''Euhrychiopsis lecontei'', also known as the milfoil weevil, is a type of

weevil Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small – less than in length – and herbivorous. Approximately 97,000 species of weevils are known. They belong to several fa ...

that has been investigated as a potential

biocontrol Biological control or biocontrol is a method of pest control, controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or phytopathology, plants by bioeffector, using other organisms. It relies o ...

agent for Eurasian water milfoil. It is found in the eastern and central

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and western

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

Life cycle

''E. lecontei'' is a

holometabolous Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the clade Holometabola. Immatur ...

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

, undergoing true

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

. Development is temperature dependent, but the time to develop from eggs to larvae is about 4 days, from larvae to pupae 13 days, and from pupae to adults 13 days. Larvae are stem borers and damage plant tissue from about 7 cm from the tip of the plant.

Use as a Biocontrol

Milfoil weevils occur in natural populations in much of North America on their native host, Northern watermilfoil ( Myriophyllum sibiricum). They often reach sufficient densities to suppress invasive Eurasian watermilfoil (

Myriophyllum spicatum ''Myriophyllum spicatum'' (Eurasian watermilfoil or spiked water-milfoil) is a submerged perennial aquatic plant which grows in still or slow-moving water. Eurasian watermilfoil is native to Europe, Asia, and North Africa, but has a wide geograph ...

) infestations after a prolonged infestation or artificial augmentation. Studies indicate that for effective control a density of about 1 weevil per two stems of milfoil (0.5 weevils per stem) is necessary. There are mixed reviews that fish such as

bluegill The bluegill (''Lepomis macrochirus''), sometimes referred to as "bream", "brim", "sunny", or, in Texas, "copper nose", is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds and wetlands ea ...

s can reduce weevil populations as research has only been conducted in very limited settings. Augmenting native weevil populations as a biological control is effective as long as there is a small amount of milfoil to sustain the population. Milfoil weevils are commercially available as a management option for Eurasian water milfoil by a firm based in the United States and Canada.

References

{{DEFAULTSORT:Euhrychiopsis Lecontei Baridinae Beetles of North America Beetles described in 1896