Agromyza Frontella Research Articles

Size influences male mating success in the alfalfa blotch leafminer (Diptera: Agromyzidae)

Male size is an important parameter in mate choice for many species and has been associated with such female life-history parameters as increased fecundity or fertility and larger progeny (Phelan and Baker 1986; Savalli and Fox 1998, 1999; Brown 1999). In the alfalfa blotch leafminer, Agromyza frontella (Rondani), intraspecific larval competition may significantly influence the size of both males and females (Quiring and McNeil 1984a). The influence of female size on female reproductive success has been studied (Quiring and McNeil 1984b, 1984c), but to date, no attention has been given to the possible effects of male size. The objectives of this study were to determine if differences in male size, the result of intraspecific larval competition, affected male longevity and reproductive success, as well as various parameters of female reproduction.

Stereoselective syntheses of isomers of 3,7-dimethylnonadecane, a sex pheromone of the alfalfa blotch leafminer (Agromyza frontella (Rondani))

Two related stereoselective syntheses of 3,7-dimethylnonadecane, a sex pheromone of the alfalfa leafminer, are described to show that pulegone can serve as a useful starting material for the preparation of chiral aliphatic isoprenoid compounds. The schemes are designed to place the stereogenic center of pulegone at C.3 in one synthesis and at C.7 in the other so that the optical properties of the products can be compared with one another and with the values calculated using Brewster's rules. Key words: chiral hydrocarbons, stereoselective synthesis, pheromone, Agromyza frontella.

Pheromone synthesis, CXXV. Synthesis of the four possible stereoisomers of 3,7‐dimethylnonadecane, the female sex pheromone of Agromyza frontella Rondani

AbstractThe synthesis of the four possible stereoisomers of 3,7‐dimethylnonadecane (1) has been achieved by starting from the enantiomers of methyl 3‐hydroxy‐2‐methylpropanoate (2) and (R)‐(+)‐citronellic acid (3).

Encapsulation of Eggs and Larvae of Dacnusa dryas (Hymenoptera: Braconidae) by the Alfalfa Blotch Leafminer (Diptera: Agromyzidae) and its Importance in Host-Parasite Coexistence

Eggs and larvae of the braconid parasite, Dacnusa dryas (Nixon), were encapsulated by third instars of the alfalfa blotch leafminer, Agromyza frontella (Rondani). Capsule formation was followed by death of the parasites and melanization and size reduction of the cadaver. The incidence of encapsulation of solitary parasites was consistently low, decreasing the effective rate of parasitism by an average of 10%. Supernumeraries were encapsulated without exceptions. The importance of encapsulation to the stability of the host-parasite association is discussed.

Effect of age and mating status on the mating behaviour and pheromone titre in alfalfa blotch leafminer females Agromyza frontella (Diptera: Agromyzidae)

The receptivity of 1- to 7-day-old virgin Agromyza frontella (Rondani) females did not change with age. In bioassays the cadavers of newly-emerged virgins (< 1 day old) elicited less courtship from males than those of older virgin females, but no differences were noted between cadavers of 1- to 6-day-old virgins. Females mated on the day of emergence and showed behavioural changes that reduced further encounters with males, although about 50% subsequently mated a second time. In bioassays, males in the presence of cadavers of mated females exhibited less mating behaviour than when presented cadavers of similar-aged virgins. The levels of 3,7-dimethylnonadecane, the female sex pheromone, increased with age in virgin females, but following mating the titre decreased and remained low for the remainder of the female's life. The apparent discrepancy between certain bioassay results and the observed pheromone titres are discussed within the context of available information on semiochemically-mating in Diptera.

NOTE ONCYRTOGASTER VULGARISWALKER (HYMENOPTERA: PTEROMALIDAE), A SECONDARY PARASITE OF THE ALFALFA BLOTCH LEAFMINER (DIPTERA: AGROMYZIDAE), WITH DESCRIPTIONS OF THE IMMATURE STAGES

AbstractCyrtogaster vulgarisWalker, a pupal parasite of the alfalfa blotch leafminer,Agromyza frontella(Rondani), acts as a secondary agent as well. The adults, which deposit their eggs within host puparia, apparently do not discriminate between healthy leafminers and those parasitized byDacnusa dryas(Nixon). The egg and larval cephalic structures ofC.vulgarisare described and illustrated and the final-instar larval skins of the two parasite species are compared.

AN INTRASPECIFIC COMPETITION MODEL FOR THE LEAFMINER, AGROMYZA FRONTELLA (RONDANI)

AbstractA mathematical model was constructed to simulate the effect of intraspecific larval competition on the survival of Agromyza frontella (Rondani). It was shown that the probabilities of cannibalism and starvation can be expressed as functions of larval density and food availability (leaflet surface area), and that expected pupal weights can be determined from the amount of food available to the third-instar larva. Predictions were compared with data from laboratory experiments and field samples with excellent results.

Observations on the mating behavior of the alfalfa blotch leafminer,Agromyza frontella (Rondani) (Diptera: Agromyzidae), and evidence of a female sex pheromone

The mating behavior of Agromyza frontella was studied under laboratory conditions. Adults were able to mate on the day of emergence, with no evident periodicity throughout the photophase. The host plant was essential for mating to occur, its presence affecting female receptivity rather than male copulatory behavior. Males generally entered a stationary phase once in the proximity of a female, before undertaking a final approach. This stationary behavior frequently resulted in male aggregations around a female, and under such conditions males exhibited a characteristic wing vibrating behavior. As male wing vibration was not an essential behavior for successful mating, and rarely occurred during male encounters in the absence of females or when only one male was near a female, it was considered as being primarily a male-male signal. The majority of females that mated exhibited an ovipositor pumping behavior that stimulated the male approach. However, such behavior was not essential to attract mates, as dead females elicited the entire sequence of male mating behavior. This suggested the presence of a cuticular sex pheromone, as reported for other species of higher Diptera. Whole virgin female (<24- h or 3- day-old) hexane extracts applied to male cadavers increased the time males spent on the plant, the number of contacts with the treated cadavers, the incidence of attempted copulations, and the wing vibrating behavior between males compared with controls using untreated cadavers. The results obtained indicate that females control copulation in A. frontella and that both semiochemical and visual cues are important in eliciting male mating behavior.

Population Dynamics of the Alfalfa Blotch Leafminer, Agromyza frontella (Diptera: Agromyzidae), in Eastern Ontario: Impact of the Exotic Parasite Dacnusa dryas (Hymenoptera: Braconidae)

Colonization of eastern Ontario by the alfalfa blotch leafminer, Agromyza frontella (Rondani), during the mid-1970s was characterized by a rapid population buildup followed by an equally rapid decline to more tolerable levels. This decline occurred because of maggot mortality within the leaf mines from a combination of intrinsic and extrinsic factors. A gradation to still lower levels resulted from attacks of the introduced exotic parasite Dacnusa dryas (Nixon). Thirty host life tables were derived from population and mortality data collected after establishment of the parasite and were compared to similar data for the period of colonization. Analysis of population change showed that D. dryas has become the principal agent that determines population trends and that maggot mortality is no longer the key factor, primarily because of a diminished level of larval intraspecific competition. D. dryas was released as a single species introduction, and within 3 yr of its establishment, it had caused a 50-fold reduction in numbers of its host. The success of the parasite is attributed to a high dispersal capability, a high degree of host specificity, excellent synchronization with its host, and a rapid rate of acclimation. Since the establishment of the parasite in eastern Ontario, generation survival of the leafminer has fallen by more than two-thirds, and populations have collapsed to subeconomic levels.

SEASONAL DEVELOPMENT, BEHAVIOR, AND HOST SYNCHRONY OF DACNUSA DRYAS (NIXON) (HYMENOPTERA: BRACONIDAE) PARASITIZING THE ALFALFA BLOTCH LEAFMINER, AGROMYZA FRONTELLA (RONDANI) (DIPTERA: AGROMYZIDAE)

AbstractStudies in eastern Ontario showed that the exotic parasite Dacnusa dryas (Nixon) typically has three generations a year that correspond seasonally to those of its host, the alfalfa blotch leafminer, Agromyza frontella (Rondani). The mature larvae of the third generation enter diapause in September and resume development in the spring. The egg – first instar interval, which occurs within the actively feeding leafminer, developed at rates similar to those of the host larva. The remaining two instars and the pupa, which occur within the host puparium, developed at rates similar to those of the host pupa; in the two non-diapausing generations, the durations of these stages decreased with rise in temperature from 13 to 23 °C. Coincidence of wasp flight and hatch of leafminer eggs was high in all three generations. This host–parasite synchrony results mainly from a sequence of three events during their life cycles: lack of development of the parasite beyond the first instar within the host larva, a temperature-dependent rate of development of the subsequent stages which is similar to that of the host pupa, and different overwintering strategies which result in the parasite emerging later than its host to sustain the relationship. Behavior of the parasite is described in relation to host detection, egg deposition, and reproduction.

Daily patterns of abundance and temporal distributions of feeding, mating and oviposition of the dipteran leaf miner, Agromyza frontella

AbstractObservations of adult Agromyza frontella (Rondani) (Diptera: Agromyzidae) in alfalfa, Medicago saliva L. (cv. Saranac), fields in two regions of Quebec, Canada, demonstrated that males were most abundant on alfalfa plants early in the morning and in the late afternoon/early evening, which coincided with the occurrence of bimodal mating activity. Male abundance and incidence of mating were usually negatively correlated with air temperature, solar insolation and wind speed and positively correlated with relative humidity. The daily pattern of female abundance on alfalfa varied less than that of males. Females fed and oviposited throughout the day, and the frequency of these activities were usually positively correlated with air temperature and solar insolation and negatively correlated with relative humidity. Possible reasons for the sexual dimorphism in the daily activity patterns of this leaf miner, and their significance for individual fitness, are discussed.RÉSUMÉPatron d'abondance diurne et distribution temporelle de l'alimentation, l'accouplement et de la ponte d'une mineuse diptère, Agromyza frontella (Diptera).L'observation visuelle des adultes de la mineuse virgule de la luzerne, A. frontella, dans des champs de luzerne de deux regions differentes du Québec, ont démontré que les ma&amp;#x030c;les étaient plus nombreux sur les plantes t&amp;#x006f;&amp;#x030c;t le matin, vers la find de l'après — midi et t&amp;#x006f;&amp;#x030c;t en soirée, ce qui a coincidé avec l'occurence bimodale de l'accouplement. L'abondance diurne des femelles variait moins que celle des ma&amp;#x030c;les et les femelles se nourrissaient activement pendant toute la journée. La fréquence de l'alimentation et de la ponte chez les femelles (les ma&amp;#x030c;les n'étant observé que très rarement en train de se nourrir) étaient corrélées positivement à la température ambiante de l'air de méme qu'à l'insolation mais étaient négativement corrélées à l'humidité relative. Contrairement aux femelles, l'abondance des ma&amp;#x030c;les et l'incidence de l'accouplement étaient habituellement corrélées négativement à la température ambiante de l'air, à l'insolation et à la vitesse du vent alors qu'elles étaient positivement corrélées à l'humidité relative. Plusieurs hypothèses pouvant expliquer le dimorphisme sexuelle des activitées diurnes de cette mineuse ainsi que leurs implications quant à la “fitness”, des individus, sont discutés.

Foraging behavior of a Dipteran leaf miner on exploited and unexploited hosts.

The foraging behavior of females of the leaf miner, Agromyza frontella (Rondani), (Diptera: Agromyzidae) when encountering unexploited or exploited alfalfa plants was studied in large field cages and in laboratory bioassays. Females did not recognize any exploited leaflets before contacting them and did not distinguish between leaflets with an egg or first instar larva and unexploited leaflets, even after contact. Only one fly oviposited in leaflets which contained 80-120 nutrition holes, one late second or third instar larva or which were marked with an epideictic pheromone in field cages. In laboratory bioassays females oviposited less in leaflets containing a second or third instar larva or an empty larval mine than in unexploited ones. Females foraging on unexploited leaflets engaged in area-restricted search and 10 of 11 females remained on the test plant for the full 60 min of observation. However, females foraging on exploited plants were much more active, spent a greater proportion of their time searching for suitable hosts, had the highest rates of visitation to all above ground plant parts and emigrated to the cage walls before 60 min had elapsed. These quantitative measures of foraging behavior indicated that females ranked plants after landing on them in the following order: unexploited plants >plants marked with pheromone or with many nutrition holes >plants with late instar larvae. The order of host ranking by foragers was in general agreement with the suitability of the host plants for larval survival, development and reproduction, as estimated from previous laboratory studies.Females of A. frontella foraging on unexploited alfalfa plants fed and oviposited significantly more often in the upper apical leaflets than in the lower, older leaflets. However, the choice of feeding site by flies on exploited plants did not vary with leaflet position (age), indicating that females fed in order to sample leaflet quality and that females investigated lower (older) leaves after they discovered that the preferred upper leaves were occupied. These data suggest that high quality oviposition sites may be limiting for A. frontella females, which could explain why superparasitism of leaflets sometimes occurs in nature, even when unexploited sites are available.

Potential for Injury to Alfalfa by Alfalfa Blotch Leafminer (Diptera: Agromyzidae): Simulations with a Plant Model

Computer simulation studies reported here examine potential for injury to alfalfa, Medicago sativa L., by Agromyza frontella (Rondani), the alfalfa blotch leafminer (ABL). A validated, physiological model of alfalfa growth, ALSIM 1 (Level 2), was modified to incorporate eight hypothesized mechanisms of injury by ABL. A phenological model forecasting occurrence of damaging stages of ABL was used to time simulated injury under nine weather regimes. Sensitivity of yield, quality (leaf fraction), and end-of-season root reserves to different types and degrees of injury were examined. Leaf mining by third instars had virtually no effect on yield during any harvest period under any weather conditions. Leaf fraction of harvested hay increased slightly. There was essentially no impact on end-of-season root reserves. Model results were insensitive to major qualitative changes in the way larval injury was represented. Simulated pinholing injury by adult female ABL had a greater effect. Greatest reduction in total yield (15%) occurred when pinholing was combined with low rainfall. Pinholing also significantly increased the leaf fraction of harvested hay but had little or no influence on end-of-season root reserves. Sensitivity analyses showed that ALSIM was more responsive to all types of damage during the period of ABL adult activity than during the period of larval mining. The model was most sensitive to changes in rates of photosynthesis and assimilate accumulation, and to a lesser degree to changes in level of soil moisture at which water stress was initiated and rate of evaporation from the canopy. During the period of ABL activity, the model was fairly insensitive to alteration of light absorption by the canopy and insensitive to changes in leaf area index and senescence rate of leaves. Cutting management (scheduling) was examined as a factor influencing simulated impact of ABL on alfalfa. Early harvest most often reduced percentage yield loss caused by ABL and reduced the already small effect of ABL on end-of-season root reserves.

CANOPY PHOTOSYNTHESIS AND DRY MATTER PARTITIONING OF ALFALFA INFESTED BY THE ALFALFA BLOTCH LEAFMINER (Agromyza frontella (Rondani))

The impact of the alfalfa blotch leafminer, Agromyza frontella (Rondani) on alfalfa (Medicago sativa L. ’Saranac’) was evaluated during three growth cycles in 1982 and 1983 when experimental plots were treated with either carbofuran, acephate, or water. No significant differences in forage accumulation, canopy apparent or net photosynthesis were detected between treatments and controls, even though highly significant differences in A. frontella densities were evident. The results are discussed with respect to the questionable pest status of this insect in the alfalfa ecosystem.Key words: Alfalfa, photosynthesis, growth analysis, alfalfa blotch leafminer

LIFE HISTORY AND DESCRIPTION OF THE IMMATURE STAGES OF DACNUSA DRYAS (NIXON) (HYMENOPTERA: BRACONIDAE), A EUROPEAN PARASITE OF THE ALFALFA BLOTCH LEAFMINER (DIPTERA: AGROMYZIDAE) IN EASTERN CANADA

AbstractDacnusa dryas (Nixon), a multivoltine parasite of the alfalfa blotch leafminer, Agromyza frontella (Rondani), has become established in eastern Canada. Adults deposit their eggs singly in the hemocoel of the actively feeding host larvae. A trophamnion forms between the chorion and the embryo and the elliptical egg swells, becoming spherical and transparent. On hatching, the trophamnion adheres to the 1st instar throughout its development. The first moult occurs in the newly formed puparium where development of the parasite is completed. Winter is passed as a mature larva within the soil-borne host. Descriptions of the immature stages are given.

Population Dynamics of Alfalfa Blotch Leafminer, Agromyza frontella (Diptera: Agromyzidae), in Eastern Ontario: Analysis of Numerical Change During the Colonization Phase

Following its invasion of eastern Ontario during the mid-1970's, numbers of the alfalfa blotch leafminer, Agromyza frontella (Rondani), increased rapidly to economic proportions and then receded to near tolerable levels. Thirty-three life tables were compiled from population and mortality data collected during this colonization phase. Analysis of the components of mortality using a variance/covariance matrix of the separate mortalities, as expressed as k values, showed that maggot mortality within leaf mines was the key factor that determined population trends. Maggot mortality was the result of two contemporaneous processes fluctuating with a similar order of magnitude: exploitation and interference competition among instars, and predation by a complex of indigenous nabids and mirids. Although the former process was density dependent, its regulatory potential was damped by the inverse response of the predators, whose activity diminished the competitive interaction. Prepupal mortality was high but relatively invariant. Mortality from other causes was low and contributed little to population trend. Life tables for the larval stage in central Quebec resembled those for Ontario.

BIONOMICS OF THE DAMSEL BUG, NABIS AMERICOFERUS CARAYON (HEMIPTERA: NABIDAE), A PREDATOR OF THE ALFALFA BLOTCH LEAFMINER (DIPTERA: AGROMYZIDAE)

AbstractThe damsel bug, Nobis americoferus Carayon, develops through two generations a year in eastern Ontario. In early fall, females of the second generation develop a reproductive diapause but both sexes continue to feed until freeze-up. Post-diapause development begins in late March. Eggs are deposited singly in plant stems but several may be laid in close proximity. In alfalfa, most eggs were found where stem diameter measured from 0.8 to 1.9 mm but height of oviposition site was not related to length of stem. Females reared at 23°C laid an average of 157 eggs during a 3-week oviposition period. The immature stages of the first generation occurred from mid-April to mid-July and those of the second generation from mid-July to early September. The duration of each stage of N. americoferus, fed pea aphids, Acyrthosiphon pisum (Harr.), and held at four constant temperatures, 18, 23, 28, and 31°C, decreased with increasing temperature. There was a highly correlated linear relationship between rate of development and temperature for all stages. The theoretical temperature threshold for development of eggs was 11.1°C and that for the nymphal stage was 10.6°C; degree-day requirements for these stages were 123.5 and 370.4, respectively. Developmental rate of nymphs varied with host as well as temperature; nymphs fed larvae of the alfalfa blotch leafminer, Agromyza frontella (Rondani), developed significantly faster than those fed pea aphid.

Yield Losses Caused by Alfalfa Blotch Leafminer (Diptera: Agromyzidae)

Yield losses caused by larval feeding of alfalfa blotch leafminer, Agromyza Frontella (Rondani), averaged 7.7% in central New Jersey and southeastern Pennsylvania in second cuttings of alfalfa in 1981 and 1982. Based on pooled data from six fields, the loss was highly significant. An economic injury level of 30 large mines per stem (i.e., mines formed by third [mature] instars), which causes an 11% yield loss, was established.

Analysis of a Successful Classical Biological Control Project: the Alfalfa Blotch Leafminer (Diptera: Agromyzidae) in the Northeastern United States

Control of the alfalfa blotch leafminer, Agromyza frontella (Rondani), in the United States by exotic parasites is an example of classical biological control. This project was analyzed to identify research principles for future projects. Key events that influenced research were 1) identification of the pest; 2) establishment of a specific project without other research objectives; 3) development of recovery techniques; 4) determination that an empty ecological niche existed in the invaded region; and 5) parasite release procedures. Of 14 species introduced, 3 were established: Dacnusa dryas (Nixon) (Braconidae), Chrysocharis punctifacies Delucchi (Eulophidae), and Miscogaster hortensis Walker (Pteromalidae). The effective braconid and eulophid species were r-strategists with some K-oriented characteristics, were multivoltine, utilized alternate hosts, occupied a previously vacant niche in the invaded area, were intrinsically superior competitors and long lived, had high searching capacities, and were from many localities in Europe. Benefit in 1983 was 13 million; research cost was ca. 1 million. Research approaches, parasite selection, life table studies, and role of alternative hosts are considered.

Effect of Larval Cannibalism on the Development and Reproductive Performance of Agromyza frontella (Rondani) (Diptera: Agromyzidae)

In laboratory studies, we investigated the effects of cannibalism by the leafminer, Agromyza frontella (Rondani), of different instars on the subsequent development and reproductive performance of survivors. The treatments were one larva alone (CI), two larvae developing without cannibalism (CII), a first instar cannibalizing another first instar (11), a second instar cannibalizing a first instar (21), a second instar (22), or a third instar (23), and a third instar cannibalizing a second (32). In the 21, 23, and 32 treatments, cannibals completed larval development slightly faster than individuals developing alone in leaflets, although in 32 they suffered higher larval mortality, probably due to wounds incurred during interactions with the larvae they ate. The sex ratio differed between treatments but no consistent effect of cannibalism was observed. Pupal developmental time and the fecundity of mated females did not differ significantly between cannibals and noncannibals. However when cannibals successfully eliminated another larva from their leaflet their pupal weights and overall survival were higher than those of individuals developing two/leaflet without cannibalism, suggesting the most significant effect of cannibalism is to reduce exploitation competition by eliminating a competitor.