Philippe René. 2000. Coconut entomology mission Riau Sakti United Plantations (RSUP) Pulau Burung, Sumatra, Indonesia, 29th May to 17th June 2000 : Study of Sufetula n.spp. (Lepidoptera, Crambidae, Spilomelinae) root-mining caterpillars on PB 121 hybrid coconut palms. Montpellier : CIRAD-CP, 69 p. N° de rapport : CP_SIC 1266
Résumé : This mission was used to take stock of all the trials and observations carried out in the 6 months since the last mission in November-December 1999. Two new primary root sampling methods were tested during this mission: - One consists in digging larger 100 x 50 x 40 cm. holes. The root segments are then 100 cm. long at the most. The distances between two old attacks are measured, along with the length of new healthy roots. In that way, it is possible to assess the frequency of attacks by the pest involved, and the effectiveness of the treatments carried out. With these new data, an attempt will be made to determine the parameter that can be correlated with nut load on the coconut palms. It will involve either the number of attacks on a given number of primary root segments, or the distances between two attacks, the number of segments without attack or the number of segments with one (or more) reiterations. - The second method consists in carefully uncovering one to three primary roots per coconut palm, over their entire length, and measuring the distances between attacks all along the root. This gives a clear picture of the intensity of larva attacks depending on the appearance of the root reiterations. Application of these two methods, during visits in several plots at RSUP, provided a clearer understanding of the effect of attacks by this pest on yields. For the time being, it is possible to establish a "qualitative" correlation between the appearance of the uncovered roots and a visual evaluation of nut loads on the coconut palms. In zones without a cover crop (trial RS-CC 07: new planting far away from all the old coconut palms, and RS-ES 74: a replanting surrounded by old coconut palms, seed garden), adult Sufetula populations are very small. A full-scale trial is under way in two complete blocks to try and rehabilitate adult coconut palms severely attacked by this pest. The aim is to define a simple intervention strategy as soon as possible, combining complete plot cleaning (chemical weeding and removel of dry fronds and coconut husks), and protection against erosion at the base of the palms with cocopeat + fibres. This work is not progressing at a satisfactory rate due to frequent heavy rainfall. Obviously, fertilization needs to be normal, and regular in particular. New insecticide trials (Suscon, Bionim and Nim 47) against the larvae have shown that Suscon (an insecticide with very slow Chlorpyrifos ethyl release) is as effective as Dursban EC (Chlorpyrifos ethyl). However, two Swedish products derived from Neem (Azadirachta indica - Bionim and Nim 47) have not given satisfaction. Two batches of 30 coconut seedlings, one set up in a pineapple monoculture, the other one in an area invaded by weeds, but without ferns (Nephrolepis sp) at several hundred metres from coconut palms, had not been attacked by Sufetula larvae after 4 months. This clearly proves that Sufetula populations are very low to zero within the pineapple monoculture, and in the zone invaded by weeds other than ferns. However, remember that the ferns do not serve as secondary hosts for these insects, which merely prefer cool, humid places and erect stems to settle on.
Auteurs et affiliations
- Philippe René, CIRAD-CP-COCOTIER (FRA)
Autres liens de la publication
Source : Cirad - Agritrop (https://agritrop.cirad.fr/475845/)
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