INFLUENCE OF PHEROMONE DOSE, TRAP HEIGHT, AND SEPTUM AGE ON EFFECTIVENESS OF PHEROMONES FOR CARPOPHILUS-MUTILATUS AND C-HEMIPTERUS (COLEOPTERA, NITIDULIDAE) IN A CALIFORNIA DATE GARDEN

Synthetic pheromones for Carpophilus mutilatus Erichson and C. hemipte rus (L.) were field tested in a planting of 'Deglet Noor' dates in sou thern California to determine effects of pheromone dose, trap height, and age of pheromone formulation on trap catch. Fermenting whole-wheat bread dough was the pheromone synergist in all cases. C. mutilatus wa s the most abundant nitidulid in the date garden, and trap catches wer e as high as 114,000 beetles per trap per 3-d period. For C. mutilatus , pheromone doses from 50 to 15,000 mug were significantly more attrac tive than controls, and trap catch increased with pheromone dose. Catc h of C. mutilatus to its pheromone (500 mug) was significantly greater at a 3-m trap height than at 0.3 m. C. hemipterus responded significa ntly to its pheromone at all doses (15 to 15,000 mug). In addition, C. mutilatus, C. obsoletus Erichson, and C. (Urophorus) humeralis (F.) r esponded to the C. hemipterus pheromone, and all four species responde d best at the highest doses. With the C. hemipterus pheromone (500 mug ) at trap heights between 0.3 and 3 m, captures of C. hemipterus, C. m utilatus, and C. obsoletus increased with trap height, but those for C . humeralis were greatest near the ground. Rubber septa with pheromone for either species became less effective over time. After 1 wk, septu m activity ranged from 18% of its original value (C. mutilatus respond ing to the C. mutilatus pheromone) to 90% (C. obsoletus responding to the C. hemipterus pheromone). In all experiments and with all species, males and females responded similarly. Trap responses are influenced strongly by the availability of food; in one case, sudden appearance o f an abundant food source on the ground decreased responses of C. muti latus by 99% within 1 wk. Implications of the study for using the pher omones in practical pest management are discussed.