popular science on agriculture, rural areas and farmers | professional melon-eating insects - melon silk borer
2024-09-11
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in beijing, there is a lepidopteran pest that specializes in eating melons - the melon borer. usually, the pest enters its peak period from late august to the end of september. in september, pest investigators found traces of its damage in many parks, but unfortunately, many producers do not know much about this pest, and some even mistake insect pests for diseases, missing the opportunity to prevent and control it. today, the city's plant protection technicians will give a detailed introduction to this insect that specializes in eating melons.
what does it look like?
look at the pictures to identify them!adultthe whole body is black with a metallic luster, the body length is about 11 mm, and the wingspan is about 23-26 mm. two obvious characteristics are: the outer periphery is black, with a large white triangle in the middle; the second is the yellow-brown hair cluster at the end of the abdomen. the adult is most easily confused with the box silk moth, but the box silk moth does not have such obvious hair clusters, and the white triangle is light in color, and there is a crescent-shaped spot on the front edge.eggit is oval, flat, light yellow, and has a reticular pattern on the surface, like fish scales.larvathere are five instars in total. the last instar larvae are 23-26 mm long. the head and pronotum are light brown, the chest and abdomen are grass green, there are two wide milky white longitudinal stripes on the body, and the spiracles are black.pupait is about 14 mm long, dark brown, with a smooth and thin head and wings that end at the sixth abdominal segment. it usually has a thin cocoon on the outside.
adult
egg
larva
pupa
damage to leaves
melon
a, b, d, f (photographer: zhang zhi) c, e (photographer: shi yingchun)
how to eat melon
only the larvae of the melon borer can eat melons. when eating leaves, they eat the melon flesh and the remaining epidermis on the back of the leaves, making the leaves appear gray and white. after the third instar, the larvae often roll up the leaves to the left and right, sew the leaves or tender shoots together with silk, hide inside to eat, causing holes or notches in the leaves, and in severe cases only the veins remain. when eating melon strips, they mainly eat young fruits close to the leaves or the ground, nibble on the epidermis of the melon strips, gradually bore into the melon and then eat the melon flesh under the skin, seriously affecting the yield and quality. sometimes they can also feed on the tender shoots of the plant or bore into the stems and vines to cause damage.
what kind of habits do you have?
the insect has a wide temperature adaptation range and can grow and develop at 15-35℃. the optimum temperature is 26-30℃. it likes a high humidity environment. humidity below 70% is not conducive to larval activity. adults are active at night and have weak phototropism. they lurk in hidden places or leaves during the day. the peak of egg laying is 4-5 days after emergence. they like to lay eggs on loofahs, cucumbers and wax gourds, and the eggs are mainly laid on the back of the leaves. the newly hatched larvae are gregarious and gradually disperse to cause harm as the age increases; the larvae are more active and will spin silk and droop when startled, and move to other places to cause harm; they can feed day and night. the first to fourth instar larvae do not eat much, and the fifth instar larvae eat a lot. the amount of food they eat is close to or exceeds the sum of the first four instars. when the leaves are eaten up, they will gnaw or bore into fruits or stems. the mature larvae pupate in the damaged rolled leaves, the top nodes of the bamboo poles of the support, the grass ropes of the melon rack, or in the 5-10 cm topsoil layer at the root zone.
the reason for this year's re-issue
melon borer likes a hot and humid environment. beijing has had a lot of rainfall since august, and the meteorological conditions are favorable for its egg laying and hatching. according to the investigation, most of the current larvae are second and third instar larvae and only damage the leaves. as the age of the insects increases, the damage to the leaves will gradually appear, and the risk of damage to the melon strips or vines will further increase. it is expected that the number of greenhouses where insects are found will increase further in the next stage, and the degree of damage in the greenhouses where insects are found will be further aggravated.
what producers should do
first, we should strengthen field investigation, identification and monitoring to timely grasp the insect situation; second, we should seize the early stage to carry out prevention and control in time to reduce production losses. third, we should strengthen prevention to prevent the transfer and spread of adult insects. fourth, we should strictly implement the safety interval after spraying to ensure the quality and safety of agricultural products. (source: beijing agricultural and rural publicity center)
