Extraction of Pest Insect Characteristics Present in a Mirasol Pepper (Capsicum annuum L.) Crop by Digital Image Processing

One of the main problems in crops is the presence of pests. Traditionally, sticky yellow traps are used to detect pest insects, and they are then analyzed by a specialist to identify the pest insects present in the crop. To facilitate the identification, classification, and counting of these insects, it is possible to use digital image processing (DIP). This study aims to demonstrate that DIP is useful for extracting invariant characteristics of psyllids (Bactericera cockerelli), thrips (Thrips tabaci), whiteflies (Bemisia tabaci), potato flea beetles (Epitrix cucumeris), pepper weevils (Anthonomus eugenii), and aphids (Myzus persicae). The characteristics (e.g., area, eccentricity, and solidity) help classify insects. DIP includes a first stage that consists of improving the image by changing the levels of color intensity, applying morphological filters, and detecting objects of interest, and a second stage that consists of applying a transformation of invariant scales to extract characteristics of insects, independently of size or orientation. The results were compared with the data obtained from an entomologist, reaching up to 90% precision for the classification of these insects.

Discriminación del parasitoide Jaliscoa hunteri (Hymenoptera: Pteromalidae) sobre un huésped natural y uno facticio

La cría masiva de organismos benéficos sobre el huésped natural suele ser muy costosa. Por lo tanto, huéspedes más fáciles de cultivar se buscan para reducir los costos de producción; sin embargo, ellos pueden perder su efectividad en campo. Por consiguiente, el objetivo de este estudio fue comparar la capacidad de discriminación del parasitoide Jaliscoa hunteri (Hymenoptera: Pteromalidae) sobre su huésped natural (Anthonomus eugenii Cano) o uno facticio (Callosobruchus maculatus Fabricius). Los ensayos se realizaron en unidades de ovoposición artificiales utilizando hembras colectadas en campo y hembras obtenidas de una colonia que tenían 13 generaciones, criadas sobre un huésped facticio. La procedencia de las hembras utilizadas en la investigación no afectó la preferencia de ovoposición y la alimentación sobre el huésped; sin embargo, las hembras silvestres y de laboratorio prefirieron más al huésped natural que al facticio.

Domestication of Chili Pepper Has Altered Fruit Traits Affecting the Oviposition and Feeding Behavior of the Pepper Weevil

The pepper weevil, Anthonomus eugenii, Cano (Coleoptera: Curculionidae), is one of the most destructive pests of chili pepper. It causes extensive damage on varieties selected for consumption. However, the occurrence of this pest on wild and ornamental peppers remains unknown. We investigated the consequences of chili domestication on the feeding and oviposition of A. eugenii on fruits and flowers. We used plants of one wild accession, Bird Eye Pepper, five ornamental varieties (Pops Yellow, Black Pearl, Sedona Sun, Chilli Chilli, and Salsa Deep), and two domesticated varieties selected for consumption (Scotch Bonnet and Jalapeño). First, we characterized the plants according to their fruit and flower sizes, pericarp thickness, capsaicin level, fruit position, and flower color. Then, we evaluated the susceptibility of fruits and flowers to A. eugenii. Overall, domestication increased fruit and flower sizes and pericarp thickness, altered capsaicin levels, and altered fruit position and flower color. Weevils laid more eggs and caused more feeding damage on varieties selected for consumption than on wild and ornamental plants. Our results add to the growing literature on the consequences of crop domestication on herbivores. This knowledge could be integrated into breeding programs to select varieties resistant against the pepper weevil.

COMPOUNDS FROM PEPPER FLOWERS AND FRUITS AS POTENTIAL ATTRACTANTS FOR THE CAPTURE OF PEPPER WEEVIL

Two field experiments were conducted to evaluate synthetic attractants derived from pepper flowers, flower buds and fruits, alone or in combination with the aggregation pheromone. The evaluation was carried out with the release and recapture of Anthonomus eugenii adults at different distances from the four cardinal points in separate trials. The volatility of the synthetic mixture and aggregation pheromone was determined by gas chromatographic analysis of the volatiles captured by dynamic headspace. The traps with synthetic mixture and essential oil captured insects at 10 m, while the aggregation pheromone trapped up to 60 m. The combination of synthetic mixture or essential oil with the aggregation pheromone did not increase the number of recaptures compared to the single pheromone. The synthetic mixture together with geranic acid recaptured adults up to 15 m, although they were not significantly different from the control. The exclusion of geranic acid from the aggregation pheromone significantly reduced the number of recaptured insects (P<0.05), while geranic acid alone failed to capture weevils. The results could be improved by increasing the concentrations of the compounds or by adding other compounds released during the reproductive stages of pepper. These results could guide future efforts for the development of tools based on synthetic plant volatiles for the monitoring of this pest.

Isolation of native entomopathogenic fungi with potential for control of the pepper weevil, Anthonomus eugenii Cano, in Puerto Rico

Entomopathogenic fungi were isolated parasitizing coffee borer beetle (Hypothenemus hampei Ferrari) and banana weevils (Cosmopolites sordidus Germar) in different parts of the island of Puerto Rico to be identified and examined for their pathogenicity on pepper weevil (Anthonomus eugenii Cano). Fungi were isolated and purified in acidulated potato dextroseagar (PDA) in the laboratory of the Plant Disease Clinic at the Agricultural Experiment Station, Juana Díaz. Seven fungal isolates were obtained from the municipality of Comerío, and one from the municipality of Adjuntas. Morphology, DNA sequences of different genetic regions of interest, and microsatellites were used for identification of fungal isolates. Two of the eight isolates were identified as Beauveria bassiana, three as Beauveria caledonica, two as Paecilomyces fumosorosea and one as Paecilomyces lilacinum. Pathogenicity tests were conducted in vitro using conidia suspension (1 x 106 conidia/mL). Insects were inoculated by immersion (10 sec) in the conidia suspension. Daily mortality data was taken (TL50, TL90) and the mean of the treatments were determined. All the fungal species were pathogenic to A. eugenii. The most effective treatments were: P. fumosorosea (Pae1) and B. bassiana (Bb1 & Bb3) with TL50 of 2.39, 2.53 and 2.56 days, respectively, while TL50 for the control was 6.56. A 100% mortality for treatments occurred between the fourth and sixth day compared to control, which reached it in 12 days. These isolates have the potential to be used on an integrated management program for the control of the pepper weevil.