Browsing by Author "Tipping, Philip W."

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    Classical biological control and apparent competition: Evaluating a waterhyacinth invaded community module
    Tipping, Philip W.; Smith, Melissa C.; Lake, Ellen C.; Minteer, Carey R.; Goode, Ashley B. C.; Foley, Jeremiah R.; Gettys, Lyn A. (2020-05)
    The scope and complexity of interactions within community food webs necessitates their simplification to a community module scale for conducting empirical studies. An outdoor mesocosm study in the USA quantified the strengths of direct and indirect interactions between two herbivore congeners that fed on two aquatic plant species while sharing a parasitoid. Kalopolynema ema (Hymenoptera: Mymaridae) is a stenophagous native egg parasitoid that attacks the hemipteran species in this study, Megamelus davisi (Hemiptera: Delphacidae), a native herbivore that feeds on the native aquatic species Nuphar advena, and the introduced biological control agent Megamelus scutellaris (Hemiptera: Delphacidae) that feeds on the non-native aquatic species waterhyacinth, Pontederia crassipes. The presence of M. scutellaris did not significantly increase parasitism of M. davisi indicating that apparent competition was not a factor in this community module. There was no evidence of any trophic cascades caused by these interactions based on the relative growth rates of biomass and leaf area for both plant species. Synthesis and applications. The relative strengths of community interactions varied with herbivore densities suggesting that should negative indirect effects with biological control agents occur they would likely be transient and closely linked to population dynamics as influenced by abiotic factors like temperature. Despite identifying potential negative interactions using path analysis, we saw no apparent competition following the insertion of a weed biological control agent into a community that contains an ecological analog. In this example, the primary negative interaction was biotic resistance to Megamelus scutellaris from attack by Kalopolynema ema. Adopting weed management tactics that emphasize efficacy, sustainability and environmental benevolence argue for the use of classical biological control when appropriate.
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    Herbivore suppression of waterlettuce in Florida, USA
    Foley, Jeremiah R.; Williams, Jacob; Pokorny, Eileen; Tipping, Philip W. (Academic Press, 2023-04)
    Waterlettuce, Pistia stratiotes L. (Araceae: Pistieae) is an invasive free-floating aquatic weed found throughout the world that has been targeted for control using various methods including classical and conservation bio-logical control and, herbicides. In Florida, herbicides are the primary strategy employed by land managers, often without regard to the impact of herbivorous arthropods including Samea multiplicalis Guenee (Lepidoptera: Crambidae), Elophila [=Synclita] obliteralis Walker (Lepidoptera: Crambidae), Argyractis [=Petrophila] dru-malis (Dyer) (Lepidoptera: Crambidae), Draeculacephala inscripta VanDuzee (Hemiptera: Cicadellidae), Rho-palosiphum nymphaeae L. (Hemiptera: Aphididae), Orthogalumna terebrantis Wallwork (Acarina: Galumnidae), and Neohydronomus affinis Hustache (Coleoptera: Curculionoidea). A series of field experiments from 2009 to 2012 were conducted at three sites in Florida to quantify the levels of suppression by these species, using an insecticide-check approach to produce restricted and unrestricted herbivory conditions. Four of the species (E. obliteralis, S. multiplicalis, O. terebrantis, and N. affinis) were found at every field site. At the end of the experiment, plots exposed to unrestricted herbivory contained 63.1 % less biomass and covered 32.0 % less surface area compared to plots with restricted herbivory. These results indicate that naturally occurring and introduced species are suppressing the growth of waterlettuce populations in the field in Florida. Future research will examine the synergistic potential of actively managing herbicides and herbivorous arthropods to suppress waterlettuce.
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    Host range of Lepidelphax pistiae (Hemiptera: Delphacidae) and its potential impact on Pistia stratiotes L. (Araceae)
    Goode, Ashley B. C.; Minteer, Carey R.; Foley, Jeremiah R.; Tipping, Philip W.; Valmonte, Ryann J.; Knowles, Brittany K.; Gettys, Lyn A. (2019-07-03)
    Pistia stratiotes L. (Araceae) is a floating aquatic plant that has become invasive in Florida. It is primarily controlled with herbicides, but two biocontrol agents have previously been released to assist in management of this species. A new potential biocontrol agent from Argentina, Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae), has been evaluated comprehensively for specificity after initial host range studies done in its native range indicated that it is likely specific to P. stratiotes. Host range studies indicated that this insect is specific to P. stratiotes, with no survival or reproduction occurring on any of the 42 other plant species tested. Impact studies indicated that this insect can significantly damage P. stratiotes at medium and high population densities, which were comparable to those seen in its native range. Lepidelphax pistiae is sufficiently specific enough to warrant release and has a high probability of aiding management of P. stratiotes populations in Florida. [GRAPHICS] .
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    The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland
    Tipping, Philip W.; Martin, Melissa R.; Foley, Jeremiah R.; Pierce, Ryan M.; Gettys, Lyn A. (Cambridge University Press, 2021-03)
    The potential of Melaleuca quinquenervia (Cav.) S.T. Blake to reinvade cleared areas was evaluated over a 13-yr period that included two wildfires and the introduction of biological control agents. The first wildfire occurred in 1998 and was followed by a mean of 591.5 recruited seedlings m(-2). Recruits from that fire were cleared 7 yr later in July 2005 for a second experiment to evaluate seedling recruitment into cleared areas. Seed rain, seedling recruitment and mortality, and sapling growth rates were measured in four plots located around individual large reproductive trees. A second natural wildfire in 2007 burned through those plots, leading to increases in seed rain followed by a pulse in recruitment of 21.04 seedlings m(-2), 96.5% fewer than after the 1998 fire. Recruits in half of the plots around each tree were then treated with regular applications of an insecticide to restrict herbivory by biological control agents, while herbivory was not restricted in the other half. There was no difference in seedling mortality between treatments 1,083 d post-fire (2007) with 96.6% seedling mortality in the unrestricted herbivory treatment and 89.4% mortality in the restricted herbivory treatment. Recruits subjected to the restricted herbivory treatment grew taller than those in the unrestricted herbivory treatment, 101.3 cm versus 37.4 cm. Many of the recruits were attacked by the biological control agents, which slowed their growth. Although solitary M. quinquenervia trees retain some capacity to reinvade areas under specific circumstances, there was a downward trend in their overall invasiveness at this site, with progressively smaller recruitment cohorts due to biological control agents. Land managers should prioritize removing large reproductive trees over treating recently recruited populations, which can be left for many years for the biological control agents to suppress before any additional treatment would be needed.
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    Small-scale dispersal of a biological control agent - Implications for more effective releases
    Goode, Ashley B. C.; Minteer, Carey R.; Tipping, Philip W.; Knowles, Brittany K.; Valmonte, Ryann J.; Foley, Jeremiah R.; Gettys, Lyn A. (2019-05)
    Eichhornia crassipes (Martius) Solms Laubach (Liliales: Pontederiaceae) was introduced to Florida in the 1880s as an ornamental and it once infested thousands of square kilometers across the state. Megamelus scutellaris Berg (Hemiptera: Delphacidae) was developed as a classical biological control agent for this plant primarily because its free-living life stages allow it to better integrate with herbicides, which are currently used as the main control method for E. crassipes in Florida. Mass rearing and distribution programs can accelerate the benefits of biological control by augmenting natural dispersal, but an optimal release strategy must consider the entire system including the agent, the target weed, and the habitat. The effectiveness of various release strategies was evaluated using a tank experiment where single and multiple releases of either adult M. scutellaris only or E. crassipes infested with M. scutellaris eggs were compared to control treatments. The post-release dispersal capability of brachypterous M. scutellaris was evaluated using a linear transect of E. crassipes. Two density release treatments were tested and emerging nymphs were used as a proxy for female dispersal distances. All release treatments resulted in successful M. scutellaris population establishment and levels of M. scutellaris were not significantly different among them. The dispersal experiment indicated that adult females oviposit near the release point before dispersing. While the release experiment indicated that all treatments were similar, the continually fluctuating populations of E. crassipes makes establishment of populations difficult in the field. By releasing both adults and infested plants, additional propagule pressure can be attained from a single release event which can counter the tendency of adult M. scutellaris to disperse rapidly following release.
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    Temperature dependent survival and fecundity of Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae), a potential biological control agent of Pistia stratiotes L. (Araceae)
    Goode, Ashley B. C.; Minteer, Carey R.; Tipping, Philip W.; Pokorny, Eileen; Valmonte, Ryann J.; Foley, Jeremiah R.; Knowles, Brittany K. (2020-04-02)
    Lepidelphax pistiae Remes Lenicov (Hemiptera: Delphacidae) is monophagous on Pistia stratiotes L. (Araceae), an invasive floating plant in Florida. Temperature studies were conducted to determine the optimal temperature for development and reproduction for this potential biological control agent. Egg development time decreased as temperature increased from 17 degrees C to 30 degrees C. No eggs developed and no nymphs survived at 15 degrees C. Adult females survived the longest at 15 degrees C, indicating that they might be more resilient to cold temperatures. Optimal temperature for nymph development was 25 degrees C with 29% surviving to adulthood in 18.2 +/- 0.4 days.