Effects of Short Exposures to Spinosad-Treated Wheat or Maize on Four Stored-Grain Insects

Efficacy of alpha-cypermethrin and thiamethoxam against Trogoderma granarium Everts (Coleoptera: Dermestidae) and Tenebrio molitor L. (Coleoptera: Tenebrionidae) on concrete

“…One moderating factor to this effect is the scenario of "delayed mortality" which is the mortality that occurs after the removal of the insects from the exposure to the toxic agent. Athanassiou et al (2010) found that adults of R. dominica that had been exposed on grains treated with spinosad for 48 h were dead 7 d after their removal from the treated substrate and their placement on untreated grains. Similar results have been reported in the case of spinetoram (Vassilakos and Athanassiou, 2012).…”

Efficacy of partial treatment of wheat with spinosad against Rhyzopertha dominica (F.) adults

“…Exposing R. dominica adults to this rate for 14 d caused a significant reduction in progeny production. Moreover, a brief exposure to spinosad residues is sufficient to cause mortality of R. dominica adults which is typically manifested as delayed toxicity, even after removal of adults from treated grain (Getchell and Subramanyam, 2008;Athanassiou et al, 2010;Boina et al, 2012). Athanassiou et al (2009) reported that 83% of R. dominica adults were dead in 14 d when they were released on surface of wheat kernels in a plastic vial in which only the top 1/8th layer was treated with spinosad.…”

“…However, adults surviving until day 7 in grains with uneven distribution of insecticide could still mate and lay eggs as well as continue further infestation and grain damage (Athanassiou et al, 2010). The results of the present study indicated that treating all wheat kernels in a grain mass at a rate 10 times lower than labeled (0.1 mg kg À1 ) or treating <50% of kernels at labeled rate results in survival of adults for a longer period of time than treating all kernels at labeled rate.…”

Geographic variation in cypermethrin insecticide resistance and morphometry in Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

“…The proportion of the total population sprayed determines the extent to which insecticide resistance may evolve in an area [20] . Untreated areas may act as refugia providing susceptible or at least less resistant individuals, which have the potential to dilute insecticide resistance after breeding with resistant individuals, resistant gene frequencies remaining at an acceptable level for successful control [21] . Moreover, resistant individuals positively selected in sprayed areas are often counter selected in those refugia due to fitness cost associated with the resistance mechanism.…”