Field efficacy of brief exposure of adults of six storage pests to nitrogen-controlled atmospheres

Abstract

Aulicky R., Kolar V., Plachy J., Stejskal V. (2017): Field efficacy of brief exposure of adults of six storage pests to nitrogen-controlled atmospheres. Plant Protect. Sci., 53: 169-176.The efficacy of a brief exposure (1, 7, and 10 days) to a nitrogen-controlled atmosphere (N-CA) for major storage pests in a field validation study in the Czech Republic is reported. The main goal was to estimate how quickly the mobile adult stages of six species of storage beetles (oryzaephilus surinamensis, cryptolestes ferrugineus, tribolium confusum, tribolium castaneum, Sitophilus granarius, and Sitophilus oryzae) are killed after introduction of the infested commodity to prevent their further spread to the surrounding storage bins. The trials were conducted in a metal bin containing 25 t of seeds using the system of continual top-down nitrogen filling to replace the oxygen. The composition of N-CA in the silo was measured continually. The target N-CA concentration (i.e., ≤ 1% O 2 and 99% N 2 ) was reached at the bottom of the silo after 12 h of the purging phase of nitrogen silo filling. A one-day exposure to N-CA corresponds to top-down filling, which initially gives higher concentrations of N 2 in the upper than in the lower part of the silo: low efficacy was reached at the silo bottom (0-33.3%), while higher efficacy (16.7-100%) was reached at the top of the silo bin. The mortality variation at both locations was species dependent: the most sensitive was o. surinamensis, and the least sensitive were S. granarius and S. oryzae. Seven days of N-CA exposure led to 100% mortality of all tested species except for S. granarius (96.7% mortality at the bottom), while 10 days of N-CA exposure led to 100% mortality of all adults located at both the bottom and the top of the silo. This experiment showed that one day of exposure to N-CA caused significant mortality to reduce the spread of insects from the top of the silo but not from the silo bottom, and 10 days of exposure completely prevent the adult mobile pest stages of all tested species from spreading from the treated silo and causing cross-infestation in the storage facility.

Effect of Nitrogen on Stored-Product Insect Control at Industrial Scale

“…In our case, this is where we have found most of the survival, suggesting that the exposure intervals should be longer. Vials with already-infested grains have been proven useful in different types of trials at a commercial scale, such as in heat treatments [ 32 ], phosphine application [ 33 , 34 , 35 ], and also in modified atmospheres [ 15 , 17 , 19 ]. This technique suggested that, in contrast with T. confusum , our tests showed that the “short protocol” was unable to provide 100% kill of R. dominica adults.…”

Biological Activity of Some Local Plant Powders against the Saw- Toothed Grain Beetle, Oryzaephilus surinamensis (L.)

“…The stock cultures were set up by introducing newly emerged beetles (about three hundred adults) in two-kg capacity jars, half filled with previously sterilized and conditioned standard diet. The insect standard diet was composed of wheat flour, crushed wheat and dry yeast powder at 5:5:1, respectively according to the method described by Leelaja et al (2007) and Kolar et al (2017). The jars were tightly covered with muslin cloth, held in place by rubber bands and the adults were left to oviposit for two weeks, then removed by sieving.…”

Using Nitrogen for the Control of Stored Product Insects: One Single Application for Multiple Purposes

“…Moreover, this application exceeded three weeks, which indicates the increased duration that is needed in large structures [25]. However, follow-up trials in silos in the Czech Republic provided complete (100%) mortality of O. surinamensis, T. confusum, T. castaneum, S. oryzae, the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae), and the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae), but again in increased exposure intervals [26].…”