ABSTRACT
The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a common pest in rice mills. With limited information in the literature addressing T. castaneum in rice processing facilities, we examined the spatial and temporal distribution of T. castaneum inside and outside of three commercial rice milling facilities and one rice packaging plant from June 2012 to August 2014 using pheromone-baited dome traps. Each mill had very different population trends with fewer numbers collected in rough rice storage areas. T. castaneum were more commonly collected in processing areas. Beetle infestation at all the mills was evaluated using the threshold of mean beetle capture of 2.5 beetles per trap per 2 wk period. Trap captures were below threshold for all but one facility. Temperatures inside were ~1°C warmer than outside temperatures, with these temperature differences more noticeable during cool months (October-March). Higher numbers of T. castaneum were captured in 2012 in comparison to 2013, with higher beetle numbers observed during warmer (April-September) than cooler months. With variation in trap capture of T. castaneum occurring among all facilities, this study illustrates that having a monitoring program designed for each facility is important to help managers decide when and where to apply pest management tactics. The use of pheromone traps could provide information to mill managers to find locations within a mill that are most vulnerable to infestation by T. castaneum, and to assist with the timing of control interventions.
Subject(s)
Coleoptera , Oryza , Tribolium , Animals , Insect Control , PheromonesABSTRACT
This study was conducted at Oklahoma State University, Stillwater, OK, to evaluate the response to deltamethrin concentrations for adults of three stored-product insects, Tribolium castaneum (Herbst), Sitophilus oryzae (L.), and Rhyzopertha dominica (F.). In insect toxicological studies, knockdown is the state of intoxication and partial paralysis as a result of exposure to an insecticide. Deltamethrin concentrations ranging from 0.48 to 140 mg/m(2) (1 to 3,000 ppm) were sprayed on glass Petri dishes. After the dishes dried, 20 adult insects of each species were placed on the treated dishes to determine the contact toxicity of deltamethrin. Assessments for knockdown were made at 15-min intervals for up to 8 h after initial exposure and then again after 24 or 48 h. Insects were then transferred to clean untreated Petri dishes with diet and observed from 0.5 to 72 h. Mortality was assessed 72 h after transfer to untreated dishes with food material. Deltamethrin was highly effective against all three species tested and achieved 99% knockdown of insects of all species within 4 h after exposure at concentrations ≥1.2 mg/m(2) Although some insects recovered from initial knockdown at concentrations ≤48 mg/m(2), nearly all the insects were killed at 140 mg/m(2) when exposed for 48 h. LC95 values for all species tested, for the 48-h exposure period, were <140 mg/m(2), the concentration of deltamethrin that could potentially be present in new ZeroFly Storage Bag fabric. ZeroFly bags are used for stored-product insect pest control.
Subject(s)
Coleoptera , Insect Control , Insecticides , Nitriles , Pyrethrins , Animals , Dose-Response Relationship, Drug , Tribolium , WeevilsABSTRACT
Several physical and chemical attributes of rice were evaluated to determine which character would be best to use to assess multiple rice varieties for resistance to the lesser grain borer, Rhyzopertha dominica (F.). Laboratory tests were conducted on single varieties of long-, short-, and medium grain-rice to develop procedures and methodologies that could be used for large-scale screening studies. Progeny production of R. dominica was positively correlated with the percentage of broken hulls. Although kernel hardness, amylose content, neonate preference for brown rice, and adult emergence from neonates varied among the three rice varieties tested they did not appear to be valid indicators of eventual progeny production, and may not be useful predictors of resistance or susceptibility. Soundness and integrity seem to be the best characters to use for varietal screening studies with R. dominica.