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AVOCADO SEED MOTH

 

Stenoma catenifer  Walsingham -- Leipidoptera, Stenomidae

 

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       Stenoma catenifer, the avocado seed moth, is a new world species that is thought to feed exclusively on the fruit and seeds of plants in the family Lauraceae. It has been recorded feeding on fruit of avocados (Persea americana) and the greenheart tree, Chlorocardium rodiei, an important timber tree in Guyana (Cervantes Peredo et al., 1999). Stenoma catenifer is a well known avocado pest attacking fruit in Mexico, Guatemala, Costa Rica, Panama, Bolivia, Colombia, Peru, Ecuador, Venezuela, and Brazil (Acevedo et al., 1972; Boscán de Martínez and Godoy, 1984). Avocados in Guyana are likely attacked as this moth has been recorded from fruit of greenheart in this country (Cervantes Peredo et al., 1999).

 

       Levels of S. catenifer infestation in avocados can be high. In some avocado growing regions of Brazil 100% of the crop can be infested with S. catenifer (Nava et al., 2005a), and in orchards that are sprayed with broad spectrum insecticides 7-11 times over the course of a single growing season up to 60% of fruit can be infested with larval S. catenifer (Nava et al., 2005b). Consequently, this pest is considered to be one of the major impediments to commercial avocado production in Brazil (Nava et al., 2005a,b). In Venezuela, avocado fruit infestation with S. catenifer larvae can be as high as 80% (Boscán de Martínez and Godoy, 1982).

 

       Eggs and ovipositionStenoma catenifer eggs are small and oval in shape (on average eggs are 0.59 ± 0.04 mm long and 0.38 ± 0.2 mm wide) (Cervantes Peredo et al., 1999). Eggs are laid singly and are initially white or pale cream when first laid and later darken as they mature. Female moths oviposit at night with peak oviposition occurring within four hours of darkness in which time 80% of eggs are laid (Nava et al., 2005a). Stenoma catenifer females tend to lay eggs on rough surfaces and in crevices such as the fruit pedicel or necrotic spots on fruit (Hohmann et al., 2003).

 

       Oviposition studies in cages indicate that up to 68% of oviposited eggs can be laid on the branch to which the avocado fruit pedicel is attached (Hoddle unpublished data, 2007). In the laboratory, caged females can be induced to lay eggs on rough quilted paper towel as long as avocado fruit are provided as a stimulus to induce egg laying (Nava et al., 2005a).

 

       Larvae.  First instar larvae are pale cream to a very light violet in color. As larvae pass through successive instars they become progressively more violet in color. The final fifth instar (up to 25 mm in length) is characterized by having violet dorsal coloration contrasting strikingly with a blue-turquoise colored ventral surface. When fifth instar larvae are ready to pupate the majority (>95%) will abandon the seed or fruit within which they are feeding, initiate active walking and climbing for approximately 12 hours, after which they will enter a quiescent period for another ~12 hours, often in a protected spot (e.g., under paper towel in the lab). During this quiescent period larvae will spin a very lose and fragile silk tent within which they will pupate.

 

       Pupae.  Pupae are “free” chrysalises that may be loosely attached with fine weak silk strands to a substrate but can be easily dislodge with gentle prodding. In the field, S. catenifer pupate in the soil at 0.5-2.0cm depth after leaving the fruit they were feeding in (Boscán de Martínez and Godoy, 1984). Young pupae are a striking turquoise blue in color and within 4-8 hrs of initial pupation this color becomes reddish-brown as pupae mature and melonize. Male and female pupae can be separated based on the presence of a small “suture” that divides abdominal segment 9 in the males (Cervantes Peredo et al., 1999). Some S. catenifer larvae (<5%) will pupate within the seed in which they were feeding (Hoddle unpublished data).

 

       Adults.  Adult moths are light tan color, and wings are marked with numerous black spots. The most characteristic marking on the forewings is the easily observable “C” shape of spots as the distal end of the forewings. Adult females are about 15 mm in length (tip of head to tip of wings) when in the resting position with wings folded across the dorsum. Wing span for females with forewings fully spread is around 28-30 mm in breadth. Males tend to be slightly smaller (2-3 mm shorter) than females and are similarly colored (Hoddle unpublished data 2007).

 

       During the day, the majority of adult S. catenifer rest in dried leaf duff, weeds, and other litter in avocado orchards and this behavior has been recorded in more natural forest situations as well (Cervantes et al., 1999). Flight monitoring of 45 laboratory-reared adult S. catenifer into an avocado orchard at 2:00pm in the afternoon revealed the following: (1) Adults (n=15) released individually at 1.5 meters on open ground in full sun all flew immediately into orchard weeds and dried avocado leaves and hid. (2) Adults (n=15) released individually at 1.5 meters immediately under the shade of an avocado canopy all flew directly to the ground and similarly hid amongst and under dried avocado leaves or in soil cracks. (3) Adults (n=15) released individually at ~3.5 meters of height within the canopy of avocado trees all flew directly to the ground to seek refuge. The distance measured for adult Stenoma flight upon release from plastic vials ranged from 3 to 12 meters.

 

Biocontrol

 

       Hymenoptera: Braconidae) (Nava et al., 2005b). Ichneumonids have also been recorded from S. catenifer larvae and include: Eudeleboea sp., and Pristomerus sp. (Nava et al., 2005b).

 

       The second most important parasitoid attacking S. catenifer in Guatemala is a solitary braconid, Macrocentrus sp. Adult parasitoids are dark yellow in color with brown markings. This parasitoid causes third and fourth instar S. catenifer larvae to abandon avocado fruit before fully maturing. A single pale colored parasitoid larva emerges from hosts which have a contracted dehydrated appearance. Macroncentrus larvae spin a very distinctive beige colored and cigar shaped cocoon. In Guatemala, the dominant larval parasitoid attacking S. catenifer is a gregarious Apanteles sp. which can succcessfully parasitize 50-100% of larvae. Estimates of parasitism levels from surveys in Guatemala are affected by location, number and time samples were taken (Hoddle unpublished data 2007). Young Apanteles sp. larvae erupt out fifth instar S. catenifer larvae and about 4-8 hours after emergence the majority of larvae have spun silk cocoons. The number of parasitoid larvae emerging from S. catenifer larvae ranges 2-27, and averages 8-9 larvae per host. A small number of S. catenifer larvae die in avocado seeds and parasitoids pupate within larval feeding galleries within the avocado seed. Adult parasitoids are black with orange coxae.  The sex ratio is around 53% male and 87% of adult parasitoids successfully emerge from cocoons.

 

       Terrestrial predators are likely to be important natural enemies of S. catenifer because mature S. catenifer larvae emerge from the protection of avocado seeds to pupate in the soil and adult moths seek refuge in leaf duff on the orchard floor during day light hours. One very common ground predator encountered in Guatemalan avocado orchards during the day and night was the lycosid spider Hogna sp. In laboratory trials, this predator readily consumed larval, pupal, and adult S. catenifer. Spiders were still alive 36 hrs post-feeding indicating that immature and adult S. catenifer life stages did not have any adverse intoxicating effect on these predators.

 

REFERENCES:          [Additional references may be found at:   MELVYL Library ]

 

Acevedo, E., Vasquez, J., and Sosa, C. 1972. Estudios sobre el barrendor del heuso del aguacate Stenoma catenifer Walsingham (Lepidoptera: Stenomidae). Agrociencia 9: 17-24.

 

Boscán de Martínez, N. and Godoy, F.J. 1982. Apanteles sp. (Hymenoptera: Braconidae) parasito del taladrador de fruto del aguacate Stenoma catenifer Walsingham (Leipidoptera: Stenomidae) en Venezuela. Agronomia Tropical 32: 319-321.

 

Boscán de Martínez, N. and Godoy, F.J. 1984. Observaciones preliminares sobre la biologia de Stenoma catenifer Walsingham (Lepidoptera: Stenomidae) taladrador del aguacate (Persea americana Mill.). Agronomia Tropical 34: 205-208.

 

Cervantes Peredo, L., Lyall, C.H.C., and Brown, V.K. 1999. The stenomatine moth, Stenoma catenifer Walsingham: a pre-dispersal seed predator of Greenheart (Chlorocardium rodiei [Schomb.] Rohwer, Richter and van der Werff) in Guyana. Journal of Natural History 33: 531-542.

 

Garcia, A.M., Villa, M.M., Gutiérrez, A.M. 1967. El aguacate: plagas and enfermades. Fitofilo 20: 5-30.

 

Hoddle, M.S., and C.D. Hoddle. 2008a. Bioecology of Stenoma catenifer (Lepidoptera: Elachistidae) and associated larval parasitoids reared from Hass avocados in Guatemala. J. Econ. Entomol. 101: 692-698.

 

Hoddle, M.S., and C.D. Hoddle. 2008b. Lepidoptera and associated parasitoids attacking Hass and non-Hass avocados in Guatemala. J. Econ. Entomol. 101: 1310-1316.

 

Hoddle, M.S., and C.D. Hoddle. 2008c. Aspects of the field ecology of Stenoma catenifer (Lepidoptera: Elachistidae) infesting Hass avocados in Guatemala. Fla. Entomol. 91: 693-694.

 

Hoddle, M.S., J.G. Millar, C.D. Hoddle, Y. Zou, and J.S. McElfresh. 2009. Synthesis and field evaluation of the sex pheromone of Stenoma catenifer (Lepidoptera: Elachistidae). J. Econ. Entomol. (in press).

 

Hoddle, M.S., J.G. Millar, C.D. Hoddle, Y. Zou, J.S. McElfresh, and S.M. Lesch. 2009. Field optimization of the sex pheromone of Stenoma catenifer (Lepidoptera: Elachistidae): Evaluation of lure types, trap heights, male flight distances, and number of traps needed per orchard for detection. Journal of Economic Entomology (submitted).

 

Hohmann, C.L., Dos Santos , W.J., Menegium, A.M. 2000. Avaliação de técnicas de manejo para o controle de broca-do-abacate, Stenoma catenifer (Wals) (Lepidoptera: Oecophoridae). Rev. Bras. Frutic. Jaboticabal 22: 359-363.

 

Hohmann, C.L., Meneguim, A.M., Andrade, E.A., Novaes, T.C., and Zandoná C. 2003. The avocado fruit borer Stenoma catenifer (Wals.) (Lepidoptera: Elachistidae): egg and damage distribution and parasitism. Revista Brasileria de Fruticultura 25: 432-435.

 

Millar, J.G., M.S. Hoddle, J.S. McElfresh, Y. Zou, and C.D. Hoddle. 2008. (9Z)-9,13-tetradecadien-11-ynal, the sex pheromone of the avocado seed moth, Stenoma catenifer. Tetrahedron Letters 49: 4820-4823.

 

Nava D.E., Parra, J.R.P., Diez-Rodríguez, Bento. J.M.S. 2005a.Oviposition behavior of Stenoma catenifer (Lepidoptera: Elachistidae): chemical and physical stimuli and diel pattern of egg laying. Annals of the Entomological Society of America 98: 409-414.

 

Nava D.E., Parra, J.R.P., Costa, V.A., Guerra, T.M., and Cônsoli, F.L. (2005b). Population dynamics of Stenoma catenifer (Lepidoptera : Elachistidae) and related larval parasitoids in Minas Gerais, Brazil. Florida Entomologist 88: 441-446.

 

Nava D.E., de Lara Haddad, M., and Parra, J.R.P. 2005c. Exigências térmicas, estimativa do número de geroções de Stenoma catenifer e comprovação de modelo em campo. Pesq. Agropec. Bras., Brasilia 40 : 961-967.

 

Ventura, M.U., Destro, D., Lopes, E.C.A., and Montalván, R. 1999. Avocado moth (Lepidoptera: Stenomidae) damage in two avocado cultivars. Florida Entomologist 82: 625-631.