Richard T. Arbogast

Monitoring Insect Pests in Retail Stores by Trapping and Spatial Analysis

Abstract Stored-product insects are a perennial problem in retail stores, where they damage and contaminate susceptible merchandise such as food products and animal feed. Historically, pest management in these stores has relied heavily on chemical insecticides, but environmental and health issues have dictated use of safer methods, and these require better monitoring. A monitoring procedure that employs an array of moth and beetle traps combined with spatial (contour) analysis of trap catch was tested in three department stores and two pet stores. The rate of capture increased with the level of infestation but was essentially constant over 4- to 5-d trapping periods. Contour analysis effectively located foci of infestation and reflected population changes produced by applications of the insect growth regulator (S)-hydroprene. The most abundant insects were Plodia interpunctella (Hübner), Lasioderma serricorne (F.), Oryzaephilus mercator (Fauvel), Tribolium castaneum (Herbst), and Cryptolestes pusillus (Schönherr). The results indicate that contour analysis of trap counts provides a useful monitoring tool for management of storage pests in retail stores. It identifies trouble spots and permits selection, timing, and precision targeting of control measures to achieve maximum pest suppression with minimum pesticide risk. It permits managers and pest control operators to visualize pest problems over an entire store, to monitor changes over time, and to evaluate the effectiveness of control intervention. The contour maps themselves, along with records of control applications and stock rotation, provide permanent documentation of pest problems and the effectiveness of pest management procedures.

Stored‐product insects in a flour mill: population dynamics and response to fumigation treatments

In a wheat flour mill, seasonal trends in stored‐product insect trap capture, relationships between trap captures inside and outside the mill, and between pheromone trap capture and product infestation, and the impact of fumigation on pest populations, were assessed. Mark‐recapture was used to evaluate the potential for movement of insects outside the mill into the mill. For Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) and Trogoderma variabile Ballion (Coleoptera: Dermestidae), pheromone trap captures outside were higher than inside the mill, and when inside and outside trap captures were correlated, both indoor and outdoor trap captures tended to cycle according to a seasonal pattern; fumigations did not consistently influence pheromone trap captures, and in only one instance were they found in product samples. Mark‐recapture data indicated that P. interpunctella was capable of entering the building from outside. Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) trap captures, in contrast, tended to be lower outside compared to inside, followed a pattern of sharp decline after fumigation treatment, and then steadily increased (0.002–0.005 beetles/trap/day) until the next fumigation. This pattern, other than potentially the rate of increase, was not impacted by season and outside trap capture levels. Tribolium castaneum was the primary species infesting the product. The information generated in this study provides some of the information needed to develop improved monitoring and management programs.

Long-Term Monitoring of Tribolium castaneum in Two Flour Mills: Seasonal Patterns and Impact of Fumigation

ABSTRACT Data from long-term Tribolium castaneum (Herbst) pheromone trapping programs in two flour mills was used to evaluate the impact of structural fumigations (n = 23) on pest populations. The two mills differed in mean number of beetles captured and proportion of traps with captures of one or more beetles, but in one of the mills the mean number of beetles captured was reduced after implementing a more intensive integrated pest management program. Mean number of beetles per trap and proportion of traps with captures increased by 52.7 ± 8.2 and 24.8 ± 4.7% from one monitoring period to the next but decreased by 84.6 ± 4.6 and 71.0 ± 5.1% when fumigation occurred between periods, respectively. Mean number of beetles per trap and proportion of traps with captures immediately after fumigation were both positively correlated with number captured per trap and proportion of traps with captures in the monitoring period immediately before fumigation. Mean daily air temperature inside the mill fluctuated with the season, and although always warmer than the outside temperature, the relative difference varied with season. Relationship between inside and outside temperature could be explained well by an exponential equation with the parameters a = 20.43, b = 2.25, and c = -15.24 (r2 = 0.6983, which is 94% of the maximum r2 obtainable). Although outside temperature differed between spring and fall fumigations, inside temperature and reduction in beetle captures was not affected by season. A better understanding of pest populations and the impact of structural treatments within commercial food facilities is critical for improving the management of pest populations and for the adoption of methyl bromide alternatives.

Multitrophic interaction facilitates parasite–host relationship between an invasive beetle and the honey bee

Colony defense by honey bees, Apis mellifera, is associated with stinging and mass attack, fueled by the release of alarm pheromones. Thus, alarm pheromones are critically important to survival of honey bee colonies. Here we report that in the parasitic relationship between the European honey bee and the small hive beetle, Aethina tumida, the honey bees alarm pheromones serve a negative function because they are potent attractants for the beetle. Furthermore, we discovered that the beetles from both Africa and the United States vector a strain of Kodamaea ohmeri yeast, which produces these same honey bee alarm pheromones when grown on pollen in hives. The beetle is not a pest of African honey bees because African bees have evolved effective methods to mitigate beetle infestation. However, European honey bees, faced with disease and pest management stresses different from those experienced by African bees, are unable to effectively inhibit beetle infestation. Therefore, the environment of the European honey bee colony provides optimal conditions to promote the unique bee–beetle–yeast–pollen multitrophic interaction that facilitates effective infestation of hives at the expense of the European honey bee.

Insect infestation of a botanicals warehouse in north-central Florida.

The insect populations of a botanicals warehouse in north-central Florida were studied to gain a better understanding of insect problems associated with stored botanicals and to identify measures that could be taken to mitigate the problems. The warehouse contained either dried saw palmetto berries, Serenoa repens (Bartram) Small, or dried passion-flower (maypop) vines, Passiflora incarnata (L.), depending on the season. Insect populations were monitored intermittently for one year using arrays of moth and beetle traps. Capture rate, relative abundance, and spatial distribution of different species were examined over time. The six most abundant species in order of abundance were: Cadra cautella (Walker), Lasioderma serricorne (F.), Oryzaephilus mercator (Fauvel), Typhaea stercorea (L.), Plodia interpunctella (Hubner), and Tribolium castaneum (Herbst). All of these appear capable of infesting saw palmetto, but the major pests were C. cautella and L. serricorne. Oryzaephilus mercator and P. interpunctella were also important, but T. castaneum and T. stercorea were minor. Passion-flower was a less suitable host than saw palmetto for all of the species except T. stercorea. Nevertheless, all of the six species infesting saw palmetto except O. mercator were captured in numbers sufficient to indicate that they were also capable of infesting passion-flower. Lasioderma serricorne was the major pest. Spatial analysis of trap captures revealed that the insect distributions changed as different botanicals were brought in, removed, or redistributed in the storage area. Potential measures to mitigate insect problems in stored botanicals are discussed, including spatial targeting of insect control and sanitation efforts.

Long-term monitoring of Tribolium castaneum populations in two flour mills: rebound after fumigation.

ABSTRACT Structural fumigations of food processing plants to manage stored-product insects has been a major component of pest management programs, but limited information on field efficacy is available. Efficacy, based on pheromone trapping data, consists of initial reduction in captures after treatment and rebound in trap captures over time. Pattern of Tribolium castaneum (Herbst) rebound was evaluated after 21 fumigations in two flour mills. Rebound in mean number of beetles captured and the probability of a trap capturing one or more beetles was evaluated. Rebound to a threshold mean beetle capture of 2.5 beetles per trap per 2-wk period took 174 ± 33 d and rebound took longer after fall (248 ± 50 d) than spring (104 ± 21 d) fumigations. Rebound to the probability of capture threshold of 0.50 was 120 ± 21 d, but there was no significant effect of season. Improvement in integrated pest management (IPM) practices in one of the mills was associated with an increase in time to reach mean beetle capture threshold (49 ± 15 d before and 246 ± 71 d after) but not in time to reach the probability of capture threshold (38 ± 14 d before and 165 ± 46 d after). There was a negative correlation between number captured after fumigation and time to rebound to threshold. After improved IPM there was a significant reduction in the number of beetles per trap immediately after fumigation. Above these two thresholds the degree of change in trap captures is significantly greater than below, which suggests they might be useful in evaluating risk in a pest management program.

Relative humidity: Its importance in the control of stored-product insects with modified atmospheric gas concentrations

Abstract Adults of Tribolium confusum Jacquelin duVal and T. castaneum (Herbst) (Coleoptera: Tenebrionidae) and Oryzaephilus surinamensis (L.) (Coleoptera: Cucujidae) were exposed at four relative humidities to binary mixtures of oxygen and nitrogen or to ternary mixtures of oxygen, nitrogen, and carbon dioxide. In most instances, mortality increased with decreased relative humidity when the insects were exposed for limited periods of time to either the binary or the ternary mixtures.

Insect infestation of farm-stored maize in South Carolina: Towards characterization of a habitat

Protecting stored grain from insect damage, with minimum pesticide risk, will require pest management based on comprehensive understanding of storage environments and their interactions with pest populations. Computer modeling offers the means to this understanding. To obtain data sets for modeling selected pests of stored maize, we studied maize storages on six farms in a four-county area of southwestern South Carolina. Grain moisture content was measured monthly, and grain temperatures were recorded hourly for one storage season. Insect populations were monitored by taking grain and pitfall trap samples at weekly or monthly intervals. Hourly mean grain temperatures remained below optimal levels for growth and development of insects during most of the storage period. Grain moisture content varied from 11.2 to 16.4%. Forty three species of insects and one species complex, representing 26 families in four orders, were detected. The estimated importance of each species in the farm storage habitat, as measured by relative abundance and frequency of occurrence, depended on whether grain sampling or trapping was used. With trapping, Cryptolestes species (mostly C. pusillus (Schonherr)), the Carpophilus dimidiatus complex (C. dimidiatus (F.), C. freemani Dobson and C. mutilatus Erichson), Sitophilus species (mostly S. zeamais Motschulsky), Xylocoris flavipes (Reuter) and Oryzaephilus surinamensis (L.) appeared most important. With grain sampling, S. zeamais, Sitotroga cerealella (Olivier) and C. pusillus appeared most important. Insects were most abundant (or active) in the fall and again in the spring, if storage extended that long. Grain samples indicated more insects near the grain surface, but traps sometimes detected more near the bottom of the bulk.

External morphology of some eggs of stored-product moths (Lepidoptera pyralidae, gelechiidae, tineidae)☆

The eggs of closely related stored-product moths are difficult or impossible to separate by light microscopy. Although the scanning electron microsocpe (SEM) reveals details of the chorion that are useful in determining species, no comparative SEM studies of these eggs have been published. A study was therefore undertaken to determine the features of chorionic sculpturing that are useful in identifying the eggs of stored-product moths and to construct a taxonomic key to some of the more important species. Surface features of the chorion considered in conjunction with overall shape were adequate to separate all the species examined. The most useful diagnostic characters included the pattern of ridges, carinae, and cells; the structure of the aeropyles; and the texture of the chorion on the cell discs. Following are diagnostic characters for the 10 species studied: The egg of Sitotroga cerealella is fusiform, truncate at the anterior end, and marked by a reticulate pattern of prominent longitudinal ridges joined by lesser cross ridges. That of Tineola biselliella is subcylindrical and marked by a pattern of irregular polygons; the primary cells are oval to nearly circular, and the aeropylar openings are unguarded. The eggs of Galleria mellonella and Achroia grisella are also marked by irregular polygons. These eggs, however, are spheroid, ellipsoid, ovoid, or obovoid; the primary cells are wedge-shaped with rounded outer margins; and the aeropylar openings are surrounded by distinct collars. In G. mellonella, the pattern of polygons is at least faintly visible over the entire surface and the carinae surrounding the primary cells are of uniform width, but in A. grisella the pattern is limited to the anterior end and the carinae are conspicuously broader around the outer margins of the primary cells. The eggs of the remaining species are marked by reticulate patterns of intersecting sinuous ridges. The cell discs of Plodia interpunctella and Anagasta kuhniella are roughened by numerous small excrescences, and most of the ridges bear carinae along their crests. In P. interpunctella, the excresences are rounded, the carinae are prominent and more or less continuous over the entire surface, and the primary cells are subequal. In A. kuhniella, the excresences are sharp edged, the carinae are weak and often disconnected, and some of the primary cells are much larger than others and overlap the ends of adjacent cells. The cell discs of Cadra figuldella, Ephestia cautella, Ephestia elutella, and Corcyra cephalonica are smooth. In C. figuldella, E. cautella, and E. elutella, the ridges lack carinae except in the micropylar area and there are prominent tubercles at most ridge intersections. Cadra figuldella has widely spaced ridges and broad cell discs, while the Ephestia species have closely spaced ridges and restricted cell discs. The aeropylar openings of E. elutella are surrounded by distinct collars, but those of E. cautella are unguarded. The eggs of C. cephalonica lack prominent tubercles; carinae extend well beyond the micropylar area on the anterior end, and there are a few short carinal segments on the posterior end.

Evaluating Light Attraction to Increase Trap Efficiency for Tribolium castaneum (Coleoptera: Tenebrionidae)

ABSTRACT The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a major coleopteran pest in flour mills and storage facilities. An aggregation pheromone has been identified for this pest; however, the pheromone is of limited value for population monitoring. To develop more efficient methods to monitor this pest, experiments were conducted to determine whether light functioned as an attractant for the red flour beetle. Light-emitting diodes (LEDs) of various wavelengths were examined as light sources because they produce bright, narrow light spectra. A comparison of responses to light spectra across the visible and UV regions of the electromagnetic spectrum indicated that the beetle was most attracted to near UV LED at a 390 nm dominant wavelength. The use of LEDs in competitive laboratory experiments resulted in a 20% capture of released beetles, compared with a 1% capture with the aggregation pheromone alone. Even more beetles were captured with a combination of LEDs and commercially available chemical lures in traps. LEDs can easily be added onto existing trap designs or new traps can be designed to take full advantage of positive phototaxis.