Economic injury levels of the alfalfa weevil on alfalfa were investigated in New York State. The dry weight food consumption for the larval stage of the alfalfa weevil averaged 7.34 mg/larva. For every gram (dry weight) of alfalfa consumed, 1.59 g (live weight) in insect tissue was produced. In the laboratory, it was found that insect food consumption could account for only about 50% of the total weight loss in alfalfa plants after 10 days of larval feeding. Therefore, alfalfa weevil damage to alfalfa was more than the larval food consumption, and this was believed to be due to the loss of the plant’s photosynthetic potential. In the field on first growth alfalfa, the economic injury level was calculated to be 56 larvae/stem. First growth alfalfa was less severely injured by alfalfa weevil larvae than our second growth alfalfa infested with equal populations of alfalfa weevils. It was shown that first growth alfalfa was able to compensate for 87% of the insect feeding while second growth alfalfa could compensate for only 50%. Since the alfalfa plant’s capacity to compensate for alfalfa weevil feeding can vary due to environmental conditions and plant characteristics, economic injury levels must be adjustable. To provide more reliability to economic injury levels, we propose that in alfalfa the following seven measurements be made: (1) alfalfa weevil larval density; (2 and 3) parasites and predators of the weevil; (4) rainfall and moisture level; (5) plant nutrients; (6) alfalfa variety; and (7) stage and previous management of alfalfa stand.

The success of introducing natural enemies for biological control was found to be about 75% higher employing new parasite–host (predator–prey) associations than those based on long-evolved associations between parasites and hosts. The lack of evolved interspecific balance in new species associations appears to explain the higher success rate. New exploiter–victim associations expand opportunities for the biological control of both introduced and native pests and should be used as the preferred method in selecting biological control agents.

The pH changes occurring in different rearing media, both with and without housefly larvae (Musca domestica L.), were evaluated. In standard medium which consisted of non-fat milk, brewer's yeast, liver, agar, and water, the pH surrounding the eggs and first-stage larvae was about 5.6. As the larvae grew and agitated the medium, at 5 mm. depth the pH increased and by 72 hours read about 7.5. This 7.5 was significantly higher than the pH 5.0 recorded at the same depth and time in the standard medium without larvae.

From a study of the ecology of the insect invasions occurring in the Maritime Provinces the following generalizations are made: (1) The Maritimes have served as a focal point of many invasions because they have several international ports that are surrounded by diverse human modified environments. (2) Plant and animal communities of the Maritimes are relatively simple, which makes invasions easier and more successful. (3) The lack of evolved homeostasis between the invader and its adopted community may have been one of the prime reasons for outbreaks in the species populations newly introduced. (4) Both native and introduced parasites and predators have provided effective control of introduced pests.

An investigation was made of the influence of age of the host (Musca domestica Linn.) in the pupal stage on the oviposition behavior and development of the pteromalid parasite Nasonia vitripennis (Walk.). Five age groups of hosts were employed in 10 pair combinations with an excess of hosts available for selection. Except for the 1-day-old hosts, more of the younger hosts of the combinations produced parasite progeny while the older hosts had a high percentage yielding neither fly nor parasite. Parasite production per pupa was 6.25 on the youngest hosts, with the number decreasing to 4.85 per host at 5 days. Hosts 2, 3, and 4 days old combined with 1-day-old hosts had higher rates of parasitism than when combined with hosts of other ages. The ranking for successful parasitization of hosts, by age of pupae, was 2, 3, 1, 4, and 5 days old.

An investigation was made of the impact of a series of environmental catastrophes upon herbivore population regulation through density-dependent genetic feedback interactions with simulated plants. Mean density and amplitude of fluctuation of the herbivore in the control system (only susceptible alleles in the plant population) were higher than in the genetic feedback system (3 resistant alleles and 3 susceptible alleles in the plant population). Mean density and amplitude of fluctuation of the herbivores in the catastrophic system (only susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes) were lower than in the control and genetic feedback systems, but both mean density and amplitude of fluctuation were higher than in the genetic feedback and catastrophic system (3 resistant and 3 susceptible alleles in the plant population and the herbivore population subject to a series of environmental catastrophes). The results of this experiment suggest that genetic feedback can exert a controlling influence in population dynamics even in systems where environmental catastrophes are a common occurrence.

The habits and dispersal of the pteromalid parasite Nasonia vitripennis and its housefly host, Musca domestica, and their density relationships were investigated. Male parasite longevity averaged 1.62 days and female longevity 6.96 days. The average number of progeny per female parasite was 139.8. When 25 pairs of parasites were placed with 300 housefly pupae of three sizes, the percentage parasitism was 45.0 for the small (less than 2.0 mm. in diameter), 72.8 for the medium (from 2.0 to 2.5 mm.), and 65.7 for the large (greater than 2.5 mm.). The number of parasites produced per parasitized pupa was 2.20 for the small, 4.30 for the medium, and 6.11 for the large pupae. Increasing the extent of superparasitism produced significantly smaller parasite progeny. A significantly greater normal mortality occurred in small housefly pupae (21.5 per cent) compared with either the medium (6.3 per cent) or the large (5.2 per cent).

The parasite dispersed significantly faster when unfed than when fed. Housefly pupae which had been previously exposed to parasites also stimulated the tendency for subsequent parasite emigration. Housefly dispersal was found to be density-dependent under the experimental conditions of the multi-cell population cage.

With an increasing parasite-host ratio the rate of parasitization increased until all hosts at a 1 to 1 ratio were parasitized in 24 hours; percentage of parastized hosts producing parasites reached a peak of 71 per cent at the 1 to 2 ratio; and above the 10 to 1 ratio all parasite progeny died due to super-parasitism.

The ecology and evolution of the parasite (Nasonia vitripennis Walker) and host (Musca domestica L.) were investigated in a specially designed multicelled population cage which provided ample space–time structure to the environment for free parasite–host interactions. The population characteristics exhibited by a control or newly associated parasite–host system were compared with an experimental parasite–host system which already had evolved a degree of ecological homeostasis. Population fluctuations in the experimental parasite population were dampened compared with the control parasite population which fluctuated with great intensity; and in addition, the mean number of parasites in the experimental systems was significantly lower (about 1/4) than the mean number of parasites in the control system.

The new association approach for selecting biological control agents has been reanalyzed in the light of recent data. The results support the conclusion that the new association approach is ecologically and statistically sound. One of the major advantages of this approach is its capacity to control native pests, which make up 60–80% of all pests. The specificity of biocontrol agents newly associated with the target hosts is similar to other biocontrol agents. In addition, the new association approach is as safe as the old association approach in terms of environmental risks. Recent trials in the use of new associations have been most encouraging, and suggest that this approach should contribute to the future success of biological pest control worldwide.

Demographic analysis of a species population can be useful in gaining insight into its dynamics in a particular environment. The calculated intrinsic rate of increase of a population may be valuable in predicting population performance. As a single, discrete value, it serves as a quantitative measure, or ecological index, of the response of a species to a set of environmental conditions (Birch 1948; Messenger 1964).

Considerable evidence substantiates the idea that native pests can be controlled by parasites and predators of allied species and genera. In a survey of 66 pest species, which were successfully controlled by biological means and for which the habitats of all species could be verified, it was found that 39% were controlled by an introduced parasite or predator of an allied species or genus. Although relatively few attempts have been made to control native and imported pests with parasites and predators of species allied to the pest species, the proportion of successes is surprisingly high. Employing these species has certain advantages, especially in the control of imported pests, because no ecological homeostasis has evolved and the association between the parasite and host (predator and prey included) is new.

A laboratory system was developed that allowed populations of the house fly, Musca domestica, and its hymenopterous, wasp parasitoid, Nasonia vitripennis, to interact and fluctuate in numbers, subject only to an upper limit on Musca density. In one (experimental) treatment, the selection pressure from Nasonia was allowed to operate, while in the control all Musca adults were replaced in each generation by individuals from a Musca population not exposed to Nasonia. Evolution for resistance of Musca to Nasonia became noticeable within four generations in the experimental treatment. Measured changes finally included increased fly pupal weight (although larval development period was not allowed to increase), less time spent as pupa, increased pupal mortality, and reduced fecundity of adults. Total per-generation increase of both control and experimental Nasonia was much reduced on experimental compared with control Musca. This was caused by reductions both in the longevity of female Nasonia and in the number of progeny they produced each day. From early in the experiment the increased resistance of Musca produced lower Nasonia densities in the experimental treatment. During the first 20 or so generations no difference could be detected in mean Musca density between the two treatments. After that time the density of adult Musca became greater, and fluctuated less, in the experimental than in the control treatment. This situation continued until the experiment ended at 50 generations.

The density and spatial relationship between the wasp parasite, Nasonia vitripennis, and the housefly host, Musca domestica, were investigated. As parasite dispersion decreased in a defined space, parasitism increased from 30 to 76% and host survival decreased from an average of 65.0 to 18.9%. The number of host pupae producing parasite progeny and the survival of host pupae decreased as the proportion of small host pupae increased. With host numbers increasing and parasite numbers constant, the mean number of eggs deposited per host increased significantly from 31.25 to 87.25 and the number of stings increased from 2.25 to 8.00. As parasite density increased and host number remained constant, the number of hosts which were nor attacked declined from a mean of 2.2 with 1 parasite to none with 32 parasites. Host survival declined from about 50% at the 1:8 ratio of female parasites to hosts to no survival at the 2:1 ratio.

During the course of a census of arthropods in a collard crop (Brassica oleracea var. acephala) (Cruciferae) in central New York State in summer 1985, the authors witnessed frequent incidents of unusual feeding behavior in mirid bugs. In late July and early August, numerous observations were made by three of the authors (TWC, OSN, and BAC) of apparent feeding by nymphal (2nd–4th instar) and adult tarnished plant bugs, Lygus linolaris (Palisot de Beauvois), on cocoons of Apanteles glomeratus (L.), a braconid parasitoid of the imported cabbageworm, Pieris rapae (L.). The predation occurred in a period of unusually high P. rapae population densities (estimated at 150 000 ha−1), when A. glomeratus cocoons were abundant on collard leaves.

Rule of Law reform efforts in developing areas face daunting challenges: (1) the stigma of imperialism when Western-style institutions are imposed, (2) the unwillingness of local communities to embrace the reforms, and (3) a severe shortage of resources – human, physical, and financial.

At the same time, some of these developing and post-conflict societies have highly functional customary law institutions (in Africa, e.g., a tribal chief applying a customary law handed down by oral tradition). These systems enjoy public confidence and function on very limited budgets – often providing prompt and accessible dispute resolution in the community. Unfortunately these indigenous systems do not always adhere to minimum standards of justice and human rights. In response, Rule of Law reformers in such communities are now working to codify customary law, and/or create rights of appeal from the customary courts.

These efforts, however, threaten to deprive the indigenous communities of ownership of and control over their law. Rule of law reformers must learn the lessons of colonialism, lest they perpetrate a new imperialism. Instead, customary adjudication should be subject only to collateral review. Statutory courts should defer fully to customary law adjudicators on the principles and application of customary law, and review their decisions only for compliance with minimum standards of justice and human rights (ideally those recognized in the local constitution and international human rights instruments the country has ratified). Collateral review dignifies customary adjudication by respecting the customary courts' determinations of law, while providing a safety net for those whose fundamental rights may be violated in customary court process. This approach eschews the cultural imperialism inherent in so many rule of law reforms, relying on the more appropriate, and ultimately more effective, indigenous systems to build the rule of law in a way that the local populations will recognize, respect and, hopefully, embrace.