As intensity of agricultural practices increases in South Florida, areas tend to become unsuitable environments for insect-mediated interactions to persist, affecting productivity of crop plants and farmers’ livelihood in the long-term. Habitat resource enhancement strategies have been applied to cope with invasive pests and loss of pollinators resulting from importations, tourism industry, habitat fragmentation, hurricanes and unsustainable farming practices. However, inclusion of native perennial plants as insectary plants should be explored to achieve a long-term restoration of local biodiversity to enhance natural pest control and biotic pollination in agricultural ecosystems. The plan of this project is to transplant seedlings of native perennial legumes in two types of farms (conventional and organic) to assess how the changes in habitat resources affect the diversity and abundance of beneficial insects that can contribute to crop production. In addition, farmers collaborating in this project will be interviewed to gather their observations during the process. The long-term goal is to cultivate native plants as insectary plants in farms to increase the range of native vegetation, natural enemies, and pollinators, while enhancing crop production. The objectives of this project are centered on using linkages between natural and human systems to determine how the changes in habitat resources affect the diversity and abundance of beneficial insects and food production. The support of the local extension office will allow this project to reach other farmers through presentations given during growers’ meetings to provide information regarding native insectary plants as alternative resources for beneficial insects.
|This project will investigate the effects of a native perennial legume on beneficial insects, crop production and farmer behavior in agricultural sites. The aims of this project are centered on how the changes in habitat resources affect the diversity and abundance of beneficial insects and food production. Specifically, this project aims to:
1. Determine if the rate of pollinator visitations will be greater for crops located in areas nearby native insectary plants. Given that preliminary observations of Senna mexicana chapmanii show that pollinators such as caterpillars of Sulphur butterflies feed on their leaves and bees feed on their pollen, the crops located near Senna mexicana chapmanii will possess a greater rate of pollinator visitations.
2. Determine whether the number of natural enemies will be greater for crops located in areas nearby native insectary plants. Given that natural enemies such as parasitoids, wasps, beetles and ants use Senna mexicana chapmanii for shelter and nutrition, the crops located near Senna mexicana chapmanii will possess a greater number of natural enemies that attack their pests.
3. Determine if crop production will be greater for crops located in areas nearby native insectary plants. Because of increased biotic pollination and increased natural pest control from insects attracted by insectary plants, crop yield will increase.
4. Determine if farmers will prefer the inclusion of native plants as insectary plants. Given an increase in crop production, farmers will cultivate Senna mexicana chapmanii as an insectary plant.
Materials and methods
Describe the process involved in conducting the project and the logic behind the choices you made. Please be specific so that other researchers, farmers, and outreach professionals can gain from your experience.
The vegetables study for this season was initiated in February 2019 and is expected to culminate in May 2019. Under the advice of Dr. Daniel Carrillo, UF-TREC scientist, we selected the field study areas on the UF-TREC station. The USDA-ARS Chapman Field couldn’t be used as planned because the new administration considers that studies using ornamentals do not align with their mission, and therefore would not grant permission.
The project set-up incurred more expenses than we had planned on because the rules are currently quite restrictive about who can enter the station to participate in activities. While the donor who offered free set-up could not participate due to lack of specific insurance required to work inside the station, they donated all the materials for this project. The UF field office personnel was hired to perform the set-up of the field plots under their direction such as the use heavy machinery for preparation, installation and removal of materials (e.g. V-plow bed furrows, drip irrigation system), maintenance (mowing extraneous plant material, well and pump installation). While volunteer participation in the field was not possible due to rules of the research station, Andrea has recruited FIU undergraduate students who volunteer to support on material preparation for the experiments such as seed germination, repotting, and constructing frames to support her tomato plants at FIU. She also hired Ms. Blaire Kleiman, a graduate of University of Central Florida, interested in Agroecology and pursuing graduate studies in the near future. They have worked together five or more days per week in the field setting up the plantings and monitoring the insects on plants in the different treatments (described below).
The vegetable plots were established using a randomized complete block design with four blocks (Fig. 1) with a buffer of 20 m to account for variability in soil, moisture, sunlight, and irrigation direction at the field site. Each of the five rows per block contains three plots. Plots are spaced 11 m from each other (Fig. 2). Treatments were randomly assigned to each of the three plots in a row with crops cultivated i) with native/potential insectary plants (Senna Mexicana var chapmanii), ii) with non-native/commonly-used insectary plants (Lobularia maritima), iii) without any secondary plant, transplanted as strips of vegetation between two strips of crops.
We have observed that Senna mexicana and Sweet alyssum (Lobularia maritima) offer resources (shelter, pollen, foliage, extrafloral nectaries, alternative prey) to beneficial insects at a variety of developmental stages. Beneficial insects that acquire resources from these plants have been observed interacting with crops selected for this season. Cherry tomato (super sweet 100), and collard (Vates variety) were chosen for being commercially important crops in Florida that can be grown throughout the summer. These crops are commonly cultivated with high external input (e.g. pesticides), as they are influenced by fluctuation in the populations of insect pollinators, natural enemies, and pests. We have observed pests such as aphids, whitefly, and caterpillar herbivores being consumed by natural enemies (e.g. beetles, parasitoids, lacewings, predatory flies) that also depend on plant-provided resources.
- Floral visitors field survey: The length of time of visitation per flower (stay in flower until contact with the stigma) by each visitor is recorded between 8:00am and 6pm for 10-minute intervals. Quantitative and qualitative data of fruits produced by visited flowers is noted.
- Natural enemies and pests survey: The number of crop pests and predators feeding from extrafloral nectaries, flowers, leaves, and insect prey is surveyed five days per week between 9:00am-9pm. Pests are sampled within one meter of crop plants, insectary plants, and native plants. Endoparasitoids will be collected by monitoring their hosts (crop pests) in the field until emergence of parasitoid larvae from hosts. Herbivore damage on collards was recorded to determine if there is a relationship with the number natural enemies encountered and herbivory rates.
- Plant-provided resources: Starting May 2019, plants will be tested in the lab regarding the effect of flower resources on the life-span of different natural enemy species. Egg or pupa stages of natural enemies (most at the obligatory consumer stage) will be placed in insect rearing cages containing one of the potted plant species (S. mexicana, L. maritima, buckwheat and other commercially available natives will be used) or sugar water solution. Most natural enemies will be obligatory consumers of pollen, nectar, or extrafloral nectar during certain stages. Cages will be observed at 15-min intervals between 8am-9pm and the insects condition (dead, alive, or lost) and activity (resting, foraging, or feeding) will be recorded. The status of the extrafloral nectary (dry or wet) and pollen on the insect will be recorded at the termination of each replicate.
Number of farmers who participated in research
None yet, but as the vegetable season is ending the work with mangos on farms is starting. Mango growers will be interviewed before fieldwork begins and after the conclusion of the field project to gather their perception of this practice and investigate the sources used to learn about pest control and pollination. This project will be conducted with full compliance of the rules and regulations established by American University IRB. Subjects will be informed about their voluntary participation in this research and no situation will affect their ability to consent. All subjects will have privacy while participating on interviews, individually in quiet rooms. Information will be translated for participants when necessary. IRB Approval number: IRB-18-010
No Results Yet to Present!
Appendix – Field experiment set-up
Figure 1. Set-up of block of the four blocks
Figure 2. Set-up of block number 1
Educational & Outreach Activities
Aside from field experiment set-up and monitoring, none yet completed.