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A field study of the food eaten by solitary desert locusts was carried out in a winter breeding area in Mauritania. The food eaten, determined by the plant epidermis found in fecal pellets, was compared to the plant's availability in the habitat.Schouwia purpurea, well represented in the diets, was dominant at the study site. Adults had a preference forTribulus terrester. Growth and feeding on these two plants were compared. The high water content ofS. purpurea leaves limited the dry matter eaten and slowed down growth. Glucosinolates were separated and quantified by gas chromatography. There are 132μmol/g dry matter in green leaves. In multiple choice tests, with paper disks, glucosinolate extracts were phagostimulant at a low concentration (21μmol/g dry matter) and repulsive at a higher one (214μmol/ g dry matter). Biting behavior onS. purpurea was recorded and analyzed on video. The importance ofSchouwia purpurea in desert locust habitats and its defenses is discussed.

The aim of the study was to evaluate, in recipients of biventricular pacing systems, the risk of asystole due to ventricular pacing inhibition by sensing the left atrial signals by the LV lead at conventional sensitivity. Long-term ventricular sensitivity was programmed at > or = 4 m V in 17 consecutive recipients of ventricular resynchronization systems implanted for chronic management of congestive heart failure. Ventricular pacing inhibition due to AV cross-talk on spontaneous left atrial electrogram (AVCSA) was tested at a 2 mV ventricular sensitivity immediately after implantation of the stimulation system and 1 month later. Pacemaker dependence was also tested during temporary VVI pacing at a rate of 30 beats/min. AVCSA was observed in three patients. It was present on the day of implantation in one patient, and developed within the first month in two others. Asystole was observed in two of the three cases of AVCSA. Three pacemaker nondependent patients at the time of system implantation had become pacemaker dependent at 1 month. AVCSA was observed only with LV leads positioned in the great cardiac vein. In conclusion, asystole due to AVCSA was observed in 11% of recipients of ventricular resynchronization stimulation systems. Care should be taken in these patients to minimize the risk of atrial sensing by the LV lead, preferably avoiding its placement in the great cardiac vein. This phenomenon could be eliminated by the programmability of a right ventricular only sensing configuration.

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