Solanum Viarum Dunal Research Articles

Diapause Induction inGratiana boliviana(Coleoptera: Chrysomelidae), a Biological Control Agent of Tropical Soda Apple in Florida

AbstractThe South American leaf-feeding beetle Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) has been released since 2003 in the southeastern United States to control the invasive weed tropical soda apple, Solanum viarum Dunal (Solanaceae). Successful establishment of a biological control agent in temperate and subtropical regions depends on several life-history adaptations, including winter diapause. The timing of diapause allows the syncronization of insect herbivores with the phenology of plants, and field observations in Florida suggested that G. boliviana overwinters as an adult in diapause. The objectives of this study were to describe the diapause of G. boliviana and determine the effect of temperature and photoperiod on diapause induction. Compared with nondiapause adults, diapausing adults were yellow rather than green, had hypertrophied fat bodies, contained little food in the digestive tract, showed negligible ovarian development, and minimal movement of the hind wings when the beetles were placed on their dorsal sides. Although all nondiapause females laid eggs during a 30-d period, only five of 76 diapausing females laid eggs and this occurred only during the first 15 d of the treatment period. Consistent with morphological indicators of diapause, the respiration rate was 2.3 times lower and fat content was 2–3 times greater in diapausing adults compared with nondiapause adults. In a laboratory study, the critical daylength for diapause induction was found to be 12 h:28 min.

Tropical Soda Apple (Solanum viarum) Mediated Competition Via Induced Resistance: Interaction betweenGratiana boliviana, Spodoptera exiguaandFrankliniella occidentalis1

Survival assays were conducted with beet armyworm (BAW), Spodoptera exigua (Hübner), a tortoise beetle, Gratiana bolivana Spaeth, and western flower thrips (WFT), Frankliniella occidentalis (Pergande), on tropical soda apple (TSA), Solanum viarum Dunal, a relative of tomato. Both S. exigua and G. boliviana seem to induce plant defenses in tropical soda apple. Significantly more S. exigua neonate larvae survived to second instar on non-induced plants and artificial diet when compared with plants with induced defenses. Our results further suggest that the induced response in TSA was systemic, since BAW neonates suffered higher mortality in induced plants despite not being in direct contact with the damaged part of the plant. Results suggested that feeding action of G. boliviana on TSA had no significant influence on WFT host choice.

Evaluation of mortality factors using life table analysis of Gratiana boliviana, a biological control agent of tropical soda apple in Florida

Tropical soda apple (TSA), Solanum viarum Dunal (Solanaceae), has invaded many pastures and natural areas in Florida. The biological control agent Gratiana boliviana Spaeth (Coleoptera:Chrysomelidae) is providing adequate control of TSA stands in South and Central Florida. However, poor or no establishment of this agent has occurred in northern Florida. The goal of this study was to examine the mortality factors that influence the population dynamics of G. boliviana in Florida. Horizontal life tables were constructed by following cohorts of individuals in the laboratory and inside closed and open cages at field sites in Central and North Florida. Fertility life table parameters were estimated using laboratory and field data. In addition, as part of a vertical life table analysis, TSA plants were sampled every two weeks in pastures in Central Florida, and counts of all G. boliviana and other herbivores and predators were recorded. Survival to adulthood was similar between Central and North Florida (open cages: 12–19%). Intrinsic mortality (laboratory data) and biotic factors (predation) together accounted for 75% of the mortality of immature stages. Survival of beetles in a natural population determined from vertical life tables was 5%. A complex of three mirid species ( Engytatus modesta Distant, Tupiocoris notatus Distant, and Macrolophus sp.) were the most abundant predators found in the field, and are known to feed on G. boliviana eggs and larvae. Positive growth rates ( r m = 0.3) during the summer and early fall allow the beetle population to increase and provide suppression of TSA in Central Florida.

First Report of Phytophthora infestans Causing Late Blight on Solanum viarum in Colombia.

Solanum viarum Dunal (tropical soda apple) belongs to the section Acanthophora in the genus Solanum, which includes nearly 20 neotropical species of herbs and small shrubs (2). The species in this section are sometimes called the 'spiny Solanums' (2) and are adapted mainly to highly disturbed habitats and open secondary forests. The center of diversity is eastern Brazil (3). Since the early 1990s, S. viarum has been a problematic weed in Florida where it was listed as a noxious weed in 1993, followed in 1994 by its addition to the Federal Noxious Weed List of the USDA. On 17 April 2010, 12 plants of S. viarum located close to a S. betaceum crop (tree tomato) in the province of Caldas (Department of Antioquia, central northwestern Colombia) were found with symptoms similar to late blight caused by Phytophthora infestans on S. tuberosum (potato). Fifteen leaves from 12 plants with blackish, water-soaked lesions showing a white sporulation on the abaxial side were collected and processed within 3 days. The leaves were placed in a humid chamber and incubated in darkness at room temperature (18°C mean temperature) until sporulation was observed. Microscopic characteristics were consistent with Phytophthora spp. Only one axenic culture was obtained by successive subcultures in rye B agar plates. After an incubation period of 8 days, plates were washed with distilled water and ovoid, semipapillate caduceus sporangia ranging from 38 to 41 μm long (average 39; N = 86) and 23 to 29 μm wide (average 26; N = 86) were observed. To fulfill Koch's postulates and test the isolate for the ability to infect potato as well as Solanum spp. associated with potato crops in Colombia, triplicate pathogenicity tests were carried out on three detached leaves of S. viarum, S. tuberosum, and S. americanum (American nightshade). A 1 × 104 sporangia/ml suspension of the Phytophthora isolate, estimated using a haemocytometer, was obtained from 8-day-old cultures grown on rye B agar. The suspension was incubated at 4°C for 2 h to induce zoospore release. The leaves were then inoculated by spraying them until runoff. After an incubation period of 5 days at 18°C in a humidity chamber, mycelia, sporangia, and brownish lesions, similar to those described above, were observed in the leaves of all three hosts, indicating pathogenicity. DNA extraction was performed from the P. infestans isolate (4). Four nuclear loci, ITS, β-tubulin, Ras, and Avr3a, as well as one mitochondrial gene, cytochrome c oxidase 1 (Cox1), were amplified and sequenced. Sequences were compared with GenBank databases using Blastn. In all cases, the best hits corresponded to P. infestans (GenBank Accession No. HQ639930 for Avr3A, HQ639931 for β-tubulin, HQ639932 for Cox1, HQ639933 for iRas, HQ639934 for Ras, and JF419363 for ITS). Reports of P. infestans causing typical late blight symptoms on wild solanaceous plants are becoming more frequent and have been made from other countries such as Peru (1). To our knowledge, this is the first time that P. infestans has been observed and isolated from S. viarum in Colombia, introducing the possibility of this wild solanaceous weed as another late blight host.

Host Specificity ofAnthonomus tenebrosus(Coleoptera: Curculionidae), A Potential Biological Control Agent of Tropical Soda Apple (Solanaceae) in Florida

ABSTRACT Multiple-choice and no-choice tests were conducted at the Florida Department of Agriculture quarantine facility to determine the host specificity of the South American flower bud weevil, Anthonomus tenebrosus Boheman, intended for biological control of the exotic weed tropical soda apple (TSA), Solanum viarum Dunal in Florida, USA. Ninety-one plant species in 21 families were included in multiple-choice feeding and oviposition experiments, including the target weed and the 6 major cultivated Solanaceae: bell pepper (Capsicum annuum L.), chili pepper (C. frutescens L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.), eggplant (Solanum melongena L.), and potato (Solanum tuberosum L.). Plant bouquets with flower-buds of 8 to 10 randomly selected plant species, always including TSA (S. viarum) were exposed to 10–20 A. tenebrosus adults for 1 to 2 weeks. Oviposition and feeding were observed twice a week. No-choice host-specificity tests were also conducted with A. tenebrosus a...

Establishment and Initial Impact of the Leaf-BeetleGratiana boliviana(Chrysomelidae), First Biocontrol Agent Released Against Tropical Soda Apple in Florida

Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae), the first biocontrol agent introduced against tropical soda apple, Solanum viarum Dunal (Solanaceae), was released in Florida in the summer 2003. Post-release evaluations have focused on insect population changes and the impact of insect feeding damage on the plant defoliation and fruit production of the target weed. Gratiana boliviana quickly established in the release sites, and dispersed causing extensive defoliations to tropical soda apple plants and significant reduction of fruit production. Plant defoliation during the first growing season was directly associated with the increase in number of beetles observed on the tropical soda apple plants. Beetles showed a dispersal ability from the release sites of 1.6 km per year. Two years after the beetle release, most of the tropical soda apple plants at the 3-ha release site in Polk County and at the release site in Okeechobee County, Florida have been replaced by other plant species, resulting in improved pastures. No negative non-target effects have been observed, even in plants closely related, such as the non-natives Solanum capsicoides Allioni and Solanum torvum Swartz that were growing in the proximity or mixed with tropical soda apple in the monitored sites.

The effect of Gratiana boliviana (Coleoptera: Chrysomelidae) herbivory on growth and population density of tropical soda apple (Solanum viarum) in Florida

The effect of herbivory by Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) on the invasive, tropical soda apple (TSA) (Solanum viarum Dunal, Solanaceae), was investigated using exclusion methods and by monitoring the density of G. boliviana and the weed at four locations over a period of 40 months. TSA plants protected by insecticide were taller, wider, and had greater canopy cover that unprotected plants, and plants in closed cages were taller and wider than those in open cages. Survival of plants was higher in plots protected with insecticide than in unprotected plots in both years of a 2-year study. In the population dynamics study, the initial density of TSA was 4–5 times higher at one of the locations than at the other three sites, but within 3 years, TSA density at the high density site had declined by 90%. At the three sites which initially had a low abundance of TSA, density remained low throughout the study. The intrinsic rate of increase of G. boliviana varied between –3.9 and 4.5, but over the 3-year study, was not different from zero, indicating a stable population. The intrinsic rate of increase was lower than zero for the period from October to January, and greater than zero during the January to April period. In the periods from April to July and July to October, the rate of increase was not different from zero. The implications of these results for biological control of TSA in Florida are discussed.

Effects of Beetle Density and Time of Day on the Dispersal ofGratiana boliviana(Coleoptera: Chrysomelidae)

The leaf beetle, Gratiana boliviana Spaeth, is a biological control agent of tropical soda apple (Solanum viarum Dunal), a noxious weed invading the rangeland and agricultural fields of Florida and other southeastern states. In caged experiments, we examined the influence of beetle density and the time of day on the dispersal of the leaf beetle. Increasing beetle density from 2 to 100 beetles per plant did not increase G. boliviana dispersal, as long as the host plants were not severely defoliated. An increase in beetle density from 10 to 100 beetles per plant significantly reduced the per capita fecundity from 0.3 to 0.02 eggs over a 24-h period. Thus, a mass rearing method for G. boliviana should consider the potential detrimental effect of increasing density on the fecundity of the leaf beetle. When the dispersal activity of the leaf beetle was observed between 8:00 and 18:00 h, the proportion of beetles dispersing from a given plant increased throughout the morning hours and peaked at noon. A monitoring or sampling program of G. boliviana should be conducted in the early morning or late afternoon when the beetles' tendency to disperse is the lowest in order to more accurately sample for the population density in a certain area. Beetle density and the time of day interacted to influence the proportion of G. boliviana dispersing from a given plant. The proportions of beetles that dispersed were not different among the different time periods at densities of less than 40 beetles per plant. At or above 40 beetles per plant, the proportion of beetles that dispersed peaked at noon. This study suggests that a myriad of factors, including density, feeding damage, photoperiod and host plant quality, interact to determine the dispersal pattern of G. boliviana.

Preferência alimentar de adultos de Metriona elatior Klug (Coleoptera: Chrysomelidae, Cassidinae) por diferentes híbridos de Solanum melogena Linnaeus (Solanaceae)

Metriona elatior Klug is a potential biocontrol agent for Solanum viarum Dunal (tropical soda apple), because larvae and adults feed on its leaves and this species shows a low dispersion rate. Specificity plays a major role in the feasibility of an organism as a biological control agent, especially in the inundative strategy. The feeding preference of M. elatior adults was evaluated to 14 eggplant (Solanum melogena Linnaeus) hybrids. Mass rearing was carried out under lab conditions, with the insect feeding directly on S. viarum leaves. The study started with dual and multiple choice tests in 24 and 48 hour feeding times, by offering leaf disks in Petri dish conditions. Survival and leaf consumption analysis were performed in newly adults in tropical soda apple and eggplant leaves kept turgid by immersing the petioles in water. The leaf area was measured before and after four days of insect exposure. M. elatior showed higher feeding preference, survival and consumption of the weed species, especially in comparison with the hybrid Ryoma. The highest feeding preference among the eggplant hybrids was observed in ‘Minikuro Kowishiki’.

The interactions of tropical soda apple mosaic tobamovirus and Gratiana boliviana (Coleoptera: Chrysomelidae), an introduced biological control agent of tropical soda apple ( Solanum viarum)

Tropical soda apple ( Solanum viarum Dunal (Solanaceae) is a South American invasive plant of rangelands, pastures and natural areas in Florida. A chrysomelid beetle from South America, Gratiana boliviana Spaeth, has been released at >300 locations in Florida for biological control of tropical soda apple since 2003. Tropical soda apple is a host of several plant viruses, including the newly described tropical soda apple mosaic virus (TSAMV). We investigated the influence of TSAMV infection of tropical soda apple plants on developmental time, leaf tissue consumption, longevity, fecundity, and feeding preference of G. boliviana, and also tested transmission of the virus by the beetle. Developmental time was approximately 10% slower, and adults consumed only about 50% as much leaf tissue, for beetles fed on infected plants compared to uninfected plants. Longevity did not differ between females reared on infected and uninfected plants, but females fed on uninfected plants produced 71% more eggs than those fed on infected plants. Adult G. boliviana preferentially fed on uninfected plants when given a choice. There was no evidence of TSAMV transmission by G. boliviana. The potential impacts of TSAMV infection on the effectiveness of G. boliviana as a biological control agent are discussed.

Effects of Temperature on the Development and Survival of Metriona Elatior (Coleoptera: Chrysomelidae) Immatures

The larval developmental rate of the tortoise beetle Metriona elatior Klug (Coleoptera: Chrysomelidae), a potential biocontrol agent of tropical soda apple (TSA) Solanum viarum Dunal (Solanaceae), was studied in the laboratory at 3 constant temperatures (20[degree], 25[degree], and 30[degree]C), photoperiod (14:10 L: D), and relative humidity 60%- 80% in growth chambers. Sixteen neonate larvae were individually reared on excised TSA leaves placed in 0.5-liter transparent-plastic containers for each temperature treatment. Larvae were daily checked to determine the number and duration of larval instars at each of the temperature tested. At 20[degrees] and 25[degree]C, the percent survival from first instar to adult was 75 and 73%, respectively. A constant temperature of 30[degrees]C had a detrimental effect on the larvae and none reached the pupa/adult stages. The general life cycle of this beetle is discussed.

Temperature-dependent development, cold tolerance, and potential distribution of Gratiana boliviana (Coleoptera: Chrysomelidae), a biological control agent of tropical soda apple, Solanum viarum (Solanaceae)

The leaf beetle Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) was introduced from South America into the southeastern United States in 2003 as a classical biological control agent of tropical soda apple, Solanum viarum Dunal (Solanaceae). Temperature-dependent development and survival studies revealed that development was completed at temperatures >16°C and ≤34°C. The number of degree-days required to complete one generation was 341 and the estimated lower developmental threshold was 13.37°C. Using nonlinear regression, the upper lethal threshold was estimated to be 34–35°C. Cold tolerance studies revealed that the lethal time for 90% of adults (LT90) was 12.6 days at 5°C and 8.68 days at 0°C. Based on the developmental and cold tolerance data, a map predicting the areas of establishment and number of generations per year was generated, which suggests that the northern extent of the G. boliviana range in the USA will be near 32–33° north latitude. Fewer generations per year in more northern areas of the southeastern USA may decrease the effectiveness of this biological control agent.

Does Secondary Plant Metabolism Provide a Mechanism for Plant Defenses in the Tropical Soda Apple Solanum Viarum (Solanales: Solanaceae) against Spodoptera exigua and S. eridania (Lepidoptera: Noctuidae)?

Abstract Survival assays were conducted with beet armyworm Spodoptera exigua (Hubner) and southern armyworm S. eridania (Stoll) with tropical soda apple Solanum viarum Dunal, a relative of tomato. In addition, polyphenol oxidase (PPO) enzyme assays were conducted to determine if plant defense compounds are being produced by tropical soda apple in response to herbivory. Both S. exigua and S. eridania induced plant defenses in tropical soda apple. Significantly more S. exigua and S. eridania neonate larvae survived to 2nd instar on non-induced plants and artificial diet when compared with plants with induced defenses. Tropical soda apple plants fed on by S. exigua and S. eridania had significantly increased PPO activity.

Tropical soda apple mosaic virus Identified in Solanum capsicoides in Florida.

Red soda apple (Solanum capsicoides All.), a member of the Solanaceae, is a weed originally from Brazil (3). It is a perennial in southern Florida and is characterized by abundant prickles on stems, petioles, and leaves. Prickles on stems are more dense than those on its larger, noxious weed relative, tropical soda apple (Solanum viarum Dunal), and the mature red soda apple fruits are bright red in contrast to the yellow fruits of tropical soda apple (2). Virus-like foliar symptoms of light and dark green mosaic were observed on the leaves of a red soda apple in a Lee County cow pasture during a tropical soda apple survey during the fall of 2004. The appearance of necrotic local lesions following inoculation of Nicotiana tabacum cv. Xanthi nc with sap from the symptomatic red soda apple leaves suggested the presence of a tobamovirus. Tropical soda apple mosaic virus (TSAMV), a recently described tobamovirus isolated from tropical soda apple in Florida, was specifically identified by a double-antibody sandwich-ELISA (1). An additional six similarly symptomatic red soda apple plants were later collected in the Devils Garden area of Hendry County. Inoculation of N. tabacum cv. Xanthi nc with sap from each of these symptomatic plants also resulted in necrotic local lesions. Sequence analysis of the TSAMV coat protein (CP) gene amplified from total RNA by reverse transcription (RT)-PCR with a mixture of upstream (SolA5'CPv = 5'-GAACTTWCAGAAGMAGTYGTTGATGAGTT-3'; SolB5'CPv = 5'-GAACTCACTGARRMRGTTGTTGAKGAGTT-3') and downstream (SolA3'CPvc = 5'-CCCTTCGATTTAAGTGGAGGGAAAAAC-3'; SolB3'CPvc = 5'-CGTTTMKATTYAAGTGGASGRAHAAMCACT-3') degenerate primers flanking the CP gene of Solanaceae-infecting tobamoviruses confirmed the presence of TSAMV in all plants from both locations. Nucleotide and deduced amino acid sequences of the 483-bp CP gene were both 98 to 99% identical to the original TSAMV CP gene sequences in GenBank (Accession No. AY956381). TSAMV was previously identified in tropical soda apple in these two locations in Lee and Hendry counties and three other areas in Florida (1). Sequence analysis of the RT-PCR products also revealed the presence of Tomato mosaic virus in the plant from Lee County. To our knowledge, this represents the first report of natural TSAMV infection of any host other than tropical soda apple and suggests that TSAMV may be more widely distributed in solanaceous weeds than initially reported.

OPEN FIELD HOST SPECIFICITY TESTS IN BRAZIL FOR RISK ASSESSMENT OF METRIONA ELATIOR (COLEOPTERA: CHRYSOMELIDAE), A POTENTIAL BIOLOGICAL CONTROL AGENT OF SOLANUM VIARUM (SOLANACEAE) IN FLORIDA

Open field experiments were conducted in Brazil to assess the suitability of the South American leaf feeding beetle Metriona elatior Klug for biological control of tropical soda apple, Solanum viarum Dunal in the USA. A multiple choice open field test with eggplant (Solanum melongena L.), bell-pepper (Capsicum annuum L.), potato (Solanum tuberosum L.), tomato (Lycopersicon esculentum Mill.), giló (Solanum gilo Raddi), falsa-jurubeba (Solanum fastigiatum Willd.), and the target weed Solanum viarum, was conducted at the Universidade Federal do Paraná Experimental Station in Curitiba. A second multiple choice-test was conducted 2 years later at the same location excluding the target weed and exposing M. elatior adults to S. melongena, S. tuberosum, L. scullentum, and C. annuum. An S. viarum control plot was established 60 km from the choice-test field. In total, 276 teneral adult beetles were released in the first multiple choice-test. In the second test, 176 beetles were released in the choice-test plot that excluded S. viarum, and 172 adult beetles were released in the S. viarum control plot at different developmental stages of the tested plants. All the plants in each plot were visually checked once a week and the number of adults, immatures, and eggs recorded. Results in the first multiple choice-test showed a complete rejection of the crop plants by M. elatior. Minor feeding (<3%) was observed on eggplant in the second experiment in which S. viarum was excluded from the crop plots, but all M. elatior larvae died in less than a week. The tests were ended when the plants started to senesce. The results of these open field tests corroborate previous quarantine/laboratory host specificity tests indicating that host range expansion of M. elatior to include the solanaceous crops tested is highly unlikely. A petition to release M. elatior in the USA was submitted to the TAG committee in September 2006.

Bidens mottle virus Identified in Tropical Soda Apple in Florida.

Tropical soda apple (TSA) (Solanum viarum Dunal), a plant native to South America, was first identified in Florida in 1988 (4). It rapidly became a noxious weed in pastures throughout the state and it is known to be a reservoir for Cucumber mosaic virus, Potato leafroll virus, Potato virus Y (PVY), Tobacco etch virus (TEV), Tomato mosaic virus, and Tomato mottle virus, viruses that infect important vegetable crops in Florida (3). During a routine survey of Florida weeds during May of 2004, a TSA plant with chlorotic, young leaves found near Okeechobee, FL was determined to be infected with a potyvirus by using a commercially available enzyme linked immunosorbent assay kit (Agdia, Elkhart, IN). The results of a host range study indicated this potyvirus was neither PVY nor TEV. The virus caused local lesions in Chenopodium amaranticolor and systemic symptoms in C quinoa, Coreopsis sp. (C. A. Baker, unpublished), Helianthus annus, Nicotiana benthamiana, Petunia × hybrida, Verbena hybrida, and Zinnia elegans. It did not infect Gomphrena globosa, N. glutinosa, Pisum sativum, or Phaseolus vulgaris (1). Cylindrical inclusions consistent with those observed in plants infected with Bidens mottle virus (BiMoV) were observed in Z. elegans. Immunodiffusion tests with antiserum to BiMoV (Department of Plant Pathology, University of Florida) gave a reaction of identity with leaf extracts of the symptomatic zinnia, a known sample of BiMoV originally isolated from Bidens pilosa and a recent isolate of BiMoV from lettuce in Belle Glade, FL (C. A. Baker and R. Raid, unpublished). A partial polyprotein gene fragment (GenBank Accession No. EF467235) was amplified from total RNA of an inoculated C. quinoa plant by reverse transcription (RT)-PCR with previously described degenerate potyvirus primers (2). Analysis of the RT-PCR product sequence confirmed the host range results and indicated that the potyvirus infecting TSA was neither PVY nor TEV. However, the nucleotide and deduced amino acid sequences of a 247-bp portion of the RT-PCR product were 94 and 98% identical, respectively, with the coat protein sequence (GenBank Accession No. AF538686) of Sunflower chlorotic spot virus (SCSV). SCSV is a tentative potyvirus species described from Taiwan that is not yet recognized as an accepted species by the International Committee on Taxonomy of Viruses. On the basis of our concurrent host range, inclusion body, and serological data, it is likely that SCSV is in actuality the previously described and currently accepted potyvirus species BiMoV, for which no previous sequence data existed. As part of a comprehensive viral disease management plan, it is recommended that TSA plants growing in and around lettuce-production areas be controlled along with other weed hosts of this virus.

First Report of the Root-Knot Nematode Meloidogyne arenaria on Tropical Soda Apple (Solanum viarum) in Florida.

Tropical soda apple (TSA), Solanum viarum Dunal, is an invasive, noxious, perennial weed that has invaded large areas of the southeastern United States. TSA is found growing in pasture lands and is spread by cattle, wildlife, and in the movement of sod and hay. Pasture land is commonly rotated into vegetable production. In November 2003, numerous TSA plants were collected from a vegetable farm growing cucumbers and tomatoes. This land in Martin County, Florida was previously used for pasture for grazing cattle. Root galling caused by root-knot nematode (Meloidogyne sp.) was observed. Female Meloidogyne sp. were randomly extracted from the roots and placed in extraction buffer (10% wt/vol sucrose, 2% vol/vol Triton X-100, 0.01% wt/vol bromophenol blue). The females were crushed, loaded on a polyacrylamide gel, and separated by electrophoresis using the PhastSystem (Amersham Biosciences, Piscataway, NJ) (1). The activities of malate dehydrogenase and esterase enzymes were detected using standard techniques (2). Isozyme phenotype and perineal patterns consistent with Meloidogyne arenaria (Neal) Chitwood were observed. Root galling consisted of round, bead-like galls that coalesced as the infection level increased. This is consistent with galling of tomato roots by M. arenaria. Thus, TSA is a potential reservoir for M. arenaria in Florida and throughout the southern United States. The large host range of root-knot nematodes implies that multiple crops may be affected if TSA is not managed in prior land uses. To our knowledge, this is the first report of M. arenaria occurring on tropical soda apple, S. viarum.

EVALUATION OF EXOTIC SOLANUM SPP. (SOLANALES: SOLANACEAE) IN FLORIDA AS HOST PLANTS FOR THE LEAF BEETLES LEPTINOTARSA DEFECTA AND L. TEXANA (Coleoptera: Chrysomelidae)

Tropical soda apple, Solanum viarum Dunal, wetland nightshade, S. tampicense Dunal, and turkey berry, S. torvum Swartz, are considered three of Florida’s most invasive plant species. These nonnative perennial broadleaf weeds are disrupting native plant communities in agricultural areas and natural ecosystems. The lack of natural enemies in Florida is thought to be an important factor contributing to their invasiveness. The North American leaf beetles Leptinotarsa defecta (Stål) and L. texana (Schaeffer) that attack silverleaf nightshade, Solanum elaeagnifolium Cav., a native congener of the three nonnative solanums, were evaluated for their potential as biological control agents. The suitability of tropical soda apple, wetland nightshade and turkey berry as host plants for the native Leptinotarsa beetles was studied in a quarantine laboratory using single plant and paired plant tests. Neonate larvae of L. defecta developed to the pupal stage only on their natural host plant silverleaf nightshade. Feeding damage on turkey berry and wetland nightshade was negligible and no feeding occurred on tropical soda apple. In contrast, development and reproduction of L. texana on the nonnative turkey berry were comparable with silverleaf nightshade. These results suggest the nonnative turkey berry may be included in the potential host range of the native silverleaf nightshade beetle L. texana.

INSECT HERBIVORES ASSOCIATED WITH SPECIES OF SOLANUM (SOLANACEAE) IN NORTHEASTERN ARGENTINA AND SOUTHEASTERN PARAGUAY, WITH REFERENCE TO BIOLOGICAL CONTROL OF WEEDS IN SOUTH AFRICA AND THE UNITED STATES OF AMERICA

Solanum mauritianum Scopoli and Solanum sisymbriifolium Lamarck are major exotic weeds in South Africa, while Solanum viarum Dunal is similarly problematic in the United States of America. All three species are native to northeastern Argentina and southeastern Paraguay, where they were surveyed for natural enemies in February 1998. Insect agents for Solanum weeds have a tendency to extend their host ranges to include non-target Solanum species, in particular cultivated eggplant (S. melongena L.), during laboratory trials, making it difficult to promote their release. To facilitate the interpretation of such results, other native and cultivated Solanum species that grew in close proximity to the target species were also surveyed to give an indication of the insects’ field host ranges. During the survey period, 19 insect herbivore species were recorded on S. mauritianum, while 8 species were recorded on each of S. sisymbriifolium and S. viarum. Based on the insects’ occurrence, abundance and damage to their target weeds, and their absence on other non-target Solanum species, several natural enemies that warrant further investigation were identified. These include 5 species associated with S. mauritianum and 2 species associated with each of S. sisymbriifolium and S. viarum. With rare exceptions, these insects were normally associated with a single host species and none attacked cultivated eggplant.

Gratiana boliviana, a potential biocontrol agent of Solanum viarum: Quarantine host-specificity testing in Florida and field surveys in South America

Host-specificity tests andfield surveys were conducted to determine thesuitability of the tortoise beetleGratiana boliviana Spaeth (Coleoptera:Chrysomelidae) from Argentina for classicalbiological control of Solanum viarumDunal (Solanaceae) in the USA. Thehost-specificity tests were conducted at theFlorida Department of Agriculture and ConsumerServices-Division of Plant Industry quarantinefacility in Gainesville, Florida (USA). Multiple-choice host-specificity tests wereconducted in small cages using 123 plantspecies in 35 families. Adults fedsignificantly (>41% of the leaf area offeredwas damaged) on the target weed(S. viarum), and fed lightly (<20%) onSolanum torvum Sw. (noxious weed native towest-Africa). Adults did some exploratoryfeeding (<5%) on eggplant, Solanummelongena L. (economic crop), Solanumelaeagnifolium Cav. (major agricultural weedin the western US), and on Solanumtampicense Dunal (weed of Central Americanorigin). No feeding was observed on any of theother 118 plant species that were testedincluding another 21 Solanum species.G. boliviana adults laid an average of 68eggs per female on S. viarum, 5 eggs perfemale on S. torvum, and an average of0.2 eggs on eggplant. No-choicehost-specificity tests were also conducted inwhich G. boliviana adults and neonatelarvae were exposed to 19 and 22 plant speciesrespectively. Tests with the neonatesindicated this insect was able to complete itsdevelopment only on S. viarum (67%reached the pupae stage). The no-choice testswith adults indicated that this insect fed,laid eggs, and completed development only onS. viarum. The unsprayed eggplant fieldsthat were surveyed in its natural range inArgentina, Brazil, Paraguay, and Uruguay fromJune 1997 to March 2000 indicated thatG. boliviana is not a pest of eggplants in SouthAmerica. Therefore, a petition for fieldrelease of G. boliviana for classicalbiological control of S. viarum in theUSA was submitted in April 2000.