Comperiella calauanica is a host-specific endoparasitoid and effective biological control agent of the diaspidid Aspidiotus rigidus, whose outbreak from 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 the area under the ROC curve (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.

Cacao is a promising high-value crop in the Philippines and is considered one of the key players globally in providing the raw materials for chocolate making. However, before the Philippines can take this market opportunity, production constraints from various pests should be addressed. The cacao pod borer (CPB), Conopomorpha cramerella, is one of the major insect pests of cacao in the Philippines, which can cause up to 50% annual loss or even higher if proper management is not employed. Management of CPB heavily relies on chemical control but is becoming unpopular because of its high cost and health risk to people and the environment. A number of efforts have been made to develop sex pheromones to monitor and control CPB. A field bioassay of the new blend of CPB sex pheromones was conducted in southern Philippines to determine its efficiency and identify the appropriate trap height placement in a cacao field, which is important in maximizing the efficiency of the sex pheromone traps for inclusion in the integrated pest management (IPM) program of CPB. Pheromone lures at four different trap heights (1.0 m, 0.5 m above the canopy, 0.0 m or along the canopy, and 0.5 m below the canopy) and a blank lure (control) placed 1.0 m above the canopy were evaluated in terms of male CPB trap catches. Results showed significantly higher male CPB trap catches when installed at least 0.5 m above the canopy while minimal to zero male CPB catches were obtained from the control traps with blank lures, confirming the attractiveness of the new blend of the CPB sex pheromone in the field. This suggests the reliability of the pheromone-based method to monitor and control CPB and as a major component of the IPM program.

Summary Plants respond to stress or damage by releasing volatile compounds, primarily for defense purposes. These volatiles function as signals for diff erent interactions of the plant with its environment. In this study, the volatile chemical profi le of healthy Garcinia mangostana L. (mangosteen) leaves was compared against leaves infested with the scale insect, Aspidiotus rigidus Reyne (Hemiptera: Diaspididae) through solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Analyses revealed that leaves emit the terpene kaur-16-ene in response to A. rigidus infestation. Kaur-16-ene is a precursor of gibberellin, a plant hormone for growth and development. The results suggest that the emission of kaur-16-ene in infested G. mangostana may play a role relevant in increasing the resistance of the plant towards infestations by herbivores.

Summary Emission of volatile organic compounds (VOCs) in plants is triggered by several biotic and abiotic factors, such as nutrient deficiency, environmental stress, and pathogenic attacks. For instance, plants suffering from limited or excessive nitrogen (N) supply may experience internal stress which can ultimately lower their stability and immunity making them susceptible to infection and infestation. In this study, VOCs from Capsicum annuum var. longum (Solanaceae) exposed to nitrogen (1.8 g/L, 4.5 g/L, and 9 g/L urea) were extracted using a 100 μm Solid Phase Microextraction (SPME) fiber coated with polydimethylsiloxane (PDMS). Using Gas Chromatography-Mass Spectrometry (GC-MS), extracted VOCs from N-treated plants were identified as Butanoic acid, 3-hexenyl ester, (E)-; Butanoic acid, hexyl ester; Hexanoic acid, 3-hexenyl ester, (Z)-; Hexanoic acid, 4-hexen-1-yl ester; cis-3-Hexenyl cis-3-hexenoate and 4-Pentenoic acid 2-methyl-, hexyl ester. Among these volatiles, butanoic acid, 3-hexenyl ester showed the most distinctive peak from the N-treated plants in comparison with the untreated. In addition, the Green Leaf Volatiles (GLV) 3-Hexenal; 2-Hexenal; 3-Hexen-1-ol, (Z)-; 2-Hexen-1-ol, (E) and 1-Hexanol were also detected from the N-treated plants. The identification of plant volatiles provides useful information that can be used in agricultural practices and plant phenotyping.

The cacao mirid bug, Helopeltis bakeri, is a major insect pest of cacao in the Philippines. It feeds on pods causing puncture wounds that become necrotic lesions and may lead eventually to pod abortion. There is currently no semiochemical-based system developed for the monitoring and control of H. bakeri. Here, we report a kairomone identified from host plants of H. bakeri as a potential attractant. Volatile components were extracted using solid-phase microextraction (100-µm polydimethylsiloxane) and analyzed by gas chromatography - mass spectrometry. Chemodiversity analysis considering compound richness, evenness, and disparity showed similar phytochemical diversity among the six host plants, suggesting that chemodiversity is a factor in the host selection behavior of H. bakeri. Comparison of volatiles revealed that β-caryophyllene was present in all host plants. Using a wind tunnel, an impregnated lure containing 90 µg β-caryophyllene showed the highest attraction to adult H. bakeri. The results show the potential of β-caryophyllene as attractant that can be used in the development of kairomone-based trapping systems for H. bakeri as part of a holistic integrated pest management system for cacao.