Gerrit W. Cuperus

Immigration of insects into on-farm stored wheat and relationships among trapping methods.

Abstract Relationships among numbers of insects trapped by unbaited flight and probe traps, and grain trier and deep bin cup samples were studied in 1991 in three farm bins in North Central Oklahoma. Placement of flight traps at the eaves of bins resulted in higher insect catches than at other positions. In the grain mass, insects were more likely to be in the central core during the first weeks of storage. Insects favored the center of the grain mass, but no significant differences were found among temperatures and moisture contents at the different regions sampled. Increasing numbers of insects with depth and length of storage time combined with the capture pattern of grain insects by flight traps indicated that infestation occurred after grain binning. The most abundant species were Cryptolestes spp., Tribolium spp., Rhyzopertha dominica (F.), Ahasverus advena (Waltl) and Typhaea stercorea (L.). Action thresholds (the insect densities at which managers need to control insect populations) for the number of insects in weekly probe trap catches were 7.35 for R. dominica , 720.14 for Cryptolestes spp., and 101.34 for Tribolium spp. when compared with estimates from grain trier samples, and 8.04,749.03, and 68.14 insects per probe trap, respectively, when compared with estimates from cup samples.

Integrated Pest Management perceptions and practices and insect populations in grocery stores in South-central United States

Objectives of this study were to examine Integrated Pest Management (IPM) perceptions and practices in grocery stores, and to quantify by location, the occurrence and abundance of stored product insects. The first objective was accomplished by surveying grocery store employees of 322 grocery stores in Oklahoma, Arkansas and Texas using a 28 question survey. Grocers lacked knowledge of IPM practices, yet over half were interested in learning more about IPM. Present management practices are pesticide intensive with limited use of alternatives including sanitation, stock rotation and trapping. Presently, grocers depend on pest control companies to find and control problem insects in the store. Insects reported by grocers as problems were weevils, cockroaches, flies and ants. Extensive trapping in eight Oklahoma grocery stores targeted pet foods, cake mixes, and back room areas. Trapping studies showed stored product insects were abundant in all stores. The most prevalent insects found in traps included the Indian meal moth, Plodia interpunctella (Hubner); merchant grain beetle, Oryzaephilus mercator (Fauvel); and drugstore beetle, Stegobium paniceum (L.). Stored product insects were concentrated in pet food areas and were readily found in the stores.

Susceptibility of Eight U.S. Wheat Cultivars to Infestation by Rhyzopertha dominica (Coleoptera: Bostrichidae)

Abstract Cultivars of wheat, Triticum aestivum L., were assessed to determine their respective level of resistance to lesser grain borers, Rhyzopertha dominica (F.), in postharvest storage. Cultivars were representative of hard red winter, soft red winter, white spring, and durum wheat classes currently grown in the United States. Samples of each cultivar were maintained at 30.0°C and 70% RH and infested with 2- to 3-wk-old adult beetles for 1 wk. Adult progeny were counted at the end of one life cycle. Two temperatures, 27.0 and 34.0°C, were studied to examine the role of temperature (calculated in degree-days) in development. This experiment was conducted three times under similar conditions. Cultivars harboring a large quantity of progeny were considered more susceptible than those cultivars in which fewer progeny completed their life cycle. Each cultivar was analyzed for single kernel properties such as hardness, protein, and diameter. Wheat cultivar had a significant influence on quantity of progeny in all experiments. There were no significant effects on survivorship of progeny as a result of temperature when calculated in degree-days. Cultivars with smaller kernels were more susceptible to development of larger generation sizes in experiment 1 but not in the other two experiments. A kernel size experiment using large and small kernels from the same cultivar suggested that larger quantities of progeny are produced on small kernels compared with large kernels. Individual beetle weights were not influenced by temperature or cultivar. These results imply that stored grain managers should be aware of potential differences in susceptibility, attributable to wheat cultivar, to lesser grain borer infestations.

Influence of probe trap type and attractants on the capture of four stored-grain Coleoptera

Abstract We examined the effect of probe trap type and attractants on the capture of four insect species. Two commercially available pitfall probe traps were used. Treatments added to the traps consisted of a control, food bait, glycerol and either pheromone or pheromone-food bait combination if available. The insect species were Tribolium castaneum (Herbst), Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Cryptolestes ferrugineus (Stephens). There were significant differences in the numbers of insects collected by the two trap types. Also, the numbers of the different species captured were significantly different when compared across trap and treatment types. Species level analysis indicated that overall differences in numbers of the different species collected were largely the result of two species. A significant difference in capture resulting from any treatment occurred only for one of the four species. Different results might occur if feral insect populations were utilized or if trapping methods suitable for the warehouse environment were employed.

Model of Cryptolestes ferrugineus Flight Activity Outside Commercial Steel Grain Bins in Central Oklahoma

Abstract Unbaited sticky traps were placed on ropes in the four cardinal directions and at different heights on the outside of commercial steel bins containing stored wheat. Weekly trap catches of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), were examined. The number of traps per steel bin varied due to differences in dimensions, and three height classes were established, but there was no significant difference in trap catches of C. ferrugineus among height classes. Significant yearly and between-steel bin variation was found, and these effects were removed before using a response surface regression analysis to determine how well two time variables (daylength and day number) and three weather variables (minimum and maximum temperature and precipitation) could explain the seasonal variation in C. ferrugineus flight activity. These variables were used in separate analyses of C. ferrugineus trap catches in the four cardinal directions and from the three height classes (12 separate analyses). The most robust model fit was obtained when using a subset representing 208 C. ferrugineus trap catches from the northern side at height class 3 (traps s placed at least three-quarters of bin height). The full model of the two time variables and three weather variables explained 48% of the variance in this subset of trap catches, whereas a model based on weekly means of daylength and minimum and maximum air temperatures explained 40% of the total variance in C. ferrugineus trap catches. The relative trap catch response to daylength and minimum and maximum air temperatures was evaluated. High beetle flight activity around grain bins may indicate a high risk of insect infestation of stored wheat, and the presented model can therefore be used to determine time periods with high risk of beetle immigration into commercial steel bins.

Evaluation of Pecan Nut Casebearer Acrobasis nuxvorella (Lepidoptera: Pyralidae) Prediction Models Using Pheromone Trapping

Abstract Two existing models for predicting first entry of pecan nut casebearer (Acrobasis nuxvorella Neunzig) larvae into pecans were evaluated in Oklahoma over a 2-yr period. In 1996, the Texas model had a mean accuracy for predicting first significant nut entry of 5.2 d late, and the Georgia model estimated this same parameter 8.2 d early. Predictions for 1997 were better for both models with the Texas and Georgia models predicting first significant entry 3.2 and 4.0 d early, respectively. The Texas model was consistently late in predicting first significant entry dates in 1996 although three of the seven sites were within 1 d of the observed entry date. The Georgia model was consistently early in its prediction for 1996. Both models showed a mix of over and under predictions for 1997, possibly due in part to the severe spring freeze observed over much of the state. Based on 2 yr of data, as well as data collected in 1998, degree-day (DD) thresholds derived from the Texas model were established for the following phenological events; onset of trapping for adults using pheromone-baited traps (1,100 DD), initiation of scouting for eggs (1,500 DD), and initiation of scouting for damage (1,600 DD).