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Rabbit antibodies against Encephalitozoon cuniculi were detected in an enzyme immunoassay procedure in which antigen was grown and used in situ. The test appeared to be more sensitive than the indirect immunofluorescence test with which it was compared, but gave essentially the same results for the 64 sera evaluated. This procedure will allow any laboratory with cell-culture facilities to produce a diagnostic antigen without the need for antigen processing. It is simple and reliable, and does not require specialized equipment or microscopic assessment.

AbstractNymphal and adult Diaphnidia capitata(Van Duzee) have long been recognized as predators of Panonychus ulmi(Koch) and Tetranychus urticaeKoch. The eggs and oviposition sites preferred by this species are described herein to supplement available descriptions of the eggs of mirid predators of spider mites.

Two experimental paradigms were adopted to compare effects of scopolamine and its quaternary derivative, methylscopolamine, on the behaviour of albino rats in an exploration box comprising novel and familiar halves. Subjects tested with the first paradigm were exposed to one of the halves, injected and then observed 20 min later. Although both drugs reduced preferences for the previously inaccessible novel half, only scopolamine decreased rearing and increased ambulation. With the second paradigm, behaviour was assessed without any current drug influence. On the 2 days prior to testing the rats had been exposed to one half of the apparatus while drugged. Prior treatment with both scopolamine and methylscopolamine reduced novelty preference to the extent that the familiar half of the apparatus was preferred. Both drugs also reduced rearing (for females only) and ambulation. It was concluded that the results with both paradigms provided some support for the view that reductions in novelty preference by anticholinergic drugs arise from their aversive peripheral actions.

AbstractDuring 1967 Hyaliodes vitripennis(Say) proved to be an important predator of Panonychus ulmiKoch and Tetranychus urticaeKoch in an experimental orchard. The eggs of this predator, described herein, are destinctive for the species. Observations on oviposition sites for the overwintering eggs are also included.

The predaceous mirid Deraeocoris nebulosus(Uhler) is found on more than 50 species of ornamental trees and shrubs where it feeds on several important pest species (Wheeler et al.1975). It is a common mite and aphid predator in commercial apple orchards in Virginia (Parrella et al.1978). Wheeler et al.(1975) described the nymphal stages and biology, but made no mention of the egg or oviposition site. We describe the egg and oviposition site which we discovered while studying various predators of the European red mite, Panonychus ulmi(Koch), in Virginia apple orchards. Eggs and oviposition sites of other predaceous mirids associated with apple have been described (Kullenberg 1942; Collyer 1952, 1953; Sanford 1964; Horsburgh and Asquith 1968, 1970).

The interspecific interactions of 5th-instar Orius insidiosus (Say) and 2nd-instar larvae of another mite predator, Leptothrips mali (Fitch), was studied in the laboratory. L. mali is a potential prey for O. insidiosus, but has a defensive anal secretion which repels predator attacks. Most contacts between well-fed O. insidiosus and L. mali resulted in mutual avoidance. Most attacks by O. insidiosus were unsuccessful, especially if the approach was from the rear. Contact with the thrips' anal secretion resulted in immediate repelling of O. insidiosus, with subsequent cleaning activity lasting 1 to 3 min. This study indicates that these two predators are compatible, especially in the presence of another food source such as the European red mite.

Egg and nymphal development of Orius insidiosus (Say) was studied at 17, 23, 29, and 35°C. There was a linear relationship between development rate (1/days) of O. insidiosus and temperature. Developmental threshold temperatures were calculated as 10.2°C for eggs and 8.9, 7.5, 10.7, 12.4, and 9.9°C for instars 1–5, respectively. A 10.0°C developmental threshold was determined for total nymphal development. Mean degree-day requirements for development were calculated for all stages studied. Laboratory and field observations established that a number of small, soft-bodied insects and mites as well as the eggs of several Lepidoptera are acceptable as prey. O. insidiosus also fed on other beneficial species including predaceous thrips and mites. A number of general orchard predators, particularly spiders, chrysopids, and other predaceous Heteroptera, were found to prey upon O. insidiosus. Numerous weeds and crops serve as alternate sites for O. insidiosus populations. Corn and alfalfa adjacent to apple orchards in Virginia apparently serve as a reservoir for O. insidiosus throughout the season. Thistles (Carduus spp.) harbor large numbers of O. insidiosus, which prey on thrips. These natural and cultivated alternate sites may be important to management of O. insidiosus populations.

The functional responses of all feeding stages of Leptothrips mali (Fitch) to various densities of selected Panonychus ulmi (Koch) stages were determined in the laboratory at 23.9 ± 1°C. Functional response data were obtained for the following L. mali-P. ulmi combinations: first-stage larvae of L. mali with P. ulmi eggs and adults, second-stage larvae or adult female L. mali with adult P. ulmi. To estimate the relationship between the number of prey killed and prey density for the selected predator-prey combinations, various mathematical models were fit to the data. No functional response was found when first-stage larvae were provided adult female P. ulmi. A sigmoid curve best explained the relationship in all other situations. Search rate increased between the two lowest prey densities when adult thrips were provided adult mites. No such increase was observed with other L. mali-P ulmi combinations; search rate remained constant. Therefore, for these other stages, the type III response obtained cannot be explained on the basis that the search rate increases over an initial range of low prey densities. A possible explanation may be interference-stimulation of the predator by the prey above some threshold prey density.

The species composition and habitat associations of spiders were studied in one abandoned and 5 commercial apple orchards in central Virginia. Sixty-eight identifiable species were recorded from all orchards. The abandoned orchard contained 63 species while 11–17 species were found in individual commercial orchards. The Salticidae, Philodromidae, Thomisidae, Theridiidae, Anyphaenidae, and Dictynidae comprised 75–92% of the total spiders collected from each orchard. The proportions of hunting spiders found in all but one commercial orchard were similar to that found in the abandoned orchard. The many species of spiders encountered in each orchard exhibited specific habitat preferences and segregated the tree into numerous niches. Since many orchard insect pests often occupy several of these niches, different spider species may act in a complementary manner to suppress such insect pest populations.

The individual or joint potential impact of Leptothrips mali (Fitch) with Stethorus punctum LeConte or Orius insidiosus (Say) on the European red mite (Panonychus ulmi (Koch)) was evaluated in the laboratory. At a mite density of 45/arena, L. mali with S. punctum killed significantly more P. ulmi than L. mali or S. punctum alone. No difference was observed in total mites killed when the combination of L. mali or O. insidiosus was compared with individual L. mali and O. insidiosus. In 75% of replicates where L. mali was combined with O. insidiosus, the latter killed and consumed the thrips.

Population trends of selected pests in Virginia apple orchards [Panonychus ulmi (Koch), Aculus schlechtendali (Nalepa), Aphis citricola Van der Goot, Dysaphis plantaginea (Passerini), Platynota. spp.] and predators [Leptothrips mali (Fitch), Haplothrips subtilissimus Haliday, Orius insidiosus Say, Stethorus punctum (LeConte), Deraeocoris nebulosus (Uhler), Chrysopa spp.] were monitored during 1977 and 1978 under three reduced-pesticide programs. The pesticide program with phosalone and Dikar® [a blend of Dithane® M-45 (coordination product of zinc ion and manganese ethylene bisdithio=carbamate) and technical Karathane® (2,4-dinitro-6-octylphenyl crotonate, 2,6-dinitro-4 octylphenyl crotonate, and nitro-octyl-phenols)] as its major components allowed the largest number of predators to remain in the orchard and controlled most pests. Platynota spp. caused economic damage during August and September, regardless of the pesticides used or the number of predators in the orchards. L. mali and H. subtilissimus were the most abundant predators and probably responded numerically to densities of A. schlechtendali. The presence of this mite species may aid the development of large numbers of thrips within an apple orchard. O. insidiosus and D. nebulosus usually increased too late in the season to reduce aphid populations, but aphids may be important in attracting these general predators into the orchard. S. punctum’s response to densities of P. ulmi was inconsistent, but together with other predators it may have had an important role in reducing P. ulmi populations. Chrysopa spp. remained at consistently low levels throughout the study under all pesticide programs.

Leptothrips mali (Fitch) (Thysanoptera: Phlaeothripidae) was studied in the laboratory with the European red mite, Panonychus ulmi (Koch), as prey. Aspects of its development and biology were determined. Mean number of days required for development of each stage at 23.9°C were: egg, 7.5; first larva, 5.7; second larva, 5.4; prepupa, 1.0; pupa I, 1.5; pupa II, 4.0; total (egg to adult), 25.6. An inverse relationship was found with temperature and development times for the egg, first- and second-stage larvae, pupa II, and total (egg to adult) at 18.3, 23.9, and 29.4°C. The mean preoviposition period (range = 5–7 days) of mated and unmated or field-collected (FC) and laboratory-reared (LR) females did not differ. Mean numbers of eggs per female were: mated LR, 13.0; mated FC, 28.0; unmated LR, 11.7; and unmated FC, 45.1. Mean longevity of unmated females (LR and FC = 50.1 and 54.2 days, respectively) did not differ from that for mated females. L. mali completed development on Golden Delicious apple pollen in 23 days (first larva to adult), which was slower than on diets containing various stages of P. ulmi.

The functional response of Orius insidiosus (Say) to densities of the European red mite, Panonychus ulmi (Koch), was studied at 18.3, 23.9, 29.4, and 35.0°C with prey densities of 5–80 mites per cage. Mite consumption was recorded during five, 3-h intervals during the day. O. insidiosus exhibited a functional response and increasing temperatures resulted in increased feeding at most prey densities. Data provided a good fit to both type-2 and type-3 functional response models.