A Bioclimate-based maximum entropy model for Comperiella calauanica Barrion, Almarinez & Amalin (Hymenoptera: Encyrtidae) in the Philippines

Authors: ALMARINEZ, BILLY JOEL - De La Salle University; FADRI, MARY JANE - De La Salle University; LASINA, RICHARD - De La Salle University; TAVERA, MARY - De La Salle University; CARVAJAL, THADDEUS - Ehime University; WATANABE, KOZO - Ehime University; Legaspi, Jesusa; AMALIN, DIVINA - De La Salle University

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2020
Publication Date: 1/4/2021
Citation: Almarinez, B.M., Fadri, M.A., Lasina, R., Tavera, M.A., Carvajal, T.M., Watanabe, K., Legaspi, J.C., Amalin, D.M. 2021. A Bioclimate-based maximum entropy model for Comperiella calauanica Barrion, Almarinez & Amalin (Hymenoptera: Encyrtidae) in the Philippines. Insects. 12(1), Article 26. https://doi.org/10.3390/insects12010026.
DOI: https://doi.org/10.3390/insects12010026

Interpretive Summary: Recently, the coconut industry in the Philippines has been severely threatened by the false coconut scale insect. A potential biological control agent specific for this pest is a newfound species of parasitic wasp which is being evaluated and requires knowledge of the geographical distribution of both the pest and the parasite within the Philippines. Scientists in the Philippines at De La Salle University, Romblon State University, and Zamboanga Research Center, and Ehime University in Japan in collaboration scientists at the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, Tallahassee, Florida, used “Maximum Entropy” (MaxEnt) software to predict distribution of the parasite. A distribution map of the parasite was created by MaxEnt using field insect sampling and local weather data. Because the parasite is specific to the host and field sampling shows the species are often found together, we predicted that the distribution map for the parasite could also be used to predict the distribution of the host scale insect. MaxEnt provided predictive habitat suitability for the parasite which was confirmed by the presence of the host scale insect. Future efforts to control the scale insect should benefit from the use of distribution maps generated to predict presence of its parasite and lead to precision pest control applications.

Technical Abstract: Comperiella calauanica Barrion, Almarinez & Amalin (Hymenoptera: Encyrtidae) is a host-specific endoparasitoid and effective biological control agent of Aspidiotus rigidus Reyne (Hemiptera: Diaspididae), whose outbreak in 2010 to 2015 severely threatened the coconut industry in the Philippines. Using the maximum entropy (MaxEnt) algorithm, we developed a species distribution model (SDM) for C. calauanica based on 19 bioclimatic variables, using occurrence data obtained mostly from field surveys conducted in A. rigidus-infested areas in Luzon Island from 2014 to 2016. The calculated AUC values for the model were very high (0.966, standard deviation = 0.005), indicating the model’s high predictive power. Precipitation seasonality was found to have the highest relative contribution to model development. Response curves produced by MaxEnt suggested the positive influence of mean temperature of the driest quarter, and negative influence of precipitation of the driest and coldest quarters on habitat suitability. Given that C. calauanica has been found to always occur with A. rigidus in Luzon Island due to high host-specificity, the SDM for the parasitoid may also be considered and used as a predictive model for its host. This was confirmed through field surveys conducted between late 2016 and early 2018, which found and confirmed the occurrence of A. rigidus in three areas predicted by the SDM to have moderate to high habitat suitability or probability of occurrence of C. calauanica: Zamboanga City in Mindanao; Isabela City in Basilan Island; and Tablas Island in Romblon. This validation in the field demonstrated the utility of the bioclimate-based SDM for C. calauanica in predicting habitat suitability or probability of occurrence of A. rigidus in the Philippines.