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Submitted to: Journal of Entomological Society
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/15/2001 Publication Date: 10/15/2001 Citation: RIDDICK, E.W. EFFECT OF COLD STORAGE ON THE LABORATORY PRODUCTION OF COTESIA MARGINIVENTRIS (HYMENOPTERA: BRACONIDAE). JOURNAL OF ENTOMOLOGICAL SOCIETY. 2001.36(4):366-379. Interpretive Summary: Interpretive Summary In many cases, mass-produced natural enemies are overproduced and regularly discarded because market demands fluctuate with the season, weather conditions, and pest status. Thus, improved storage technology would greatly reduce the cost of commercial production. Storage techniques that increase the shelf-life of natural enemies and allow the temporary halting of the production system would be most useful. Experiments were designed to discover efficient techniques for storing mass-produced Cotesia marginiventris, a wasp that parasitizes beet armyworm caterpillars. Storage of immature wasps (pupae in cocoons) for 20 days at 10 degrees Celsius had no significant effect on adult emergence or longevity. Storage of adult wasps for 32 days at the same temperature was possible, if adults were removed from the cold for 2h, every 8th day, and fed honey. However, these stored females produced significantly fewer female progeny after being removed from the cold and placed under normal rearing conditions. These results should be important to government and university scientists interested in defining the limits of time that parasitic wasps can be stored without affecting their reproductive performance. The biological pest control industry should also be interested in this research, since many companies often have to store parasitic wasps for periods of time before shipping them to customers. Technical Abstract: Abstract I evaluated the effect of short-term cold storage on non-diapausing pupae and adults of Cotesia marginiventris (Cresson) as a step toward developing protocols for the mass production of this parasitoid. When stored at 10 degrees Celsius, successful emergence of adults from cocoons occurred within 6d and was not affected by storage time (0d, 4d, 12d, or 20d). Longevity of males and females was not affected by cold storage, but fewer males and females remained alive per consecutive 8d interval after emergence at 27degrees Celsius. A fertility experiment revealed that fewer progeny (F1 cocoons, F1 females) were produced by parental females previously cold-stored as pupae in cocoons for 20d rather than 4d. A within-storage adult survival experiment demonstrated that males and females were not affected by any of the storage times(8d, 16d, 24d, 32d). This survival rate was achieved by periodically removing the adults from the cold, placing them at 23 plus/minus one degree Celsius for approximately 2h and providing honey. Another fertility experiment revealed that more F1 males, but fewer F1 females, were produced when the parental females (which had been cold-stored as adults) were stored for 32d rather than for 16d. This study suggests that adults are more amenable to short-term storage than pupae if the adults are periodically removed for feeding. Nevertheless, cold storage of cocoons (pupae) for 20d or adults for 32d can limit the production of female progeny. |
