314 Florida Entomologist 88(3) September 2005 INFESTATION OF STORED SAW PALMETTO BERRIES BY CADRA CAUTELLA (LEPIDOPTERA: PYRALIDAE) AND THE HOST PARADOX IN STORED-PRODUCT INSECTS R. T. ARBOGAST1, S. R. CHINI1 AND P. E. KENDRA2 1Center for Medical, Agricultural and Veterinary Entomology, ARS, USDA, P. O. Box 14565, Gainesville, FL 32604 2Subtropical Horticulture Research Station, ARS, USDA, 13601 Old Cutler Road, Miami, FL 33158 ABSTRACT The almond moth, Cadra cautella (Walker), is a common storage pest known to infest a wide range of dried plant materials, and it has been recorded from a warehouse in Florida during storage of dried passion-flower (Passiflora incarnata L.) and dried saw palmetto berries Ser- enoa repens (Bartram) Small. Its status as a pest of stored saw palmetto was confirmed by trapping in a second warehouse used solely for storage of this commodity. The moth occurred in high numbers, captures were closely associated with stacks of bagged berries, and trap catch was very low after the stacks were consolidated under a tarp and fumigated. Yet the results of laboratory rearing on saw palmetto suggested that C. cautella has little ability to infest this commodity—development was protracted and highly variable in duration, mor- tality was high, and pupal weight was low. This sort of contradiction in host suitability, which we refer to as the “host paradox,” may be widespread among stored-product insects but has seldom been reported and almost never studied. Published reports suggest that the solution lies partly in dietary supplementation through fungivorous, saprophagous, or car- nivorous feeding, although more subtle factors also are suggested. Even cursory observa- tions of the host paradox should be reported to document frequency of occurrence and perhaps stimulate studies directed toward solutions. Such studies would inevitably provide better understanding of population dynamics, which would, in turn, lend support to better management of insects in commercial storage situations. Key Words: development, saw palmetto, stored-product insects, almond moth RESUMEN La polilla de la almendra, Cadra cautella (Walker), es una plaga común de almacén que es co- nocida por infestar un amplio rango de material de plantas secas, y ha sido registrada de una bodega en Florida durante el almacimiento de la flor seca de maracuya (Passiflora incarnata L.) y las moras secas del palmito Serenoa repens (Bartram) Small. Su estado como una plaga del palmito fue confirmado por medio de trampas puestas en una segunda bodega usadas so- lamente para el almacimiento de esta material. La polilla ocurre en altos numeros, las cap- turadas fueron asociadas estrechamente con los apilados de moras embolsadas y el número de polillas capturadas en trampas fue muy bajo después de que los estantes fueron cubiertos bajo una tarpa y fumigados. Aún así los resultos de criar la polilla sobre el palmito en el la- boratorio sugiere que C. cautella tiene poca abilidad de infestar este material—el desarrollo fue prolongado y altamente variable en duración, la mortalidad fue alta, y el peso de la pupa fue muy bajo. Esta clase de contradicción en el mantenimiento desarrollo sobre el hospedero, lo cual referimos como la “paradoja del hospedero”, puede ser ampliamente distribuida entre los insectos de productos almacenados pero raramente ha sida reportada y casi nunca estu- diada. Los informes publicados sugieron que la solución consiste parcialmente en la suple- mentación de dieta por medio de la alimentación fungivora, saprofaga, o carnivora, aunque se sugiere que hay unos factores mas sutiles. Las observaciones precipitadas de la “paradoja del hospedero deben ser reportadas para documentar la frecuencia de ocurrencia y tal vez con ello estimular estudios dirigidos hacia el encuentro de soluciones. Tales estudios definitive- mente proveeran un mejor entendimento de la dinámica de la población, lo cual en cambio, dara apoyo para el mejor manejo de insectos en productos comerciales almacenados. The almond moth, Cadra cautella (Walker), is has been reported from dried passion-flower and a common, often serious pest of dried plant mate- dried saw palmetto berries (Arbogast et al. 2002). rials. It has been recorded from cereal grains and Saw palmetto, Serenoa repens (Bartram) their products, dried fruit, nuts, oilseeds, pulses, Small, is one of many plants that provide botani- and cacao (Richards & Thomson 1932), and also cals for the production of pharmaceuticals and Arbogast et al.: Infestation of Saw Palmetto Berries 315 herbal supplements. It occurs in the southeastern usually six bags high, on wooden pallets, and the coastal plain of the United States from South pallets were in turn stacked one on top of another. Carolina to Mississippi, where it is a common el- In January 2001, when we first visited the ware- ement of pine flatwoods, mesic hammocks, prai- house, most of the stacks were inside the cold ries, and scrubs (Bennett & Hicklin 1998). An ex- storage room, but there were several small stacks tract of the berries, or the ground berries them- elsewhere (Figs. 1 and 2A). The door to the cold selves, are reported to be useful in maintaining storage room was kept closed, even though the re- prostate and urinary tract well-being (Koch frigeration was no longer used. In late April, all of 2001), and they are sold for this purpose as a di- the stacks were moved and consolidated in prepa- etary supplement. The berries are harvested by ration for a commercial fumigation with phos- hand from their native habitats during late sum- phine (Fig. 2 B-C), which was done under a tarp mer and fall. They are dried to a moisture content covering the stacked bags. The fumigation began of 8-14%, bagged in burlap, and stored pending on April 27, and the warehouse was closed until shipment to end processors. During storage, they May 2. are subject to infestation by a variety of stored- We made three, 24-h trapping runs, one in Jan- product insects. uary, one in late April immediately before the fu- Arbogast et al. (2002) described the species migation, and one in early May immediately after composition and spatial distribution of an insect the fumigation. The traps were pheromone-baited population infesting a botanicals warehouse at sticky traps (SP-Locator traps with SP Minimoth Mascotte, FL, which was used alternately for pheromone dispensers, AgriSense-BCS Ltd., Pon- storage of dried saw palmetto berries and dried typridd, Mid Glamorgan, UK). Trap locations passion-flower (maypop), Passiflora incarnata L. were specified in rectangular coordinates with the Cadra cautella was the dominant species, com- origin at the southwest corner of the warehouse. prising 47% of the insect population when saw The number and configuration of trap locations palmetto was in storage. To confirm the status of (Fig. 2A-C) varied slightly. Trap density was in- C. cautella as a pest of stored saw palmetto, we creased in areas with stacked commodity, but the studied the spatial relationship between adult spacing between traps was always > 4 m, the mea- moths and stacks of bagged berries in a second sured active space of the lures (Mankin et al. warehouse used solely for storage of this commod- 1999). When trap locations were not occupied by ity. We also conducted laboratory experiments to stacks, moth traps were placed 1.2 m above the test the hypothesis that successful infestation of floor, attached by means of Velcro either to the the dried berries can be explained entirely by the walls of the warehouse or to the tops of wooden suitability of this host for growth and develop- stakes supported by stands on the floor. Other- ment of the moth. The present paper reports the wise, moth traps were placed on top of the stacked results of these studies and examines the results bags or attached to walls slightly above the in the context of host range in stored-product in- stacks. Placement of traps under these circum- sects, especially the utilization of marginal host stances was necessarily imprecise, but we esti- commodities. mated that all were within <1 m of their desig- nated coordinates. The stacks ranged in height MATERIALS AND METHODS from slightly over 1 m to about 4.5 m, and trap height varied accordingly. Warehouse Studies To determine the spatial distribution of trap catch for each trapping run, the x, y-coordinates The warehouse, located in La Belle, FL, re- of the trap positions and the corresponding num- cently had been acquired for storage of saw pal- bers of moths captured were entered in Surfer 7 metto berries and previously had been used for (Golden Software, Golden, CO) for contour analy- processing and storage of fresh peppers (green sis. This software posted observed trap catch to bell peppers, jalapeno peppers, etc.). The building the appropriate coordinates on a floor plan of the was a modern steel structure 40 m wide by 55 m warehouse, which had been entered as a base long with a covered dock along the east side map, and then created a denser grid of trap catch (Fig. 1). The only walled areas within the building values by interpolation, using radial basis func- were restrooms and a small office in one corner tions (with the multiquadric function). This and a large cold storage room in another. There method of interpolation produces good represen- were sixteen propane-fired batch driers and a belt tation of most small data sets (<250 observations) drier adjacent to the dock, which served as a work (Golden Software 1999). area during drying operations and also for stor- age of crates and bagged saw palmetto debris, Laboratory Studies which is used as mulch. In addition to saw pal- metto, the building itself contained processing Laboratory cultures of C. cautella were estab- equipment and a few pallets, crates, and burlap lished in January 2001 with adults collected from bags.