Quality control tests of lab-reared Cydia pomonella and Cactoblastis cactorum field performance: Comparison of laboratory and field bioassays.

Authors: Carpenter, James; Hight, Stephen; BLOMEFIELD, TOM - Agricultural Research Council Of South Africa

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/11/2012
Publication Date: N/A
Citation: N/A

Interpretive Summary: Research, operational, and commercial programs which rely on mass-reared insects of high quality and performance, need accurate methods for monitoring quality degradation during each step of production, handling and release. With continued interest in the use of the sterile insect technique (SIT) as a tactic for the suppression/eradication of key moth pests, such as the codling moth and the South American cactus moth, it is essential to establish simple and inexpensive bioassays that detect differences in insect quality and monitor insect field performance. Although many parameters may be measured in an insectary to monitor insect production, results from laboratory bioassays are seldom linked directly to corresponding insect behaviour or performance. Additional studies are needed to evaluate the ability of simple laboratory bioassays to predict the quality and performance of mass-reared insects released in the field. Therefore, we examined laboratory and field bioassays simultaneously to discern the ability of the different bioassays to predict quality and field performance. For these studies, moth quality was degraded by exposure to several different doses of radiation. Trials were performed with lab-reared populations of the cactus moth and the codling moth. Bioassays involving males released in laboratory flight cylinders, in field cages and in the open field each detected the quality degradation caused by radiation exposure, however, the mating cage bioassay did not detect quality differences for either insect species. These data suggest that the radiation treatment degraded the ability/propensity of the male moths to fly as opposed to the ability to detect and respond to the female sex pheromone. For trials involving the codling moth, the number of males that flew from the flight cylinders was not correlated with the number of males captured in the field cage or the orchard. However, because of the influence of meteorological factors, the field cage bioassay was better than the flight cylinder bioassay in predicting the daily performance of males that had been released in the orchard. Conversely, it is likely that the controlled climatic conditions of the laboratory allowed the flight cylinder bioassay to be more sensitive in detecting daily fluctuations in the quality of moths caused by factors within the mass rearing facility. These data suggest that both laboratory and field bioassays may be required to provide feedback on quality and performance of mass-reared moths in a SIT program. In these studies where quality degradation was caused by increasing doses of radiation, the flight cylinder and field cage bioassays successfully detected quality and performance differences that were relevant to moth performance in the field

Technical Abstract: Research, operational, and commercial programs which rely on mass-reared insects of high quality and performance, need accurate methods for monitoring quality degradation during each step of production, handling and release. With continued interest in the use of the sterile insect technique (SIT) as a tactic for the suppression/eradication of key lepidopteran pests, such as the codling moth and the South American cactus moth, it is essential to establish simple and inexpensive bioassays that detect differences in insect quality and monitor insect field performance. Although many parameters may be measured in an insectary to monitor insect production, results from laboratory bioassays are seldom linked directly to corresponding insect behaviour or performance. Additional studies are needed to evaluate the ability of simple laboratory bioassays to predict the quality and performance of mass-reared insects released in the field. Therefore, we examined laboratory and field bioassays simultaneously to discern the ability of the different bioassays to predict quality and field performance. For these studies, moth quality was degraded by exposure to several different doses of radiation. Trials were performed with lab-reared populations of the cactus moth and the codling moth. Bioassays involving males released in laboratory flight cylinders, in field cages and in the open field each detected the quality degradation caused by radiation exposure, however, the mating cage bioassay did not detect quality differences for either insect species. These data suggest that the radiation treatment degraded the ability/propensity of the male moths to fly as opposed to the ability to detect and respond to the female sex pheromone. For trials involving the codling moth, the number of males that flew from the flight cylinders was not correlated with the number of males captured in the field cage or the orchard. However, because of the influence of meteorological factors, the field cage bioassay was better than the flight cylinder bioassay in predicting the daily performance of males that had been released in the orchard. Conversely, it is likely that the controlled climatic conditions of the laboratory allowed the flight cylinder bioassay to be more sensitive in detecting daily fluctuations in the quality of moths caused by factors within the mass rearing facility. These data suggest that both laboratory and field bioassays may be required to provide feedback on quality and performance of mass-reared moths in a SIT program. In these studies where quality degradation was caused by increasing doses of radiation, the flight cylinder and field cage bioassays successfully detected quality and performance differences that were relevant to moth performance in the field.