A weevil definition
The beetle species of the family Curculionidae, the most important and diverse of the superfamily Curculionoidea, order Coleoptera, are called “weevils”. The largest family is the Curculionoidae.
It is one of the most diverse and species rich animal families. The family of curculionids includes more than 100 subfamilies, more than 40,000 species are known worldwide.
They are phytophages of herbivorous habits (they are fed with vegetal foods), like their relatives the chrysomélidos.
The adult weevil is usually off-color. Its size depending on the species can vary from 1.5 to 35 mm long (excluding the face). Smaller or larger species may be found. Species vary greatly in color, shape and structure.
They are characterized by having their mouthpiece masticador at the end of a proboscis that can be relatively massive or long and narrow, according to the species.
The antennas, of mazudo end, are sheltered in furrows along the proboscis.
Its oval body is covered with a rough and hard tegument and presents a single medial suture in the lower part of the head. The size is generally small when compared to other beetles.
Curculionids are generally covered by scales or hairs, however they may be virtually nude.
Most species fly but in some environments, species that do not fly predominate.
Weevils undergo a complete metamorphosis. From the egg is born a larva. The larvae are white, semicircular and fleshy, with vestigial legs, powerful jaws and rudimentary eyes; feed only on vegetables, causing great damage to crops. The larva grows until it is pumped into a kind of capsule. After a while, an adult emerges from the capsule. Adults usually hibernate for most of the winter. There are adult males and females. After the pairing, the females lay eggs. In some cases they lay the eggs in the field, and in other cases they deposit them in the mass of grains.
Each female lays about 300 eggs. Also, the life cycle is short and there may be two or three generations in a single year. In this way, if you start the year with a single pair of weevils, by the end of the year there could be more than 5 million! And in hot places, they proliferate more.
»Damage / transmitted diseases / Health importance of weevils
All weevils feed on plant matter, both living and dead. Many weevils or weevil are considered pests of cultivated plants or stored foods such as grains.
The corn and rice weevil (Sitophilus oryzae) is native to India and infests maize, rice and other grains all over the planet. It is a common pest in kitchens that appears frequently between cookies, packaged cereals and other dry foods.
All insects that attack stored grains are characterized by their high proliferation capacity
Direct damage occurs when insects consume the grain, feeding on the embryo or endosperm, which causes weight loss, reduced germination and less nutrients. As a result, their market price declines.
Indirect damages are the warming and migration of moisture, the distribution of parasites to humans and animals, and the rejection of the product by the buyers. Grains can become hot as a direct result of an insect attack. This phenomenon is called heat bag, because the grains have a low thermal conductivity and the small amounts of heat generated by the insects do not dissipate. The high temperature stimulates the insects to a greater activity, which results in the formation of new foci, until the whole mass of grains is infested and hot
There are some species that far from being a pest are useful in biological control of weeds or in pollination.
»Species – types of Weevils
The scientific name of the tiny wheat weevil is Sitophilus granarius, that of corn and rice is called Sitophilus oryzae.
– Rice weevil
– Corn weevil
– Grain or wheat weevil (Sitophilus granarius)