Submitted to: Journal of the Australian Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/1996
Publication Date: N/A
Interpretive Summary: Nitidulid beetles ("sap" beetles) are serious pests of peaches and apricots, invading the fruits just as they ripen. In some years, beetle damage is much worse than in others. While routine treatments with insecticide could prevent beetle damage, this action could result in insecticide residues on the crop and could disrupt natural control of other pests such as mites. Needed is the ability to predict when beetle damage will be significant, so that insecticide can be used only when absolutely necessary. In a five-year study in New South Wales, Australia, beetle populations were monitored with traps baited with synthetic pheromones, and dependence of beetle abundance on temperature and rainfall was studied. (Pheromones are natural chemicals that the beetles use to attract others of their species; the beetle pheromones were identified and first synthesized by ARS scientists). Most notable was that beetle populations plummeted during the years when midsummer rainfall was very low, and subsequent crop damage was minimal. Use of weather data and routine monitoring with pheromone traps have good potential for predicting crop damage from the beetles.
Technical Abstract: Traps baited with synthetic aggregation pheromone and fermenting bread dough were used to monitor seasonal incidence and abundance of the ripening fruit pests, Carpophilus hemipterus (L.), C. mutilatus Erichson, and C. davidsoni Dobson in stone fruit orchards in the Leeton district of southern New South Wales during five seasons (1991-96). Adult beetles were trapped from September to May, but abundance varied considerably between years with the amount of rainfall in December-January having a major influence on population size and damage potential during the canning peach harvest (late February-March). Below average rainfall in December-January was associated with mean trap catches of <10 beetles/trap/week in low dose pheromone traps during the harvest period in 1991/92 and 1993/94, and no reported damage to ripening fruit. Rainfall in December-January 1992/93 was more than double the average, and mean trap catches ranged from 8-27 beetles/week during the harvest period with substantial damage to the peach crop. December-January rainfall was also above average in 1994/95 and 1995/96 and means of 50-300 beetles/trap/week were recorded in high-dose pheromone traps during harvest periods. Carpophilus spp. caused economic damage to peach crops in both seasons. These data indicate that it may be possible to predict the likelihood of Carpophilus beetle damage to ripening stone fruit in inland areas of southern Australia, by routine pheromone-based monitoring of beetle populations and summer rainfall.