Studies on damage caused by Cryptorhynchus mangiferae to mangoes
Cryptorhynchus (Sternochetus) mangiferae (EPPO A1 quarantine pest) is considered as a quarantine pest in several regions of the world because it was felt that it could cause serious economic damage to mango production. In particular, the following types of damage were considered: 1) pulp damage (caused by the neonate burrowing through the pulp to the developing seed) rendering mango fruits unmarketable or unappetizing; 2) reduction of germination capacity of mango seeds; 3) premature fruit drop. Studies were carried out in Hawaii (US) to assess the effect of C. mangiferae more particularly on mango seed germination. Naturally infested mango seeds were collected from mature fruits (polyembryonic and monoembryonic cultivars) and planted in pots. Results showed that germination rates for infested seeds were equal to those of uninfested seeds for a polyembryonic cultivar (Mangifera indica cv. Common). For the monoembryonic cultivar (cv. Haden), germination rate was significantly reduced but was still ; 70%. Mango seeds were also artificially damaged by cutting away 25, 50 or 75% of the cotyledon before planting. None of these treatments was significantly different from undamaged controls, indicating that mango seeds can tolerate substantial damage and still germinate. Observations were also made on pulp damage caused by C. mangiferae. Out of a total of 3602 fruits, only 4 fruits (0.11%) showed evidence of direct damage to the pulp. However, it is recalled that in South Africa, pulp damage is reported when C. mangiferae adults emerge (exit holes) from fruits still attached to the trees in late-season cultivars. Preliminary studies on fruit drop did not show a significant impact of C. mangiferae on premature fruit drop but further studies are needed. The authors concluded that C. mangiferae might be a less serious pest than previously thought.
Sources
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Follet, P.A. Gabbard, Z. (2000) Effect of mango weevil (Coleoptera: Curculionidae) damage on mango seed viability in Hawaii.
Journal of Economic Entomology, 93(4), 1237-1240.
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