But newly published research by UC Davis agricultural entomologist Christian Nansen and insect physiologist Michael Strand of the University of Georgia reveals a new, non-destructive and quite accurate method to characterize physiological responses to parasitism: proximal remote sensing or body reflectance response data.
They published their research, “Proximal Remote Sensing to Non-Destructive Detect and Diagnose Physiological Response by Host Insect Larvae to Parasitism,” Dec. 4 in the journal Frontiers in Physiology.
Nansen, first author of the paper and an associate professor in the UC Davis Department of Entomology and Nematology, specializes in insect ecology, integrated pest management and remote sensing. Strand, a professor of entomology at the University of Georgia, is an international authority on the physiology of insect parasitism.
The scientists studied two common parasitic wasps or parasitoids, Microplitis demolitor, and Copidosoma floridanum, which lay their eggs in the larval stages of the soybean looper moth, Chrysodeixis includens. The pest, found throughout much of North and South America and elsewhere, feeds on soybeans.
“Based on reflectance data acquired three to five days post-parasitism, all three treatments (control larvae, and those parasitized by either M. demolitor or C. floridanum) could be classified with more than 85 percent accuracy,” they wrote.
Due to parasitism-induced inhibition of growth, “it's easy to differentiate soybean loopers parasitized by M. demolitor from non-parasitized larvae as long as the developmental stage of the host larva is known,” they said. In addition, a single M. demolitoroffspring emerges from the host larva 7-9 days post-parasitism to pupate, while non-parasitized larvae continue to increase in size to the final instar.
Copidosoma floridanum minimally alters host growth until late in the final instar, when thousands of wasp progeny complete their development. This wasp is known for having the largest recorded brood—3,055 individuals--of any parasitoidal insect.
The researchers said that the accuracy rate of more than 85 percent holds promise. “The hyperspectral proximal imaging technologies represent an important frontier in insect physiology, as these technologies can be used non-invasively to characterize physiological response across a range of time scale factors, such as minutes of exposure or acclimation to abiotic factors, circadian rhythms, and seasonal effects. Although this study is based on data from a host-parasitoid system, results may be of broad relevance to insect physiologists.”
Both of the wasps they studied are idiobionts and endoparasitoids.
Nansen noted that “many species of minute wasps are parasitoids of eggs and larvae of other insects, and parasitism represents one of the most extreme life strategies among animals”
“Living inside the body of another animal,” he said, “poses a series of non-trivial challenges, including how to overcome/suppress the defense response by the host; how to obtain oxygen; how to feed on the host without killing it--because once the host is dead, then microbial organisms and general decomposition will make the host body unsuitable--and how to manage waste.”
Nansen likened the developing parasitoids to astronauts flying in a space capsule. “A developing parasitoid faces a long list of serious practical challenges, so the evolutionary selection pressure has been immense and lead to some of the most extreme cases of co-evolution.”
And those soybean loopers? Those major pests of soybeans? Thanks to this research, we now know more about physiological responses to parasitism--and there's more to come. (We're also admiring the amazing photography of Jena Johnson!)
As the researchers said: "The hyperspectral proximal imaging technologies represent an important frontier in insect physiology."
Mosquitoes will take the spotlight, front line and center, this month.
On Wednesday, April 8, Regents Professor Michael Strand of the University of Georgia, Athens, and internationally recognized for his research on parasite-insect host interactions, will speak on "The Role of Microorganisms in Growth, Development and Reproduction of Mosquitoes” at the UC Davis Department of Entomology and Nematology seminar from 12:10 to 1 p.m. in 122 Briggs.
Next the Pacific Branch of the Entomologist Society of America (PBESA) will honor medical entomologist Thomas W. Scott, distinguished professor of entomology, UC Davis Department of Entomology and Nematology, at its 99th annual conference, April 12-15, in C'ouer d'Alene, Idaho. He will receive the coveted C. W. Woodworth Award for his outstanding work on dengue, a mosquito-transmitted disease.
And then on Friday, April 24, UC Davis will co-host the fourth annual Bay Area World Malaria Day Symposium, set from 8 a.m. to 4 p.m., Friday, April 24 on the Clark Kerr campus, UC Berkeley. UC Davis and Zagaya, a non-profit organization that envisions a malaria-free world, are partnering on the project.
Michael Strand Seminar April 8
Professor Strand's talk is much anticipated. "Mosquitoes are well recognized as the most important arthropod vectors of disease-causing pathogens," Strand says in his abstract. "Interest in the gut microbiota of mosquitoes has risen recently as a potential tool for manipulating vector competency. In contrast, much less is known about the role of this community in mosquito growth, development and reproduction. In this talk I will discuss recent results from our lab group regarding the composition of the gut microbiome in different mosquito species and insights we have gained about the function of this community in mosquito biology and evolution."
Strand focuses his research in the areas of parasite-host interactions, virology, immunity and development. Current projects center on virus-host interactions, function of the insect immune system, and regulation of reproduction in mosquitoes and other insects.
Strand will be introduced by molecular biologist Shirley Luckhart, professor in the Department of Medical Microbiology and Immunology School of Medicine, and co-director of the UC Davis-based Center for Vector-borne Diseases (CVEC).
Talk will turn to dengue at the PBESA meeting in Co'eur d'Alene, Idaho. Professor Scott, who has researched mosquito-borne disease for 35 years and is retiring in June, is a global authority on the epidemiology of mosquito-borne disease, mosquito ecology, evolution of mosquito-virus interactions, and evaluation of novel products and strategies for mosquito control and disease prevention. Among the top vector biologists in the world, he is recognized as the leading expert in the ecology and epidemiology of dengue.
Scott is known for his holistic and comprehensive approach in finding solutions to protect the world's population from dengue, a disease that infects some 400 million per year. Some 4 billion people in 128 countries, more than half of the world's population, are at risk for dengue. Currently no vaccine or drug is effective against this life-threatening disease.
Scott's most significant research contributions concern the ecology and epidemiology of dengue:
- Blood feeding behavior, longevity, dispersal, and vector-virus interactions of the mosquito Aedes aegypti;
- Longitudinal cohort studies of spatial and temporal patterns in human dengue virus infection in Peru and Thailand; (dengue research in Peru, Thailand, Puerto Rico and Mexico for the past 25 years)
- Impact of human movement on mosquito contact rates and spatial dimensions of dengue virus transmission; and
- Mathematical and computer simulation modeling of mosquito population biology and mosquito-borne pathogen transmission.
Scott co-founded the Center for Vector-Borne Research (CVEC), comprised of researchers throughout the UC System. See more information on Scott.
Patrick Duffy, chief of the National Institutes of Health's Laboratory of Malaria Immunology and Vaccinology, will keynote the fourth annual Bay Area World Malaria Day Symposium, set Friday, April 24 on the Clark Kerr campus, UC Berkeley. The symposium, to take place from 8 a.m. to 4 p.m., will be co-hosted by UC Davis and Zagaya.
Duffy is an internationally recognized expert in human malaria pathogenesis, malaria in pregnancy, and malaria vaccine development. He has published more than 100 papers on malaria over his nearly 25-year career.
UC Davis co-host Shirley Luckhart, professor in the Department of Medical Microbiology and Immunology School of Medicine, and co-director of the Center for Vector-borne Diseases, will be one of the speakers.
Meanwhile, take a look at the spectacular mosquito images taken by entomologist/photographer Jena Johnson of Athens, GA (she is married to Michael Strand). This is the Aedes aegypti mosquito blood-feeding on her.
It's a buggy new year! One of the fascinating things about beginning the new year is the Entomological Society of America's "World of Insects" calendar. Amazing images of insects (and one spider!) jump out at you.
One of my favorites is a black soldier fly, Hermetia illucens, an image captured by entomologist Jena Johnson of Athens, Ga. It's "Mr. October."
Johnson writes: "Soldier flies, like many other dipterans, have beautifully patterned eyes attributable to cornea filters that cause colorful metallic reflections. Adults of this species are black with dark wings and are 14-17 millimeters long. Although harmless, they are somewhat similar in appearance to mud dauber wasps, and they even mimic their movements. They also have two distinctive translucent spots on their first abdominal segments that make them appear to have narrow, wasplike waists. The larvae develop in decomposing organic matter and are considered to be beneficial in helping to reduce large amounts of animal manure and other biological wastes. Soldier fly larvae are a good protein food source for livestock, exotic pets and even humans. In the summer, adults are often attracted to fluorescent lights, which is how this one was lured in for a photograph in Athens, Georgia."
"The first time I looked into the eyepieces of a microscope to see the magnified beauty of an insect I knew I would spend my life involved somehow in learning more about this diverse and fascinating group of animals," Johnson told Bug Squad. "After working at the University of Florida for a couple of years I went on to earn a master's degree at Clemson University. I worked as an entomology laboratory technician at the University of Wisconsin and am currently at the University of Georgia. For many years I photographed insects with a 35mm film camera but when digital cameras became more affordable a few years ago, my passion for insect photography was reignited. I photograph insects for the pure joy it brings me. I live in Athens, Georgia with my husband Michael Strand, who is also an entomologist."
Michael Strand, by the way, will be the featured speaker April 8 in the series of noonhour seminars hosted by the UC Davis Department of Entomology and Nematology. (See list of seminar speakers.)
Jena Johnson, who is currently hotographing a variety of mosquito species emerging from pupae at the water's surface, is an alumnus of BugShot, an insect photography workshop. One of the instructors is noted insect photographer Alex Wild, who received his doctorate in entomology at the University of California, Davis, with professor/ant specialist Phil Ward. Wild, who has just accepted a position at the University of Texas, Austin, blogs about insects at myrmecos.net and about photography at Compound Eye, Scientific American. Wild's Oct. 26 2011 seminar at UC Davis on "How to Take Better Insect Photographs" is the department's most viewed seminar on UCTV.
It's obvious that people like bugs, and people enjoy capturing macro images of bugs!
A colorful image of a clown grasshopper by Francisco Lopez-Machada of Cali, Colombia, graces the cover of ESA's "World of Insects" calendar. It also appears as "Mr. August."
The list of images and the photographers:
January: Spitting spider, Scytodes thoracica, by Daniel D. Dye II of Brooker, Fla.
February: Speckled-winged grasshopper, Arphia conspersa, by Johan Pretorius of Scottsbluff, Neb.
March: Imperial moth, Eacles ormondei peruviana, by Christopher Conland of Escondido, Calif.
April: Red dwarf honey bees, Apis florea, by Darren McNabb of Iowa City, Iowa
May: Stink bug, Edessa sp., by Francisco Lopez-Machado of Cali, Columbia
June: White-lined sphinx moth, Hyles lineata, by Keith Kennedy of Raleigh, N.C.
July: Dog-day cicada, Tibicen canicularis, by Keith Kennedy of Raleigh, N.C.
August: Clown grasshopper, Paramastax rosenberg, by Francisco Lopez-Machado of Cali, Colombia
September: Rove beetle, Philonthus caeruleipennis, by Tom Myers, Lexington, Ky.
October: Black soldier fly, Hermetia illucens, by Jena Johnson of Athens, Ga.
November: Luna moth, Actias luna by Tom Myers, Lexington, Ky.
December: Flameskimmer dragonfly, Libellula saturata, by Kathy Keatley Garvey of UC Davis
The 7000-member ESA recently held its annual meeting in Portland, Ore., with president Frank Zalom, distinguished professor of entomology and an integrated pest management specialist at UC Davis, presiding.