Laboratory evaluation of two insecticide-incorporated nets for the management of <i>Prostephanus truncatus</i> (Horn) (Coleoptera: Bostrichidae)

The invasive larger grain borer (Prostephanus truncatus) is a major pest of stored maize and threatens to expand its range under climate change. With the phase-out of methyl bromide and increasing resistance to phosphine, the most commonly used fumigant, there is a need for alternative management tactics. Here, we present an evaluation of the effectiveness of 2 types of insecticide-incorporated nets (0.4% deltamethrin, D-Terrence, Vestergaard, Lausanne, Switzerland; and 0.34% alpha-cypermethrin, Carifend, BASF Ag, Ludwigshafen, Germany) against adults of P. truncatus. To do this, we evaluated mortality in Petri dishes that had been lined with the 2 netting types. Netting of both types with no insecticide treatment served as the control. Twenty adults were placed into each dish, and insects were exposed for 60, 90, 120, 240 min, 1, 3, and 5 d. Mortality was immediately measured at the end of the exposure time, and delayed mortality after exposure to a clean food source was then evaluated after 7 d. Both long-lasting insecticide-incorporated netting types were effective for controlling P. truncatus. Carifend was 4.6 times more effective than the control, and D-Terrence was 8 times more effective than the control in terms of mortality. Overall, D-Terrence provided better efficacy in terms of mortality and a quarter fewer adults alive after 7 d with supplemental food compared to Carifend. Our study highlights the effectiveness of insecticide-incorporated nets as an alternative pest management tactic.