Data from: Assessing organic chemical management strategies for control of <i>Sitophilus zeamais</i> and <i>Prostephanus truncatus</i> at food facilities

<p dir="ltr"><i>Source Insects & Commodities</i></p><p dir="ltr">Unsexed adults of a field colony of S. zeamais from Eastern Kansas (collected in 2019) and unsexed adults of a colony of P. truncatus from Mexico were used in all experiments for this study. These colonies were reared and maintained on tempered organic maize (Heartland Mills, Marienthal, KS, USA) at 27.5 °C, 65% RH, and 16:8 (L:D) h photoperiod in an environmental chamber (Percival Scientific, Perry, IA, USA). Insects used in experiments were 2–3 weeks old. The commodity in the experiments below consisted of organic maize (Heartland Mills, Marienthal, KS, USA) that was frozen prior to use for 72 h to ensure it was pest free. Maize was allowed to come to room temperature prior to use and its grain moisture was 12%.</p><p dir="ltr"><i>Organic Insecticide Formulations, Insect Conditions, and Progeny Production</i></p><p dir="ltr">We selected 2 kg lots of corn and treated them with either Tersus (pyrethrins T.; 5% pyrethrins, 119.8 g/L active ingredient (a.i.), McLaughlin Gormley King Co., Minneapolis, MN, USA), Sensat (8.66% spinosad, 87.5 g a.i./L, Bayer CropScience LP, Research Triangle Park, NC, USA), Centynal EC (4.75% deltamethrin, 47.9 g a.i./L, Central Life Sciences, Schaumberg, IL), Evergreen at commercially labeled rate (e.g., pyrethrins 1x; 5% pyrethrins, 49.1 g a.i./L, McLaughlin Gormley King Co., Minneapolis, MN, USA), Evergreen at three times the commercially labeled rate (e.g., pyrethrins 3x, 147.3 g a.i./L), or H2O only (negative control) and placed grain in 5-gallon (=18.9 L) buckets (n = 3 buckets per treatment). Deltamethrin was included as a conventional control. Maize was sprayed with the following formulations using an artist’s airbrush sprayer (Badger 100 series, Badger Corporation, Franklin Park, IL, USA). Pyrethrins T. was prepared by mixing 0.468 ml of Tersus concentrate in 9.53 ml of H2O and then sprayed at a rate of 0.373 ml per 500 g of grain. Spinosad was prepared by mixing 0.077 ml of Sensat concentrate in 4.923 ml of H2O and sprayed at a rate of 0.373 ml per 500 g of grain. Deltamethrin was prepared by mixing 0.141 ml of Centynal concentrate in 4.859 ml of H2O and was sprayed at a rate of 0.373 ml per 500 g of grain. Pyrethrins 1x was prepared by mixing 0.469 ml of Evergreen concentrate in 9.53 ml of H2O and sprayed at a rate of 4.47 ml per 6 kg of grain. Pyrethrins 3x was prepared by mixing 1.406 ml of Evergreen in 8.59 ml of H2O and sprayed at a rate of 4.47 ml per 6 kg of grain. The water control was sprayed at a rate of 4.47 ml of H2O per 6 kg of grain and was considered the untreated control. There were three separate formulation events prepared for each insecticide treatment, and therefore each bucket was considered an independent replication. Buckets of treated maize were placed in a 110-MT capacity grain bin on 12 Sep 2024. Temperature and RH were monitored with Hobo dataloggers (Onset Computer Corp, Bourne, MA, USA) every 5 min for the sampling period. After one week (initial) and after seven months, we collected n = 6 replicate vials filled with 80 g samples from each treatment bucket (n = 18 total replicates). A total of 25 P. truncatus or S. zeamais were added to each sample. After an exposure time of 24 h and 168 h, the condition of each individual was evaluated. Condition was rated as alive, affected, and dead (after Morrison et al. 2018 and Ranabhat et al. 2022). Briefly, alive individuals were moving normally in species-specific patterns with no aberrations, while dead adults were completely immobile (no twitching of limbs, even after prodding). Affected adults comprised those in between those two extremes, often exhibiting twitching of extremities and antennae, an inability to right self when on back, or slow, erratic movements. Immediately after each condition assessment, the first individual to be rated as alive or affected out of 25 was selected from each sample for Ethovision analysis (n = 6 replicates per treatment, species, residual time, and exposure time). Following the final condition assessment and Ethovision trials, we removed all adults from each sample vial and retained the vials for 6 weeks to evaluate progeny production (number of adults emerging from the maize kernels).</p><p dir="ltr"><i>Movement Tracking with Ethovision</i></p><p dir="ltr">To assess the insecticide effect on insect mobility, individuals classified as either alive or affected was selected from each replicate in every residual period and exposure time for each species and tracked with a network camera (Basler AG, Ahrensburg, Germany) coupled with Ethovision XT (v. 16.0, Noldus Software, Leesburg, VA, US). Insects were placed separately into arenas consisting of 90-mm Petri dishes lined with 85 mm Whatman #1 filter (GE Healthcare, Chicago, IL, USA). All insecticide and control treatments were represented in every round of Ethovision. The camera was placed 80 cm above the arenas, and trials lasted 30 min. At the end of the trial, the total distance moved (cm), the average instantaneous velocity (i.e., speed with a direction, cm/s), frequency entering a mobile state, and cumulative duration spent mobile was recorded. To account for cursor bounce, an input filter was applied that discarded the accumulated distance if it was >5 cm/s. Each trial was manually checked for irregularities, and any with suspicious accumulations of distance were re-run. There was a total of n = 6 replicate individuals per treatment combination, totaling to 8,970 min of video for 299 individuals for both species.</p>

Tags: aged-residues, bayer, bostrichidae, centynal, cgahr, coleoptera, conventional-insecticides, curculionidae, deltamethrin, ethovision, evergreen, food-facilities, integrated-pest-management, ipm, larger-grain-borer, longevity, maize-weevil, mgk, mortality, movement, omri, organic, organic-insecticides, progeny, progeny-production, prostephanus-truncatus, pyrethrins, sensat, sitophilus-zeamais, species-of-concern, spinosad, sublethal-effects, tersus, usda
Organization: Department of Agriculture