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Abstract. Females of the parasitoid fly Emblemasoma auditrix find their host cicada (Okanagana rimosa) by its acoustic signals. In laboratory experiments, fly phonotaxis had a mean threshold of about 66 dB SPL when tested with the cicada calling song. Flies exhibited a frequency dependent phonotaxis when testing to song models with different carrier frequencies (pulses of 6 ms duration and a repetition rate of 80 pulses s^-1). However, the phonotactic threshold was rather broadly tuned in the range from 5 kHz to 11 kHz. Phonotaxis was also dependent on the temporal parameters of the song models: repetition rates of 60 pulses s^-1 and 80 pulses s^-1 and pulse durations of 5-7 ms resulted in the highest percentages of phonotaxis performing animals coupled with the lowest threshold values. Thus, parasitoid phonotaxis is adapted especially to the temporal parameters of the calling song of the host. Choice experiments revealed a preference of a song model with 9 kHz carrier frequency (peak energy of the host song) compared with 5 kHz carrier frequency (electrophysiologically determined best hearing frequency). However, this preference changed with the relative sound pressure level of both signals. When presented simultaneously, E. auditrix preferred 5-kHz signals, if they were 5 dB SPL louder than the 9-kHz signal.

Abstract.: Metastasized malignant melanomas can affect all organs of the human body. However, isolated metastatic spreading into the gallbladder is rare. We treated two asymptomatic patients who had undergone primary curative resection of a melanoma. Gallbladder structures suggesting the presence of tumors were noticed in the follow-up investigations. The two patients underwent laparoscopic cholecystectomy to clarify their pathological relevance. Histologically, the tumor was a metastasis of the malignant melanoma in each case. Surgery is indicated in stage IV in isolated metastatic spreading to the gallbladder in order to avoid symptoms or tumor complications. Since the vast majority of melanoma metastases of the gallbladder are located intraluminally and lymphadenectomy in the region of the hepatoduodenal ligament does not appear to be appropriate, the operation should be carried out laparoscopically. The value of postadjuvant chemoimmunotherapy after metastasis resection is being investigated in numerous studies at present.