early subordinates rarely retreat from queens and spend a large proportion of their nest time on the face of the nest where they are more active than the queen. These behaviors are reversed in more mature colonies with queens spending more time on the nest face and showing increasing activity and aggressive behavior towards subordinates.

A mathematical model is developed which simulates the effect of the number of eggs in females, food source, and soil conditions, on ovogenesis and oviposition of Japanese beetle populations. The number of eggs in females is used as the state indicator, and simulated trends are compared to field data. Potential applications in pest management are discussed.

The distribution of lesser maple spanworm, Itame pustularia (Gn.) (Lepidoptera: Geometridae) larvae in red maple, Acer rubrum L., crowns and of pupae under these trees, and the relationship between the number of shoots on these trees and several easily-measured tree dimensions are used to design sampling techniques for estimating the mean number of larvae per shoot and the mean number of pupae per unit area in epidemic populations. An estimate of the total number of larvae per unit area is obtained from the product of larval density and the number of shoots per unit area. Some indication of how this latter estimate might be obtained is discussed. Because of the strong relationship between stem diameter and the number of shoots on a tree, a double sample procedure can be designed based on shoot counts from a relatively small number of trees. Auxiliary measurements on a large number of trees can improve the precision of the estimate.

Results of previous research revealed that the effect of Bacillus thuringiensis on spruce budworm was a septicemia enterotoxicosis dependent on the ability of spores to penetrate to the insect hemolymph. Some scientists still maintain that the role of B. thuringiensis crystals (endotoxin) is primordial and is by itself responsible, by toxemia, for mortality in Choristoneura fumiferana. Consequently, new studies were undertaken to confirm the role of spores in B. thuringiensis infection of this insect. Infection tests were carried out with normal, irradiated, acrystalliferous and non-sporogenous strains of B. thuringiensis, with purified and semi-purified crystals, with pure spore preparations of B. thuringiensis and with enomopathogenic Bacillus cereus. The results of these tests revealed that acrystalliferous strains of B. thuringiensis and B. cereus infected larvae of C. fumiferana more successfully than purified or semi-purified crystals.

Callibaetis ferrugineus (Walsh) and C. fluctuons (Walsh) nymphs moved from the shallow, peripheral area of a pond during the late summer and autumn to the deeper water where they overwintered. In the spring they returned to the peripheral area where they were found throughout the summer. C. ferrugineus and C. fluctuans are ovoviviparous. A relationship between ovoviviparity and seasonal movements of the nymphs is suggested.