Solanum Carolinense Research Articles

Synanthedon rileyana (H. Edwards) Response to Selected Clearwing Pheromone Blends

Male moths of the horse nettle borer, Synanthedon rileyana (H. Edwards), were attracted to various blends of (E,Z)-3,13-ODDOH alcohol and (E,Z)-3,13-ODDA acetate. Fields containing horse nettle, Solanum carolinense L., were utilized in Ohio and Arkansas during these attractancy trials in 1988 and 1989. Efficacy was determined by the number of males trapped in sticky traps. The optimum ratio of alcohol to acetate was found to be 100:25 to 100:50 confirming earlier observations and expanding the knowledge through replicated experiments in two states. A second blend of 100:3 (E,Z)-3,13-ODDOH and (E,Z)-2,13-ODDA also attracted more males than the blank traps did at both locations. Seasonal moth emergence, reflected by the number of male moths trapped, begins in Ohio in mid-July and peaks by mid-August.

Sex allocation and reproductive success in the andromonoecious perennial Solanum carolinense (Solanaceae). I. Female success

Relative allocation of resources to growth vs. reproduction has long been known to be an important determinant of reproductive success. The importance of variation in allocation to different structures within reproductive allocation is somewhat less clear. This study was designed to elucidate the importance of allocation to vegetative vs. reproductive functions, and allocation within reproductive functions (sex allocation), to realized female success in an andromonoecious plant, Solanum carolinense. Allocation measurements were taken on plants in experimental arrays exposed to natural pollination conditions. These measurements included total flower number, the proportion of flowers that were male, flower size, and vegetative size. Flower number explained the majority of the variation among individuals in their success-that is, there was strong selection for increased flower production. There was also selection to decrease the proportion of flowers that were male, but neither flower size nor vegetative size (a measure of overall resource availability) were direct determinants of female success. After Bonferroni corrections for multiple comparisons, most phenotypic correlations among the traits measured were nonsignificant. Thus, in this andromonoecious species there is not a strong relationship between resource availability (vegetative size) and female success, and female success is instead determined by the relative production of the two different flower types.

Factors Affecting Presence of Horsenettle(Solanum carolinense L.) in Pastures of Central Japan.

Factors Affecting Presence of Horsenettle(Solanum carolinense L.) in Pastures of Central Japan.

Effects of temperature on survival and preimaginal development rates of Colorado potato beetle on potato and horse‐nettle: potential role in host range expansion

AbstractThe effect of temperature on the ability of Colorado potato beetles (Leptinotarsa decemlineata, Say) to use horse‐nettle (Solanum carolinense L.) as a host plant was determined for larvae from colonies originating from two geographically separated populations, one adapted to horse‐nettle (NC) and the other unadapted to horse‐nettle (MA). Survival and developmental rate on horse‐nettle and potato were measured for larvae from both colonies over a range of constant temperatures (12–30 °C) and one fluctuating temperature regime (22 °C to 30 °C). The ability of Colorado potato beetles to use horse‐nettle as a larval host was strongly influenced by temperature, but the effects of temperature differed greatly between beetles from the two colonies. Survival of adapted larvae on horse‐nettle was highest and comparable to that on potato at the constant 30 °C and the fluctuating temperature regime. Below 30 °C, survival of adapted larvae decreased drastically but some larvae survived at all temperatures except the lowest (12 °C). In contrast, survival of unadapted larvae to adult occurred only at 30 °C, and was low (10%). At lower temperatures, all larvae died. On potato, the effect of temperature was less dramatic, and consistent across colonies. At 12 °C, survival to adult was poor (ca. 10%), but at higher temperatures, survival increased sharply and larvae from both colonies survived equally well. On potato, small but statistically significant differences in developmental rates between beetle colonies were detected at the constant but not at the fluctuating temperature regimes. Also, the developmental day degree requirements (DD) and the low temperature development threshold (T0) values for the various developmental stages did not differ between colonies on potato. On horse‐nettle, development times for both colonies were always significantly longer and DD requirements were greater than on potato. At 30 °C, the only constant temperature at which larvae from the unadapted colony completed development, the development rate to adult emergence was similar to that of beetles from the adapted colony. Differences between colonies in performance on horse‐nettle were not a result of host‐independent, genetically based differences in the thermal requirements of the two populations. Our findings are consistent with the hypothesis that adaptation to horse‐nettle by Colorado potato beetle may be facilitated by a genotype × environment interaction involving temperature. These findings have important implications for host plant utilization, host range expansion and selection of pest biotypes adapted to plant resistance traits used in crop protection.

The quantitative genetics of sex allocation in the andromonoecious perennial, Solanum carolinense (L.)

The quantitative genetics of allocation to sexual functions was examined in the andromonoecious plant, Solanum carolinense. A restricted maximum likelihood (REML) analysis was employed to determine heritabilities and genetic and environmental correlations for flower number, the proportion of those flowers that were male, and the size of flower parts (corolla diameter, pistil length, and anther length and width) in each of three populations used in a diallel crossing design. All floral characters were highly heritable. The sizes of flower parts were positively genetically correlated with one another, which will restrict the independent evolution of these parts. Negative genetic and environmental correlations exist between flower size and proportion male flowers, indicating the potential for the evolution of individuals with either many, small male flowers or few, large, cosexual flowers. The high heritabilities of the traits examined as well as the genetic correlations among them indicate the potential for the evolution of gender specialization in this species, because flower size and number have the potential to affect sex-specific reproductive success.

The quantitative genetics of sex allocation in the andromonoecious perennial, Solanum carolinense (L.)

The quantitative genetics of allocation to sexual functions was examined in the andromonoecious plant, Solanum carolinense. A restricted maximum likelihood (REML) analysis was employed to determine heritabilities and genetic and environmental correlations for flower number, the proportion of those flowers that were male, and the size of flower parts (corolla diameter, pistil length, and anther length and width) in each of three populations used in a diallel crossing design. All floral characters were highly heritable. The sizes of flower parts were positively genetically correlated with one another, which will restrict the independent evolution of these parts. Negative genetic and environmental correlations exist between flower size and proportion male flowers, indicating the potential for the evolution of individuals with either many, small male flowers or few, large, cosexual flowers. The high heritabilities of the traits examined as well as the genetic correlations among them indicate the potential for the evolution of gender specialization in this species, because flower size and number have the potential to affect sex-specific reproductive success.

Impact of two specialist insect herbivores on reproduction of horse nettle, Solanum carolinense.

The frequency of coevolution as a process of strong mutual interaction between a single plant and herbivore species has been questioned in light of more commonly observed, complex relationships between a plant and a suite of herbivore species. Despite recognition of the possibility of diffuse coevolution, relatively few studies have examined ecological responses of plants to herbivores in complex associations. We studied the impact of two specialist herbivores, the horse nettle beetle, Leptinotarsa juncta, and the eggplant flea beetle, Epitrix fuscula, on reproduction of their host, Solanum carolinense. Our study involved field and controlled-environment experimental tests of the impact on sexual and potential asexual reproduction of attack by individuals of the two herbivore species, individually and in combination. Field tests demonstrated that under normal levels of phytophagous insect attack, horse nettle plants experienced a reduction in fruit production of more than 75% compared with plants from which insects were excluded. In controlled-environment experiments using enclosure-exclosure cages, the horse nettle's two principal herbivores, the flea beetle and the horse nettle beetle, caused decreases in sexual reproduction similar to those observed in the field, and a reduction in potential asexual reproduction, represented by root biomass. Attack by each herbivore reduced the numbers of fruits produced, and root growth, when feeding in isolation. When both species were feeding together, fruit production, but not root growth, was lower than when either beetle species fed alone. Ecological interactions between horse nettle and its two primary herbivores necessary for diffuse coevolution to occur were evident from an overall analysis of the statistical interactions between the two herbivores for combined assessment of fruit and vegetative traits. For either of these traits alone, the interactions necessary to promote diffuse coevolution apparently were lacking.

Population Dynamics of the Colorado Potato Beetle (Coleoptera: Chrysomelidae) on Horsenettle in Michigan

Field studies during 1986–1988 in southwestern Michigan showed that horse-nettle, Solanum carolinense L., could be an important reservoir of Colorado potato beetle, Leptinotarsa decemlineata (Say), populations when potatoes, Solanum tuberosum L., are not planted. Early in the season, Colorado potato beetle laid most of its eggs on nonhost plants. Accumulated total larval mortality ranged between 82 and 99%. Predators with chewing mouth parts caused higher egg mortality at the beginning of the season whereas predators with piercing-sucking mouth parts preyed upon more egg masses by the middle of the season. Populations of Coleomegilla maculata De Geer were correlated with beetle 1st-instar densities and Perillus bioculatus F. was one of the most numerous predators of Colorado potato beetle. Given a choice of 7 potential host plant species, only horsenettle and potato were colonized by a Colorado potato beetle population adapted to horsenettle. Potato was a better host than horsenettle for this population, which has been isolated from potatoes for ≈40 yr.

S-allele sequence diversity in natural populations of Solanum carolinense (Horsenettle)

S-allele diversity in Solanum carolinense was surveyed in two natural populations, located in Tennessee and North Carolina, with a molecular assay to determine the genotype of individual plants. A total of 13 different S-alleles were identified and sequenced. There is high overlap between the two populations sampled, with 10 alleles shared in common, one allele found only in Tennessee, and two found only in North Carolina. The number of alleles in this species appears to be extremely low compared with other species with gametophytic self-incompatibility. Sequence comparisons show that most alleles are extremely different one from another in their primary sequence and a phylogenetic analysis indicates extensive trans-specific evolution of S-lineages. In addition, some alleles appear to be derived much more recently. The implications of these observations are discussed in the light of recent theoretical results on S-allele population diversity and persistence.

Recruitment of Colorado Potato Beetles (Coleoptera: Chrysomelidae) to Solanaceous Hosts in the Field

Field recruitment on 10 solanaceous plant species by adult Colorado potato beetles, Leptinotarsa decemlineata (Say), and their oviposition, was investigated by frequent collection of adults and eggs from replicated Latin-square plots over 5 yr in Michigan, Maine, and Massachusetts. Preferred plants for adults were potato, Solanum tuberosum L.; bitter nightshade, Solanum dulcamara L., and buffalobur, Solanum rostratum Dunal; eggplant and horsenettle, Solanum melongena L. and Solanum carolinense L., were of intermediate rank in recruitment of adults. The remaining species (tomato, Lycopersicon esculentum L.; black nightshade, Solanum nigrum L.; silverleaf nightshade, Solanum eleaegnifolium Cavanilles; groundcherry, Physalis heterophylla Nees; jimsonweed, Datura stramonium L.) were not preferred. Adult recruitment and oviposition changed over the season and differed from site to site, but was not influenced by the host-plant origin of recruited adults. Daily collections of adults in Massachusetts in 1991 showed four distinct periods of adult recruitment. These differed in relative importance depending on whether plots were near or distant to previous and current year's potato fields. Early overwintered recruitment was highest and relatively less different between near and distant plots, reflecting the importance of flight during this period. Late overwintered recruitment was mostly by short-distance dispersal of adults that had already fed on potato plants, based on oviposition of collected females. Summer females also appeared to be previously fed, and their recruitment to distant plots suggested dispersal mostly by flight. Prediapause dispersal resulted in recruitment mostly to plots a short distance from potato fields. Reproduction, as measured by egg masses per adult, increased over the season, with summer adults showing the highest egg mass-adult ratio. Recruitment of adults and their oviposition in the field were positively associated with no-choice assays of fecundity and larval survival in the laboratory using the same plant species, but with relatively more rejection of intermediate-ranked hosts in the field.

Vegetational Gradients and Proximity to Woodchuck (Marmota monax) Burrows in an Old Field

Comparison of vegetation near and distant from 10 woodchuck ( Marmota monax ) burrows in a diverse field 6 years old revealed differences at both community and species levels. Total plant cover increased with distance from burrows. Species-richness was low near and distant from burrows and relatively high at intermediate distances, a result consistent with the intermediate disturbance hypothesis. Horsenettle ( Solanum carolinense ), Kentucky blue-grass ( Poa pratensis ), and fescue ( Festuca elatior ) increased, and orchardgrass ( Dactylis glomerata ) decreased with distance from burrows. While woodchucks strongly affect only a small fraction of the field (ca. 2%), they are important agents in creating a vegetational mosaic and in creating source areas for species of colonizing plants.

Plant life span and response to inoculation with vesicular-arbuscular mycorrhizal fungi

To determine if annual and perennial species from weakly mycotrophic families exhibit the same differential patterns of responsiveness to vesicular-arbuscular mycorrhizae (VAM) as do members of the strongly mycotrophic grass family (Poaceae), this study examined the responses of congeneric, sympatric annual and perennials species from the Caryophyllaceae and Solanaceae to inoculation with the VAM fungus Glomus intraradices. The perennial Solanum carolinense responded as positively to G. intraradices as did perennial grasses. The other perennials examined, Solanum dulcamara and Silene nivea, were both relatively unresponsive to VAM inoculation and had mean responsiveness values below the typical level for annuals from strongly mycotrophic families. The annual Solanum nigrum exhibited a small positive response to inoculation, and was as responsive as many annuals from more mycotrophic families, especially at low P supply rates. The annual Silene noctiflora was strongly inhibited by inoculation. Mortality over 8 weeks was fivefold higher in VAM-inoculated Silene noctiflora than in uninoculated plants. Among the four herbaceous species examined, the species which persists longest in old-field succession in eastern North America was also the most responsive to VAM inoculation. Mechanisms are proposed for successional persistence and replacement based on VAM responsiveness and soil nutrient pool sizes.

Plant Litter: Light Interception and Effects on an Old‐Field Plant Community

We studied the effects of litter of the annual grass Setaria faberii, the perennial herb Solidago spp. (mostly S. canadensis), and leaves of the hardwood tree Quercus alba on a successional plant community. We also assessed light interception by these litter types in the laboratory. Light extinction followed the Beer—Lambert exponential law. Solidago litter had the highest transmittance constant and Quercus litter the lowest. The three types of litter produced different light mosaics at the microsite (0.8 cm diameter) scale. In the field, all three litter types affected community structure, by the effect of Quercus was the strongest. Litter reduced the density of the two dominant grasses, Setaria faberii and Panicum dichotomiflorum. Quercus and Setaria litter resulted in biomass compensation (i.e., fewer but larger individuals) by S. faberii but not by P. dichotomiflorum, which probably was always outcompeted by S. faberii. Solanum carolinense, the main dicot in the community, was unaffected by litter addition. Setaria and Solidago litter enhanced the establishment of Erigeron annuus, but Quercus litter reduced it. Litter reduced the number of flowering individuals of S. faberii and the number of seeds per plot; Quercus litter increased the production of seeds per individual. We conclude that species—dependent effects of litter on plant populations may significantly alter interspecific interactions and change plant community structure through direct and indirect effects.

Temperature-Dependent Development and Phenology of Pepper Maggots (Diptera: Tephritidae) Associated with Pepper and Horsenettle

Emergence and developmental rates of nondiapausing pepper maggot, Zonosemata electa (Say), pupae, reared from naturally infested pepper ( Capsicum annuum L.) and horsenettle ( Solanum carolinense L.) fruit, were compared at seven constant temperatures: 5, 10, 15, 20, 25, 30, and 35°C. Pupae originating from pepper had significantly greater pupal weights and percentage of adult emergence than pupae from horsenettle. However, host plant origin, color, sex, and weight had little influence on pupal developmental times across temperatures. Nonlinear and linear models were fit to the temperature versus developmental data and used to predict adult emergence in the field. A nonlinear, four-parameter, poikilotherm model, fitted ( r2 = 0.99) to median development rates of pepper and horsenettle pupae combined, indicated that development was linear between 10 and 25°C, optimal at 26°C, and dropped to near zero at 35°C. The lower developmental threshold (± SE) for horsenettle- and pepper-reared pupae combined (9.33 ± 0.09°C)was determined by linear regression and the x intercept method. Completion of pupal development for the combined sample required 602 ± 13 degree-days (±SE) above the base temperature. Contrary to previous reports, phenology of adult pepper maggot in the field was unaffected by host plant origin. A degree-day model incorporating a 9.5°C developmental threshold and soil temperatures (10 cm depth) accurately predicted (±l d) the 50% emergence points (E 50 ) of adults reared from both host plants. A stochastic simulation model, incorporating a nonlinear developmental rate function and 2-h soil temperature records, also predicted the E 50 point accurately (±1.5 d). The simulation model accurately predicted the E 5 and E 75 to E 100 points, making it useful in management situations where emergence percentiles other than 50% are required.

Feeding Preferences of the Prairie Vole (Microtus ochrogaster) for Seeds and Plants from an Old-Field Successional Community

Feeding Preferences of the Prairie Vole (Microtus ochrogaster) for Seeds and Plants from an Old-Field Successional Community

Carolinoside: A phytosteroidal glycoside from Solanum carolinense

The glycoside of a new class of phytosteroids has been isolated from Solanum carolinense. The steroidal aglycone (carolinone) is alkylated at C-3 and is identified as C-[(2,4,5-trideoxy-3-keto-4,5-dehydro)-pentulopyranosyl]-(5 → 3)-)-(13,14- seco-l4β,17α-dihydroxy) estrogen. The hydrolytic labile glycosyl moiety is identified as O(β- d-glucopyranosyl) (1 → 1)-[ l-(2,6-dideoxy-3-C-methyl)-arabinopyranose]. The linkage of this disaccharide in the steroidal glycoside (carolinoside) is shown to be O-(α-pentulopyranosyl)-(1 → 4)- O-(α- l-arabinopyranosyl)-(1 → 1)- d-glucopyranose. Carolinoside occurs at concentrations of 10 −7-10 −6 M in leaf tissue and was shown to be the host plant specific feeding induction factor for Manduca sexta.

Plant Influences on Parasitism of Two Leafminers: A Test of Enemy‐Free Space

We evaluated the importance of host plant traits as causes for a much greater parasitoid species richness on Tildenia inconspicuella (Lepidoptera: Gelechiidae), a leafminer on horsenettle, Solanum carolinense, than on tildenia georgei, a leafminer on groundcherry, Physalis heterophyllaa var. ambigua. In three field experiments, we found no evidence for short—term effects of host plants on parasitoids. None of the parasitoid species normally associated with the horsenettle miner successfully parasitized groundcherry miners transferred to horsenettle. Rates of parasitism and composition of parasitoid species did not differ for horsenettle miners on horsenettle vs. on eggplant, nor for groundcherry miners in tied vs. untied leaves. Instead, long—term effects of host plant morphology on leafminer behavior explained differences in parasitism between the two leafminer species. Whereas the mine structure of the groundcherry miner allows the larva to leave its mine and move freely over the leaf surface, the horsenettle miner stays within its mine, even when disturbed. We found that this difference has made the horsenettle miner vulnerable to more parasitoid species; it can be exploited, not only by parasitoids that can attack vagile hosts, but also by parasitoids restricted to concealed, sedentary hosts. Evidence further indicated that horsenettle trichome morphology has favored the evolution of this obligate endophytism in the horsenettle miner by selecting against mine architectures that would allow miners easy access to the leaf surface. When experimentally placed on leaf surfaces, miner larvae could not feed on horsenettle because they could not penetrate its meshwork of stellate trichomes. On groundcherry, where trichomes are thin and flexible, larvae easily initiated mines. We argue that obligate endophytism, which is uncommon among related gelechiids, is a specific adaption to horsenettle morphology that has made the horsenettle miner available to more parasitoid species than its vagile relatives.

PATTERNS OF PRE‐ AND POSTFERTILIZATION RESOURCE ALLOCATION WITHIN AN INFLORESCENCE: EVIDENCE FOR INTEROVARY COMPETITION

I investigated the distribution of ovules and seeds on the inflorescence of Solanum Carolinense L. (Solanaceae). Ovules did not appear to vary in size, but the number of ovules per ovary and the size of ovaries decreased significantly along the inflorescence (from basal to distal positions). Experimental removal of basal ovaries at an early stage resulted in increased ovary size and number of ovules in distal ovaries, suggesting a dynamic system of control. Mature fruits displayed a similar pattern of decreasing mass and seed number with position along the infructescence. It is not clear whether the patterns of allocation to fruits are related to the patterns of allocation to ovaries in a simple cause‐and‐effect relationship. However, a satisfying hypothesis that explains these and other patterns of allocation is that they are all manifestations of, or adaptations to, interovary competition along the inflorescence.

Infestation of Solanum carolinese Fruit by Frumenta nundinella: Are Larvae Affected by Interfruit Competition?

I examined the interaction between Solanum carolinense L. and its hostspecific herbivore, Frumenta nundinella Zeller, for evidence of competition. Intraspecific competition could have occurred among fruit-infesting larvae or among seedcontaining fruits, and interkingdom competition could have occurred between the insect (infested fruits) and the plant (seed-containing fruits). The relationships among position (basal to distal) along the infructescence, fruit mass, infested fruit mass, pupa mass and pupa sex were determined by correlation. Mass of seed-containing fruits decreased significantly with position along the inflorescence in glasshouse and field plants, suggesting that fruits competed for resources. Mass of infested fruits also decreased significantly with position, but the relationship was not as strong. Pupa mass did not vary systematically with position, suggesting that distal pupae were not at a competitive disadvantage compared to basal pupae or fruits. Distal pupae gained their mass from smaller fruits than did basal pupae, so apparent pupa efficiency (pupa mass/fruit mass) increased significantly with position and decreased significantly with fruit mass. Overall, pupa mass and fruit mass were significantly and positively related. One hypothesis that may explain these results proposes that larvae are sinks that stimulate the plant to retain and provide for infested fruits, partly overcoming the usual resource gradient along the infructescence.

A POSSIBLE ROLE FOR ETHYLENE DURING IAA‐INDUCED POLLEN EMBRYOGENESIS IN ANTHER CULTURES OF SOLANUM CAROLINENSE L

Pollen embryogenesis in Solanum carolinense was induced by culturing anthers containing bicellular pollen grains on medium supplemented with indole‐3‐acetic acid (IAA). Pollen embryogenesis was also promoted by Ethrel and the ethylene precursor, aminocyclopropane carboxylic acid (ACC), although not to the same degree as IAA alone. Furthermore, IAA stimulated ethylene accumulation in culture to the same extent as did Ethrel and ACC. It is suggested that IAA induced pollen embryogenesis at least partially, through auxin‐mediated ethylene production. However, since CoCl2, an inhibitor of ethylene synthesis, reduced the amount of ethylene in IAA‐treated cultures but did not eliminate the formation of pollen embryos, IAA also appears to have a direct effect on morphogenesis in anther cultures.