Host preferences of the cocoa pod borer, Conopomorpha cramerella (Lepidoptera:Gracillariidae), the main threat to cocoa production in Southeast Asia

Authors: NIOGRET, JEROME - Niogret Ecology Consulting; EKAYANTI, ARNI - Niogret Ecology Consulting; Kendra, Paul; INGRAM, KEITH - Mars, Inc; LAMBERT, SMILJA - Mars, Inc; EPSKY, NANCY - Retired ARS Employee; MARELLI, JEAN-PHILIPPE - Mars, Inc

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2020
Publication Date: 4/21/2020
Citation: Niogret, J., Ekayanti, A., Kendra, P.E., Ingram, K., Lambert, S., Epsky, N., Marelli, J. 2020. Host preferences of the cocoa pod borer, Conopomorpha cramerella (Lepidoptera:Gracillariidae), the main threat to cocoa production in Southeast Asia. Entomologia Experimentalis et Applicata. 168(3): 221-227. https://doi.org/10.1111/eea.12882.
DOI: https://doi.org/10.1111/eea.12882

Interpretive Summary: The cocoa pod borer, (CPB) Conopomorpha cramerella Snellen (Lepidoptera: Gracillariidae), is the most serious insect pest of cocoa (Theobroma cacao), responsible for major declines in cocoa production in southeast Asia in recent decades. Despite its economic importance, much is still unknown about the ecology of this pest, including its host preferences. Therefore, ARS scientists in Miami, FL, in collaboration with scientists at Niogret Ecology Consulting LLC and Mars Wrigley Confectioners, Inc., conducted research in Indonesia to learn more about the host-seeking behaviors of female CPB. In laboratory choice tests, female CPB were more attracted to cocoa pods that to other host fruits, including rambutan, langsat, and Fiji longan. In addition, more eggs were laid on unripe cocoa pods than on ripe pods of the same size. When several cocoa clones were compared, CPB egg-laying preferences were not correlated with the degree of CPB infestation observed in the field. Consequently, female CPB preferences do not appear to be a major factor in explaining ‘resistance’ or ‘susceptibility’ of particular cacao clones. These results improve our understanding of the host-seeking behaviors of female C. cramerella and of particular clones susceptible to attack. This information will facilitate development of improved integrated pest management strategies for this pest.The cocoa pod borer, (CPB) Conopomorpha cramerella Snellen (Lepidoptera: Gracillariidae), is the most serious insect pest of cocoa (Theobroma cacao), responsible for major declines in cocoa production in southeast Asia in recent decades. Despite its economic importance, much is still unknown about the ecology of this pest, including its host preferences. Therefore, ARS scientists in Miami, FL, in collaboration with scientists at Niogret Ecology Consulting LLC and Mars Wrigley Confectioners, Inc., conducted research in Indonesia to learn more about the host-seeking behaviors of female CPB. In laboratory choice tests, female CPB were more attracted to cocoa pods that to other host fruits, including rambutan, langsat, and Fiji longan. In addition, more eggs were laid on unripe cocoa pods than on ripe pods of the same size. When several cocoa clones were compared, CPB egg-laying preferences were not correlated with the degree of CPB infestation observed in the field. Consequently, female CPB preferences do not appear to be a major factor in explaining ‘resistance’ or ‘susceptibility’ of particular cacao clones. These results improve our understanding of the host-seeking behaviors of female C. cramerella and of particular clones susceptible to attack. This information will facilitate development of improved integrated pest management strategies for this pest.

Technical Abstract: Insects ensure the survival of their offspring by depositing their eggs in suitable environments. Even generalist egg-laying insects often show preferences towards specific hosts. The cocoa pod borer (CPB) Conopomorpha cramerella (Snellen, 1904) (Lepidoptera: Gracillariidae) successfully infests and reproduces on relatively few host plants, but only has a major economic impact on the cocoa. Our study showed that, when given the choice, CPB significantly favored cocoa pods compared with any other host fruits available. Females also oviposit more eggs on unripe fruits compared with ripe fruits of similar size. When several cocoa clones were compared, CPB egg-laying preference was not correlated to the degree of CPB resistance of the cocoa clones observed in the field. Consequently, the preference of CPB for any specific clone does not seem to be the main factor explaining the resistance of some of the cocoa clones in the field.