Black Margined Blister Beetle Feeding On Pollen
Amino acids are limiting nutrients for growth, development, reproduction and fecundity of most insects. Many insects are adapted to grow and develop on foods that are deficient in essential amino acids or diets with protein and amino acid content far less than the optimal balance. These insects have evolved many solutions to survival on low amino acid diets.
Some insects have symbiotic bacteria in their digestive systems that fix atmospheric nitrogen into amino acids. These symbionts receive a steady supply of energy from excess carbohydrates in the insect diet. The excess carbohydrates are the recipient of the nitrogen in the fixation process that in net convert carbohydrates into amino acids and other nitrogenous chemicals.
Other insects blend nitrogen rich food sources with nitrogen poor foods to create a balanced diet. Mosquito larvae feed on detritus deficient in the nitrogen needed for egg production. The adult females feed on blood which creates stress for the insect during its processing. Herbivorous beetles larvae may balance their amino acid intake by eating pollen, which is high in protein. Caterpillars and aphids are notorious overeaters consuming excess food, excreting excess carbohydrates and efficiently acquiring the nitrogen content.
Understanding how insects meet their needs for amino acids helps us understanding the ecological constraints that regulate insect populations.
Cricket King Cake
Mardi Gras is Tuesday, February 28, 2017 and New Orleans prepared. The festival features parades with floats, music and exotic cuisine. A Mardi Gras favorite is king cake with its traditional purple, gold and green sprinkles. This year (2017) the Audubon Butterfly Garden and Insectarium of New Orleans will be serving “Cricket King Cake”, a traditional king cake decorated with non-traditional roasted crickets. Samples are free with general admission while supplies last.
What are the limits of learning in bees with their tiny bee brains? Bees are known to be able to learn complex cognitive tasks. Can bees be taught to perform tasks not encountered in daily life such as playing soccer?
Worker Honey Bee
All animals have microbes in the gut. Some animals have dozens of different bacteria, but others have only a few. The typical honey bee adult worker has in its gut about 1 billion bacteria but only 8 types. These bacteria are mostly unique to bees and not found in other animals. The largest numbers are in the hindgut. Few are found in the midgut and crop.
What function do they have? In most animals they can provide metabolic supplements and protection against pathogens. Bacteria can secrete substances with antimicrobial properties that exclude other potentially pathogenic bacteria. Many possible functions have not yet been elucidate for bees.
Nancy A Moran. Genomics of the honey bee microbiome. Current Opinion in Insect Science
Volume 10, August 2015, Pages 22–28.
Red Aphids on a Cup Plant
In plants, most sugar is transported in the phloem passing through units stacked the length of the plant called sieve tubes. Each sieve tube contains valves that can open or block flow of sugar. The valves are formed by proteins called “forisomes” that contract and block transport through the sieve tube in the presence of calcium and open when calcium concentration is low. These valves keep a plant from losing its liquid when it is cut. Cutting a plant stem causes sieve tube blockage on both sides of the cut. This is why lawn grass does not dehydrate when mowed.
Aphids have the ability to feed on the phloem tissue of plants. The stylets of their sucking mouthparts are inserted into a phloem sieve tube and the aphids ingest the sugary phloem. How do aphids prevent blockage of sieve tubes?
When stylets pierce a sieve tube, the aphid secretes a watery saliva that contains calcium chelating proteins. The secreted proteins bind to calcium inside the sieve tube and lower the concentration to levels at which the forisomes are open. These secretions allow aphids to feed continuously on phloem with interruption of flow by the plant’s defenses.
Photo: Thierry Heger
The kissing bug, Rodnius prolixus,
feeds on the blood of mammals including humans. It is called the kissing bug after its habit of feeding on saliva. Rhodnius requires a blood meal in each immature stage. Laboratory studies of Rhodnius have elucidated some of its feeding secrets. How does a bug decide whether or not to feed?
Rhodnius has a sucking tube that it can use to sip saliva from the skin surface or stick into the skin to drink blood. It will also feed on artificial solutions in the laboratory. Liquids are pumped by the pharynx into the insect. As the liquid passes the pharynx, it passes taste receptors responsive to nutrients in the liquid. The energy molecule, ATP, is detected and will act as a feeding stimulant. Receptors measure the concentration and ratios of sodium and potassium salts in the liquid. Only salt concentrations between 0.1 and 0.15 M trigger feeding. This is the concentration range of these salts in blood. Liquids with high salt concentration (> 3M) are rejected as are liquids that lack salts. Salts are monitored continuously during feeding. A sudden change in salt concentration outside the acceptable range will terminate feeding.
Rhodnius depends on blood for survival. It has evolved receptors and sensory feedback that trigger feeding on liquids that mimic blood and reject liquids that are not similar enough to blood. Rhodnius is adapted to engorge on blood but drink little of other liquids.
Gina Pontesa, Marcos H. Pereirab & Romina B. Barrozoa. Salt controls feeding decisions in a blood-sucking insect. Journal of Insect Physiology Volume 98, April 2017, Pages 93–100.
Soldier Fly Larvae In Compost
Black soldier flies are attracting substantial interest for their activity as composters, animal and fish feed. Livestock operations have waste that attracts nuisance flies. Black soldier flies can compete for the same food but are not pests as adults. Replacing the population of pest flies with black soldier flies would be helpful to livestock operations.
Black soldier flies are common in the warm temperatures of summer but do less well in cooler temperatures. Maintaining soldier flies year round requires providing the adults flies with suitable conditions for mating during cold winter months. Black soldier flies mate in the air and require a substantial flight space. They are sensitive to light and temperature, preferring direct sunlight and temperatures between 70 and 80. Anecdotal success stories can be found online but are not necessarily successful for everyone. A more rigorous study of mating conditions for black soldier flies would be appreciated by many fans of this insects.