Pg. 36 Basboorders by Lietsjiebome

Die basboordermot, Salagena sp se larwes vreet die bas en hout van lewende bome. Die insek is waargeneem by lietsjieaanplantings op sowel jong as ou bome. Besmette bome gaan nie dood nie, maar enkele takke kan terugsterf as gevolg van ringelering deur die larwes. Hierdie larwes is ook op pekanneutbome waargeneem, veral op jong borne en oorgewerkte bome waar jong nuwe lote straf aangetas word.

Die wyfie le ongeveer 270 roomkleurige eiers in groepies op die bas van takke. ‘n Paar weke na eierlegging, wanneer die jong larwe uitbroei, vreet hulle aan die bas en boor later in die harde hout in. lndringing vind gewoonlik by vertakkings plaas en kan by takke van enige dikte voorkom. Die gate in die takke wat as skuilplek vir die larwes dien, is ongeveer 70 mm lank en sowat 5 mm in deursnee, wanneer die larwes hulle maksimum grootte bereik. Die larwes is donkerbruin, effens harig en word ongeveer 30 mm lank.

Vreetmerke op die bas word bedek deur die larwe se uitskeidings wat met spindrade aanmekaar geheg is, op so ‘n wyse dat die larwe vryelik daaronder kan beweeg. Namate die larwe voed, word hierdie “huis” van spindrade en uitskeiding groter gebou en kan dit rondom ‘n tak aangetref word. In so ‘n geval word die tak geringeleer en kan dit terugsterf.

Papievorming vind in die gat plaas met die kop in die rigting van die opening. Wanneer die papie gereed is om uit te broei (November tot Januarie), beweeg dit tot in die opening, sodat die mot dan daarvandaan ontsnap. Papiedoppe kan dikwels in die opening gesien word.

Summary:

• The bark borer moth, Salagena sp. larvae feed on the bark and wood of living trunks of litchi trees.
• These insects have been observed in litchi plantations on both young and old trunks.
• Infested trunks do not die, but some branches may die back due to girdling by the larvae.
• The larvae also affect pecan trees, especially young and pruned trunks where new shoots are severely damaged.
• The female lays about 270 cream-colored eggs in groups on the base of branches; larvae hatch a few weeks later and bore into the wood.
• Entry usually occurs at branch junctions and can affect branches of any thickness.
• The tunnels used by larvae are approximately 70 mm long and 5 mm in diameter when the larvae reach full size; larvae are dark brown, slightly hairy, and about 30 mm long.
• Feeding marks on the bark are covered with larval secretions bound together with silk threads, creating a “house” that grows as they feed, allowing the larvae to move freely underneath.
• This girdling can cause the branch to die back.
• Pupation occurs within the tunnel, oriented towards the opening, and adult moths emerge from November to January; pupal casings can often be seen in the opening.
• Other host plants found in the Nelspruit area include pecan, macadamia, cowpea, avocado, lavender tree (Heteropyxis natalensis), marula (Slerocarya birrea), wild fig (Ficus sp.), raasblaar (Combretum zeyheri and C. collinum), Pappea capensis, and waterberry (Syzigium cordatum).
• Two parasitic wasp species help control the pest; one also parasitizes the pecan stem borer (Eulophonotus myrmeleon).
• Various insecticides provide good control by spraying the lesions on branches; it is not necessary to remove larval secretions before spraying.
• Recommended insecticides include: Carbaryl 85% wp at 25 g/100L water, Fenvalerate 20% EC at 5 ml/100L water, and Cyfluthrin 5% EC at 6 ml/100L water.