Screen Cages Research Articles

Effects of Host Plant Phenology on Oviposition Preference ofCrocidolomia pavonana(Lepidoptera: Pyralidae)

Field studies have demonstrated mixed success in trap cropping to manage Crocidolomia pavonana (=binotalis) [F.], a major pest of cruciferous crops in Asia. A possible explanation for this is an influence of host plant phenology on oviposition preference. We tested this in simultaneous two-choice oviposition bioassays under laboratory conditions. In cylindrical cardboard experimental arenas, with 5-cm2 leaf windows, individual C. pavonana females were offered eight sequential phenological stages of cabbage (Brassica oleracea L., Capitata group, cultivar Gloria) with a constant stage of preflowering Indian mustard (Brassica juncea, variety rugosa, cultivar Green Wave). Results showed a significant effect of cabbage developmental stage on oviposition preference. We continued with two-choice bioassays, using whole leaves, in screen cage experimental arenas. Females were offered the three most preferred phenological stages of cabbage and differing stages of four potential trap crop alternatives: preflowering Indian mustard; preflowering Chinese cabbage (B. rapa L., variety pekinensis [Lour.] Olsson); preflowering, flowering, and “with silique” sawi manis (B. rapa, variety parachinensis [Bailey] Tsen and Lee); and preflowering and flowering sayur pahit (B. rapa, variety parachinensis [Bailey] Tsen and Lee). Results indicated that the phenological stages of both plants had a significant effect on relative oviposition preference. However, patterns of preference changed in the context of the different plant species combinations. In addition, implicit hierarchical preference order was frequently contradicted. These results have implications for the improvement of trap cropping strategies to manage C. pavonana and for the potential success of biological control of Plutella xylostella [L.], where these pests occur in complex.

Transmission of Claviceps africana Spores from Diseased to Non-Infected Sorghum by Corn Earworm Moths, Helicoverpa zea

ABSTRACT The potential of corn earworm moths Helicoverpa zea, an important pest of sorghum in Texas, as a passive vector of sorghum ergot, Claviceps africana was assessed. Laboratory-reared (females and males) and field-moths trapped in sex pheromone traps were confined in screen cages with potted male-sterile sorghum line AT×623 that had been artificially infected with sorghum ergot and was producing massive amounts of honeydew that contained spores of the fungus. In the cages, moths were observed feeding on the honeydew. When laboratory-reared moths contaminated with C. africana spores were released for 12 or 48 h in cages containing healthy greenhouse- or field-grown male-sterile sorghum plants at anthesis, the levels of ergot severities on the panicles ranged from 0.5–90%, per panicle. The levels of ergot infection on greenhouse- and field-grown AT×623 exposed to ergot contaminated field-trapped males for 48 h ranged from 0–81.7%. Mean external contamination of laboratory-reared and field-trapped moths placed in a soapy wash was 1.4 × 105 and 4.7 ×104 conidia/ml, respectively. This study demonstrated that contaminated adult corn earworm could transmit the sorghum ergot from diseased to healthy panicles when environmental conditions are favorable for infection. Thus, migrating moths and other highly mobile pest species have the potential to transport C. africana over relatively large distances.

Using Self-compatible Inbreds of Broccoli as Seed Producers

The discovery that broccoli (Brassicaoleracea L., Italica Group) sprouts contain high levels of sulforaphane, a constituent that may provide chemoprotection against certain carcinogens, has stimulated much interest in seed production of this crop. Studies were undertaken to determine the potential for producing broccoli seed using self-compatible selections from open-pollinated (OP) populations or doubled-haploid (DH) programs. In all outdoor and greenhouse trials, three OP selections and seven DH lines produced selfed seed, but seed weight per plant and number per plant varied significantly among the entries. In all environments there were individuals with relatively high (i.e., >3 g/plant) production that were significantly different from low (i.e., <2 g/plant) producers. The relative productivity of some lines varied greatly between experiments, which indicates that seed production of particular genotypes is affected differently by environmental conditions. This indicates the importance of identifying lines that are high producers of selfed seed across different environments. Two OP cultivar-derived lines (USVL102 and USVL104) and two DH lines (USVL062 and USVL093) were identified that consistently produced relatively high yields in greenhouse and screen cage trials. These lines are good candidates for evaluating seed production in field tests and as possible sources of seed for sprouting.

Overwintering of honey bee queens en mass in reservoir colonies in a temperate climate and its effect on queen performance

SUMMARYThe mass storage of mated honey bee (Apis mellifera) queens in reservoir colonies over the winter was investigated under continental climatic conditions. The mated queens were stored in (a) queenright reservoir (QRR) colonies on a frame with partitioned honeycomb, (b) QRR colonies on frame holding wire screen cages, (c) queenless reservoir (QLR) colonies on frame with partitioned honeycomb, and (d) QLR colonies on frame holding wire screen cages. In addition to mass storage, the queens were individually wintered in colonies held in Kirchainer mating hives and in 5–frame nucleus hives with standard combs as the control group. The queen survival in reservoir colonies was observed from October 2000 to March 2001. No queen survived the winter in QRR colonies, whereas 16.7% of the queens stored in screen cages and 40.5% of the queens on honeycomb in QLR colonies survived for five months. The queen survival in mating hives and in 5–frame nucleus hives was 80.0% and 83.3%, respectively. Reproductive performances of surviving queens overwintered in reservoir colonies, mating hives and 5–frame nucleus hives were evaluated by comparing brood areas and adult bee populations produced in test colonies. There were no differences in numbers of frames of bees and in brood production of queens in test colonies. Thus, mass storage of queens over the winter did not impair their reproductive performance.

FIELD EFFICACY OF TWO COMMERCIAL PREPARATIONS OF ENTOMOPATHOGENIC NEMATODES AGAINST LARVAE OF DIAPREPES ABBREVIATUS (COLEOPTERA: CURCULIONIDAE) IN ALFISOL TYPE SOIL

Abstract Spring and fall field trials were conducted to determine the efficacy of two species of entomopathogenic nematodes for the control of larvae of Diaprepes abbreviatus in a citrus grove with alfisol type soil (sandy clay loam). Both Steinernema riobrave (Bio Vector 355) as a water-dispersible granule and Heterorhabditis indica (Grubstake™ 100) as a paste on sponge at rates from 22-108 IJ’s/cm2 failed to reduce larval populations in the tree rhizosphere at 25 d post-treatment. Larval parasitism by entomopathogenic nematodes in baited screen cages was sporadic over time, with the only significant treatment effect occurring at the highest rate (108 IJ’s/cm2) of S. riobrave in the fall at 7 d post-treatment. Possible constraints to nematode efficacy are discussed.

How long do females listen? Assessment time for female choice in the gray treefrog, Hyla versicolor

A satisfactory understanding of the process of mate choice by female frogs requires that we know how sensitive females are to the variation in males’ calls under natural conditions and what is the time scale or ‘‘window’’ over which females compare males. In natural choruses, gray treefrog females may sit near calling males for many minutes before approaching a particular individual to mate, while in laboratory-based tests they may approach a speaker following less than 30 s of exposure to broadcast calls. Females prefer long to short calls. In order to estimate ‘‘assessment time’’ of females in nature, calls were broadcast from four pairs of 360-deg speakers surrounded by screen cages at a pond in Missouri. One speaker per pair presented calls of constant duration, while the other speaker shifted between calls longer or shorter than the constant duration call. The period over which this change in call duration occurred differed for each of the four pairs of speakers. The numbers of females captured at the speaker array over the breeding season indicated that the most likely assessment time was close to 2 min. This estimate is similar, but not identical, to that obtained from additional laboratory tests.

Rearing methods for the black soldier fly (Diptera: Stratiomyidae).

The black soldier fly, Heretia illucens (L.), is a nonpest tropical and warm-temperate region insect that is useful for managing large concentrations of animal manure and other biosolids. Manure management relying on wild fly oviposition has been successful in several studies. However, confidence in this robust natural system was low and biological studies were hampered by the lack of a dependable source of eggs and larvae. Larvae had been reared easily by earlier investigators, but achieving mating had been problematic. We achieved mating reliably in a 2 by 2 by 4-m screen cage in a 7 by 9 by 5-m greenhouse where sunlight and adequate space for aerial mating were available. Mating occurred during the shortest days of winter if the sun was not obscured by clouds. Adults were provided with water, but no food was required. Techniques for egg collection and larval rearing are given. Larvae were fed a moist mixture of wheat bran, corn meal, and alfalfa meal. This culture has been maintained for 3 yr. Maintainance of a black soldier fly laboratory colony will allow for development of manure management systems in fully enclosed animal housing and in colder regions.

Oviposition site and food preference of the green June beetle (Coleoptera: Scarabaeidae).

Relative preferences of green June beetle, Cotinis nitida (L.), adults and grubs for different organic fertilizers were determined in field and laboratory choice experiments. Six organic fertilizer treatments (low rate of broiler litter, high rate of broiler litter, cow manure, hay, Milorganite, or no fertilizer [the control]) were applied to sandy-loam soil and exposed to adults in 2.7 by 3.7 by 2.4-m screen cages. More eggs and larvae were found in pots treated with broiler litter (43%), cow manure (23%), and hay (30%) than in pots treated with Milorganite (4%) or no fertilizer (0%). Orientation preferences of third-instar grubs were tested in Y-tube and satellite olfactometers. Of the five treatments (broiler litter, cow manure, hay, Milorganite, and a blank control), preference was greatest for broiler litter and cow manure, but all organic fertilizer treatments were generally preferred over the blank control. These experiments suggest that use of organic fertilizers may result in higher densities of green June beetle grubs both by attracting the ovipositing females, and by acting as a food attractant for the mobile larvae.

Behavioral and electrophysiological responses of Arhopalus tristis to burnt pine and other stimuli.

The exotic longhorn beetle Arhopalus tristis is a pest of pines, particularly those damaged by fire, and a major export quarantine issue in New Zealand. Actinograph recordings of caged individuals showed that males and females were most active from dusk to midnight. Olfactometer experiments indicated that females moved upwind toward odors from burnt pine (80%, N = 75), compared to unburnt pine (20%). Oviposition choice tests showed that eggs were predominantly laid on burnt logs (79%, N = 20), compared to unburnt logs. Beetles were trapped by funnel traps baited with burnt (mean catch per trap 7.8) and unburnt (mean catch 4.1 per trap) pine bark from inside a screen cage (4 x 3 m), while unbaited traps had a mean catch 0.1 beetles (N = 8 replicates). The treatment of burnt pine bark with a 1:1:2 mixture of green leaf volatiles (E)-2-hexen-1-ol and (E)-2-hexenal) in mineral oil as a repellent reduced trap catch by fivefold in a similar experiment (mean catches of 1.2 beetles per trap to burnt pine bark plus repellent treatment and 6.2 beetles per trap to burnt pine bark alone). The treatment of burnt pine bark with this solution also reduced oviposition by 98.5% (mean eggs per log of 11.1 on burnt pine and 0.3 on burnt pine plus repellent), indicating that oviposition cues have the potential to be significantly disrupted. The electrophysiological responses of adult beetles were recorded to a range of odorants. Normalized responses to monoterpenes known to occur in Pinus radiata ranged from about 20 to about 150, with alpha-terpineol giving the greatest responses in both sexes. Green leaf volatiles also gave high responses. The potential exists to improve the management of this insect using chemical cues in various ways.

Comportamento de Hedypathes betulinus (Klug, 1825) em erva-mate em campo

Foi avaliado o comportamento de cópula, postura, alimentação e deslocamento da broca da erva-mate, Hedypathes betulinus (Klug, 1825), na área experimental da Universidade Federal de Santa Maria. Essas características da broca foram avaliadas por um período de quatro dias através de observações visuais (de hora em hora), em duas gaiolas teladas colocadas sobre um ramo da planta, e contendo dois casais do inseto/gaiola. Observou-se que o macho, quando acompanhado de uma fêmea, tenta copular imediatamente, realizando cópulas durante todos os perí odos do dia, principalmente entre 14 e 18h, e em toda a extensão do ramo. A postura ocorreu nos ramos de 15-20mm de diâmetro. A maior intensidade de alimentação ocorreu no período compreendido entre 10 e 18h, sendo preferencialmente realizada em ramos de 30-40mm de diâmetro. O inseto apresentou comportamento sedentário e de fácil localizaç ;ão em função de sua limitada e lenta movimentação. Esses resultados são importantes para localização, amostragem, catação manual e manejo da praga.

Trapping Male Oriental Fruit Flies (Diptera: Tephritidae): Does Feeding on a Natural Source of Methyl Eugenol Reduce Capture Probability?

Males of the oriental fruit fly, Bactrocera dorsalis (Hendel), are strongly attracted to methyl eugenol (ME), a naturally occurring compound reported from ten different plant families (Metcalf 1990). Increasing evidence indicates that this attraction reflects enhanced competitiveness in sexual selection: males that feed on pure ME (Tan & Nishida 1996) or flowers containing ME (Shelly, unpublished data) or ME-like compounds (Nishida et al. 1997) have a pronounced mating advantage over unfed males. Control efforts take obvious advantage of this association, and traps baited with ME and insecticide have been used in numerous programs of male annihilation (Cunningham 1989). In fact, ME traps were successful in eradicating B. dorsalis from entire islands in the western Pacific (Steiner et al. 1965). Despite its past successes, the effectiveness of this method is potentially constrained by at least two factors. First, individual males display variable levels of attraction to ME, and this variation appears to have a heritable component (Shelly 1997). Consequently, prolonged, low-level use of ME traps could select for non-responsiveness to the lure and thus inadvertently reduce the likelihood of eradication (Cunningham 1989). In addition, Shelly (1994) demonstrated that B. dorsalis males that fed on ME were less likely to be captured in traps than control males. Thus, the possibility exists that males that have located and fed on natural sources of ME will avoid ME traps, thereby hampering control efforts. Here, I describe field experiments that examined whether males that fed previously on flowers of Cassia fistula L., which contain ME (Kawano et al. 1968), or flowers of Fagraea berteriana A. Gray, which contain ME-like compounds (Nishida et al. 1997), were less likely to be trapped in ME traps than control unfed males. Flies used in all experiments were from a laboratory stock started with 300-400 adults reared from field-collected mangos. The colony was housed in a large screen cage (1.2 m by 0.6 m by 0.6 m) with superabundant food (a mixture of honey and protein hydrolysate) and water. Ripe papayas were provided periodically for oviposition. Room temperature was maintained at 20-22?C and 65-75% RH, and under these conditions generation time was about four weeks. The experiments were performed when the colony was 3-7 months old, and correspondingly the flies used were 3-7 generations removed from the wild. Sexes were separated within seven days of eclosion, well before reaching sexual maturity at 15-20 days (Foote & Carey 1987). Males in the treatment category were exposed to flowers either one time only (single feeding trials; both plant species) or two times (repeat-feeding trials; F. berteriana only) prior to release. The single-feeding trials were conducted as follows. For C. fistula, flowering stems were removed from a tree growing near the laboratory, put in water, and then placed into screen cages (30 cm cubes). A total of 140-160 flowers was placed in a given cage. Flowers of F. berteriana were obtained commercially as leis (a Hawaiian necklace of flowers). Flowers were used on the day of purchase (presumed fresh), and 40-50 flowers were placed in each cage. Flowers of both plant species were placed in the cages at 0800 hr and immediately thereafter I introduced 50 males (22-26 days old) per cage (along with food and water). Males had been marked

Oviposition site selection of Episyrphus balteatus

AbstractThe oviposition behaviour of Episyrphus balteatus DeGeer (Diptera: Syrphidae) was investigated in four‐choice experiments in screen cages and in experiments with direct behavioural observations. Females laid hardly any eggs in the absence of aphids and preferred larger aphid colonies to small ones. Honeydew attracted the females via olfaction and elicited oviposition. Females were able to perceive the presence of conspecific eggs and oviposited less often in aphid colonies in which eggs were present. The oviposition deterring stimulus was also active when the eggs were removed, hence, the deterrent did not act visually, but probably olfactorily.

Longevity of Musca domestica L. (Diptera: Muscidae) parasitized by Habronema muscae Carter (Nematoda: Habronematidae)

The present work had as objective to evidence the influence of the parasite Habronema muscae on the Musca domestica longevity. Muscids larvae belonging to second generation, with aproximately 30 h old, were submitted to infection in artificial diet, in which were inoculated H. muscae eggs, obtained from maceration of female helminths. The muscid larvae and pupae were mantained in artificial chamber at 27o C, 60 ± 10% RH and 14 h of photophase. After emergence, the adults were distributed in screen cages, The number of dead muscids were conferred daily, with posterior dissection and ratification of infective nematode larvae. The mean intensity of infection was 3.11 infective larvae per muscid (range: 0-14) in the infected group. The infected group showed a significative reduction on mean longevity, when compared with the control (25.0 and 32.5 days, respectively). There was no difference between mean longevity from male and female dipterous.

Detection of acute alcohol intoxication and chronic alcohol dependence by trauma center staff.

Trauma patients with acute alcohol intoxication or chronic alcohol dependence are at greater risk for morbidity and mortality. We hypothesized that relying on clinical suspicion to detect acute alcohol intoxication and chronic alcohol dependence in trauma patients is inaccurate, influenced by injury factors, and biased by race, gender, age, and socioeconomic status. Trauma patients were screened with a blood alcohol concentration and with the Short Michigan Alcohol Screening Test and CAGE questionnaire. Before screening, physicians and emergency department nurses were asked whether the patient was acutely intoxicated (blood alcohol concentration > 100 mg/ dL) or had a chronic alcohol problem. Sensitivity, specificity, positive, and negative predictive values were determined by comparing responses with blood alcohol concentration, Short Michigan Alcohol Screening Test, and CAGE questionnaire results, stratified by injury and demographic factors. Clinical evaluations were obtained on 462 patients. Overall, 23% of acutely intoxicated patients were not identified by physicians. The miss rate increased to one third in severely injured, chemically paralyzed, or intubated patients. Specificity was also poor. Patients with a negative blood alcohol concentration were more likely to be falsely suspected of intoxication if they were either young, male, perceived as disheveled, uninsured, or having a low income (p < 0.05). Staff identified < 50% of patients with a positive Short Michigan Alcohol Screening Test or CAGE, and falsely identified 26% of patients as alcoholic. Formal alcohol screening should be routine because clinical detection of acute alcohol intoxication and dependence is inaccurate. Screening should also be routine to avoid discriminatory bias attributable to patient characteristics.

Dynamics of Beauveria bassiana and Metarhizium anisopliae Infecting Hypothenemus hampei (Coleoptera: Scolytidae) Populations Emerging from Fallen Coffee Berries

The aim of this research was to evaluate the effect of soil sprays of the entomopathogens Beauveria bassiana and Metarhizium anisopliae on coffee berry borer (cbb) adults, Hypothenemus hampei, emerging from fallen berries through time. Each fungus was applied to a plot 5000 m2 in size of the Colombian variety in the third harvest year. The experimental plot was formed with 9 trees, and the experimental unit was the central tree. In this tree all the green uninfested berries were left and the whole tree covered with a screen cage to avoid further cbb infestation or escape. Nine treatments replicated ten times were arranged in a complete randomized design. Conidia of each fungus were suspended in emulsified oil and water and applied on the base of the trees at a dosage of 1 109 conidia/tree. Under each experimental tree 350 cbb-infested coffee berries were placed on the soil to serve as a source for aerial infestation of the trees. Infested berries were applied the same day of the spray and at 2, 5, 10, 15, 20, 25 and 30 days after fungus application. Results showed that infection levels of both fungi on cbb were the highest during the first five days after application, reaching nearly 30% for B. bassiana and 11% for M. anisopliae. However, the infection decreased for 20 days but peaked again at 25 days post-treatment with 24.3% for B. bassiana and 7.7% for M. anisopliae. These results are explained by the formation of propagules in the soil by these fungi, due probably to the accumulation of infective conidia on infected insects which infect other insects leaving the fruits. The two species were recovered from the soil even after two months and fluctuation in numbers of colony forming units was attributed to the rainfall during the study period and the fungus conidiation. B. bassiana was shown to be more infective than M. anisopliae, considering that the latter is more frequently associated to soil habitats. The authors believe efficiency of these fungi can be increased if improvements are made to the formulations, e.g., using a granulated formulation to avoid leaching of the conidia from the soil during heavy rainy seasons. During this study it was found that H. hampei is a new host of Paecilomyces lilacinus.

Improvement of ion plated Ag and Au film adhesion to Si3 N4 and SiC surfaces for increased tribological performance

A modified dc diode plating system, utilising a metallic screen cage as a cathode and designated screen cage ion plating, is used to deposit Ag and Au lubricating films on Si3 N4 and SiC surfaces. When deposition is performed in Ar or N2 glow discharge, the surface displays poor adhesive strength (<5 MPa). A dramatic increase in adhesive strength (>80 MPa) is achieved when plating is performed in a reactive 50O2–50Ar glow discharge. The excited/ionised oxygen species (O+2 /O+) in the glow discharge contribute to the oxidation of the Si3 N4 or SiC surfaces as determined by X-ray photoelectron spectroscopy depth profiling. The reactively sputter oxidised Si3 N4 or SiC surfaces and the activated oxidised metastable Ag or Au species formed in the plasma, cooperatively contribute to the increased adhesion. As a result, the linear thermal expansion coefficient mismatch at the interface is reduced. These lubricating Ag and Au films under sliding conditions reduce the friction coefficient by a factor of 2·5–4.

Effect of curing conditions on properties of iron-resin materials for low frequency uses: C.Gelinas et al. (Quebec Metal Powders Ltd, Quebec, Canada.)

The validity of “sputtering and re-condensation” model in active screen plasma nitriding for nitrogen mass transfer mechanism is investigated. The dominant species including NH, Fe-I, N2+, N-I and N2 along with Hα and Hβ lines are observed in the optical emission spectroscopy (OES) analysis. Active screen cage and dc plasma nitriding of AISI 316 stainless steel as function of treatment time is also investigated. The structure and phases composition of the nitrided layer is studied by X-ray diffraction (XRD). Surface morphology is studied by scanning electron microscopy (SEM) and hardness profile is obtained by Vicker's microhardness tester. Increasing trend in microhardness is observed in both cases but the increase in active screen plasma nitriding is about 3 times greater than that achieved by dc plasma nitriding. On the basis of metallurgical and OES observations the use of “sputtering and re-condensation” model in active screen plasma nitriding is tested.

Bioassays for measuring ovipositional and larval preferences of leafrollers (Lepidoptera: Tortricidae) for different cultivars of apple

Bioassays are described for measuring the ovipositional and larval preferences of three leafroller species, Planotortrix octo, Epiphyas postvittana, and Ctenopseustis obliquana, for different apple (Malus domestica) cultivars. In four‐cultivar choice tests, mated female moths were offered terminal shoots in a large screen cage; first instar larvae selected terminal leaves in a smaller test arena. There were high levels of oviposition and settlement on all cultivars which agreed with field evidence of their susceptibility. However, there was overall higher oviposition of the three leafroller species (combined) on ‘Royal Gala’ compared to ‘Jonafree’, and for E. postvittana, higher oviposition on ‘Liberty’ than ‘Jonafree’. These cultivar preferences were also expressed in the responses of the first instar larvae of the respective species. The preference of E. postvittana larvae for ‘Liberty’ and ‘Royal Gala’ rather than ‘Fiesta’, and the preference of P. octo larvae for ‘Liberty’ rather than ‘Jonafree’, were not matched by adult oviposition behaviour of the species. C. obliquana showed no significant cultivar preferences but the acceptance ranking of the cultivars was the same in both the oviposition and larval tests. The bioassays are considered suitable for testing of leafroller oviposition and larval preferences using a wider genetic pool of apple cultivars in parallel with measurements of leafroller colonisation in the field.

Parasitism by Trichogramma spp. (Hymenoptera: Trichogrammatidae) in Relation to Nantucket Pine Tip Moth (Lepidoptera: Tortricidae) Egg Density and Location

Patterns of parasitism by Trichogramma spp. relative to density and location of Nantucket pine tip moth, Rhyacionia frustrana (Comstock), eggs were examined during 1994 in a 13-ha, 2-yr-old Pinus taeda L. plantation in northeastern Georgia. Egg densities were adjusted by temporarily enclosing trees in fine mesh screen cages and introducing different numbers of tip moths. After exposing eggs to naturally occurring parasitoids, all shoots were removed, and eggs were counted and evaluated for parasitism. Tip moth egg densities ranged from 203 to 2,579 per tree for the spring generation, and from 1 to 89 per tree for the summer generation. Tip moths deposited significantly greater numbers of eggs on needles than shoots on high-versus low-egg-density trees. Overall parasitism rates were 37.2 and 43.3% for spring- and summer-generation eggs, respectively. Parasitism was density independent at the whole-tree level in both generations, but spring-generation parasitism was strongly inversely density dependent in the top whorl. Numbers of eggs per needle fascicle ranged from 1 to 15 for spring-generation trees. Actual numbers of parasitized eggs per discovered fascicle (one on which parasitism occurred) increased with egg density, but the percentage of parasitized eggs decreased. Egg density had no effect on fascicle discovery. These factors produced an inversely density-dependent relationship between egg parasitism and density at the fascicle level. Eggs located on shoots suffered significantly greater parasitism rates than those on needles. Implications of these results are discussed.

Oviposition Preferences of the Polyphagous Moth Choristoneura parallela (Lepidoptera: Tortricidae): Effects of Plant Species, Leaf Size, and Experimental Design

The fireworm Choristoneura parallela (Robinson) is a major pest of cranberry in New Jersey. Eggs typically are laid on the leaves of various weed species, and larvae disperse onto cranberry by ballooning. We used laboratory-reared moths and greenhouse experiments to investigate oviposition preferences among 3 weed species: greenbrier, Smilax rotundifolia L.; leatherleaf, Chamaedaphne calyculata (L.); and sheep laurel, Kalmia angustifolia L. In no-choice tests conducted in screen cages using cuttings, leatherleaf received the most egg masses whereas the other species did not differ. In this test there were no differences among species in the latency to the 1st egg mass; and the latency between the 1st and 2nd egg masses did not differ for greenbrier compared with the other species but was shorter for leatherleaf than for sheep laurel. The results were similar in 3-way choice tests conducted in screen cages using cuttings with leatherleaf receiving the highest percentage of egg masses and the other species not differing. However, a different preference hierarchy was found in 3-way choice tests conducted in plastic boxes using a single leaf of each species: greenbrier received the highest percentage of egg masses, leatherleaf received more than sheep laurel, and sheep laurel received no egg masses. Two-way choice tests using paired leaves in plastic boxes showed that larger greenbrier and leatherleaf leaves were preferred over smaller ones of the same species, but that leatherleaf was preferred over sheep laurel even when sheep laurel leaves were larger. These results demonstrate that this moth exhibits oviposition preferences among plant species but that the preference hierarchy depends on the experimental situation, and that both the species and the size of individual leaves can be factors.