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The common parasite species attacking Trichoplusia ni (Hubner) (Lepidoptera: Noctuidae) in southern California were investigated in the laboratory to demonstrate discriminatory abilities. Copidosoma truncatellum (Dalman) (Hymenoptera: Encyrtidae), a polyembryonic, egg-larval parasite, exhibited time-dependent, intraspecific discrimination. The solitary larval parasite, Microplitis brassicae Muesebeck (Hymenoptera: Ichneumonidae), discriminated between unparasitized hosts and those parasitized by Hyposoter exiguae (Viereck) (Hymenoptera: Ichneumonidae) or M. brassicae , but did not discriminate hosts containing C. truncatelium immatures. Multiple parasitization by these two species in hosts containing C. truncatellum resulted in successful development of C. truncatellum in most cases, with some hosts yielding M. brassicae or H. exiguae . In studies with Varia ruralis (Fallen) (Diptera: Tachinidae), the hymenopterous parasites had a competitive advantage when multiple parasitization occurred, but in the case of C. truncatellum, timing of parasitization by V. ruralis affected the results, with some 7- to 9-day-old hosts producing both C. truncatellum and V. ruralis .

Trichogramma (Trichogrammanza) Carver, known only from southeast Australia, is reviewed and 2 new species, T. (T.) carverae and T. (T.) tenebrosum, are described. Results of cross-breeding studies between 2 forms of T. (T.) funiculatum Carver are briefly discussed.

Laboratory investigations were conducted on the biology of Apanteles subandinus Blanchard and the effect of temperature and relative humidity on its bionomics. Temperature responses of this parasite were compared with those of Apanteles scutellaris Muese-beck and their common host, the potato tuberworm, Phthorimaea operculella (Zeller). Responses of the parasites and their host to physical factors were evaluated by using the intrinsic rate of natural increase (r) as a bioclimatic index. At 80°F and 50 per cent relative humidity (R.H.) the mean duration of the life cycle of A. subandinus from egg to adult was 15 days; egg, 1 day; first in-star, 4.5 days; second instar, 2.5 days; third instar, 2 days; prepupa, 0.5 days; and pupa, 4.5 days. The parasite egg is deposited at random in the body cavity of the host larva where the parasite larva develops. There are three instars, the first being mandibulate-caudate and the other two hymenopteriform. The mature larva emerges from the host, killing it in the process, and spins a silver-white cocoon. There is essentially no preoviposition period in A. subandinus and the parasite is an arrhenotokous species, the virgin female producing only male progency. Between 60 and 90°F, speed of development was directly related to temperature. A constant temperature of 95°F prevented development of the parasite beyond the first instar. Longevity and reproductive periods were inversely related to temperature, longevity following the pattern of the curve of physiological longevity. Production of progeny was maximum at 80°F. As determined by calculations of the intrinsic rate of natural increase, A. subandinus persisted and increased in numbers between 60 and 90°F. Optimal temperature for the parasite was 85°F. Relative humidity did not affect development. At 80 and 85°F, maximum progeny production occurred at 50 per cent R.H. This level of humidity was also optimal for population growth. Apanteles scutellaris developed and reproduced at 95°F, a temperature at which A. subandinus could not develop. The optimal temperature for A. scutellaris was 90°F. The potato tuberworm host developed at 95°F but this temperature caused male sterility, preventing production of progeny. The shortest developmental period of the potato tuberworm occurred at 90°F. Comparisons of the temperature responses of the two parasites and their host revealed that the parasites have a higher power of increase than the host, and that A. scutellaris is better adapted to high temperatures than is A. subandinus.

Studies were conducted on the biology, and on temperature and humidity responses, of Agathis unicolor (Schrottky), and exotic species. Results were compared with similar studies on the native species, A. glbbosa (Say), and their common host, the potato tuberworm, Phthorimaea operculella (Zeller). The two species of parasites were reared at several constant temperatures and humidities, and life-table data were obtained in each test environment. These data were used to calculate the intrinsic rate of natural increase, which was used as a bioclimatic index for each of the two species. The influence of several different constant temperatures and humidities on the parasites, and on host-parasite relationships, was evaluated on the basis of relative changes in the intrinsic rate of increase, developmental time, and the mean generation time. The egg of A. unicolor is deposited in a ganglion of the ventral nerve cord of the host larva. Parasite larvae develop within the host body cavity and, after emergence, spin their silky-white cocoons inside the host cocoons. There are three larval ins tars, the first being both caudate and mandibulate, and the other two, hymenopteriform. The mean minimum developmental time from egg to adult emergence was 18 days at 26.7 C 50 ± 2 percent relative humidity (RH). Measurements and morphological descriptions of the immature stages are presented, and mating and ovipositional behavior of the adults are described. The optimum host density for maximum parasite progeny was 85 larvae per tuber. The biology of A. unicolor is similar to that of A. gibbosa. Temperature and rate of development of both parasites were linearly related. However, at 35.0 C, A. unicolor could not develop beyond the prepupal stage. Longevity and reproductive periods were inversely related to temperature, and survivorship curves of both parasites conformed to the curves of physiological longevity. On the basis of the intrinsic rate of natural increase, A. unicolor survived and reproduced from 21.1 to 32.2 C. Agathis gibbosa survived and reproduced from 21.1 to 35.5 C. Both parasites developed best at 50 percent relative humidity. Comparisons of the intrinsic rate of natural increase, developmental time, and mean generation time indicated that A. gibbosa would be better able to suppress populations of the host than A. unicolor.

The effectiveness and selectivity of the combination Dipel® (Bacillus thuringiensis Berliner var kerstaki ) plus pirimicarb® for control of the complex of lepidopterous larvae [Trichoplusia ni (Hubner), Pieris rapae (L.), and Plutella xylostella (L.)], and aphids [Brevicoryne brassicae (L.) and Myzus persicae (Sulzer)] attacking broccoli were evaluated on 5 different plantings at 2 locations in southern California. During the preheading stage of plant growth, Dipel 1.0 Ib + pirimicarb 0.25 lb AI/acre, applied as needed, significantly reduced lepidopterous larval and aphid populations. However, control of larvae was less consistent than that by methomyl at 0.9 lb AI/acre. Weekly applications of Dipel 1.0 Ib + pirimicarb 0.25 lb during head formation were as effective as methomyl 0.45 lb in preventing insect contamination of the heads. B. brassicae was consistently the most serious insect contaminant of the broccoli heads. The effects of the Dipel + pirimicarb and methomyl treatments on parasitization of T. ni and P. xylostella at 14 days posttreatment were minimal. At 6 and 7 days posttreatment, Dipel + pirimicarb interfered less with parasitization than did methomyl.

Studies on integrating Phyloseiulus persimilis Athias-Henriot releases, chemical applications, cultural manipulations, and natural predation for control of the two-spotted spider mite, Tetranychus urticae (Koch), on strawberry were conducted in southern California during 1965–66. Treatments consisted of a pre-planting furrow application and a post-planting sidedress application of phorate granules, foliage spray application of binapacryl, and 2 nonpesticide checks in one of which sanitation (nonfunctioning senescent leaves removed from field) was practiced. Treatment plots were established in a randomized complete block design and replicated 4 times. Mass releases of P. persimilis were made on ½ of each plot at weekly intervals during March at the equivalent rate of 384,000 per acre total for the period. Populations of prey and predators were sampled at weekly intervals throughout the study. In the check plot, the spider mite population declined from an average of 13.1 mites per leaflet on September 28, 1965 (5 weeks after transplants were planted) to a low of 1.0 per leaflet on January 4, 1966, reached a peak of 162.7 on March 15, after which it declined to an average of less than 1.0 per leaflet by May 17, remaining below 0.5 per leaflet through the end of the study on June 28. Reduction of the spider mite population in the check was due primarily to the combined action of 8 predators, of which the six-spotted thrips, Scolothrips sexmaculatus (Pergande), was the dominant species. Removal of the non functioning leaves resulted in an overall 55.4% reduction in the spider mite population, with a corresponding reduction in total predator numbers during a 6-week period subsequent to their removal. Because of the unusually early increase in and the high population reached by the two-spotted spider mite, plant damage was not prevented by P. persimilis releases although the pest population was reduced by an overall average of 18.9%. P. persimilis reached its peak population 6-8 weeks after initial releases, averaging up to 4.6 actives per leaflet and occupying 75-100% of the leaflets sampled. Mass releases of P. persimilis had no adverse effect on natural predation, Strawberry yield was increased by an overall average of 18.1% where P. persimilis was released. Good initial spider mite control was obtained with the phorate treatments. However, they were no longer effective by the time the P. persimilis releases were made in March. Suppression of the spider mite in the binapacryl plots was followed by even higher populations, indicating an indirect adverse effect of chemical control and emphasizing the desirability of developing an effective integrated control program.

The population dynamics of mite species on apple foliage was studied in a natural (unsprayed check) and 2 artificial (captan and DDT-captan) environmental blocks established in a mature ‘Northwestern Greening’ apple orchard in Door County, Wisconsin, from 1959 through 1962. The phytophagous species, including Panonychus ulmi (Koch), Eotetranychus uncatus Garman, Bryobia arborea Morgan & Anderson, and Aculus schlechtendali (Nalepa), reached their highest numbers each year in the DDT-captan block except for B. arborea which was highest in the check block in 1959. The population of each species was lowest each year in the check block. The predaceous phytoseiid mites reached their highest numbers in the check block in 1959, check and captan block in 1960, and captan block in 1961 and 1962. Their populations were annually lowest in the DDT-captan block, indicating a generally adverse effect by DDT. The population of the predaceous mite Agistemus fleschneri Summers was similar in each environmental block in 1959 but reached its highest peaks and seasonal averages in the DDT-captan block each year thereafter. Two fungusfeeding species, Tarsonemus setifer Ewing and Calvolia sp., reached their highest numbers in the captan block in 1959 and in the check block each year thereafter. The higher populations of the phytophagous species in the DDT-captan block were attributed to the more luxuriant foliage, resulting from control of apple scab, Venturia inequalis (Winters), by captan; lower phytoseiid mite populations; and a stimulative effect apparently induced by physiological changes in the host trees by DDT. Nine species of phytoseiids were present with Typhlodromus caudiglans Schuster and T. fallacis (Garman) being the most common in the check and DDT-captan blocks, respectively. The high numbers of T. fallacis and A. fleschneri in the DDT-captan block indicate that they are tolerant to DDT. The low numbers of T. setifer and Calvolia sp. in the captan and DDT-captan blocks were attributed primarily to the reduction of apple scab by captan. The data further indicate that an apple orchard is an exceeding complex agro-ecosystem which is easily disrupted by pesticide applications.

A 4-year study of the naturally occurring biotic control factors affecting the eye-spotted bud moth, Spilonota ocellana (Denis and Schiffermuller), on apple in Wisconsin revealed the existence of parasitic, predatory, and microorganismal agents. Nine hymenopterous parasites, three predators, and four pathogens were involved. Principal parasitic species were Itoplectis conquisitor (Say) and Habrocytus phycidis Ashmead. Aspergillus flavus Link and a polyhedral virus were the most prevalent causes of disease. A high mortality occurring in the pupal stage could not be attributed to known causes. It is postulated that the comparatively low numbers of primary species and their small part in the regulation of the eye-spotted bud moth population may have been due mainly to the extensive use of pesticides in the area. The need for the use of selective pesticides in an integrated control program is emphasized.

Investigations from 1958 through 1962 in a young apple orchard in Door County Wisconsin revealed that the eye-spotted bud moth, Spilonota ocellana (Denis • Schiffermuller), pupated primarily in twig nests which were constructed some distance from the larval feeding sites. Larvae were shown to complete their development sooner on Red Delicious than on Cortland. Bud development was not regarded as a primary contributing factor to these developmental differences.