ALFALFA BLOTCH LEAFMINER, AGROMYZA FRONTELLA (DIPTERA: AGROMYZIDAE), EFFECTS ON ALFALFA IN VERMONT

Abstract

Seven years of field evaluation has shown the alfalfa blotch leafminer, Agromyza frontella (Rondani), to be of minor economic importance in Vermont. Although response to certain insecticidal treatments resulted in highly significant reduction in leaf mining at time of cut, no other differences were shown. Analyses of fiber content as measured by lignin, cell wall constituents, acid detergent fiber, quality as measured by % protein and % digestibility, and yields in dry weight (kg/ha) showed no significant differences. Comparison of leaflet dehiscence from field-cured and baled samples failed to indicate differences between blotched and healthy alfalfa.Two imported parasite species, Chrysocharis punctifacies Delucchi and Dacnusa dryas (Nixon), are established within the state; we predict that these parasites combined with native species will effect a decline in alfalfa blotch leafminer levels below any conceivable economic threshold.

A SEQUENTIAL DECISION PLAN FOR MANAGEMENT OF THE ALFALFA BLOTCH LEAFMINER, AGROMYZA FRONTELLA (DIPTERA: AGROMYZIDAE)

“…There is a considerable degree of uncertainty about the status of the leafminer as an economic pest in the northeastern United States, and direct comparison of reported data on damage threshold has been hampered by differences in experimental design (Byers 1977;Hendrickson 1981;MacCollom et al 1982). From these and other reports (e.g.…”

“…It is also apparent that leafminer populations increase with northerly latitude from New England, where mining rates are low (e.g. MacCollom et al 1982), to QuCbec and Ontario, where mining rates of 75 to 80% are commonly reported (Guibord and Letendre 1979;Harcourt and Guppy 1982). As investigations continue, methods of damage assessment will no doubt be standardized and an acceptable economic threshold will be established for the species throughout its range.…”

PERFORMANCE OF THE ALFALFA BLOTCH LEAFMINER, AGROMYZA FRONTELLA (DIPTERA: AGROMYZIDAE), ON FOUR ALFALFA VARIETIES

“…Since its initial introduction into North America in 1968 (Miller and Jensen 1970), the alfalfa blotch leafminer, Agromyza frontella (Rondani), has spread throughout much of north-eastem North America (Andaloro and Peters 1977;Guppy 1981;Thompson 1981), yet its status as an insect pest remains somewhat unclear. Thompson (1981) reported that alfalfa blotch leafminer (ABL) attack resulted in no reduction in dry yield matter in Prince Edward Island, a finding confirmed by MacCollom et al (1982) in Vermont. MacCollom et al (1982) also measured fiber content, cell wall constituents, percent proteins and digestibility and found no significant differences between attacked and control plants.…”

“…This has been confirmed in the case of the spring black stem (Richard and Guibord 1980). Chemical control of this pest has been questioned from an economic standpoint (Thompson 1981;MacCollom et al 1982) and the introduction of European parasites is being used, with quite a degree of success, as an alternate control strategy (Hendrickson and Plummer 1983;Harcourt pers. comm.).…”

Notes on the bionomics of Agromyza nana Meigen (Dipt., Agromyzidae) in Hungary

“…,frontella and supplied data of the foliage consumed by the larvae, of the reproduction of the species, of the longevity of the imagos and on its seasonal history, and also valuable observations were made on the effects of temperature on its development, the rate of development, infestation and survival. MACCOLLOM et al (1982) beside a survey of damage causedreviewed the articles important in the evaluation of the infestation. The present investigations are by no means comparable to those excellent papers on A. frontella but A .…”