| ชื่ออาจารย์ที่ปรึกษา |
ปัทมาภรณ์ กฤตยพงษ์, Ph.D.วัชโรบล ธีรคุปต์, Ph.D.จอห์น อาร์ มิลน์, Ph.D.เฉลิม สินธุเสก, Ph.D.
Pattamaporn Kittayapong, Ph.D.Vacharobon Thirakhupt, Ph.D.John R. Milne, Ph.D. Chalerm Sindhusake, Ph.D. |
| บทคัดย่อ(English) |
Odonate insects are important predators of rice pests that play a valuable role in the rice ecosystem. Twenty-nine odonate species, 15 zygopterans and 14 anisopterans, were collected from rice fields in 36 provinces around Thailand from 1998 to 2000. Within all rice odonate species, three zygopteran species, ~iAgriocnemis pygmaea~i, ~iAgriocnemis f. femina~i and ~iIschnura senegalensis~i, had the highest numbers of individuals. Within the anisopterans, the species with the highest number of individuals was ~iDiplacodes trivialis~i. The distributions of 15 coenagrionid and 11 libellulid odonate species were extended with many new provincial records. The distribution and phylogenetic relationships of the reproduction-modifying bacteria called ~iWolbachia~i in odonate insects were also studied. Using a PCR-based method and ~iwsp~i gene primers, four odonate species, ~iAgriocnemis f. femina~i, ~iPseudagrion pruinosum~i (Zygoptera), ~iBrachythemis contaminata~i and ~iNeurothemis t. tullia~i (Anisoptera) were found to be infected with ~iWolbachia~i and the percentage of ~iWolbachia~i infection among species of the Order Odonata was 13.79 %. All procedures used for phylogenetic reconstruction (maximum parsimony, maximum likelihood and neighbor- joining methods) place all odonate ~iWolbachia~i strains in the ~iCon~i and ~iPip~i subgroups within the B group of ~iWolbachia~i strains. The ~iwsp~i gene sequences of ~iAgriocnemis f. femina~i and ~iBrachythemis contaminata~i were in the ~iPip~i subgroup, but ~iWolbachia~i sequences from ~iNeurothemis t. tullia~i and ~iPseudagrion pruinosum~i were grouped together into the ~iCon~i subgroup of B group ~iWolbachia~i strains. The low ~iWolbachia~i infection frequencies and identical ~iwsp~i gene sequences in odonate species that are not closely related suggest that ~iWolbachia~i might have recently invaded rice field odonate populations through some means of horizontal transmission. Identical ~iwsp~i gene sequences were found from all three positive populations of ~iA. f. femina~i collected from different regions of Thailand. This finding supports the hypothesis that ~iWolbachia~i-infected damselflies spread into uninfected populations. Further study should be done to investigate the rates at which ~iWolbachia~i-infected damselflies could spread into uninfected populations. |
