Population-Mediated Responses of Lasioderma serricorne (Coleoptera: Anobiidae) to Different Diagnostic Protocols for Phosphine Efficacy.

We evaluated different monitoring protocols for phosphine resistance in adults of three populations of the cigarette beetle, Lasioderma serricorne (F.), termed LB, 2KT, and E1. The protocols evaluated were as follows: 1) the Food and Agriculture Organization (FAO) bioassay, i.e., the exposure at 30 ppm of phosphine for 20 h, 2) the dose response, based on the exposure at 50-1,000 ppm of phosphine for 3 d, 3) the Cooperation Center for Scientific Research Relative to Tobacco (CORESTA) bioassay, which is based on exposures of 4 d at 200 ppm, and, if there are surviving individuals, of 10 d at 700 ppm, and 4) Detia Degesch Phosphine Tolerance Test Kit (DDPTTK), based on the evaluation of the exposed insects for short intervals of exposure (in our case 90 min) at 3,000 ppm. From the populations tested, E1 indicated the highest survival in the FAO bioassay. Moreover, adults of this population were able to survive at 200 ppm, in the dose response, in contrast with the other populations. However, both 2KT and E1 gave similar results in DDPTTK, but only E1 had survivors after 7 d postexposure. Finally, only adults of E1 survived the CORESTA bioassay for 200 ppm and 4 d, but not for 700 ppm and 10 d. Our results show that, at least in the range of the populations tested here, there are some trends that are comparable among the different diagnostics for L. serricorne, which can be utilized further in designing a widely adopted standardized protocol.