Browsing by Author "Valmonte, Ryann J."

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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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    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.