Biology of Anthonomus testaceosquamosus Linell, 1897 (Coleoptera: Curculionidae): A New Pest of Tropical Hibiscus

Originating in northeastern Mexico and southern Texas, the hibiscus bud weevil (HBW), Anthonomus testaceosquamosus Linell 1897, was discovered infesting China rose hibiscus (Hibiscus rosa-sinensis L.) in south Florida in May 2017. Although the biologies of the congeneric boll weevil, A. grandis Boheman 1843, and pepper weevil, A. eugenii Cano 1894 are well documented, no data are available regarding the biology of HBW. Here, we present a comprehensive study on the biology of this pest when reared at 10, 15, 27 and 34 °C and on different food sources. This weevil has three larval instars and its life cycle was completed only at 27 ± 1 °C. Weevil development was similar on an artificial diet when compared with a diet of hibiscus buds. Adult HBW could survive solely on pollen, but reproduction did not occur. Without water, HBW survived for ≈15 days; survival times reached nearly 30 days when water was accessible. Our results suggest that if left unmanaged, HBW has the potential to cause significant economic damage to the hibiscus industry. Given that a comprehensive understanding of a pest’s biology is critical for development of effective integrated pest management, our results provide a foundation for future research endeavors to mitigate the impact of this weevil in south Florida.

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.

Assessing New Tools for Management of the Pepper Weevil (Coleoptera: Curculionidae) in Greenhouse and Field Pepper Crops

The pepper weevil, Anthonomus eugenii Cano, is an economically important pest of field and greenhouse pepper crops in North America. In this study, a series of insecticides covering a broad-spectrum of insecticidal modes of action were assessed for their potential in managing the pepper weevil under laboratory and greenhouse conditions. To accomplish this, laboratory mini-spray tower and greenhouse cage trials were conducted that evaluated the efficacy of 16 conventional, reduced-risk, and microbial insecticides. In laboratory trials, adult weevils were sprayed with insecticides, placed on treated leaves within a cup cage, and were monitored for their survival over 10 d. Of the 16 insecticides tested, 8 provided greater than 60% weevil control, a threshold considered necessary for including products in further greenhouse testing. In greenhouse trials, adult weevil mortality, bud and foliar damage, bud and fruit abortion, and subsequent weevil offspring emergence were measured following each of three weekly insecticide applications. The most efficacious insecticides included kaolin clay and mineral oil, which performed as well as the thiamethoxam-positive control, and incurred 70 and 55% of adult weevil mortality, respectively. Additionally, kaolin clay and mineral oil reduced offspring weevil emergence by 59 and 54%, respectively, compared with untreated controls. Despite the clear challenge that controlling this pest represents, this study has identified useful new tools for the integrated management of the pepper weevil, which may accelerate the rate at which these become available for use in greenhouse and field pepper production.