Effective use of a growth-inhibiting sheet containing pyriproxyfen for cigarette beetle <i>Lasioderma serricorne</i> larvae: an implication from sheet shape and flour-food accumulation

Growth-inhibiting sheets containing pyriproxyfen have recently been developed to control the cigarette beetle Lasioderma serricorne. In this study, we evaluated effective use of a commercially available sheet through a rearing experiment in which the distribution of whole-wheat flour as a food and the shape of the sheet were manipulated. The results based on three replications indicated that the sheet effectiveness decreased by 0.51 times with each 1 cm increase in the flour depth on average, and that the effect was weakened by 0.58 times under conditions where the sheet shape did not match with the coverage of the flour. We also detected a 4.06-fold greater risk of allowing the individuals to develop from larvae into adults when the sheet shape was not matched compared to when it was matched. These findings suggest that an application covering the targeted area by the sheet without any gaps is essential to qualitatively and quantitatively prevent any development of the larvae.