Evaluating Penetration Ability of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) Larvae into Multilayer Polypropylene Packages
The larvae of the Indian meal moth, Plodia interpunctella (Hübner), can invade or penetrate packaging materials and infest food products. Energy bars with three polypropylene packaging types were challenged with eggs (first instars), third instars, and fifth instars of P. interpunctella to determine package resistance at 28 °C and 65% r.h. The packing types were also challenged with two male and two female pupae of P. interpunctella under similar conditions in order to determine which package provided the greatest protection against larval penetration. Samples infested with eggs, third instars, and pupae were evaluated after 21 days and 42 days to count the number of larvae, pupae, and adults found inside the packages. Packages challenged with fifth instars were observed after 21 days to count the number of larvae, pupae, and adults inside each package. The number and diameter of the holes were determined in each package, followed by the amount of damage sustained to the energy bar. Third and fifth instars showed a higher tendency to penetrate all of the packaging types. First instars showed a reduction in package penetration ability compared with third and fifth instars. The increase in exposure time resulted in an increase in the damage sustained to the energy bars. Among packaging types, the thickest package (Test A) was most resilient to penetration by all of the larval stages. In conclusion, energy bar manufacturers need to invest more effort into improving packaging designs, creating thicker gauge films, or advancing odor barrier technology, in order to prevent penetration and infestation by P. interpunctella larvae.
A Survey of Stored Product Insects in Hawaii
Although stored product insects have been recorded in Hawaii since 1877, no methodical survey had been conducted. The aim of the study reported here was to determine the occurrence, distribution, frequency, and economic importance of stored product insects in Hawaii. Previous records of stored product insects in Hawaii are shown in Table 1. Bridwell (1918) considered that problems with stored product insects were of sufficient importance to warrant full time attention. The committee on common names of economic insects in Hawaii listed the following eight stored product species in 1921; (Anon. 1921) cadelle, Tenebroides mauritanicus (Linnaeus); drugstore beetle, Stegobium paniceum (Linnaeus) (listed as Sitodrepapanicea (Linnaeus)); driedfruit beetle, Carpophilus hemipterus (Linnaeus); granary weevil, Sitophilus granarius (Linnaeus) (as Sitophila oryzae (Linnaeus)); red flour beetle, Tribolim castaneum (Herbst) (as rusty flour beetle, Tribolium ferrugineum (Fabricius)); wardrobe beetle, Attagenus fasciatus (Thunberg) (as Attagenus gloriosae (Fab ricius)); tobacco moth, Ephestia elutella (HUbner) (as cereal moth); Mediterranean flour moth, Anagasta kuehniella (Zeller) (as Ephestia kuhniella Zeller).
Resistance of Polymer Films to Penetration by Lesser Grain Borer and Description of a Device for Measuring Resistance
In tests with a newly developed laboratory device for determining the resistance to penetration of flexible packaging films by adults of Rhyzopertha dominica (F.), polyurethane and polyester films were the most resistant of 18 types tested. Polypropylene and fluorinated carbon polymer films varied in resistance to penetration. Plasticized polyvinyl chloride, ionomer, cellulose propionate, polyvinyl alcohol, saran, and polyethylene-ethylene vinyl acetate copolymer films were susceptible to penetration, as were 7 types of cellophanes.