THE EFFECTIVENESS OF CARBON DIOXIDE AND NITROGEN ON DIFFERENT DEVELOPMENTAL STAGES OF Cadra cautella (LEPIDOPTERA: PYRALIDAE)

Abstract

The efficacy of CO2 and N2 gases alone or in a mixture was tested against eggs, larvae, and pupae of the almond moth, Cadra cautella, a major date fruit pest, under temperature regimes of 5°C and 25°C. Our results indicated that exposing different stages to higher concentrations of CO2 significantly affected egg hatchability, larval mortality, and pupal mortality as compared to 100% N2 gas, at both temperature regimes. Application of CO2 at lower doses (below 50%) did not give 100% mortality of any developmental stage even at longer exposure timings. However, treatments at higher doses (75 and 100% CO2) were effective at 24 h and longer treatment duration. The application of 100% N2 did not effectively control C. cautella. Of all the stages, the larvae of C. cautella were most susceptible to the gases. Our results indicated that temperature has a significant effect on the efficacy of gases or their combinations tested after an exposure of 48 h and longer. Based on current findings, we conclude that CO2 gas is a good candidate for successful control of C. cautella immature stages under storage conditions and can be a potential alternative to highly toxic methyl bromide.

Comparative efficacy of modified atmospheres enriched with carbon dioxide against Cadra (=Ephestia) cautella

“…However, our results are contradictory for some stages, such as the egg stage and 3 day‐old pupae, in which we did not find any statistical difference in lethal time between the two CO 2 concentrations. This is also in accordance with the literature, in which, in some situations, the time‐mortality response in different gas concentrations can be the same or nearly the same for some stages or some exposure periods …”

“…In a study with postembryonic stages of C. cautella at 25 ± 1 °C and at 99.9% CO 2 , the order of tolerance was reported as larvae > pupae > adult . The order of tolerance of different stages of C. cautella exposed to 75% or 100% CO 2 at 25 °C was reported as eggs = pupae > larvae . Temperature also plays an important role in the response shown at different gas compositions.…”

“…This is also in accordance with the literature, in which, in some situations, the time-mortality response in different gas concentrations can be the same or nearly the same for some stages or some exposure periods. 17,18,20,21,24,27 Differences in the mortality response to MAs between different development stages or even between the same stages of different ages were noted in several stored-product insects by many authors. 17,18,23,26,[39][40][41][42] Metabolically active stages were reported to be more sensitive than metabolically inactive ones.…”

“…Development stage and age determine mortality time in C. cautella ; 7–24 h old eggs were found as the most tolerant to 100% N 2 or CO 2 at 25 °C . Besides eggs, differences in the susceptibility to MAs were also observed in larvae and pupae stages and in different age groups of each stadium …”

“…Development stage and age determine mortality time in C. cautella; 7-24 h old eggs were found as the most tolerant to 100% N 2 or CO 2 at 25 ∘ C. 22 Besides eggs, differences in the susceptibility to MAs were also observed in larvae and pupae stages 23,24 and in different age groups of each stadium. [25][26][27] This study was undertaken to obtain detailed information for the control of different age groups of all immature stages (three different ages for the eggs and pupae, and two different ages for larvae) and adults of C. cautella. Experiments were conducted at 65% RH, which is the optimum level for the development of C. cautella, [28][29][30][31] previously used by many authors.…”