Grant Information
| Knowledge Area | Subject of Investigation | Field of Science | Percent |
|---|---|---|---|
| 215 - Biological Control of Pests Affecting Plants | 1099 - Tropical/subtropical fruit, general/other | 1070 - Ecology | 34% |
| 215 - Biological Control of Pests Affecting Plants | 1099 - Tropical/subtropical fruit, general/other | 1080 - Genetics (excludes breeding) | 33% |
| 215 - Biological Control of Pests Affecting Plants | 1099 - Tropical/subtropical fruit, general/other | 1130 - Entomology and acarology | 33% |
Each year exotic species invade the USA and become pests, which require control measures to protect our agriculture. These insects often become pests because they arrive here without the natural enemies that would keep their populations in check in their native area. In biological control the goal is to reunite the pest with their natural enemies. Initially research is done on the safety of importing such natural enemies, and when found to be safe they are imported and released for the control of the exotic pest. In addition to imported natural enemies, native natural enemies also play some role in the control of these exotic pests. The use of exotic natural enemies has the advantage that once established they will provide some level of control of the pest thus reducing the need for chemical control. Often exotic pests are both a problem in agriculture and in urban environments, an example of this is the Asian Citrus Psyllid which can transmit the lethal citrus disease HLB. While in commercial citrus groves chemical control may be feasible, this is not a good option for the citrus found in the urban environment, thus making biological control one of the few options in that environment.To increase the success of this biological control method studies are required to determine 1. the identity of the natural enemies, 2. Do differences exist between different populations of the same species of natural enemy? To answer these questions we use a set of DNA finger printing techniques so that we know exactly what we are importing and releasing. Another factor that we study in this project is the effect of prolonged rearing on the effectiveness of the natural enemy. Long term rearing often leads to "domestication" of the natural enemy, meaning it will perform very well in the mass rearing environment but not very well when they are released in the field. Our research seeks to do the mass rearing in such a way that the field effectiveness of the natural enemy is optimized. Using DNA-fingerprinting techniques we also determine which of the native predators have the largest impact on the exotic pest. Once that is known we can try to protect these predators in the environment, by for instance timing insecticide treatments when few of the predators are killed by the insecticide.Ultimately, the goal of this work is to depress the pest populations in the field by natural means rather than by chemical pesticides, thus reducing the pollution that the pesticides cause in the environment.
Goal A: Objective 3 Use a set of genes (28sD2, ITS2, COI) for determining the phylogenetic position of different populations of the imported species, so as to have:1. Markers that can be used in the post release studies to determine the effectiveness of different biotypes of the imported parasitoid, and 2. to assure that established wasps indeed originate from the imported population. Goal A: Objective 5. Release, establish and redistribute natural enemies to assure the populations in the new environment harbor genetic variation to adapt to the local circumstances. Established populations may be genetically enriched by releasing additional genetic variation.Goal B: Objective 7. Molecular gut content analysis is used to determine which predators feed on pest population intended for control. In general a prey specific quantitative PCR reaction is developed to amplify the DNA of the host in the gut of the predator. In addition studies are done to evaluate the digestion rate of host DNA in gut of the predator, so as to normalize the host DNA detection frequency. Based on the number of the particular predator in the environment and the normalized detection frequency in the predators gut, the species with the highest impact on the pest prey species can be detected. Once this is known methods can be developed to conserve that particular predator as good as possible in the environment for improved control of the pest.Goal C. Objective 11. During mass rearing two genetic effects are thought to play a major role in the quality of the natural enemies used in the field. 1. Loss of genetic variation when large, initially genetically variable populations are maintained for an extended number generations, and 2. Adaptation to the mass rearing circumstances that will lead to a reduction in field effectiveness of the natural enemies, such adaptations can take place in a very short time. Methods will be tested to maintain genetic variation in the overall population and restrict the potential of the overall population to adapt to the mass rearing conditions. Tests will be done in either field cages or in the open field to determine the performance of mass reared populations exposed to different rearing conditions. Using different molecular markers (COI or nuclear markers [RAD-SEQ]) the performance of differently treated populations will be determined by releasing similar numbers of individuals of each population marked with different markers, and comparing the release frequencies of the markers with the frequency of the markers in the offspring of the released populations. Factors that can be tested is duration of mass rearing, performance of different inbred strains, inbred populations versus outbred populations, small natural enemies versus large natural enemies etc.Goal D: Objective 13. The economics of mass reared natural enemies will be determined using the relative performance of the natural enemy as determine under goal C objective 11. While at present simply the number of natural enemies is the criterion for many insectaries, which sometimes results in many natural enemies of substandard performance in the field, the results from Goal C, Obj 11 can be used to optimize the mass rearing so as to produce natural enemies for the following relationship: #of natural enemies * relative field performance/ cost of production.
Target Audience
Our main target audience reached during this project are citrus and avocado growers as well as biocontrol scientists. We have given numerous talks to citrus growers on our work on the parasitoid Tamarixia radiata - a parasitoid of the asian citrus psyllid-, and on the native predators of the asian citrus psyllid. Our work on the biological control of the ambrosia beetle Euwallacea fornicatus has been reported on numerous times to the California avocado growers and has been presented at the annual entomological society of America meetings
Changes / Problems
Nothing Reported
Training & Professional Development
I have continued to teach my biological control classes. In addition, we teach all graduate students in our program the use of molecular markers to resolve entomological questions. During the reporting period I was the major professor for four graduate students at UCR. Several students from abroad have also received training in our lab, one from Brazil and two from the Netherlands.
Dissemination Streams
We have participated in many meetings organized by the Avocado Commission and the Citrus Research board to disseminate the results of our work to growers and interested scientists. We have given extensive training to both the USDA and the CDFA in the mass rearing Tamarixia parasitoids for the control of the Asian Citrus Psyllid. Several talks were given for the International Organization on Biological Control on the genetics of mass rearing of natural enemies, both at the international congress of Entomology in Orlando, Florida and in a workshop in Switzerland and a contribution was given to a meeting in Malaysia.
Next Reporting Steps
Nothing Reported
Target Audience
Our main target audience reached during this period are citrus and avocado growers as well as biocontrol scientists. We have given numerous talks to citrus growers on our work on the parasitoid Tamarixia radiata - a parasitoid of the asian citrus psyllid-, and on the native predators of the asian citrus psyllid. Our work on the biological control of the ambrosia beetle Euwallacea fornicatus has been reported on numerous times to the California avocado growers and has been presented at the annual entomological society of America meetings
Changes / Problems
Nothing Reported
Training & Professional Development
I have continued to teach my biological control classes. In addition, we teach all graduate students in our program the use of molecular markers to resolve entomological questions. During the reporting period I was the major professor for four graduate students at UCR.
Dissemination Streams
We have participated in many meetings organized by the Avocado Commission and the Citrus Research board to disseminate the results of our work to growers and interested scientists. We have given extensive training to both the USDA and the CDFA in the mass rearing Tamarixia parasitoids for the control of the Asian CItrus Psyllid. Several talks were given for the International Organization on Biological Control on the genetics of mass rearing of natural enemies, both at the international congress of Entomology in Orlando, Florida and in a workshop in Switzerland.
Next Reporting Steps
We plan on importing natural enemies of the Euwallacea sp. into our quarantine facility to start testing the specificity of these natural enemies to determine if they can be used here in the US as biocontrol agents against these pest species. In addition, we will so additional foreign exploration particularly in Taiwan for natural enemies of these beetles. We will also field test native entomopathogenic fungi against these invasive beetles in a field project in California. <br><br>
<br>What was accomplished under these goals? 1) Goal A Obj 1. For the Asian citrus psyllid extensive work has been done in determining the effectiveness of native predators in their feeding on various stages of the psyllid. Collections of predators made both during the day and at night were tested to determine which of the native predators fed on the asian citrus psyllid. The predators with the highest numerical incidence in the field and the relatively highest percentage of detection of feeding on the psyllid were further studied to determine the relative rate of digestion of the psyllids. Based on this work several predators were identified that had the largest impact on the Asian Citrus Psyllid. The most effective predator was a green lace wing species where many of the collected larvae showed evidence of recent feeding on ACP. Goal A Obj 2 Foreign exploration was done in south east Asia to determine the presence of natural enemies in the native range of the Euwallacea fornicatus species complex. Natural enemies were found in Taiwan. Several parasitoids were detected a bethylid parasitoid and a Braconid parasitoid were found both parasitizing adult beetles inside their galleries. Work is underway to obtain cultures of these natural enemies to study their potential for biocontrol in California.Goal C obj 11. We have been working on maintaining the genetic quality of Tamarixia radiata parasitoids originally collected from Pakistan by keeping isolated population, in each of these isolated populations inbreeding takes place and what little genetic variation was present in these populaitons is lost in a short time, thus not allowing these populations to adapt to prolonged mass rearing (domestication). By combining wasps from the different isolated populations the genetic variation present in the original population is restored to some extent, and then allowing the wasps in mass production only to be maintained for a limited number of generations one can avoid domestication during this phase. This system has been set up here in California where we maintain the small populations, mix them and allow them to reproduce for one generation in our lab before they are used as starting material in mass rearing facilities for distribution. In the mass reaing facilites the wasps are maintained for maximally 3 generations before new starting material is supplied and the cycle is repeated. We are now starting to replace the original Pakistani colonise with Tamarixia lines that are recollected from California, with the idea that these wasps have been selected for the California conditions and thus may be more effective in controlling the ACP populations in California. <br><br><b>Publications</b><br>
Target Audience
Our main target audience reached during this period are citrus and avocado growers as well as biocontrol scientists. We have given numerous talks to citrus growers on our work on the parasitoid Tamarixia radiata - a parasitoid of the asian citrus psyllid-, and on the native predators of the asian citrus psyllid. Our work on the biological control of the ambrosia beetle Euwallacea fornicatus has been reported on numerous times to the California avocado growers and has been presented at the annual entomological society of America meetings
Changes / Problems
Nothing Reported
Training & Professional Development
I have continued to teach my biological control classes. In addition we teach all graduate students in our program the use of molecular markers to resolve entomological questions. During the reporting period I was the major professor for five graduate students at UCR. We have participated in many meetings organized by the Avocado Commission and the Citrus Research board to disseminate the results of our work to growers and interested scientists. We have given extensive training to both the USDA and the CDFA in the mass rearing Tamarixia parasitoids for the control of the Asian CItrus Psyllid.
Dissemination Streams
I have presented numerous talks and field day presentations on the polyphagous shot hole borer invasion of southern California mainly in meetings organized by the California Avocado Commission for Avocado growers, Similarly we have given several presentations for the Citrus Research Board on the mass rearing of Tamarixia radiata and biological control of the Asian Citrus Psyllid in Southern California. In southeast Asia during our field work there for the polyphagous shot hole borer, I have presented talks on biological control and on the phylogeography of the shot hole borers. In addition, we have presented our work at the Entomological Society of America annual meeting
Next Reporting Steps
We plan on importing natural enemies of the Euwallacea sp. into our quarantine facility to start testing the specificity of these natural enemies to determine if they can be used here in the US as biocontrol agents against these pest species. In addition we will so additional foreign exploration particularly in Taiwan for natural enemies of these beetles. We will aslo field test native entomopathogenic fungi against these invasive beetles. <br><br>
<br>What was accomplished under these goals? Goal A Obj 1. For the Asian citrus psyllid extensive work has been done in determining the effectiveness of native predators in their feeding on various stages of the psyllid. Collections of predators made both during the day and at night were tested to determine which of the native predators fed on the asian citrus psyllid. The predators with the highest numerical incidence in the field and the relatively highest percentage of detection of feeding on the psyllid were further studied to determine the relative rate of digestion of the psyllids. Based on this work several predators were identified that had the largest impact on the Asian Citrus Psyllid. Goal A Obj 2 Foreign exploration was done in south east Asia to determine the presence of natural enemies in the native range of the Euwallacea fornicatus species complex. Natural enemies were found in the form of entomopathogenic fungi and nematodes in Vietnam, while in Taiwan a Bethylid parasitoid was detected that parasitized adult beetles inside the galleries. Work is underway to obtain culutres of these natural enemies to study their potential for biocontrol in California.Goal C obj 11. We have been working on maintaining the genetic quality of Tamarixia radiata parasitoids originally collected from Pakistan by keeping isolated population, in each of these isolated populations inbreeding takes place and what littel genetic variation was present in these populaitons is lost in a short time, thus not allowing these populations to adapt to prolonged mass rearing (domestication). By combining wasps from the different isolated populations the genetic variation present in the original population is restored to some extent, and then allowing the wasps in mass production only to be maintained for a limited number of generations one can avoid domestication during this phase. This system has been set up here in California where we maintain the small populations, mix them and allow them to reproduce for one generation in our lab befor they are used as starting material in mass rearing facilities for distribution. In the mass reaing facilites the wasps are maintained for maximally 3 generations before new starting material is supplied and the cycle is repeated. <br><br><b>Publications</b><br>