John A. Goolsby

Matching the origin of an invasive weed for selection of a herbivore haplotype for a biological control programme

The Florida Everglades have been invaded by an exotic weed fern, Lygodium microphyllum. Across its native distribution in the Old World tropics from Africa to Australasia it was found to have multiple location‐specific haplotypes. Within this distribution, the climbing fern is attacked by a phytophagous mite, Floracarus perrepae, also with multiple haplotypes. The genetic relationship between mite and fern haplotypes was matched by an overarching geographical relationship between the two. Further, mites that occur in the same location as a particular fern haplotype were better able to utilize the fern than mites from more distant locations. From a biological control context, we are able to show that the weed fern in the Everglades most likely originated in northern Queensland, Australia/Papua New Guinea and that the mite from northern Queensland offers the greatest prospect for control.

Phylogenetic Relationships, Species Limits, and Host Specificity of Gall-Forming Fergusonina Flies (Diptera: Fergusoninidae) Feeding on Melaleuca (Myrtaceae)

Abstract Phylogenetic analysis of recently described gall-forming Fergusonina Malloch flies was performed using DNA sequence data from the mitochondrial cytochrome oxidase I gene. Fifty-three flies reared from nine species of Melaleuca L. were sequenced. Species boundaries delimited by mitochondrial data confirm recent morphological investigation with one exception. Fergusonina turneri Taylor, believed to feed on both Melaleuca quinquenervia (Cav.) S. T. Blake and Melaleuca fluviatilis Barlow, seems to be comprised of two cryptic species, each specialized on one of the two hosts. Because F. turneri is under consideration as a potential biological control agent for invasive M. quinquenervia in the Florida Everglades, understanding cryptic variation and the degree of dietary specialization of this species is critical.

Augmentative biological control of whiteflies using transplants

Field studies showed that transplants can be used to move parasitoids into fields of commercially grown cantaloupe, Cucumis melo (Cucurbitaceae), and augment parasitism of sweet potato whitefly, Bemisia tabaci biotype B (= Bemisia argentifolii) (Homoptera: Aleyrodidae). Methods were developed to inoculate cantaloupe seedlings with newly imported Eretmocerus spp. (Hymenoptera: Aphelinidae), then transfer plants into both organic and conventional fields of cantaloupe in the desert growing region of southeastern California. Several obstacles to inoculating “banker plants” with an adequate number of parasitized whiteflies were overcome and numbers of parasitoids per transplant increased. In 1999 the use of banker plants was compared to a standard hand-release method and a no-release control in a replicated study at an organic farm. Augmentation through releases of parasitoids increased parasitism over that in the no-release controls (p <0.05). Banker plants increased the proportion of parasitized whiteflies more than the hand-release method (0.21 vs. 0.08). During a region-wide demonstration spring 2000, plots receiving banker plants significantly increased parasitism over paired control plots at seven commercial farms of cantaloupe. Parasitism in banker plant treated plots in 2000 was higher in organic fields (seasonal average =0.30) than conventional ones (seasonal average =0.06). Differences may be due to the use of imidacloprid, a systemic insecticide, in conventional fields for whitefly control. Over the 2-year study, however, releases of parasitoids did not consistently reduce densities of B. tabaci. Only in late season at some sites in 2000 were whitefly densities lower in release plots than paired controls. Most of the parasitoids recovered and identified from plots receiving parasitoids were the same as those released, Eretmocerus spp. (ex. Ethiopia M96076), and E. hayati(M95012, ex. Pakistan).

Host range of the European, rhizome-stem feeding scale Rhizaspidiotus donacis (Hemiptera: Diaspididae), a candidate biological control agent for giant reed, Arundo donax (Poales: Poaceae) in North America

Abstract 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.

Biology of the Armored Scale Rhizaspidiotus donacis (Hemiptera: Diaspididae), a Candidate Agent for Biological Control of Giant Reed

ABSTRACT The development, survival, and reproductive output of the armored scale Rhizaspidiotus donacis Leonardi (Hemiptera: Diaspididae) were determined as part of an evaluation of this scale for biological control of giant reed, Arundo donax L. Scale crawlers produced by females collected in southern France and Spain lived for less than two d in the absence of a host. On A. donax shoots held under a diurnally variable temperature regime (15–26°C), crawlers settled on leaf collars and axillary stem bases and completed the first instar within 14 d. Winged adult males emerged within six wk and lived 1.7 d in vials. Immobile adult females were observed 75 d after crawler release. Development time to adult was reduced 15% in males and 28% in females when scales were reared at a constant temperature of 26°C. Survival from crawler to adult was 20–25%. The generation time for laboratoryreared females was 170d and their average life span was 203 d. Females from field collections produced an average of 85 live crawlers, 2.7-fold more than did colony-reared females. Across 31 field collections, female size was correlated to the percentage of scales that were reproductive. However, among eight collections from two Spanish sites, size varied but was not correlated to reproductive success. Peak reproduction from field collections occurred between November and March, and the scale completed two generations per year. Biological information about R. donacis will aid production, release, and field evaluation of this scale for biological control of invasive A. donax in North America.

Pathogenic landscape of transboundary zoonotic diseases in the Mexico-US border along the Rio Grande

Transboundary zoonotic diseases, several of which are vector borne, can maintain a dynamic focus and have pathogens circulating in geographic regions encircling multiple geopolitical boundaries. Global change is intensifying transboundary problems, including the spatial variation of the risk and incidence of zoonotic diseases. The complexity of these challenges can be greater in areas where rivers delineate international boundaries and encompass transitions between ecozones. The Rio Grande serves as a natural border between the US State of Texas and the Mexican States of Chihuahua, Coahuila, Nuevo León, and Tamaulipas. Not only do millions of people live in this transboundary region, but also a substantial amount of goods and people pass through it everyday. Moreover, it occurs over a region that functions as a corridor for animal migrations, and thus links the Neotropic and Nearctic biogeographic zones, with the latter being a known foci of zoonotic diseases. However, the pathogenic landscape of important zoonotic diseases in the south Texas–Mexico transboundary region remains to be fully understood. An international perspective on the interplay between disease systems, ecosystem processes, land use, and human behaviors is applied here to analyze landscape and spatial features of Venezuelan equine encephalitis, Hantavirus disease, Lyme Borreliosis, Leptospirosis, Bartonellosis, Chagas disease, human Babesiosis, and Leishmaniasis. Surveillance systems following the One Health approach with a regional perspective will help identifying opportunities to mitigate the health burden of those diseases on human and animal populations. It is proposed that the Mexico–US border along the Rio Grande region be viewed as a continuum landscape where zoonotic pathogens circulate regardless of national borders.

Development of an Inundative, Aerial Release Technique for the Arundo Wasp 1 , Biological Control Agent of the Invasive Arundo donax L.

Abstract. 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.

The effect of the armored scale, Rhizaspidiotus donacis (Hemiptera: Diaspididae), on shoot growth of the invasive plant Arundo donax (Poaceae: Arundinoideae)

Abstract The effect of feeding by the armored scale, Rhizaspidiotus donacis (Leonardi, 1920) (Hemiptera: Diaspididae) on the growth of the plant Arundo donax L. (Poaceae) was evaluated under field conditions in its native range. The study was designed to evaluate the impact of R. donacis, a candidate agent for biological control of A. donax which is invasive in arid riparian ecosystems of the Southwestern USA and Mexico. The study was carried out at five A. donax sites in the Province of Alicante, Spain, differing in altitude and climate. At each site, 30 infested lateral shoots were selected and 15 were randomly treated monthly with imidacloprid insecticide. Shoot lengths were measured monthly over a 1-year period in a comparative growth analysis. Shoots infested with R. donacis had an over 2-fold reduced growth rate as compared to treated shoots. Growth of shoots varied by site, and the effect of R. donacis on growth was most pronounced in the late spring, when mature females produced first instar scale crawlers. The impact of R. donacis on A. donax growth under field conditions in the native range, combined with its narrow host specificity, indicate that R. donacis is a promising candidate for biological control of A. donax in North America and other areas invaded by this weed.

Austromusotima, a New Musotimine Genus (Lepidoptera: Crambidae) Feeding on Old World Climbing Fern, Lygodium microphyllum (Schizaeaceae)

Abstract During the search for natural enemies of Old World climbing fern, Lygodium microphyllum (Cav.) R. Br. (Schizaeaceae), in Australia and southeastern Asia, Cataclysta camptozonale (Hampson) was found to be highly specific to this aggressive vine and was tested as a biological control agent. This musotimine moth species has long been misplaced in a European acentropine genus; therefore, we propose Austromusotima, new genus, to accommodate Austromusotima camptozonale, new combination, as the type species. The syntype series of Oligostima camptozonale is a mixture of specimens of the former species (sensu stricto) and its sibling, Austromusotima metastictalis (Hampson), new combination. A lectotype is designated for A. camptozonale to stabilize the use of the name. The immature stages of A. camptozonale are described and compared with other known musotimine immatures. The immatures of Eugauria albidenta (Hampson) and Cataclysta angulata Moore are illustrated for the first time. Austromusotima is most closely related to Cataclysta seriopunctalis Hampson based on adult morphological characters, but immatures of C. seriopunctalis are unknown, and therefore, this species is not included in Austromusotima. The important, yet incongruent, results between immature and adult characters are discussed in the context of phylogenetic relationships of Austromusotima to other taxa.

Effect of nitrogen fertilization on growth of Arundo donax and on rearing of a biological control agent, the shoot gall-forming wasp Tetramesa romana

The shoot tip-galling wasp Tetramesa romana Walker (Hymenoptera: Eurytomidae) has been released for biological control of giant reed or arundo (Arundo donax L.) (Poaceae), an invasive grass in the USA and Mexico. The role of urea fertilization to improve plant-based mass-rearing was examined. In a greenhouse study, rhizomes were fertilized with urea pellets at rates equivalent to 1000 kg (low), 2000 kg (moderate), and 4000 (high) kg N per ha–1. Total nitrogen content of ungalled stems was significantly 0.60–0.65% higher under low and moderate fertilization compared to unfertilized pots, and shoot water content was elevated 3–4% at all urea levels. Moderate fertilization significantly (by 1.4-fold) increased the relative growth rate of all shoots in pots, but did not affect final dry biomass. Fertilization did not affect number and duration of probing events by females. The percentage of shoots colonized by wasps that were galled, progeny production per shoot and per female, and emergent wasp size were not affected. However, average generation time (adult to adult) of emergent wasps was 4–5 days shorter on shoots in pots under moderate and high urea fertilization. After a four-week wasp emergence period, only 3–9% of progeny remained in fertilized shoots, while 21% of progeny remained inside unfertilized shoots. In field plots, fertilization did not affect gall density per m shoot length or per female released. Urea fertilization increased the efficiency of greenhouse rearing of the arundo wasp and availability of adults for release, even without direct effects on gall production.