Ecological interactions

1.     Genetics diversity of Brazilian pepper:  In collaboration with the University of Miami and Florida Atlantic University, the laboratory is investigating the genetic diversity of Brazilian pepper in Florida and other areas of the world where the plant is exotic (Texas, California, Hawaii, Puerto Rico, Virgin Islands) and comparing that to diversity in the native South American range.  Identification of the source of invasive populations may be helpful for better targeting foreign exploration for natural enemies.  Results to date provide evidence of the introduction into Florida of two types of Brazilian pepper; one on the west coast and the other on the east coast.  The source of the west coast introduction has been found in southeastern Brazil, but the source of the east coast introduction has yet to be identified.  Additionally, we have found that the two types have hybridized extensively since arriving in Florida.  Finally, our data suggests that populations in Hawaii, Florida, Texas and the Virgin Islands originated in Florida. 

2.    Salt tolerance studies:  Brazilian pepper in Florida is known to colonize a variety of habitats from saline mangrove areas to upland fresh water sites.  We are investigating whether trees growing in saline sites have a greater tolerance for salt water than trees growing at fresh water sites.  Preliminary data suggests that Brazilian pepper from mangrove habitats is more tolerant of saline conditions than Brazilian pepper collected from fresh water sites.

3.    Allelopathic interaction:   We are investigating possible allelopathic relationships between Brazilian pepper and selected native plants.  Results have demonstrated that some native plants, such as Bidens alba and Rivina humilis, are negatively affected by aqueous extracts of Brazilian pepper leaves.  Leaf extracts of wax myrtle had no effect on germination or growth of Brazilian pepper, but root exudates of wax myrtle negatively influenced both germination and growth of the exotic plant.

Brazilian pepper flowering

Biological Control

1.    Rearing of the Brazilian pepper sawfly, Heteroperreyia hubrichi, as a Potential biological control agent against Brazilian pepper:  The Brazilian pepper sawfly has been the subject of investigation by the University of Florida since the early 1990s, and was approved for release by USDA’s Technical Advisory Group in 1997.  In accordance with NEPA requirements, Dr. Jim Cuda of the UF Department of  Entomology and Nematology in Gainesville prepared and submitted Environmental and Biological Assessments (EA and BA) for the sawfly in 2004.  In anticipation that the EA and BA will be approved, the sawfly is being mass reared at the BCRCL.   

2.    Bitrophic effect of Brazilian pepper on the sawfly:  Drs. Jim Cuda and Bill Overholt are investigating the effect of Brazilian pepper genotypes on performance of the sawfly.  They will also examine the bitrophic effects of salt water irrigation of Brazilian pepper on the sawfly and various plant nutritional regimes on the sawfly.

3.    Release and evaluation of the sawfly:  As soon as APHIS approves the release of the sawfly, a field cage study will be initiated.  Growth and reproduction of Brazilian pepper will be compared in infested and uninfested cages.

H. hubrichi

female

Adults mating

1.  Genetic characterization of air potato:  Air potato occurs in the wild in both Asia and Africa.  In collaboration with Florida Atlantic University, studies were conducted to determine the origin or Florida air potato.  Analysis of chloroplast DNA revealed an African origin.

2.    Foreign exploration for natural enemies:  Collaboration has been established with Makerere University in Uganda and the Crops Research Institute in Ghana to catalog the insect herbivores of air potato.  To date, several herbivores have been found, but little is yet known about their biologies or host ranges.

3.     Exclusion studies:  Reciprocal studies on herbivory of air potato are being initiated in Ghana and Fort Pierce.  The level of herbivory will be measured on plants protected with weekly insecticide sprays and unprotected plants.  We hypothesize that herbivory in Florida will be minimal or non-existent, whereas in Ghana, plants will be heavily consumed.  

Air Potato

1.  Mass rearing, field releases and evaluation of the biological control agent Gratiana boliviana:  The introduced tropical soda apple (TSA) chrysomelid beetle, Gratiana boliviana, is being mass reared for release and evaluation on local ranches.  First releases were made in August, 2004.  The beetle readily colonized the site, and caused considerable damage to TSA plants.  However, the beetle population decreased during the winter months, but is beginning to resurge in the spring of 2005.

  2.  Gratiana Release Results

  3.  Gratiana Releases mapped in Google Earth - Updated 7/13/2007

       If you don't have Google Earth  software download it here: Google Earth

  4.  Gratiana boliviana site

TSA

G. boliviana mating

2. Pictures

1. Solanum diphyllum , 2. Solanum capsicoides, 3. Solanum torvum, 4. Solanum tampicense

1.     Characterize the life history and reproductive parameters of Ischnodemus variegatus under laboratory and field conditions

2.     Assess the host specificity of I. variegatus under greenhouse and field conditions

3.     Evaluate the impact of Ischnodemus variegatus on Hymenachne amplexicaulis

4.     Map the distribution of Hymenachne amplexicaulis and Ischnodemus variegatus in Florida

Infestation in Sarasota Co.

I. variegatus mating

1. Foreign exploration for natural enemies in East Africa.  Collaboration has been established with the International Center of Insect Physiology and Ecology (ICIPE) in Nairobi, Kenya, the National Agricultural Research Organization (NARO) in Uganda and the National Institute for the Environment and Conservation of Nature (INECN) in Burundi.  Two potential biological control agents were found in Lake Tanganyika during a preliminary survey to East Africa in September, 2005. 

2. New!! Hydrilla collections and voucher specimens from Africa mapped in Google Earth

3. Hydrilla pictures-Africa

4. African Hydrilla Survey Forms

5. Hydrilla reports

1. Learn about the training program at BCRCL

2. Pictures from previous scholars

3. Resources on Weed Biological Control