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Tetramesa romana is a biological control agent of the giant reed, Arundo donax (Poaceae: Arundinoideae), which is an invasive weed in the riparian habitats of the Rio Grande Basin of Texas, the southwestern U.S.A. and northern Mexico. Field evaluations were conducted in the native range of T. romana in Mediterranean Europe and in the introduced ranges of Texas, California, and South Africa to compare densities of the wasp. Population densities and percentage parasitism levels for the 2017 year are compared to meteorological variables (average temperature, precipitation, and heat units). In the introduced ranges of Texas (intentional) and South Africa (adventive) T. romana population densities were 39 and 10-fold higher than in the native range, respectively. Percentage parasitism of T. romana in Texas and in the native range of Thessaloniki, Greece were 2.0% and 34.3%, respectively. Annual heat unit accumulation was 1.3-2.7-fold higher at Texas sites than at other introduced or native sites, and heat units were positively associated with exit hole counts at introduced sites. Annual precipitation was 2-fold higher at Texas and South African sites than in California and the native range sites. Favourable weather conditions and reduced parasitism in Texas along the Rio Grande, as compared to the native range, allows T. romana to reach higher population levels and cause considerable damage to A. donax. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes are a promising alternative for tick control, especially to protect wildlife. Two entomopathogenic nematode species Steinernema riobrave Cabanillas, Poinar, and Raulston and Heterorhabditis floridensis Nguyen, Gozel, Koppenhöfer, and Adams were tested for in-vivo efficacy against southern cattle fever tick, Rhipicephalus (= Boophilus) microplus Canestrini. Twelve heifer calves were experimentally infested three times at 1-week intervals with 125 mg of larvae of southern cattle fever ticks on days 0, 7, and 14. On Day 21, the animals were randomly divided into three treatment groups and sprayed with water only (check) or 5,000 infective juvenile S. riobrave or H. floridensis nematodes per milliliter. Number of ticks dropped, reproductive index, percentage of inhibition of oviposition, and hatching rate were calculated. S. riobrave and H. floridensis affected all life stages of the tick, and caused 14.5 and 25.4% reduction in production of adult engorged female ticks during the first 21 days post treatment. The nematodes significantly affected the reproductive parameters of treated ticks, but not egg hatchability. To our knowledge this is the first study to show a negative impact on ticks by entomopathogenic nematodes applied directly to the mammalian host of the tick. But, additional research is needed to enhance tick control using entomopathogenic nematodes. Novel formulations that enhance penetration or survival by nematodes should be investigated. [ABSTRACT FROM AUTHOR]

The southern cattle fever tick, Rhipicephalus microplus Canestrini, is widely distributed in tropical and subtropical regions, causing huge economic losses to milk and meat production. Application of acaricides is the most widely used control strategy, but because of increasing evidence of resistance to acaricide and environmental concerns, novel strategies are needed. Use of entomopathogenic nematodes is a promising alternative for tick control. Six species of nematodes, Steinernema riobrave Cabanillas, Poinar, and Raulston (355 strain), S. carpocapsae (Weiser) (All strain), S. feltiae Filipjev (SN strain), Heterorhabditis bacteriophora Poinar (VS strain), H. indica Poinar, Karunakar, and David (HOM1 strain), and H. floridensis Nguyen, Gozel, Koppenhöfer, and Adams (K22 strain) were tested for pathogenicity against R. microplus (Deutch strain). Engorged female ticks were exposed to 1,250, 2,500, and 5,000 infective juvenile nematodes for 24, 48, and 72 hours in Petri dishes, and tick mortality over time, pre-oviposition period, egg mass weight, reproductive index, percentage inhibition of oviposition, and hatching percentage were evaluated. Dose-dependent mortality was recorded in Heterorhabditis species S. riobrave and S. carpocapsae which increased with exposure time. Minimum LC50 (95% CL) values of 1999 (1947-2052) and 69 (63-75) infective juveniles per Petri dish were calculated for S. riobrave and H. floridensis, respectively, at 72 hours of exposure. Infective juvenile concentration and exposure time did not influence the pre-oviposition period. Differences in egg mass weight and reproductive index among the treatments and check group were observed with respect to concentration and exposure time. Reduction in hatchability was recorded only in ticks exposed to S. riobrave. Overall, H. floridensis was the most virulent species against engorged R. microplus females, adversely impacting most biological parameters. S. riobrave showed potential especially because it is native to South Texas and commercially produced. Future studies are warranted to evaluate the potential of this nematode species for biological control of the cattle fever tick under field conditions. [ABSTRACT FROM AUTHOR]

The fundamental host range of the arundo leafminer,Lasioptera donacisa candidate agent for the invasive weed,Arundo donaxwas evaluated.L. donaciscollects and inserts spores of a saprophytic fungus,Arthrinium arundinis, during oviposition. Larvae feed and develop in the decomposing leaf sheath channel tissue. Thirty-six closely related and economic grass species along with several key habitat associates were evaluated in no-choice tests.L. donacisand its associated saprophyte completed development only onA. donax, in concurrence with published reports from its native range in Mediterranean Europe. The arundo leafminer feeding leads to premature defoliation, constituting a different mode of attack on the host plant as compared to two previously released insects, the arundo wasp and arundo scale, which feed on shoot tips and rhizomes, respectively. Defoliation ofA. donaxis expected to increase light penetration into stands ofA. donaxwhich increases visibility for law enforcement, reduces the survival of cattle fever ticks, and enhance recovery of the native riparian vegetation along the Rio Grande and other habitats where this weed is invasive. [ABSTRACT FROM PUBLISHER]

Arundo donax L. (Poaceae) is native to Mediterranean Europe and invasive in the Rio Grande Basin of North America. Rhizomes from nine sites in France and Spain infested with a candidate control agent, the armoured scale Rhizaspidiotus donacis (Hemiptera: Diaspididae) weighed 50% less than those from nine sites without scale. [ABSTRACT FROM AUTHOR]

A box aerial-release system has been developed for the mass release of the arundo wasp, Tetramesa romana Walker, a biological control agent of giant reed, Arundo donax L., an invasive weed of waterways and riparian areas in the southwestern U.S. and Mexico. Because A. donax infests lengthy stretches of remote areas inaccessible by vehicle, an aerial release system may be the best way to disseminate biological control agents. The release system involves a paper box that can be easily loaded with chilled, immobile insects. The box opens upon contact with blades installed on a chute in the floor of an airplane. Preliminary tests in the field demonstrated the effectiveness of this system. All boxes recovered after test releases were successfully opened by the release chutes. Post-release emergence rates of insects were great and insect mortality rates were low, especially at moderate ambient temperatures (20-25°C). The box aerial-release system proves to be an appropriate method for release, especially at the early stages of an inundative biological control program for A. donax. [ABSTRACT FROM AUTHOR]

The armored scale Rhizaspidiotus donacis (Leornardi) was evaluated as a potential biological control agent of the invasive reed grass Arundo donax in North America. No-choice tests, native range field surveys and non-target host exposures were used to determine the fundamental host range of the scale collected from Caloma, Spain and Perpignan, France. Thirty-five species, including two genotypes of A. donax and seven ecotypes of Phragmites australis, along with closely related grasses, economic grasses and habitat associates were tested. In quarantine no-choice testing using releases of 200 crawlers per plant, normal development of R. donacis was observed on A. donax and A. formosana, with very limited survival to the adult stage on Spartina alterniflora and Leptochloa spp. In follow-up studies using 1000 crawlers per plant, 10 live adult females were found on Leptochloa virgata, and one adult female on Spartina alterniflora, but average adult female abundance per plant was (2580%) 26-times lower on L. virgata and over (39,090%) 100-times lower on S. alterniflora than on A. donax. Field surveys were conducted at five locations in Spain and France at which A. donax infested with R. donacis, co-occurred with two non-target species of concern and R. donacis was only found on A. donax. Six-month field host exposures in Spain using potted Leptochloa plants entwined with heavily infested A. donax confirmed that R. donacis is specific to Arundo under field conditions. Based on our results, the scale R. donacis appears to be specific to the genus Arundo and is unlikely to harm native or cultivated plants in the Americas. [ABSTRACT FROM AUTHOR]

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. [ABSTRACT FROM PUBLISHER]

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. [ABSTRACT FROM PUBLISHER]