Impacts of seasonal kaolin particle films on apple pest management

The impact of multiple applications of the kaolin-based particle film M96-018 on the population density of selected pests of apple, Malus domestica (Borkh) (Rosaceae), and their natural enemy populations were measured in several Washington State orchards from 1997 to 1999. Densities of western tentiform leafminer, Phyllonorycter elmaella (Doganlar and Mutuura) (Lepidoptera: Gracillariidae), were significantly higher and percent parasitism was generally lower in treated plots than in untreated plots. The effect of M96-018 on green aphids (Aphis spp.) (Hemiptera: Aphididae) was variable between orchards; however, populations of rosy apple aphid, Dysaphis plantaginea Passerini (Hemiptera: Aphididae), were higher in treated plots than in untreated plots. M96-018 reduced the mean density of the white apple leafhopper, Typhlocyba pomaria (McAtee) (Hemiptera: Cicadellidae), and the density of spiders (Araneae) compared with untreated plots. Fruit injury by codling moth, Cydia pomonella (L.), and fruittree leafroller, Archips argyrospilus (Walker) (Lepidoptera: Tortricidae), was significantly reduced in the treated plots compared with the untreated plots. The effect of M96-018 on the mullein bug, Campylomma verbasci (Meyer) (Hemiptera: Miridae), was variable between orchards and years. Stink bug (Hemiptera: Pentatomidae) density and related fruit injury were unaffected by M96-018. Fruit infestation by San Jose scale, Quadraspidiotus perniciosus (Comstock) (Hemiptera: Diaspididae), was significantly higher in treated plots than in untreated plots. Discontinuing applications of M96-018 at mid-season reduced the number of aphid-infested leaves and increased fruit injury by leafroller compared with a full-season program. No differences in pest densities occurred in plots treated for one versus two consecutive years; however, the density of phytophagous mites (Acari: Tetranychidae) was significantly higher the subsequent year after plots were treated with M96-018. Further studies are needed to elucidate how these disruptive impacts of particle films can be minimized.

TEMPERATURE-DEPENDENT DEVELOPMENT AND PREDICTION OF HATCH OF OVERWINTERED EGGS OF THE FRUITTREE LEAFROLLER, ARCHIPS ARGYROSPILUS (WALKER) (LEPIDOPTERA: TORTRICIDAE)

Thermal responses and temperature-dependent development of laboratory- and field-overwintered eggs of the fruittree leafroller, Archips argyrospilus (Walker), were described using data from constant-temperature laboratory experiments. The time required for completion of hatch of overwintering eggs declined throughout winter until the end of January, after which increasing exposure to natural or artificial cold conditions had minimal effect on median hatching time. There was little year to year variation in response to cold treatments, and thus it was concluded that diapause is terminated by 1 February. Time to hatch decreased with increasing temperature. Distributions of hatch times were near normal, with mean and median development times similar at any given temperature. Development time (days ± SD) at a mean temperature of 20 °C was similar under constant (10.7 ± 1.1) and fluctuating (9.1 ± 1.4) temperature regimes. A nonlinear, six-parameter, biophysical model, fitted (r2 = 0.99) to median hatching rates at 11 temperatures (0.5–30 °C) indicated development was nonlinear below 10 °C, increased linearly between 10 and 25 °C, was maximal at 27.5 °C, and decreased above 27.5 °C. The lower developmental threshold (± SE), estimated to be 4.95 ± 0.54 °C by linear regression (r2 = 0.98) and the x-intercept method, was used to construct a degree-day (DD) model for predicting egg hatch. Median egg development required 154 DD above 4.95 °C. Observed median egg hatch in two different field sites and years was within ± 3 days of the predicted date, using max–min air temperatures, a base temperature of 5 °C, and a starting date of 1 February for accumulating DD. This model should prove useful for scheduling management actions against fruittree leafroller on apples and pears.

A STRAIN OF FRUITTREE LEAFROLLER, ARCHIPS ARGYROSPILUS (LEPIDOPTERA: TORTRICIDAE), TOLERANT TO AZINPHOS-METHYL IN AN APPLE ORCHARD REGION OF THE OKANAGAN VALLEY OF BRITISH COLUMBIA

Probit analysis of the dosage response of first instar, fruittree leafroller larvae to azinphos-methyl indicated that a strain from a commercial orchard in East Kelowna, B.C. was 7.8 times more tolerant than a susceptible strain. Azinphos-methyl applied to experimental apple blocks in the same area did not provide satisfactory control. Leafroller damage as high as 10.5% was found in several orchards which had received multiple azinphos-methyl and other organophosphorous insecticide treatments. The development of an organophosphorous resistant strain of fruittree leafroller in this orchard area is strongly suggested. Bacillus thuringiensis applied at the pink stage of apple blossom development gave adequate control of fruittree leafroller in East Kelowna field trials and will be suggested as the control material for commercial orchards in this area.

RESPONSE OF FOUR LEAFROLLER SPECIES (LEPIDOPTERA: TORTRICIDAE) TO SEX ATTRACTANTS IN BRITISH COLUMBIA ORCHARDS

The sex pheromones of Archips argyrospilus (Walker), Archips rosanus (L.), Choristoneura rosaceana Harris, and Pandemis limitata Rob. were evaluated in orchards with the objective of developing a method of monitoring leafroller population densities. The sex pheromones were specific for three species but not for C. rosaceana. This leafroller was captured in traps containing A. rosanus sex pheromone more frequently than in traps with its own attractant. The trapping program indicated that C. rosaceana and P. limitata were abundant in the southern fruit growing region of British Columbia and that A. argyrospilus and A. rosanus were the predominant species in the northern region. The traps can be used to identify leafroller species in orchards and to indicate when moths are active which may help in timing control measures.

FIELD EVALUATION OF SYNTHETIC SEX PHEROMONE ATTRACTANTS FOR THE EYE-SPOTTED BUD MOTH (LEPIDOPTERA: OLETHREUTIDAE) AND THREE LEAFROLLER SPECIES (LEPIDOPTERA: TORTRICIDAE)

Synthetic sex pheromones were evaluated in apple orchards against the pests Spilonota ocellana (D. & S.), Archips argyrospilus (Walker), Choristoneura rosaceana (Harris), and Pandemis limitata (Robinson). Significant correlations between spring larval counts and captures of males in summer in pheromone traps occurred only at moderate to high population levels. Correlations between captures of males in summer and fruit damage occurred only with S. ocellana. The attractants for S. ocellana, A. argyrospilus, and C. rosaceana appear satisfactory but that for P. limitata, possibly due to species identification uncertainty and low populations, requires further evaluation.

PEST MANAGEMENT: CONTROL OF ARCHIPS ARGYROSPILUS AND ARCHIPS ROSANUS (LEPIDOPTERA: TORTRICIDAE) ON APPLE

Two leafroller spades are major pests of apple in British Columbia, Archips argyrospilus (Walker) and Archips rosanus (Linnaeus). Field observations showed that both species overwinter in the egg stage and that larval emergence times are similar. Experiments demonstrated that both species are susceptible to sprays of azinphos-methyl, diazinon, or trichlorfon applied at either the pink bud or petal fall stages. Dipel (Bacillus thuringiensis) failed to control larvae of either species.

PEST MANAGEMENT: MONITORING POPULATIONS OF ARCHIPS ARGYROSPILUS AND ARCHIPS ROSANUS (LEPIDOPTERA: TORTRICIDAE) WITH SEX PHEROMONE TRAPS

The sex pheromones of Archips argyrospilus (Walker) and Archips rosanus (L.) were field evaluated to determine if they could be used to monitor populations in orchards where pest management programs were applied. Traps baited with the sex pheromones of A. argyrospilus caught males which reflected population levels estimated by other sample methods. Traps baited with the sex pheromones of A. rosanus caught high numbers of males but the numbers did not correlate with other population estimates. A. rosanus has a wide host range, and trap data indicate that males were attracted from sources outside the monitored orchards. Results indicated that the sex pheromones of A. argyrospilus could be used to estimate populations but with A. rosanus further studies on trap placement are necessary to minimize male influx.

PEST MANAGEMENT: EXPERIENCE IN SIX BRITISH COLUMBIA APPLE ORCHARDS

A 2-year study on management of apple pests was carried out on six orchards in the interior of British Columbia. Sample techniques and treatment thresholds were satisfactory for most pests with the exception of fruittree leafroller, Archips argyrospilus (Walker), western flower thrips, Frankliniella occidentalis (Pergande), and the mirid Campylomma verbasci (Meyer). The number of chemical sprays per orchard averaged eight when the study was initiated. In 1973, the sprays required for pest control were reduced to an average of 5.6 per orchard, and in 1974, this figure was further reduced to 3.1. This reduction in chemical sprays was accomplished without an increase in insect or mite injury to fruit or foliage.