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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. Public domain – authored by a U.S. government employee

Changes to the historical flow and nutrient levels of freshwater bodies in Florida have made control of waterhyacinth difficult. Biological control agents were introduced to augment herbicidal control of this plant. The newest insect agent, Megamelus scutellaris, was released in 2010, has established, and has been documented dispersing more than 6 kms away from release locations, across aquatic and terrestrial habitats. These insects were able to successfully disperse away from herbicide treated areas and across terrestrial habitats to reach new mats of waterhyacinth. Macropterous individuals were the first M. scutellaris documented at three non-release sites, indicating that the established wild populations are producing flighted individuals and are dispersing actively. Established populations appear to have reached an equilibrium density of 10.74 +/- 19.74 M. scutellaris/ m2 and this does not fluctuate with additional releases. Published version Public domain – authored by a U.S. government employee

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. Public domain – authored by a U.S. government employee

Biological experiments involving animals in K–12 classrooms can be time consuming or logistically difficult. Insects are small and easy to obtain, making them suitable for classroom use. We provide an experiment using insects that will teach students how to use the scientific method to formulate and test a hypothesis. The experiment is based on a case study involving an insect used as a biological control agent that targets an invasive weed, and the rigor of the experiment can easily be tailored to different grade levels. Using ~1 m2 arenas set up in the classroom, students measure insect jumping or walking distances as a proxy for dispersal capabilities in the field, and more advanced classes can investigate variables that affect jumping or walking distance and direction.

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 re...

Multiple biological control agents have been developed and released to increase control and reduce treatment costs ofPontederia (Eichhornia) crassipesin Florida. Although two species of weevil (Neochetina eichhorniaeandNeochetina bruchi) and the planthopper (Megamelus scutellaris) utiliseP. crassipesfor feeding and reproduction, little is known about their interactions including any negative interactions that might reduce their individual or overall effectiveness in suppressing the plant.Megamelus scutellariswas provided with the choice of weevil-damaged or undamaged plants and allowed to oviposit. Plants were then monitored individually for nymph emergence to determine the plant preference for adults. There were no differences in F(1)emergence numbers among the treatments indicating that in this specific situation the potential for negative interactions betweenNeochetinaspp. andM. scutellarisis minimal. Additional studies are required to quantify the potential for other types of interactions among these biological control agents. Public domain – authored by a U.S. government employee

A postsecondary institution partnered with several high schools in a large, urban and highly diverse school district in the southeast U.S. through a GK-12 program funded by the National Sci...

The biological control agent Megamelus scutellaris Berg (Hemiptera: Delphacidae) was released in Florida in 2010 to improve control of the invasive aquatic plant, Pontederia (Eichhornia) crassipes (Mart.) Solms (Commelinales: Pontederiaceae). A native egg parasitoid, Kalopolynema ema (Schauff and Grissell) (Hymenoptera: Mymaridae), was documented utilizing M. scutellaris, potentially limiting its effectiveness as a biological control agent. An experiment to determine if the distance from K. ema’s native host impacted parasitism rate of M. scutellaris was conducted in artificial ponds with naturally occurring populations of the native insect species. Models indicated that parasitism decreased with distance from the native host and with increasing M. scutellaris density. Although parasitism increased with K. ema density, rainfall, and temperature, parasitism was low with over half of the test plants indicating no signs of parasitism on M. scutellaris. The lack of a density dependent response by K. ema suggests it will not interfere with biological control of P. crassipes in Florida.

In Florida, waterhyacinth (Pontederia [Eichhornia] crassipes) (Martius) Solms Laubach (Pontederiaceae) is primarily controlled by herbicides, but overall control is enhanced by insect biological control agents that decrease growth and reproduction and slow regrowth. However, herbicide applications often disrupt the biological control agent populations when applied indiscriminately. Previous studies identified the utility of preserving populations of biological control agents in the vicinity of herbicide treated areas by establishing refuges for the insects. The objectives of this experiment were to quantify the impact of insect refuges, using groups of untreated P. crassipes within treated mats, on the regrowth of the new mat and the ability of biological control agents to persist following an herbicide treatment. Pontederia crassipes mats were grown with and without biological control agents, then treated with 2 concentrations of the herbicide penoxsulam. Plant growth metrics and biological control agent densities were monitored pre- and post-treatment and compared using ANCOVAs and non-parametric Kruskal-Wallis tests. Although the systemic activity of penoxsulam in the water column prevented the establishment of refuges in this study, biological control agent populations persisted following herbicide applications without additional releases and were able to remain at field densities after the decay and loss of P. crassipes. The treatment with no biological control agents and only half-label rate herbicide grew more densely, had greater dry weight biomass, higher relative growth rate, and produced more inflorescences than the plants in treatments with biological control agents. The half-label herbicide and biological control agent treatment performed as well as both treatments with label rate herbicide, and with and without biological control agents, respectively, in lowering P. crassipes density, final dry weight biomass, and relative growth rate. Although the concept of refuge systems at operational field scales requires further study, demonstrating the ability of biological control agents to persist even on sprayed mats is a necessary first step in determining the temporal and spatial factors that might influence the utility of such refuges.