Economically speaking, Plodia interpunctella
, the Indianmeal moth, may be the most important pest of dried goods in homes and food storage facilities world wide. The larvae feed on a broad range of grains and dried goods, including seeds, dried fruit, rice, pasta, bread, dog food, and spices. The larvae spin a web over the surface of the food source and feed within this web, which also accumulates frass and sheddings. Flying adults moths are signs of an infestation. The adults do not feed, just live to mate and lay between 50-400 eggs in available dried foods. Larvae go through five instars and grow to about 1 cm long. Mature larvae often travel quite a distance to find an appropriate pupation spot, generally away from their food source (pupae and cocoons are often found under cabinets or on ceilings).
In homes or in low-level infestations, Plodia interpunctella
males can be trapped in pheromone traps, disrupting mating and thus managing the problem. Pheromone traps use chemically-synthesized mimics of pheromones that female P. interpunctella
emit to attract males when they are ready to breed. Attracted males get stuck in sticky paper inside the trap. For large infestations, pheromone traps are useful for monitoring Indianmeal moth populations, but traps get overwhelmed easily and so traps are not adequate to control the poplulation. Such large infestations can be more difficult to control. Laboratory studies have shown P. interpunctella
to develop resistance quickly to Bacillus thuringiensis
(Bt), a common bacterial control of insect pests, and also to chemical fumigants (e.g. malathion and dichlorvos). Growth regulators have been tried, but are not effective at controlling populations of the larvae. More integrative approaches combine chemicals with freezing or heating infested food products, sanitary conditions, and keeping food in well-sealed containers to effectively control Indianmeal moth populations.
(Fasulo and Knox 2009
; Mohandass et al. 2007)