Rapid Response Arthropod Diagnostic Services

Linda Benedict, Pollet, Dale K., Carlton, Christopher E.  |  12/11/2007 2:56:56 AM

Red imported fire ants. (Photo by Michael A. Seymour.)

Christopher Carlton, Victoria Bayless and Dale Pollet

The first step in successfully dealing with insect-related problems, whether in urban or agricultural settings, is identifying the organisms. In this context, “insect” refers to all arthropod groups, with insects being the most diverse of several classes of arthropods, which include spiders, mites, scorpions and their relatives.

With about 95,000 species of insects in North America alone, identification requires a high level of expertise in taxonomy – the practice of classifying plants and animals according to their natural relationships. In addition, maintaining a collection requires specialized techniques in curating. Diagnosticians rely on well-curated collections of reference specimens and taxonomic literature to provide timely identification and evaluation of samples, photographs or descriptions submitted by citizens and first responders.

Historically, taxonomy services in Louisiana have been handled through the Louisiana State Arthropod Museum (LSAM) in the LSU AgCenter’s Department of Entomology, while diagnostic and control questions have been handled through AgCenter extension faculty. The merger of extension and research faculties within the Department of Entomology has facilitated coordination between these two overlapping responsibilities and has improved the speed of delivering information to end users.

In addition, the dramatic increase in public access to information technology during recent years has revolutionized the speed of delivery of insect diagnostic information.

During 2004-2006, the staff of the LSAM processed more than 150 requests for insect diagnostic information per year. They use electronic data sources, digital photographs and Internet resources in combination with the insect collection to serve Louisiana’s needs for rapid, accurate information about current and potential pests.

Diagnostic services for urban pest management
Requests to identify and evaluate potential pests in urban settings mainly involve known or suspected structural, stored-product, lawn-and-garden or household nuisance pests. Major pests – subterranean termites for example – are handled by research specialists or trained pest control operators. Structural pests that require a higher level of taxonomic expertise include the numerous species of powder post beetles. Infestations of these pests often have legal ramifications for contractors and lumber suppliers. Correct species identification is critical because liability issues may depend on details of life history or geographic origins that differ among species.

Likewise, correct identification of stored-product pests is critical to tracking sources of infestations in homes, factories and warehouses. Suspected household pests include mole crickets, cicada killer wasps, convict caterpillars, lace bugs, long horned beetles emerging from firewood, cigarette and drugstore beetles, ants of all kinds, lady beetles and their larvae, assassin bugs, solitary bees, fire brats and various scale insects.

One of the challenges involving inquiries about suspected pests in  urban settings is correctly evaluating whether the species involved represents an incidental, non-threatening occurrence or whether it signifies a persistent population that presents a nuisance or more serious kind of threat. Identifying the species involved helps to determine if control measures need to be taken.

Medical/veterinary concerns  
Medical and veterinary diagnostic work overlaps broadly with urban issues because many of the insects that may be simple nuisances or curiosities in some contexts have implications to human health in others. Assessing the context of the inquiry and advising homeowners accordingly is an important part of diagnostic work. For example, while assassin bug inquiries are often from gardeners curious about what the insects are doing in the garden, these same species are also capable of delivering a painful bite. A limited number of rarely encountered assassin bugs may also serve as vectors of Chagas disease – a serious, debilitating tropical disease. Again, knowing the species involved is essential to understanding the level of action warranted.

Inquiries from veterinary and health care workers generally involve unusual and infrequent situations. Examples include identification of the organism that causes paederine dermatosis, a skin inflammation from a particular kind of staphylinid beetle, and identifying suspected blister beetles following livestock toxicity from contaminated hay.

Private citizens usually request identification about stinging or biting insects and spiders. Their concerns most frequently involve suspected brown recluse or brown widow spiders and buckmoth caterpillars. In addition, there are each year several cases of delusory parasitosis, a mental health condition characterized by imaginary infestations by biting or otherwise-tormenting organisms. These sufferers often provide samples containing household dust and skin debris, but they almost never contain organisms. These difficult cases often require referral to mental health providers. In other cases, simply reassuring individuals that, in fact, their suffering is not caused by any organism is sufficient to put them on a path to recovery.

Public education  
One of the most rewarding aspects of insect diagnostic work is providing information that educates the public about the importance of insects and related arthropods to ecosystem function and their relevance to daily life. This is also the most rapidly expanding area of insect diagnostics due in large part to growing public access to digital technology and home-based Internet communication.

Many of these inquiries are predictable based on the seasonal cycles of species. For examples, inquiries about the identity of the large, subtropical golden silk orb-weaver spiders and the beautiful scarlet-bodied wasp moth come in late summer and early fall. Spring brings questions about forest tent and whitemarked tussock moth caterpillars, and summer brings inquiries about a diversity of entomological curiosities and oddities. Most of these questions are motivated by curiosity and a desire to learn rather than by concern, fear or a perceived need to eliminate the creatures.

Entomology museums in the information age
Electronic information transmission, storage and retrieval and the availability of vast amounts of entomological information on the Internet have revolutionized the process of inquiry evaluation and delivery of information in insect diagnostics. But nothing can replace the entomology museum as a central library of information about the identification, life histories and distributions of the vast diversity of insects and related arthropods.

Faculty in the LSU AgCenter museum are in the process of creating a database of more than 750,000 specimens in the collection. This will provide immediate access to detailed data about all collection species, including the estimated 15,000 species of insects found in Louisiana. This project will help facilitate delivery of fast, accurate taxonomic information to citizens of Louisiana.

Christopher Carlton, Professor and Director, and Victoria Bayless, Research Associate and Curator, Louisiana State Arthropod Museum, Department of Entomology, LSU AgCenter, Baton Rouge, La., and Dale Pollet, Professor, Department of Entomology, LSU AgCenter, Baton Rouge, La.

(This article was published in the fall 2007 issue of Louisiana Agriculture.)
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