Effect of Relative Humidity and Product Moisture on Response of Diapausing and Nondiapausing Indianmeal Moth (Lepidoptera: Pyralidae) Larvae to Low Pressure Treatments

Abstract

Low pressure treatment in flexible polyvinyl chloride containers is a potential alternative to chemical fumigants for California tree nuts. Laboratory studies investigated the effect of relative humidity and product moisture on weight loss and mortality of diapausing and nondiapausing larvae of the Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), exposed to 50 mmHg. Diapausing larvae were far more tolerant than nondiapausing larvae to low pressure; exposure times nearly twice those of nondiapausing larvae were required to obtain comparable weight loss or mortality levels in diapausing larvae. Relative humidity was found to have a large effect on both weight loss (assumed to be due to moisture loss) and mortality of both nondiapausing and diapausing larvae. Mortality and weight loss increased as humidity levels decreased. By controlling the relative humidity of the treatment chamber, product moisture also strongly affected weight loss and mortality. The results suggest that for tree nuts, product moisture levels may affect the efficacy of low pressure treatments.

Effects of low-pressure storage of food commodities on the mortality of adult stored product insects

“…Adults and larvae may later be present in the final packaged products (Riudavets et al, 2009;Noomhorm et al, 2009). Although stored product insects are relatively more susceptible to the MA treatments, their eggs are relatively tolerant to the high CO2 environment (Adler, 1999;Adler et al, 2000;Johnson, 2010).…”

“…Therefore, low pressure may also be used in combination with high CO2 in the containers or packages. Johnson & Zettler (2009) and Johnson (2010) showed that vacuum treatment could be effectively used to control storage pests of tree nuts.…”

“…Lowpressure storage or vacuum packaging of foods is considered an effective and portable modified atmospheric (MA) technique. It provides an environment with low oxygen (O2) (2-5%) and relatively high CO2 (>30%), within relatively a short period of time after removing the atmospheric gasses within the package or storage containers (Johnson & Zettler, 2009;Johnson, 2010;Kučerová et al, 2013). It is an alternative storage technique for refrigeration of shelf-stable and some perishable food products.…”

Response of Ceratitis capitata, Bactrocera dorsalis, and Bactrocera cucurbitae (Diptera: Tephritidae) to Metabolic Stress Disinfection and Disinfestation Treatment

“…The egg is typically the most tolerant life stage (Mbata and Phillips 2001). Lowering the humidity during low pressure treatment can enhance insect mortality (Johnson 2010). Effective low pressure treatments can be several hours or several days in duration depending on the level of pressure and other factors (Johnson and Zettler 2003, Liu 2003, Mbata and Phillips 2004.…”

Potential for Hypobaric Storage as a Phytosanitary Treatment: Mortality of <I>Rhagoletis pomonella</I> (Diptera: Tephritidae) in Apples and Effects on Fruit Quality

“…Published research into the use of low pressure for disinfestation of stored products infested by stored-product pests dates back to Ͼ85 yr (Back and Cotton 1925, Bare 1948, Calderon et al 1966, Calderon and Navarro 1968, Navarro and Calderon 1979, Friedlander and Navarro 1983, Mbata and Phillips 2001, Johnson and Zettler 2009, Johnson 2010. Low oxygen concentrations cause the insect mortality rather than any physical effect of the low pressure or dehydration resulting from low moisture Calderon 1979, Friedlander andNavarro 1983).…”