John R. Meyer

Survival and growth of peach trees and pest populations in orchard plots managed with experimental ground covers

Abstract Field experiments conducted in North and South Carolina (USA) demonstrated that survival and growth of peach trees ( Prunus persica (L.) Batsch) as well as the severity of orchard pest populations (arthropods and nematodes) are profoundly affected by the plant species selected for orchard ground cover. Cover crops of brome ( Bromus mollis L.), hard fescue ( Festuca longifolia Thuill.) and rattail fescue ( Vulpia myuros (L.) C. Gmelin) caused high mortality in young peach trees. Bahia-grass ( Paspalum notatum var. sauri Parodi) stunted tree growth, and Korean lespedeza ( Lespedeza stipulacea Maxim.) supported unacceptably large populations of arthropod pests. Nimblewill ( Muhlenbergia schreberi J.F. Gmelin) emerged from these experiments as the most promising candidate for ground cover in commercial peach orchards. This short-statured perennial grass tolerated drought, grew well in partial shade, did not harbor two-spotted spider mites ( Tetranychus urticae Koch) or catfacing insects (Hemiptera), inhibited populations of ring nematodes ( Criconemella xenoplax (Raski) Luc and Raski), and survived winter weather with little injury. Nimblewill successfully crowded out most weed species, but it did not appear to be highly competitive with peach trees for water and nutrients even when growing directly under the tree canopy.

A NEW SPECIES OF ANICETUS (HYMENOPTERA: ENCYRTIDAE) PARASITIZING TERRAPIN SCALE, MESOLECANIUM NIGROFASCIATUM (HEMIPTERA: COCCIDAE)

Anicetus carolinensis Meyer (Hymenoptera: Encyrtidae) is proposed as the name of a new species found parasitizing terrapin scale, Mesolecanium nigrofasciatum (Pergande) (Hemiptera: Coccidae), in North Carolina. Both sexes are described and illustrated together with notes on the life history, host range, and reproductive behavior of the species.

Response of Grape Root Borer (Lepidoptera: Sesiidae) Neonates to Root Extracts from Vitaceae Species and Rootstocks

ABSTRACT Observations at regular intervals of the location of newly hatched grape root borer, Vitacea polistiformis (Harris), larvae moving freely within circular petri dish bioassays were used to measure and compare their response to dry filter paper discs treated with ethanol- or hexane-based extracts of roots from known and potential Vitaceae hosts and a nonhost. Larvae responded most strongly to discs treated with ethanol extracts, suggesting the presence of behaviorally active, polar compounds associated with roots. In single extract bioassays comparing extract versus solvent treated discs, larvae responded positively to ethanol extracts from all Vitis species and rootstocks and Virginia creeper [Parthenocissus quinquefolia (L.) Planch.], but not to apple (Malus domestica Borkh). Paired extract bioassays, in which an extract from the commercially important 3309 rootstock was used as the standard and presented simultaneously with extracts from other root sources, revealed examples of equal, significantly weaker and significantly stronger responses to the 3309 extract. Extracts of the 420 A and V. riparia ‘Gloire’ rootstocks appeared to possess qualities that elicited a consistently greater response than to 3309 extract in these pair-wise comparisons. The active compounds were eluted in ethanol during a 30-min extraction; larvae responded equally to 30- and 60-min 3309 root extracts in paired extract bioassays. Larvae responded equally to extracts of 3309 roots from three spatially separate vineyards in northern Virginia. These results are discussed in relation to the subterranean, plant-insect interactions of grape root borer neonates with the numerous native and non-native Vitis species that may serve as hosts in the eastern United States.

Movement between wild and cultivated blueberry by two species of sharpnosed leafhoppers (Homoptera: Cicadellidae) in North Carolina

Field-collected Scaphytopius spp. adults were marked with fluorescent pigment, released in a cultivated blueberry (Vaccinium corymbosum L.) field and an adjacent wooded site in Bladen Lakes State Forest, NC, and recaptured on yellow sticky traps. Of those S. magdalensis (Provancher) released in the wooded site, 17.3, 27.1 and 43.7% were recaptured in the wooded area during generations I-III, respectively. Of those S. magdalensis released in the cultivated field, recapture in the same field was 11.5 and 27.9% during the first two generations, but only 1.5% at the beginning of the 3rd generation. Adults apparently moved out of the wild habitat during the 1st generation and out of cultivated fields during the 3rd. This movement pattern was not found in S. verecundus (Van Duzee). First-generation S. magdalensis should be controlled during their flight into cultivated fields.

Effect of Dormant Oil Treatments on White Peach Scale (Homoptera: Diaspididae) and its Overwintering Parasite Complex

The effect of dormant oil treatments on the overwintering parasite complex of white peach scale, Pseudaulacaspis pentagona (Targioni-Tozzetti) was evaluated in a peach orchard in the southern coastal plain of North Carolina in 1988 and 1989. Oil treatments resulted in significant reductions in the emergence of adult hymenopteran parasites in both years. However, mortality was not complete, and a sufficient number of parasites survived to repopulate the orchard in spring.

Abiotic factors affecting flight activity of the sharpnodes leafhopper, Scaphytopius magdalensis (Provancher) (Homoptera: Cicadellidae)

Abiotic factors that significantly influence catch of Scaphytopius magdalensis on sticky traps were identified for each leafhopper generation in North Carolina. Regression models were generated to ...

Seasonal dispersal and host preference by adult sharpnosed leafhoppers (Homoptera: Cicadellidae) in North Carolina woodlands

Scaphytopius spp. were sweep-sampled weekly from 20 April to 20 November 1984 in creeping blueberry, Vaccinium crassifolium Andrews, near a commercial blueberry field in North Carolina to establish migration patterns. Population growth curves of adults were compared to those of 5th-instar nymphs. Differences in curve patterns indicated adult dispersal from creeping blueberry during the first two generations and return in the 3rd generation. Adults were sampled in wild highbush blueberry, V. corymbosum L.; sheepkill, Kalmia angustifolic (Small); huckleberry, Gaylussacia frondosa (L.) Torrey & Gray; and creeping blueberry to determine inter-host dispersal and host preference. Analysis of variance on numbers of captured males showed significant differences between host species for S. magdalensis (Provancher), but none for S. verecundus (Van Duzee). The former species preferred sheepkill, highbush blueberry and huckleberry, while the latter was uniformly distributed among all four host species. It was recomme...

VARIABILITY OF GAS CHROMATOGRAPHIC AND MANOMETRIC MEASUREMENTS OF CARBON DIOXIDE PRODUCTION AND OXYGEN CONSUMPTION IN THE PLUM CURCULIO, CONOTRACHELUS NENUPHAR (HERBST)

A gas chromatographic technique for measurement of CO2 production in arthropods is described and used to characterize changes in CO2 production as diapause approaches in plum curculio. Carbon dioxide production was statistically compared to oxygen consumption (as measured by a constant pressure respirometer); variance was less for CO2 production, but both assays found significant differences between long-day and short-day plum curculio. Dry weight was not correlated with either CO2 production or O2 consumption. Carbon dioxide production and O2 consumption were positively correlated.