Citrus flower moth (Lepidoptera: Yponomeutidae

Citrus flower moth

(Lepidoptera: Yponomeutidae)

Citrus flower moth is a tiny moth which occurs in many parts of the world, including South Africa.

Nozibusiso Maphumulo

IPM-PROGRAM, NORTH-WEST UNIVERSITY

Citrus flower moth classification:

Class: Insecta (insects) Order: Lepidoptera (moths and butterflies) Family: Yponomeutidae Genus: Prays Species: citri

It is also commonly known as citrus blossom moth and lemon borer moth. The first appearance of the citrus flower moth in South Africa was reported in 1915 in KwaZulu-Natal and Pretoria. It now occurs throughout South Africa, where it mostly attacks flowers of lemon and lime. However, it has been reported to have a number of other hosts in South Africa, especially citrus plants, such as navel orange, sour orange, sweet orange, mandarin and grapefruit. Acrolepia citri is a synonym of the citrus flower moth.

Citrus flower moth lays eggs singly, either on flowers early in the season or outside fruitlets later in the season. One female can lay between 39 to 334 eggs. The life cycle of the citrus flower moth ranges from 14 to 47 days, depending on temperature. Larvae hatch after 2 to 6 days depending on temperature. The neonate larva immediately bores slightly into small fruits or flowers after hatching. The larval stage takes between 7 to 12 days before pupation takes place inside flowers, young fruits and on leaf surfaces. The duration of the pupal stage is 3 to 10 days.

Moths can survive for 2 to 18 days. Citrus flower moth can have 3-16 generations per year depending on climatic conditions. However, the specific number of generations per year in South Africa are not known, since its life cycle has not been well studied.

Eggs of the citrus flower moth are very small, approximately 0,2 mm in size. They are slightly oval in shape with a white colour. Larvae are light grey, brown or green in colour. The final instar is between 4,2 and 5,5 mm in length. Pupa are initially light green in colour, and then turn to dark brown. Adults of the citrus flower moth are small and slender with greyish-brown forewings marked with irregular spots. They have narrow light grey hindwings. Both wings are heavily fringed with a wingspan of 3,6 to 4.5 mm.

The damaging stage of the citrus flower moth is the larval stage. The larvae feed on buds and flowers, webbing them together. Mature larvae can eat entire blossoms and pea-sized fruitlets. They bore into young fruits and feed inside them. Feeding damage or penetration marks result in gumming (sticking) of the fruits and can cause brown necrotic lesions on young and mature lemon fruits. Heavy infestations can cause

Figure 1: Wilted lemon blossoms, damaged and webbed together by larvae of the citrus flower moth.

Source: https://www.citrusresourcewarehouse.org.za/home/documenthome/news-articles/south-african-fruitjournal-safj/safj-2014/2663-sa-fruit-journal-feb-march-2014-cri-lemon-borermoth-citrus-flower-moth/file

Figure 2: Necrotic lesions caused by citrus flower moth larvae that penetrated a lemon fruit.

https://www.citrusresourcewarehouse. org.za/home/document-home/newsarticles/south-african-fruit-journal-safj/ safj-2014/2663-sa-fruit-journal-febmarch-2014-cri-lemon-borer-mothcitrus-flower-moth/file

Figure 4: Citrus flower moth pupa.

https://www.prayscitri.eu/

Figure 3: Citrus flower moth larva.

https://www.prayscitri.eu/

Figure 5: Citrus flower moth adult.

https://www.prayscitri.eu/

the fruits to drop and lead to crop loss.

Citrus flower moth is of minor economic importance in South Africa. However, its importance has been increasing lately, more especially on lemon due to pesticide programmes and a decline in natural enemies.

Monitoring of citrus flowers should be conducted in spring by checking for its presence or feeding damage in blossoms. Citrus flower moth has a small population density during winter and spring and higher in autumn and summer.

Studies have shown that Bacillus thuringiensis (Bt) sprays can be effective in controlling this pest. Several larval parasitoid species which attack citrus flower moth have been reported in South Africa. Curative control practices should be applied against the first generation of larvae that feeds on blossoms in order to prevent the development of the second generation that eats small fruits because it is very difficult to control. Enquiries: mashimanenozi03@gmail.com

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