|Zhang, Q - OHIO STATE UNIVERSITY|
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 27, 1997
Publication Date: N/A
Interpretive Summary: New ways of killing insects inside of agricultural commodities are needed as the fumigants that have traditionally been used are being banned or avoided. A relatively new, nonthermal process known as pulsed electric field (PEF) has been studied to destroy microorganisms in liquid foods. Theoretically, PEF should kill insects, also, although it has never been tried. The goal of this study was to determine if PEF would kill insects, using Mexican fruit fly eggs and larvae as a model. PEF reduced egg hatch and, at higher doses (>5.0 kV/cm delivered in ten 50 us pulses) no surviving eggs matured to the latter larval stages. PEF applied to large larvae resulted in a variety of abnormal symptoms including sluggishness, malformed puparia, and necrotic spots. No larvae treated with >2.0 kV/cm survived to the adult stage. Therefore, PEF has been shown to kill insects.
Technical Abstract: Pulsed electric field (PEF) has been studied to inactivate microorganisms in liquid prepared foods in order to prolong shelf life and prevent food poisoning. It is thought to inactivate microbes by permeabilizing the cell membrane and has less adverse effects on nutritional quality and flavor of the food than traditional thermal pasteurization or sterilization methods. Quarantine treatments are similar to food pasteurization in that any quarantined insects present in the commodity must be prevented from reproducing using techniques which are not significantly detrimental to the quality of the commodity. Traditional quarantine treatments include fumigation, heat, cold, and ionizing irradiation. PEF was applied to Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), eggs and feeding third instars. The treatment disintegrated some of the eggs. Percentage egg hatch was reduced as the voltage increased until hatch was 2.9% at the maximum voltage used (ten 50 us pulses at 9.2 kV/cm). Nevertheless, no first instars treated with >5.0 kV (ten 50 us pulses) survived to the third instar. PEF did not kill third instars immediately; however, they displayed a variety of pathological symptoms including sluggishness, elongated, larviform, and partial pupariation and development of necrotic spots throughout the body. No third instars treated with >2.0 kV survived to the adult stage. Therefore, PEF has been shown to control insects, although considerable entomological and engineering work is needed before a PEF-based treatment might become practical.