Field Persistence of \u3ci\u3eSteinernema Carpocapsa\u3c/i\u3e Weiser (Ny001), \u3ci\u3eSteinernema Feltiae\u3c/i\u3e Filipjev (Valko) and \u3ci\u3eHeterorhabditis Bacteriophora\u3c/i\u3e Poinar (Oswego) in Alfalfa Fields

The long term field persistence of Steinernema carpocapsae Weiser, strain NY001, S. feltiae Filipjev, strain Valko and Heterorhabditis bacteriophora Poinar, strain Oswego was investigated in an alfalfa field infested by the alfalfa snout beetle, Otiorhynchus ligustici L. Nematodes were applied in single-species, two-species and three-species combinations at a total of 2.5 × 109 infective juveniles per hectare. Soil samples were taken approximately every two weeks from mid/late May to late October in 2004 and 2005. Two soil samplings were conducted in 2006 at the end of May and in early July. All nematodes persisted in the field at the time of the last sampling in July 2006, over two years after application suggesting long term persistence of these nematodes and the potential to coexist in combinations. Steinernema feltiae Valko was not detected in the three-species combination after June 8, 2005, approximately one year after nematode application suggesting that S. feltiae Valko cannot compete effectively when a specialized ambusher nematode (S. carpocapsae NY001) and a specialized cruiser nematode (H. bacteriophora Oswego) are present simultaneously. In 2006, two years after nematode application, a marked movement of nematodes into experimental plots where they were not applied was observed. S. carpocapsae NY001 was found in the highest number of plots where it wasn’t applied. Given the ambusher behavior of S. carpocapsae NY001, it is suspected that its movement occurred via infected, but still live adult alfalfa snout beetles

Survey for Etomopathogenic Nematodes and Entomopathogenic Fungi in Alfalfa Snout Beetle, \u3ci\u3eOtiorhynchus Ligustici\u3c/i\u3e (L.) (Coleoptera: Curculionidae), Infested Fields in Hungary and in New York State

A survey for etomopathogenic nematodes and fungi in alfalfa snout beetle Otiorhynchus ligustici (L.) infested fields was conducted in Hungary, where this beetle is native, and in New York State, where the alfalfa snout beetle is an invasive species. Soil samples were collected in Hungary and in New York in alfalfa snout beetle infested alfalfa fields in spring 2002. Galleria mellonella (L.) larvae were used as bait insects. The entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae were found in Hungary and New York. The frequency of plots with entomopathogenic fungi was not significantly different between locations in Hungary and New York. The entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis sp. were found in Hungary and New York and S. feltiae was only found in Hungary. The frequency of plots with entomopathogenic nematodes was not significantly different between locations in Hungary and New York. S. carpocapsae and S. feltiae were found in coexistence at one location in Hungary

Comparative Study of \u3ci\u3eMecinus Janthiniformis\u3c/i\u3e (Coleoptera: Curculionidae) Attack and Simulated Mowing for Control of \u3ci\u3eLinaria Dalmatica\u3c/i\u3e Spp. \u3ci\u3eDalmatica\u3c/i\u3e (Plantaginaceae)

Dalmatian toadflax, Linaria dalmatica spp. dalmatica (L.) Mill. (Plantaginaceae) has invaded over one million hectares in the western United States and Canada, in habitats similar to its native range. Two field studies were conducted to examine the impact of simulated mowing or insect herbivory on L. dalmatica growth and reproduction. Simulated mowing over the duration of the study decreased L. dalmatica total biomass per square meter, significantly reduced the total number of fruits and flowers per square meter, and resulted in significantly shorter flowering stems in the simulated mowing plots than in their controls. Plants in plots attacked by Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae) had significantly less biomass per square meter, significantly fewer total numbers of fruits and flowers per square meter, and significantly fewer reproductive structures per stem than plants in paired control plots over the duration of the study. Specifically, both management tactics resulted in a negative impact on this invasive plant. With repeated tissue removal or damage, a reduction in numbers of fruits and flowers per stem on both the stems subjected to simulated mowing and Mecinus-attacked stems relative to their controls suggests that long term stress effects on the plants may be similar. The results of these studies suggest that mowing may warrant further evaluation as a possible method of control in areas where M. janthiniformis release is not effective

Alfalfa Snout Beetle, \u3ci\u3eOtiorhynchus Ligustici\u3c/i\u3e L. (Coleoptera: Curculionidae): Methods for Egg Collection and Larval Rearing

The alfalfa snout beetle, Otiorhynchus ligustici L., is the most serious pest of alfalfa in northern New York State. Recent research efforts focused on the biological control of this insect require the availability of all life stages. With a 2-year lifecycle and a mandatory diapause, the artificial rearing of a laboratory culture appears to be a non-viable option at present, but methods described here can be used to obtain sufficient numbers of eggs and larvae over an extended period of time for research purposes. The crowding of adult beetles in egg production units (cups) had a significant, negative effect on egg production per beetle but the total egg production per cup was still higher with higher number of beetles per cup resulting in a significant saving of labor per egg produced. Larval survival rates in alfalfa-planted cans were surprisingly low given the protected conditions of the greenhouse. The larval survival rates were not significantly different among the dates for the second instar and later instars, suggesting that larval mortality occurs in the first instar in alfalfa-planted cans

Field Persistence of \u3ci\u3eSteinernema Carpocapsa\u3c/i\u3e Weiser (Ny001), \u3ci\u3eSteinernema Feltiae\u3c/i\u3e Filipjev (Valko) and \u3ci\u3eHeterorhabditis Bacteriophora\u3c/i\u3e Poinar (Oswego) in Alfalfa Fields

The long term field persistence of Steinernema carpocapsae Weiser, strain NY001, S. feltiae Filipjev, strain Valko and Heterorhabditis bacteriophora Poinar, strain Oswego was investigated in an alfalfa field infested by the alfalfa snout beetle, Otiorhynchus ligustici L. Nematodes were applied in single-species, two-species and three-species combinations at a total of 2.5 × 109 infective juveniles per hectare. Soil samples were taken approximately every two weeks from mid/late May to late October in 2004 and 2005. Two soil samplings were conducted in 2006 at the end of May and in early July. All nematodes persisted in the field at the time of the last sampling in July 2006, over two years after application suggesting long term persistence of these nematodes and the potential to coexist in combinations. Steinernema feltiae Valko was not detected in the three-species combination after June 8, 2005, approximately one year after nematode application suggesting that S. feltiae Valko cannot compete effectively when a specialized ambusher nematode (S. carpocapsae NY001) and a specialized cruiser nematode (H. bacteriophora Oswego) are present simultaneously. In 2006, two years after nematode application, a marked movement of nematodes into experimental plots where they were not applied was observed. S. carpocapsae NY001 was found in the highest number of plots where it wasn’t applied. Given the ambusher behavior of S. carpocapsae NY001, it is suspected that its movement occurred via infected, but still live adult alfalfa snout beetles

Impact of \u3ci\u3eMecinus Janthinus\u3c/i\u3e (Coleoptera: Curculionidae) on the Growth and Reproduction of \u3ci\u3eLinaria Dalmatica\u3c/i\u3e (Scrophulariaceae)

Dalmatian toadflax, Linaria dalmatica (L.) Mill. (Scrophulariaceae), a native to the eastern Mediterranean and Black Sea regions of Europe and Asia, has invaded over one million hectares in the western United States and Canada, in habitats similar to its native range. Once established, the aggressive vegetative growth of the plant allows it to invade undisturbed habitats where it can out-compete most other vegetation, placing native plant communities at risk. Biological control of L. dalmatica with Mecinus janthinus Thomson (Coleoptera: Curculionidae) has shown promise in the field. In both studies reported in this paper, the presence of insect attack reduced L. dalmatica plant growth and reduced plant reproductive potential. In a field sleeve cage study, insect- attacked stems were significantly shorter (18 cm) and had 50-70% fewer fruits and flowers than the control stems at the end of the study period. M. janthinus attacked stems showed little apical growth, fewer fruits and flowers, and lower stem biomass relative to control stems. Similar results were observed in the potted plant study where the influence of the extensive root system of the plant was eliminated. This negative impact by the insect is caused both by adult feeding in the apical portion of the plant and the physical destruction of the plant stem from larvae feeding. The decrease in the insect-attacked stem heights may also have an impact on seed dispersal from the mature reproductive structures. A combination of decreased seed production through M. janthinus biological control and poor seedling competition in the moisture limited sites common to north-central Washington State and other similarly dry habitats may negatively influence L. dalmatica populations more than general models predict

Multi-year Biological Control of Black Vine Weevil, Otiorhynchus sulcatus, with Persistent Entomopathogenic Nematodes

Abstract: The black vine weevil (BVW), Otiorhynchus sulcatus Fabricius (Coleoptera: Curculionidae), has a worldwide distribution and is a serious pest of many agricultural crops with a host plant species range of 140 plants. Common economic losses occur in small fruits, including strawberries, ornamental and nursery plants, caused primarily by the root feeding larvae resulting in reduced vigor and plant death. The susceptibility of BVW to entomopathogenic nematodes (EPNs) is well established with numerous authors publishing papers using a wide array of EPN species from commercial sources and very high application rates for use as a biopesticide. The concept of using native EPN strains that are climate adapted and retain the genetic traits of phased infectivity to persist across multiple years was successfully developed and tested on a related species, Otiorhynchus ligustici, alfalfa snout beetle. In this study, a single application of climate adapted persistent EPN strains resulted in a reduction of an economically damaging BVW population in strawberries to sub-economic levels. Subsequently, the BVW population remained undetectable for four years while the EPN populations remained moderately high

Comparative Study of \u3ci\u3eMecinus Janthiniformis\u3c/i\u3e (Coleoptera: Curculionidae) Attack and Simulated Mowing for Control of \u3ci\u3eLinaria Dalmatica\u3c/i\u3e Spp. \u3ci\u3eDalmatica\u3c/i\u3e (Plantaginaceae)

Dalmatian toadflax, Linaria dalmatica spp. dalmatica (L.) Mill. (Plantaginaceae) has invaded over one million hectares in the western United States and Canada, in habitats similar to its native range. Two field studies were conducted to examine the impact of simulated mowing or insect herbivory on L. dalmatica growth and reproduction. Simulated mowing over the duration of the study decreased L. dalmatica total biomass per square meter, significantly reduced the total number of fruits and flowers per square meter, and resulted in significantly shorter flowering stems in the simulated mowing plots than in their controls. Plants in plots attacked by Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae) had significantly less biomass per square meter, significantly fewer total numbers of fruits and flowers per square meter, and significantly fewer reproductive structures per stem than plants in paired control plots over the duration of the study. Specifically, both management tactics resulted in a negative impact on this invasive plant. With repeated tissue removal or damage, a reduction in numbers of fruits and flowers per stem on both the stems subjected to simulated mowing and Mecinus-attacked stems relative to their controls suggests that long term stress effects on the plants may be similar. The results of these studies suggest that mowing may warrant further evaluation as a possible method of control in areas where M. janthiniformis release is not effective

Alfalfa Snout Beetle, \u3ci\u3eOtiorhynchus Ligustici\u3c/i\u3e L. (Coleoptera: Curculionidae): Methods for Egg Collection and Larval Rearing

The alfalfa snout beetle, Otiorhynchus ligustici L., is the most serious pest of alfalfa in northern New York State. Recent research efforts focused on the biological control of this insect require the availability of all life stages. With a 2-year lifecycle and a mandatory diapause, the artificial rearing of a laboratory culture appears to be a non-viable option at present, but methods described here can be used to obtain sufficient numbers of eggs and larvae over an extended period of time for research purposes. The crowding of adult beetles in egg production units (cups) had a significant, negative effect on egg production per beetle but the total egg production per cup was still higher with higher number of beetles per cup resulting in a significant saving of labor per egg produced. Larval survival rates in alfalfa-planted cans were surprisingly low given the protected conditions of the greenhouse. The larval survival rates were not significantly different among the dates for the second instar and later instars, suggesting that larval mortality occurs in the first instar in alfalfa-planted cans

Vertical Distribution, Persistence, and Activity of Entomopathogenic Nematodes (Nematoda: Heterorhabditidae and Steinernematidae) in Alfalfa Snout Beetle- (Coleoptera: Curculionidae) Infested Fields

The vertical movement, persistence, and activity of four isolates of entomopathogenic nematodes, Heterorhabditis bacteriophora Poinar (Oswego), Heterorhabditis bacteriophora Poinar (NC), Steinernema carpocapsae (Weiser) (NY001),and an undescribed Steinernema species (NY008-2E), were evaluated for 24 mo at field locations in northern New York. Nematodes were released into three alfalfa fields naturally infested with alfalfa snout beetle, Otiorhynchus ligustici (L.). Each field differed in soil type and soil textural composition: silt loam, sandy loam, and loamy sand. Nematodes were recovered from soil using trap insects, Galleria mellonella larvae, and their vertical distribution was monitored at 5-cm intervals to depths of 20 cm for Steinernena species and 35 cm for Heterorhabditis species. All nematodes persisted (no significant reduction in percentage of infection of G. mellonella) for 6 mo after the initial application in all soil types. However, by the end of the second growing season (17 mo after application), all nematodes showed significant reductions in infection rates of G. mellonella except H. bacteriophora (Oswego) which showed high levels of infection for 24 mo. Nematode vertical movement was affected by soil type and varied by isolate. S. carpocapsae (NY00l)and Steinernema sp. (NY008-2E) remained primarily in soil depths <15 cm, whereas both heterorhabditids dispersed to soil depths of 35 cm. Vertical movement of H. bacteriophera (Oswego) was greatest in loamy sand and vertical movement of Steinernema sp. (NY008-2E) was greatest in sandy loam. Percentage of infection of G. mellonella by H. bacteriophora (Oswego) and S. carpocapsae (NY00l)was significantly correlated with rising soil temperatures in early spring. H. bacteriophora (Oswego) and S. carpocapsae (NYOOl)infected G. mellonella larvae in the field at soil temperatures between 15 and 18°C. Steinernema sp. (NY008-2E)infected G. mellonella larvae in the field at soil temperatures between 13 and 15°