Rice Weevils Flashcards
explain the morphology in the larva
- legless
- humpbacked
- whitish body
- small, tan head
explain the legs of a rice weevil
- hydrophobic hairs on mesothoracic legs
- 6 legs, even spaced
- modified for rummaging through rice
explain the rostrum of a rice weevil
- long, snout-like projection
- consisting of labrum, mandibles, maxillae, and labium
- used for making holes in plants/grains of rice
- females use it to make holes to place their eggs
explain the patches on a rice weevil
four distinct oranges/yellow patches on elytra
explain the thorax of a rice weevil
rounded pits scattered throughout the thorax
explain the antennae of a rice weevil
two antennae extending laterally from the rostrum
lifecycle - egg stage
- adult female drills a tiny hole into the grain with her rostrum and lays her eggs
- they lay on an average of 4 eggs per day
- takes 3 days to hatch
lifecycle - larvae stage
- once hatched, the larvae feeds on the interior of the grain, consuming the endosperm
- the larval stage typically lasts for 20-30 days, during which the larva goes through several molts
lifecycle - pupa sage
- the larvae pupate within the grain, forming a pupal chamber.
- the pupal stage lasts for around 5-7 days
- during this time, the insect undergoes metamorphosis, transforming into an adult weevil
lifecycle - adult stage
the adult weevil emerges from the pupal chamber by chewing a hole in the grain
explain the rice weevil’s reproduction
- mating usually occurs near food sources
- reproduce shortly after they emerge from the pupa stage
- enter reproductive diapause and they accumulate in the leaves duing winter
role of male weevils in reproduction
- release pheromones (chemical signaling)
- visual display
role of male weevils in reproduction - visual display
- moving their bodies
- using their antennae to tap on female antennae
role of female weevils in reproduction
- laying their eggs on wheat seeds after mating
- close the seed off after laying her eggs to protect it
- each seed can hold up to a max of one egg
- the egg size is very small, allowing them to fit into the grain seed
- female do all of the parental care
rice weevil habitats
- grain and fruit products
- maize and unpolished rice
- wheat
- humid, dark conditions
rice weevil habitats - grain and fruit products
primarily found in grain products, but can move to fruit if needed
rice weevil habitats - maize and unpolished rice
bigger adult rice weevils prefer maize and unpolished rice
rice weevil habitats - wheat
smaller and younger rice weevils prefer wheat due to competition
rice weevil habitats - humid, dark conditions
they prefer dark, enclosed spaces as well as warm, humid conditions
rice weevil effect on farmland
- harmless to humans and don’t carry diseases
- but, they harm crop life and results in lower yield and grain quality
- this causes large financial loss to farmers and grain dealers
how to control rice weevils on farmland
- they are largely affected by temperature
- controlling weevils with temperature ventilations can help preserve small amounts of grain
rice weevils role in society
- crop loss
- economic impact
- food contamination
- ecological balance and decomposition
rice weevil role in society - crop loss
infesting and damaging stored grains
rice weevil role in society - economics impact
infestations lead to costly control measures and threaten agricultural industries
rice weevil role in society - food contamination
infested grains become unstable for consumption
rice weevil role in society - ecological balance and decomposition
- part of an ecological web as a food source
- their bodies contribute to nutrient cycling
