MONITORING POPULATION LEVELS OF EIGHT SPECIES OF NOCTUIDS WITH SEX-ATTRACTANT TRAPS IN SOUTHERN ALBERTA, 1978–1983: SPECIFICITY OF ATTRACTANTS AND EFFECT OF TARGET SPECIES ABUNDANCE

The abundances of eight species of cutworm and armyworm moths were monitored with sex-attractant traps at 81 locations in a 13 000-km2 area of southern Alberta from 1978 to 1983. The life history and economic status of each species is summarized and the monitoring methodology is described. The attractants for redbacked cutworm (Euxoa ochrogaster), darksided cutworm (Euxoa messoria), pale western cutworm (Agrotis orthogonia), and army cutworm (Euxoa auxiliaris) were highly specific and > 99% of the moths caught were of the target species. Specificity of the attractants for clover cutworm (Discestra trifolii) and Leucania commoides was also high, averaging 98.3 and 96.6%, respectively, over 6 years. The attractants for variegated cutworm (Peridroma soucia) and bertha armyworm (Mamestra configurata) were less specific but the proportion of target species exceeded 80% in those years when either species was relatively abundant. For those species that were monitored over a wide range of population levels, the apparent specificity of the attractant varied directly with the number of target species moths caught. The use of efficient attractants in combination with high-capacity nonsaturating traps is clearly of advantage in enhancing specificity.

ACTION OF MOUTHPARTS DURING FEEDING IN THE DARK-SIDED CUTWORM, EUXOA MESSORIA (LEPIDOPTERA: NOCTUIDAE)

Film records of cutworms feeding on cabbage showed that in sampling and continuous feeding, the mandibles, maxillary palps, galeae, labial palps, and labrum contacted the leaf. Sampling involves palpation with the maxillary palps; this is followed by test biting, during which the galeae, labrum, and labial palps make initial contact with the plant. Test biting may be followed by continuous feeding in which all of the mouthparts contact the leaf in characteristic patterns. The actions of the mouthparts are discussed in relation to the function of their chemosensilla.

RESIDUAL TOXICITY OF SIX PYRETHROID AND TWO ORGANOPHOSPHOROUS INSECTICIDES ON SOIL SURFACE AGAINST DARKSIDED CUTWORM (LEPIDOPTERA: NOCTUIDAE) ON TOBACCO IN ONTARIO

Six pyrethroids, cyfluthrin, cypermethrin, deltamethrin, fenvalerate, flucythrinate and permethrin, and two organophosphorous insecticides, acephate and chlorpyrifos, were applied to the soil surface in the greenhouse and field to evaluate their effectiveness and residual toxicity against the darksided cutworm, Euxoa messoria (Harris), in Ontario.Four years of tests indicated that the pyrethroid insecticides were consistently similar in effectiveness and residual toxicity at the rates applied. On air-dry soil surfaces in the greenhouse, the pyrethroids were significantly more toxic and persistent than was chlorpyrifos. On moderately moist soil surfaces in the field, chlorpyrifos was as toxic to the cutworm larvae as were the pyrethroid insecticides, but less persistent. None of the pyrethroids was affected by soil moisture to the same extent as was chlorpyrifos. Acephate-treated soil surfaces, regardless of indoor or outdoor conditions, were less toxic and the toxicity less persistent than with chlorpyrifos-treated soil. Although not statistically different, the high rates of pyrethroids were consistently more toxic and persistent to the cutworm larvae than the low rates of the same materials. All the pyrethroid insecticides have excellent potential as soil treatments for controlling cutworms on tobacco.

FIELD EVALUATION OF BLACKLIGHT AND SEX ATTRACTANT TRAPS FOR MONITORING SEASONAL DISTRIBUTION OF THE DARKSIDED CUTWORM (LEPIDOPTERA: NOCTUIDAE) IN ONTARIO

Field tests were conducted annually near Delhi, Ontario from 1977 to 1981 to evaluate blacklight and sex attractant traps for monitoring adult populations of the darksided cutworm, Euxoa messoria (Harris), in the major tobacco-producing area. There were no significant differences between the catches of sex attractant traps set at 1.0 m and 0.5 m above ground level. Sex attractant traps were superior to blacklight traps for monitoring populations of this pest species. There was a variation in abundance from year to year, but the time of peak occurrence of E. messoria adults was the same in each of the 5 years.

SPATIAL AND TEMPORAL VARIABILITY IN SEX ATTRACTANT TRAP CATCHES OF EUXOA MESSORIA AND E. OCHROGASTER(LEPIDOPTER: NOCTUIDAE) IN RELATION TO THEIR BIOLOGY IN MANITOBA

Tests of intertrap variability in catches of moths of the darksided and redbacked cutworms, Euxoa messoria (Harris) and E. ochrogaster (Guenée), were conducted by placing two traps for each species baited with synthetic sex attractants at 1.6 km (1 mi) intervals to form a grid covering 64 km2 (25 mi2) near Domain, Manitoba. These sex attractants were 93 and 99.6% species specific for E. messoria and E. ochrogaster respectively. Moth catches varied between traps and flights, but the ranking of the traps by catch for each species was consistent during any given flight period. Variability in intertrap catches of E. messoria indicated the moths were not evenly distributed throughout the test area and consequently a sex-attractant trap system with 1.6 km trap spacing is not suitable for monitoring population levels. For E. ochrogaster four traps within an area of 64 km2 would be required to give a population estimate within 20% of the true mean. The flights of E. messoria are not related to degree days and started abruptly and at the same time each year suggesting that development may be synchronized by the summer diapause of the prepupae. The flights of E. ochrogaster were related to degree day accumulations above a threshold temperature of 12.5 °C. Crops had no apparent influence on the distribution of moth catches for either species.