No description available.

Juvenile reef fishes often have a color pattern different from that of adults. It has been theorized that this reduces the aggression received by juveniles from adult conspecifics. This was tested using two species of Labroides cleaning wrasses in which certain-sized individuals can quickly shift back and forth between the adult and juvenile color patterns. Adult Labroides phthirophagus has the same single-male grouping social structure as previously described for L. dimidiatus. Small L. phthirophagus and L. dimidiatus in juvenile coloration shifted to adult coloration when isolated and then quickly shifted back to juvenile coloration when chased by an adult conspecific female. In L. phthirophagus the adult females attacked small cleaners more frequently when they displayed the adult color pattern, indicating that juvenile coloration gives some protection from conspecific aggression. Two other species oflabrids, Thalassoma duperrey and Coris gaimard, showed the ability to shift back to juvenile coloration when aggression was received from con specific adults, although the shift was not nearly as rapid as seen in Labroides species. Dascyllus albisella and Zebrasomajlavescens, common reef fishes, preferred to solicit cleaning (by posing) from the adult-colored L. phthirophagus, indicating that some hosts prefer the adult color pattern. Small L. phthirophagus shifted to adult coloration more quickly when starved than when provided with host fish on which to feed, indicating that the coloration shift is motivated by hunger. Even though juvenile coloration in some fishes may reduce the aggression received from adults, in cleaner wrasses it also reduces food availability, making it advantageous for them to shift to adult-coloration as soon as possible. Cleaner wrasses have developed a quick, reversible coloration shift that allows changing to adult coloration at a small size but allows reversing coloration if too much aggression is received. / x, 59 leaves, bound : ill., maps ; 29 cm.

No description available.

Protective coloration such as aposematism and crypsis occurs in many insects but only a few species alter their defensive strategy during the same instar. We hypothesize the adult shield bug Graphosoma lineatum with an alternating black and non-melanised longitudinal striation exhibit such a change in defensive coloration. In Sweden, the non-melanised stripes of the pre-hibernation G. lineatum are pale brown and cryptic but they change during hibernation to red and aposematic. We have tested the adaptive functions of coloration of the two G. lineatum forms against bird predators. In Paper I we used great tits as predators and measured detection time of the two forms against a background of dry grass and plants, simulating late-summer conditions. We found that the birds took longer time to find the pale than the red form. Thus, the pale form of G. lineatum is more cryptic in a dry environment than the red form. In Paper II and III we used naïve predators and measured attack rate/latency on red and pale adults and fifth-instar larvae (black and brown) to investigate avoidance and generalisation between the stages. In Paper II domestic chicks initially found the red form most intimidating, but both adult forms are more intimidating than the larva. Moreover, there was a broad generalisation among forms. In Paper III naïve great tits did not find the red form significantly more aversive than the pale adult. Neither the chicks nor the tits showed any difference in the speed of avoidance learning between the two adult colour forms. In Paper IV the shieldbugs themselves were the main focus as we compared activity levels in the different colour forms and found that G. lineatum alters behaviour in accordance to their protective strategy. Thus they were significantly less active during the cryptic phase. Taken together, these experiments suggest that the pale brown adult invests in a cryptic strategy at the cost of reduced protection from aposematism, whereas the red adult benefits from aposematism at the cost of reduced camouflage. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.

Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

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This thesis investigates the possibility of using aposematic insects as guides to plants that contain pharmacologically-active compounds. Plants were monitored within national parks in the Republic of Panama over a period of six months and all insects feeding on them were collected and raised in captivity. The insects were then extracted and analyzed to determine how they were treating toxic chemical compounds in their host plant. Two principal plants were investigated with their associated insects: (1) Vismia baccifera and (2) Mikania guaco. One generalist and one specialist Lepidopteran species were found to sequester vismione B from their host plant Vismia baccifera, a cytotoxic compound active against three cancer cell lines. Two specialist Coleopterans were found to sequester the novel compound Guacanone, isolated by the primary author from the vine Mikania guaco and active against Trypanosoma cruzi, the causative agent of Chagas' disease. A generalist Coleopteran was found to not sequester this compound. (Abstract shortened by UMI.)

No description available.