Left: Blowflies reared for 5 days at the constant temperature indicated
Right: Typical Development Vs Temperature curve
Insects do not maintain a constant temperature. Insect body temperature varies with ambient temperature. Insect rate of growth and development is proportional to temperature. Below a minimum temperature, there is no development. Above the minimum temperature (Developmental Threshold), the growth rate increases to a maximum, then declines as insects suffer heat stress near the maximum tolerated temperature.
Each insect species has its own developmental threshold and development vs temperature curve. These parameters must be measured empirically and are known for most economically important insects. Knowing these parameters enables insect biologists to create models that predict when insects will be present based on temperature data alone. Good models can focus scouting and pest management measures to only those times when it would be possible for an insect stage of interest to be present. Combined with weather forecasts, the emergence of some pest species can be predicted in advance with the same certainty as the weather forecast.
Insects have remarkable methods of finding mates in their environment. Insects are known to use odors, sounds and light. Researchers* have discovered that blow fly vision is important in mate recognition. Young female blowflies are heavier than males and their wings beat at 178 Hz compared to 212 Hz for the males. When the female wings beat, they reflect light that creates a flash pattern of 178 Hz. Male blow flies are responsive to light, but are much more responsive to flashing light. The males are most responsive to lights flashing at 178 Hz which mimics the female.
*Courtney Eichorn, Michael Hrabar, Emma C. Van Ryn, Bekka S. Brodie, Adam J. Blake and Gerhard Gries. How flies are flirting on the fly. BMC Biology 2017 15:2
Plate From Metamorphosis Insectorum Surinamensium
The artistic nature illustrations of Maria Sibylla Merian have had a revived interest with a re-issue of her book, Metamorphosis Insectorum Surinamensium. Her wonderful illustrations have inspired taxidermist and artist Jeremy Johnson to render 3 dimensional sculptures of her illustrations. The Jeremy Johnson art display, Off The Page, opened at the Lloyd Library and Museum in Cincinnati, Ohio in March 2017.
Johnson is self taught in insect biology. He approaches insect displays from an artistic and taxidermist perspective that is not governed by the strict rules of scientific collections. The result is insects displayed with additional context: life cycles, natural history, habitat &c. It requires more time and fewer insects can be displayed in this manner. However, for those insects that are displayed, the context enhances public perceptions, awareness and enthusiasm.
Part of the Purdue Entomology Research Collection
The Arizona State University insect collection will more than double after a donation from private collectors Lois and Charlie O’Brien. The O’Briens have traveled the world collecting insects for decades and have amassed over 1 million specimens. Their collection specializes in leafhoppers and weevils. To oversee the collection, the O’Briens have endowed two professorships.
Insect biology has greatly benefitted from individuals with an interest in insects and collecting. With a million described insect species and perhaps 10 million undescribed, there is more work to be done than can be accomplished by scientists alone. Interested enthusiasts can build a wealth of biological information on locations and life histories of insects that can be useful to scientists and society.
The O’Briens have taken steps to preserve their collection for posterity. Not everyone does. Sometimes collections are inherited by relatives who do not want them or recognize their potential value. Universities with and Entomology or Insect Biology programs commonly accept donations and make use of the specimens. If the specimens are not suitable for the research collection, they may be useful for classes and programs that train the next generation of insect biologists.
San Bruno Elfin
Photo: Larry Orsak
Species on the Endangered Species List are protected from harm by human activities intentional or unintentional. When companies operate in areas that contain endangered species, the companies must develop a plan that will minimize the harm or potential harm to those species.
Plans are submitted to the Fish and Wildlife Service, the federal department that manages endangered species. The FWS will review the plans by its own staff and scientists, send them out for review by other scientists and make them available for review by the public. The philosophy: Many eyes are more likely to uncover problems.
The FWS has a comment period for individuals or organizations to submit thoughts and recommendations. One function of the US regulatory process is to give everyone a chance to be heard. It is certain that organized conservation groups will make use of this opportunity.
Sensitive insects in the affected area include:
Delta green ground beetle (Elaphrus viridis)
Bay checkerspot butterfly (Euphydryas editha bayensis)
Callippe silverspot butterfly (Speyeria callippe callippe)
Lange’s metalmark butterfly (Apodemia mormo langei
Mission blue butterfly (Plebejus icarioides missionensis)
San Bruno elfin butterfly (Incisalia mossii bayensis),
Photo: Ole Bidstrup
The parasitic wasp, Chelonus inanitus, relies on viruses to successfully colonize its hosts. When the wasp injects eggs into its host, the eggs are accompanied by viruses. The viruses selectively colonize the cells of the host immune system and destroy them. This allows the developing wasp to avoid attack by immune cells. The viruses also arrest the development of the caterpillar host.
The Chelonus inanitus ichnovirus is fully integrated into the wasp life cycle. The virus only replicates in the nucleus of the calyx cells in the female reproductive system. Both double stranded virus DNA and protein capsule are produced and assembled in the nucleus of the calyx cells. The virus particles are released from the cells by budding, in which the viruses are surrounded by the outer cell membrane which is pinched off, releasing the virus in to the oviduct of the wasp.
The viruses evolved from ancestors that lived independently, but are now integrated into the wasp such that neither the wasp nor the virus would survive without the other.
U. Albrecht, T. Wyler, R. Pfister-Wilhelm, A. Gruber, P. Stettler, P. Heiniger, E. Kurt, D. Schiimperli and B. Lanzrein. Polydnavirus of the parasitic wasp Chelonus inanitus (Braconidae): characterization, genome organization and time point of replication. Journal of General Virology (1994) 75: 3353-3363.
Photo: Bob Self
Formosan termites have infested the Gulf Coast of the US since the late 1940s when they hitched a ride on solid wooden packing used to crate returning military equipment. Formosan termites are a threat to wooden structure in New Orleans historic French Quarter and have spread east to Florida. Formosan termites are now having a significant effect on Jacksonville, having done enough damage to the historic Women’s Club building to lead to its condemnation and destruction.
Jacksonville is now engaging in a program to limit the damage. Formosan termites can nest in landscape trees, weakening and destroying them as well as damage buildings. This creates a large number of nesting sites that make location of nests difficult. Termite management depends on identifying areas with significant termite populations. In spring, termite reproductives swarm to find mates and start new colonies. It is easier to locate termite locations by trapping flying adults.
Jacksonville is deploying 50 termite traps that use the termites attraction to light. Solar powered lights are paired with a sticky trap that will capture termites and other insects attracted to lights. The data from the traps will be used to help inspectors search for nests, locate and destroy them to limit the population.
Once an invasive species like the Formosan termite establishes in an area, elimination or eradication may be impossible. The only option to reduce damage may be an expensive management program.