Psylla Nymphs Research Articles

The Artificial Sweetener, Erythritol, Has Insecticidal Properties Against Pear Psylla (Hemiptera: Psyllidae).

Erythritol is a dietary sweetener that is used for low-calorie or diabetic diets. Although safe for human consumption, erythritol is lethal to certain Dipteran pests, but insecticidal effects of erythritol on phloem-feeding insects have yet to be examined. Our goal was to determine whether erythritol has insecticidal activity against pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae). We first demonstrated that ingestion of erythritol solutions compared with water by pear psylla caused reduced feeding, impaired motor functions, and reduced survival time of adults. We then tested whether foliar treatment of pear leaves with erythritol was also lethal to pear psylla. Foliar treatment of erythritol led to reduced 3-d survival of pear psylla nymphs and adults, and reduced rates of oviposition by pear psylla adults. Psylla adults also preferred to settle on untreated leaves than on erythritol-treated leaves in preference assays. Finally, we conducted field experiments to test whether applications of erythritol provided pear trees with protection against pear psylla under natural field conditions. Those experiments showed a reduction in pear psylla nymphs on erythritol-treated trees compared with untreated trees, but only if the erythritol was completely dissolved into solution by heating. Laboratory trials confirmed the importance of heating. Results of our experiments demonstrate that erythritol is insecticidal to pear psylla nymphs and adults and provide the first report that erythritol is lethal to a phloem-feeding insect. These findings suggest that erythritol may provide a new safe and effective tool for the management of pear psylla.

Studies on the seasonal incidence and management of citrus psylla (Diaphorina citriKuwayama) in sweet orange

Field experiment was conducted during 2013 to study the seasonal incidence and efficacy of various insecticides and bio-rationals against citrus psylla in sweet orange. The results revealed that the peak nymphal population of citrus psylla was observed in the month of February-March and August-September and it was low in May-June and December. The reduction in the pest coincided with reduction in new flushes during April to June months and decreased with low temperature in November and December months and increased in temperature from May to June month. Among the different insecticides evaluated against citrus psylla, the treatment with abamectin 1.9 EC @ 0.4 ml/l (0.0007%) was found most effective in recording the least nymphal population of citrus psylla at 3rd, 7th and 14th days after sprays over rest of the treatments. The next best treatment was imidacloprid 17.8 SL @ 0.25 ml/l (0.004%). Dimethoate (0.06%) recorded 18.18, 13.94 and 9.35 population of citrus psylla nymphs at 3rd, 7th and 14th days after sprays whereas bio-rationals i.e. V.lecanii and B.bassiana recorded 33.97, 22.13 ,17.97 and 39.00,33.18,28.32 respectively at 3rd, 7th and 14th days after sprays.

Description of the male of Psyllaephagus euphyllurae (Masi) (Hymenoptera, Encyrtidae), a parasitoid of the olive psylla, Euphyllura olivina (Costa) (Hemiptera, Liviidae), with notes on its reproductive traits and hyperparasitoids

A colony of the encyrtid wasp <em>Psyllaephagus</em> <em>euphyllurae</em> (Masi) (Hymenoptera, Encyrtidae) has been established in the quarantine laboratory at the University of California, Riverside, California, USA as part of a classical biological control program against its invasive host, the olive psylla, <em>Euphyllura</em> <em>olivina</em> (Costa) (Hemiptera, Psylloidea, Liviidae), an important pest of olives in some parts of the world. The colony originators were reared from the same host found on abandoned, commercial olives in Catalonia, Spain; additional collections were made in Murcia. The parasitoid reproduces primarily by thelytoky; however, a few occasional males have been found in the field in Spain, but not in colonies reared under quarantine or laboratory conditions. Here, the female of <em>P</em>. <em>euphyllurae</em> is redescribed and its male is described and illustrated for the first time; the only previous mention of male <em>P</em>. <em>euphyllurae</em> was from Tunisia, reared from the same psyllid host but without any details on its morphology. A lectotype is designated for <em>Encyrtus</em> <em>euphyllurae</em> Masi. Information is given on the results of genetic matching between the two sexes of the parasitoid and also on the presence of the bacterial <em>Wolbachia</em> symbiont that apparently is affecting reproduction of this species, including its sex ratio in the field. Two species of hyperparasitoids have also emerged from the parasitized olive psylla nymphs from Catalonia: numerous specimens of <em>Apocharips</em> <em>trapezoidea</em> (Hartig) (Hymenoptera, Figitidae) and one specimen of a <em>Pachyneuron</em> sp. (Hymenoptera, Pteromalidae).

The influences of plant resistance on predation rate of Anthocoris nemoralis (Fabricius) on Cacopsylla pyricola (Förster)

Anthocoris nemoralis (Fabricius) (Hemiptera: Anthocoridae) is an important predatory insect in pear orchards and is considered as a biological control agent against the pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae). In order to investigate the effects of plant resistance on predation of C. pyricola by A. nemoralis, consumption rate of both the sexes of A. nemoralis on pear psylla nymphs was studied on three pear varieties including, “Shahmivea”, as a susceptible host plant, and “Siberi” and “Coscia”, as partially resistant host plants. Different densities of C. pyricola nymphs were offered to single A. nemoralis and predation proceeded for 24 h. The experiments were carried out under constant environmental conditions (27 ± 1 °C, 70 ± 5% RH and L:D 16:8 h). The results showed that the effect of variety on the consumption rate of A. nemoralis female was significant and most consumption happened on Shahmivea. However, different results were found when the male predator was examined. The findings have been discussed in relation with combining the predator and pear varieties for pear psylla management in a multitrophic context.

Population Dynamics and Feeding Potential of Cheilomenes sexmaculata (F.) (Coleoptera: Coccinellidae) on Certain Citrus Insect Pests

A study was carried out on the population dynamics and predatory potential of Cheilomenes sexmaculata (F.) on various citrus insect pests at National Research Centre for Citrus, Nagpur, during 2006-10. Visual observation of 3-5 minutes/tree during 2006-08 showed that the population of C. sexmaculata was significicantly higher in February (3.5/tree) and January (2.8/tree) than other month. The population of C. sexmaculata was significantly negatively correlated with wind velocity. Predatory potential studies revealed that each larva of C. sexmaculata consumed a total of 186.1 blackfly (Aleurocanthus woglumi Ashby) nymphs; 208.9 psylla (Diaphosis citri Kuwayama) nymphs and 252.8 aphids (Aphis spiraecola Patch) during 2008; a total of 189.0 blackfly nymphs/206.7. citri nymphs and 242.0 aphids during 2009 and a total of 184.8 A. nymphs/ 198.5 psylla nymphs and 260.2 aphids during 2010. Similarly, each adult of C. sexmaculata consumed a total of 540.5 blackfly nymphs: 660.2 psylla nymphs; 720.6 aphids and 210.3 leaf miner (Phyllocnistis citrella Stainton) pupae during 2008; a total of 538.3 blackfly nymphs, 651.8 psylla nymphs, 708.4 aphids and 216.1 leaf miner pupae during 2009 and a total of 519.5 blackfly numphs, 634.1 psylla nymphs, 695.7 aphids and 201.2 leaf miner pupae during preference of C. sexmaculata larvae and adults to A. spiraecola to other insect pests.

Evaluation of Effects of Two Spring Applications of Micronutrients on the Population Density of Common Pistachio Psylla (Agonoscena Pistaciae) in Pistachio Orchards

The common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Aphalaridae) is one of the most detrimental pests to pistachio trees. This pest is distributed throughout all the pistachio producing regions of Iran. Nowadays vari- ous pesticides are used to control the common pistachio psylla, but extensive pesticide spraying against this pest over a period of several years has overpowered its natural enemies. Moreover, the overlapping of generations has resulted in an abundant presence of the pest. Many herbivorous insects can make qualitative distinctions between host plants, they can feed and oviposit preferentially on higher quality plants. Cultural methods such as crop fertilization can affect the susceptibility of plants to insect pests by altering a plant tissue's nutrient level. This study tested nitrogen (N), calcium (Ca) and zinc (Zn) fertilizers on A. pistaciae in pistachio orchards. The experiment was based on complete randomized blocks with three replications and nine treatments including once-applied Zn, Ca, N, NCa, ZnCa, ZnN, ZnCaN, pesticide (amitraz) and a control (distilled water), on common pistachio psylla fed on 20-year-old pistachio trees of Ahmadaghaei rootstock. The results demonstrated that the effect of nutritional solutions on nymph and egg popula- tions showed a significant difference at a 5% level. The highest measure of control on eggs was related to amitraz, ZnCa and Zn while the least was related to NZn. The results also showed that the highest measure of pest control was related to Ca while the least was related to N and Zn. The results indicated that combinations of the elements mentioned had a stronger reducing effect on the concen- tration of pistachio psylla nymphs than the effect pesticide had.

Impact of kaolin particle film, spirodiclofen acaricide, harpin protein, and an organic biostimulant on pear psylla Cacopsylla pyri (Hemiptera: Psyllidae)

Pear psylla Cacopsylla pyri (L.) is among the most serious pests in pear orchards. Field studies were conducted in 2005 and 2006 on pear trees (Pyrus communis L.) to assess the effect of kaolin-based particle film, spirodiclofen acaricide, harpin protein, and an organic biostimulant on C. pyri infestations. Pear psylla nymph densities were effectively suppressed over the entire season by kaolin particle film and spirodiclofen treatments compared with the untreated control. Harpin protein protected pear trees almost as well as the spirodiclofen acaricide, while the organic biostimulant provided no protection. Kaolin particle film, spirodiclofen, and harpin protein-sprayed pear trees significantly outperformed their unsprayed counterparts in terms of fruit load. Based on the results of this study, it seems that kaolin particle film, spirodiclofen, and harpin protein could be used as alternatives to broad-spectrum insecticides for suppressing pear psylla infestations.

Economic Injury Level of the Psyllid,Agonoscena pistaciae, on Pistachio,Pistacia veracv. Ohadi

The pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psyllidae) is a major pest of pistachio trees, Pistacia vera L. (Sapindalis: Anacardiaceae) throughout pistachio-producing regions in Iran. Different density levels of A. pistaciae nymphs were maintained on pistachio trees by different insecticide dosages to evaluate the relationship between nymph density and yield loss (weight of 1000 nuts). Psylla nymph densities were monitored weekly by counting nymphs on pistachio terminal leaflets. There was a significant reduction in weight of 1000 nuts as seasonal averages of nymphs increased. Regression analysis was used to determine the relationship between nymph density and weight of 1000 nuts. The economic injury levels varied as a function of market values, management costs, insecticide efficiency and yield loss rate and ranged from 7.7 to 30.7 nymphal days per terminal leaflet, based on weight of 1000 nuts.

Development of Monoclonal Antibodies to Pear Psylla (Hemiptera: Psyllidae) and Evaluation of Field Predation by Two Key Predators

The pear psylla, Cacopsylla pyricola (Forster) (Hemiptera: Psyllidae), and related psyllids are important pests of pear (Pyrus spp.) worldwide. Many of these pests are thought to be partially controlled by predatory insects. To improve our understanding of the predator species that attack pear psylla, we developed monoclonal antibodies (MAbs) against this pest for predator gut content studies. Mice were immunized with homogenates of nymphal, adult, and egg stages of pear psylla. A mouse immunized with nymph homogenate showed high activity against all three antigen types and was used for MAb development. From 952 hybridomas screened, 35 showed good activity to pear psylla and low activity against nontarget arthropods. Four MAbs were retained: two from immunoglobulin M (IgM)-secreting hybridomas, both with high activity against all stages of psylla except young eggs, and two immunoglobin G-secreting hybridomas, both with high activity against psylla eggs and gravid adult females. Using one of the IgM-MAbs, pear psylla remains were detected in the predatory bugs Anthocoris tomentosus Pericart (Heteroptera: Anthocoridae) and Deraeocoris brevis (Uhler) (Heteroptera: Miridae) in laboratory feeding trials. Digestion half lives typically exceeded 24 h and were dependent on meal size and predator life stage. Gut content analysis of 970 field-collected D. brevis and Anthocoris spp. showed that the proportion which fed on psylla averaged 59% and that percentage closely tracked the density of pear psylla nymphs during three seasons. The utility of these antibodies for the study of trophic interactions and habitat management in relation to biological control of pear psylla is discussed.

Development of Monoclonal Antibodies to Pear Psylla (Hemiptera: Psyllidae) and Evaluation of Field Predation by Two Key Predators

The pear psylla, Cacopsylla pyricola (Forster) (Hemiptera: Psyllidae), and related psyllids are important pests of pear (Pyrus spp.) worldwide. Many of these pests are thought to be partially controlled by predatory insects. To improve our understanding of the predator species that attack pear psylla, we developed monoclonal antibodies (MAbs) against this pest for predator gut content studies. Mice were immunized with homogenates of nymphal, adult, and egg stages of pear psylla. A mouse immunized with nymph homogenate showed high activity against all three antigen types and was used for MAb development. From 952 hybridomas screened, 35 showed good activity to pear psylla and low activity against nontarget arthropods. Four MAbs were retained: two from immunoglobulin M (IgM)-secreting hybridomas, both with high activity against all stages of psylla except young eggs, and two immunoglobin G-secreting hybridomas, both with high activity against psylla eggs and gravid adult females. Using one of the IgM-MAbs, pear psylla remains were detected in the predatory bugs Anthocoris tomentosus Pericart (Heteroptera: Anthocoridae) and Deraeocoris brevis (Uhler) (Heteroptera: Miridae) in laboratory feeding trials. Digestion half lives typically exceeded 24 h and were dependent on meal size and predator life stage. Gut content analysis of 970 field-collected D. brevis and Anthocoris spp. showed that the proportion which fed on psylla averaged 59% and that percentage closely tracked the density of pear psylla nymphs during three seasons. The utility of these antibodies for the study of trophic interactions and habitat management in relation to biological control of pear psylla is discussed.

Fungal pathogens for arthropod pest control in orchard systems: mycoinsecticidal approach for pear psylla control

This paper reviews the research on entomopathogenic fungi in orchard systems and presents research on a mycoinsecticidal approach to an important pest of pear, the pear psylla. The review identifies the host-pathogen relationships that have been examined to date, the microbial formulation and application strategies that have been used, and the results that were obtained. The mycoinsecticides used in the pear psylla research were based on conidia of Beauveria bassiana (ARSEF #2860) and Paecilomyces fumosoroseus (ARSEF #2658). These were formulated into sprayable solutions containing water, 0.1% or 0.5% Ultrafine Sunspray oil (paraffinic oil) in water, or 0.1% acrylic polymer (StressguardTM) in water. Final spray solutions that contained 6 × 106 conidiospores/ml were applied to psylla nymph infested trees at a rate of 5.39 × 1013 conidiospores/ha during the 1993--1995 seasons. In addition, two commercial formulations of B. bassiana, GHA from Mycotech and Naturalis L from Fermone Corp., were mixed in water at the same conidiospore application rates as the other fungal isolates. Single applications of the ARSEF fungal strain/formulation combinations produced psylla nymphal mortalities that ranged from 18.2--37.1%, but the results varied with formulation. Conidia formulated with acrylic polymers in water caused significantly higher mortalities several days earlier than either the water or water and oil combination in 1993. However, no significant differences among pathogen/formulation combinations occurred in 1994 or 1995. The performance of Naturalis L was comparable to the ARSEF fungal strain/formulation combinations with peak nymphal mortalities of 34.1%, while GHA produced a significantly lower peak mortality of only 10.8%. However, because of the low conidiospore concentrations in the Naturalis L formulation, final spray solutions contained nearly 25% of the oil-like carrier. Thus, psylla mortalities may not have been entirely attributed to mycosis. Based on the results from the ARSEF fungal formulations, a mycoinsecticidal approach to pear psylla management could be a useful component in an integrated pest management program for pear.

Activity of Sugar Esters Isolated from Leaf Trichomes of Nicotiana gossei to Pear Psylla (Homoptera: Psyllidae)

Insecticidal activity of a sugar ester fraction isolated from leaf trichomes of wild tobacco, Nicotiana gossei Domin, to egg, nymph, and adult stages of pear psylla, Cacopsylla pyricola Foerster, was determined in replicated laboratory bioassays. Aqueous solutions of sugar ester concentrations ranging from 62 to 1,000 ppm (mg/liter) were applied by an ultra-low-volume spray device to petri dishes containing eggs, nymphs, or adults. Data were recorded on nymphal mortality rates 1, 3, 5, and 7 d after treatment, on the percentage of eggs hatched 7 d after treatment, on the mortality rates of eclosed nymphs 3 dafter eclosion (10 d after treatment), and on adult mortality rates 1 d after treatment. Mortality rates did not differ significantly for sugar ester concentrations of 500 and 1,000 ppm, which both produced a mortality rate of ≥94% for nymphs and adults 1 d after treatment. Lethal concentration values for sugar esters to pear psylla nymphs and adults differed significantly 1 d after treatment for the LC50 (90 versus 200 ppm, respectively), but not for the LC90 (300 versus 400 ppm, respectively). Nymphal mortality rates for each sugar ester concentration did not increase over time significantly 1 d after application, which suggests that the sugar ester is a contact insecticide that is active mainly in the liquid state. The percentage of eggs hatched was not affected by any of the sugar ester treatments 7 d after application. In contrast, the mortality rates of newly eclosed nymphs ranged from 18.7 to 67% for sugar ester concentrations of 62- 1,000 ppm. Our data suggest that both nymphs and adults would be equally controlled with sugar ester concentrations high enough to obtain a mortality rate of >90%. These results will be useful in determining the range of sugar ester concentrations for field trials. In addition, an inexpensive ultra-low-volume spray device used in the bioassays is described that is capable of applying microliter amounts of candidate insecticidal materials to target insects.

Virulence of Fungal Pathogens (Imperfect Fungi: Hyphomycetes) to Pear Psylla (Homoptera: Psyllidae)

Entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metschnikoff) Sorokin, M. flavoviride (Gams & Rozsypal), Paecilomyces fumosoroseus (Wise) Brown & Smith, and Verticillium lecanii (Zimmerman) Viegas were evaluated for pathogenicity and virulence to pear psylla, Cacopsylla pyricola (Foerster), nymphs using a detached-leaf bioassay. Isolates within B. bassiana and P. fumosoroseus were also compared. Conidia suspended in water were applied to first and second instars at various concentrations and evaluated 3, 5, and 7 d after application. All of the fungal isolates tested were pathogenic to pear psylla nymphs. B. bassiana, P. farinosus, and V. lecanii were significantly more virulent than the Metarhizium spp. (mortality range, 92.5–99.6% versus 42.3–54.7%, respectively, on 7 d at 107 conidia/ml). Similarly, the LC50s did not significantly differ for all isolates except the Metarhizium spp. and ranged between 1.4 × 102 – 2.0 × 104 conidia/ml on 7 d. Metarhizium spp. had significantly lower LC50s than the other isolates, that ranged from 2.3 × 107 – 11.7 × 1010 conidia/ml on 7 d. The fastest acting isolate when applied at 107 conidia/ml was P. fumosoroseus ARSEF #2658 with an LC50 of 1.8 d, which was significantly higher than other isolates except B. bassiana. The LC50 could not be calculated for M. anisopliae because percent mortality did not increase with time. Based on LT50, LT50, and percent mortality comparisons, P. fumosoroseus ARSEF #2658 was the most virulent fungal isolate followed by B. bassiana AHSEF #2860. The potential of these isolates as mycoinsecticides for the control of pear psylla nymphs in orchards is discussed.

Side effects of diflubenzuron on a pear psylla predator:Forficula auricularia

A series of laboratory, semi-field and field tests showed the high toxicity of diflubenzuron toForficula auricularia L. nymphs, at concentrations of 15 and 20 g a.i./hl registered in various European countries and the United States to controlCydia pomonella L. Diflubenzuron proved more selective using the 10 g/hl concentration registered in France, but several sublethal effects have been observed: morphological abnormalities, reduced weight increase and mobility. Unexpectedly for a chitin-deposit inhibitor, intake was reduced, which became apparent from the beginning of exposure to the insecticide, before the onset of the moulting process. In the semi-field tests, and despite diflubenzuron's slowing down effect on psylla nymphs, the earwig's reduced predatory activity due to the product resulted in greater growth of the psylla populations than without treatment. The field-test confirmed the efficacy ofF. auricularia as a psylla predator, and the relative selectivity of diflubenzuron at the lowest concentration.

Dispersal within and between citrus orchards and native hosts, and nymphal mortality of citrus psylla, Trioza erytreae (Hemiptera: Triozidae)

Adult citrus psylla populations were monitored in commercial citrus orchards. Most psylla were trapped in the northern and southern edge rows. It is recommended that populations are monitored with one yellow sticky trap placed in the most northern, one in the most southern and one in the central row of citrus orchards. This will provide for standardised and reliable monitoring. There was continuous movement of citrus psylla between unsprayed citrus orchard and adjacent indigenous vegetation, indicating that numbers of citrus psylla may be higher in areas where indigenous host plants grow near citrus. Parasitism of psylla nymphs on indigenous host plants was low during the months June to November when psylla breeding on citrus is at its highest. Therefore, movement of psylla parasitoids from indigenous host plants to citrus seem to be of little value and the removal of indigenous host plants is recommended.

Safer'S Insecticidal Soap for Pear Psylla Control, 1989

Abstract Treatments were applied to adjacent unreplicated rows of 15 trees. Chemical applications were made with a John Bean 400 gal speed sprayer at 300 psi with a delivery rate of 50 gal/acre. Materials were applied to runoff. In both treatments, oil at 1 gal/100, was applied on 25 Apr and 23 May. Polyram 80 WP at 1-1.5 lb/100, was applied on 14 Apr, 25 Apr, 23 May, 5 Jun, 27 Jun, 17 Jul, 24 Jul and 9 Aug. Guthion 35 WP at 0.63 lb/100 was applied at petal fall (23 May). In the standard block, Imidan 50 WP at 1 lb/100 was applied on 5 Jun and 27 Jun for plum curculio control and Mitac 1.5 EC was applied at 1.5 pt/100 on 17 Jul, 24 Jul and 9 Aug for pear psylla control. Safer's Insecticidal Soap at 2 gal/100 was applied to the treatment block on 26 May, 24 Jul, 9 Aug and 22 Aug for psylla control. Early instar and late instar pear psylla nymphs were counted from the first fully expanded leaf from 5 succulent terminals (as available) on 10 trees in each block. At harvest, 300 pears from each treatment were examined for phytotoxicity, and insect and disease damage.

MORTALITY AND DEVELOPMENT OF PEAR PSYLLA NYMPHS ON EAST EUROPEAN PEAR GERMPLASM

Four genotypes of pear (Pyrus spp.) of East European origin, a susceptible control, `Bartlett' (P. communis L.), and a moderately resistant control, NY 10352 (P. ussuriensis Maxim. × P. communis B C1 hybrid), were artificially infested with pear psylla (Cacopsyll a pyricol a Foerster) nymphs in the laboratory. Ten neonate first instars were placed on each of the two youngest leaves of four small trees per genotype. On PI 506381 and PI 506382, wild seedlings of P. nivalis Jacq., all nymphs died within 5 days. Mortality and development of nymphs on PI 502173, a wild P. communis seedling, was similar to that observed on `Bartlett', with 43% and 45% of the nymphs surviving to adulthood, respectively. On `Karamanlika' (PI 502165) and NY 10352, 15% of the nymphs developed into adults. Increased mortality and delayed development of nymphs was associated with feeding inhibition. The mode of host plant resistance to pear psylla nymphs in these accessions of East European pear is, therefore, similar to that previously characterized for NY 10352, in which the resistance is derived from germplasm of East Asian origin.

Feeding, Longevity, and Development of Pear Psylla (Homoptera: Psyllidae) Nymphs on Resistant and Susceptible Pear Genotypes

One-day-old first-instar pear psylla, Cacopsylla pyricola Foerster, were placed on ‘Bartlett’ (susceptible), NY10352 (moderately resistant), and ‘Bradford’ (resistant) pear (Pyrus spp.) genotypes. Psylla nymphs fed and developed readily on ‘Bartlett’ but fed little, developed slowly, and did not reach the fifth stadium on ‘Bradford.’ Psylla feeding on NYI0352 resulted in an extremely extended development time, with very few reaching the adult stage.

Pear, Residual Control of Pear Psylla, 1987

Abstract Mature Bartlett pear trees were sprayed with a handgun operating at 600 psi to evaluate residual life of Abamectin and amitraz for control of pear psylla nymphs. Leaves were collected from trees at intervals after applications. Ten circular disks, 2.2 cm diam, were punched from leaves and floated on wet paper towels in 15-cm plastic Petri dishes for each treatment at each postapplication interval. Ten PP nymphs were transferred to each disk. Petri dishes containing infested leaf disks were held in a growth room at 25°C and 16:8 (L:D) photoperiod. Treatments were evaluated by counting dead and live nymphs after 72 h exposure on the disks. Tests were conducted with leaves collected 1, 3, 7, 10, and 14 days after sprays were applied for the 4 May test but only 1, 7, and 14 days after sprays for the 8 and 29 Jun tests. To test toxicity of growing terminal;- to adult PP, shoots were collected from each treatment and the control 17 days after applications for the 4 May test and 1, 7, and 14 days after sprays foi the 8 and 29 Jun tests. Test shoots were placed upright in sand in clay pots. The pots were placed in a tray containing 2 inches of water to keep shoots turgid. Twenty-five summer-form adult PP were caged on each shoot for 3 to 6 days then surviving adults and eggs were counted. An intense, short rain shower occurred about 30 min after the 8 Jun application.

Pear, Pest Control, 1986

Abstract Mature pear trees were sprayed with handguns operating at 600 psi to evaluate pesticides for control of pear pests. Plots consisted of 5 2-tree replicates in randomized block design. Treatments were applied 4 times during the season, on 11 Apr, 1 May, 4 Jun and 22 Jul. Treatments were evaluated for PP and mite control by counts made at 2-week intervals, but PP populations declined in late Jul so counts made afterwards are not included in tables. Adult PP were counted from a 5 beating-tray sample/rep. Psylla nymphs and mites were counted from a 50-leaf sample/rep. Leaf samples through 27 May were collected from fruiting spurs. Later samples consisted of the proximal, distal and 3 leaves from between on each of 10 growing shoots. Leaves were brushed and resulting slides were examined using a dissecting microscope. PP and PRM russet were rated according to US grade standards for fresh market Bartlett pears on 2 samples of 25 mature fruits/rep. Fruit and foliage were examined after each spray for phytotoxicity.