An Assessment Of Tree Banding Techniques To Capture Cankerworm Defoliators Of Elm And Ash Trees In Winnipeg, Manitoba, Canada

Fall cankerworm (Alsophila pometaria L.) and spring cankerworm (Paleacrita vernata Peck) are widely distributed across North America. The larvae feed on the leaves of several species of urban street trees, and repeated severe defoliation can cause a reduction in growth and may contribute to tree mortality. This study examined the effectiveness of Tanglefoot-covered tree bands and the Bug Barrier Tree Band in preventing the upward movement of female cankerworms on the trunk by comparing capture rates of adult moths. There were no significant differences among tree species in the number of A. pometaria adults caught, while P. vernata showed a preference for elm (Ulmus spp.) over ash (Fraxinus spp.). Up to 25% of female moths crossed the Bug Barrier Tree Band, and up to 20% of females crossed the Tanglefoot-covered bands in three experiments in 2002 and 2003. There was no significant difference between the two band types in the proportion of females crossing bands. Larval populations were not large enough to determine the effect of the bands on reducing tree defoliation. The Bug Barrier Tree Band was easier to install and remove than the Tanglefoot-covered bands and required considerably less clean-up afterward.

Evaluation of Asian, European, and North American Elm (Ulmus spp.) Biotypes To Feeding by Spring and Fall Cankerworms

Nearly 40 different Asian elm (Ulmus spp.) biotypes, growing at The Morton Arboretum, Lisle, IL, were evaluated in laboratory bioassays and in the field for suitability and feeding preference of the spring cankerworm Paleacrita vernata (Peck) and the fall cankerworm, Alsophila pometaria (Harris). No-choice and multiple-choice laboratory feeding studies, and field defoliation surveys revealed that U. castaneifolia, U. changii, U. chenmoui, U. davidiana, U. elongata, U. gaussenii, U. glaucescens var. lasiophylla, U. japonica, U. lamellosa, U. lanceaefolia, U. macrocarpa, U. parvifolia, U. propinqua, U. propinqua var. suberosa, U. prunifolia, U. pseudopropinqua, U. taihangshanensis, U. wallichiana, U. wilsoniana, U. wilsoniana-98, and the simple and complex hybrids U. davidiana x U. japonica, U. davidiana x U. propinqua, U. japonica x U. ‘Morton’-Accolade™, U. ‘Morton’-Accolade™ x U. japonicapumila, U. ‘Morton Glossy’-Triumph™, and U. ‘Morton Plainsman’-Vanguard™ x U. davidiana, were less suitable for larval development and pupation and less preferred by spring and fall cankerworm larvae. Ulmus americana, U. glaucescens, U. szechuanica, and the simple and complex hybrids U. davidiana x U. ‘Morton’-Accolade™, U. szechuanica x U. japonica, U. ‘Morton’-Accolade™, U. ‘Morton Red Tip’-Danada Charm™ and U. ‘Morton Plainsman’-Vanguard™ were more suitable for and more preferred by spring and fall cankerworm larvae. Rankings for larval development time were highly correlated with larval longevity, but the proportion of larvae pupating was correlated neither with larval longevity nor with larval development time. Pupal fresh weights also were correlated neither with larval longevity nor with larval development time. Mean fecal pellet weights were correlated with the proportion of larvae pupating, but were not correlated with pupal fresh weights. Ulmus chenmoui, U. glaucescens var. lasiophylla, U. lamellosa, U. macrocarpa, U. propinqua, U. prunifolia, and U. pseudopropinqua all showed medium to heavy leaf pubescence and were less suitable and less preferred by spring and fall cankerworms. Asian elms were least preferred by cankerworm larvae, followed in order of increasing preference by European and North American elms.

OVIPOSITION TRAP TO SAMPLE EGGS OF OPEROPHTERA BRUCEATA (LEPIDOPTERA: GEOMETRIDAE) AND OTHER WINGLESS GEOMETRID SPECIES

For the last 50 years, populations of the Bruce spanworm, Operophtera bruceata Hulst, and other wingless geometrid species have been sampled using sticky bands placed around host-tree trunks to catch wingless females in search of oviposition sites. This method is tedious and, because of trap saturation by males, may underestimate female populations at moderate to high levels. A standard oviposition trap was developed to sample eggs of the Bruce spanworm and other wingless geometrid species. A small polyurethane foam band placed on a post covered by a Multi-Pher® plate detected low populations and was almost unsaturable during outbreaks. Sub-sampling can be easily done in such situations. Egg density on oviposition traps was higher than female density on sticky bands for both the Bruce spanworm and the fall cankerworm, Alsophila pometaria Harris. This suggests that the oviposition trap might be useful to sample other wingless geometrid species. Operating this system was easy and could involve woodlot owners and companies to reduce the traveling costs necessary to collect samples.

Evaluation of Selected Crabapple Cultivars for Insect Resistance

Twenty-four cultivars of Malus spp. were evaluated for resistance to naturally occurring insect pests at replicated plantings in Detroit, Lansing, and Cadillac, Michigan. ‘Adams,’ ‘Candied Apple,’ and ‘Sugar Tyme’ crabapples were the most resistant to defoliation by gypsy moth, fall cankerworm, and eastern tent caterpillar. ‘Sugar Tyme,’ in particular, was almost untouched by gypsy moth or fall cankerworm (less than 1.3% defoliation). These data must be interpreted cautiously, because previous research has shown that gypsy moth larvae are attracted to the largest Malus trees in a planting, regardless of cultivar. Two cultivars, ‘Robinson’ and ‘Red Jewel,’ were highly resistant to rose chafer and apple-and-thom skeletonizer damage. The fact that neither of these were particularly resistant to gypsy moth or cankerworm suggests a different mechanism of resistance for defoliators and skeletonizers.

PARASITOIDS OF A LOOPER COMPLEX (LEPIDOPTERA: GEOMETRIDAE) IN WEST VIRGINIA

From 1981 to 1984, a “looper” complex was responsible for the defoliation of approximately 648 000 ha of hardwood forests in several counties of eastern West Virginia. The complex consisted primarily of four species of Geometridae (Lepidoptera) with larval composition at three study sites in 1983 ranging from 77 to 94% for the half-wing geometer, Phigalia titea (Cramer); 2-13% for the linden looper, Erannis tiliaria (Harris); 8% for Phigalia strigataria (Minot); and 1–2% for the fall cankerworm, Alsophila pometaria (Harris) (Butler 1985a, 1985b, 1986).