Revista Colombiana de Entomología

Floral characteristics in five landraces accessions of pumpkin (Cucurbita argyrosperma) related to the attraction of insect visitors

Maria Luisa Balam-Pech — 2023-07-11

Pollination is extremely important for agriculture, with insects being the main pollinators. Plants have developed attraction strategies in their flowers to ensure visits from pollinators; therefore, knowing the floral characteristics that influence visits to crops could lead to improvements in yield. The floral attributes of five landraces accessions of pumpkin (Cucurbita argyrosperma) were compared: RRS004, RRS006, RRS005, RRS008 and RRS010. The experiment was carried out in a family orchard in Baca, Yucatan, Mexico. Evaluations were carried out in the period of maximum flowering, the size and area of the corolla, the height of the flower, floral display, volume and concentration of sugar in nectar, pollen production and its viability were recorded; and also, floral visitors. The results showed that there are differences in terms of floral traits between evaluated accessions, as well as the pollen and nectar floral area was associated with floral visitors. Similarly, a greater number of illegitimate visits was observed compared to legitimate visits, of which all were identified as chrysomelids (Acalymma sp.), bees (Partamona sp.), drosophilids (Drosophila sp.), thrips (Frankliniella sp.), ants (Solenopsis sp.) and wasps (Polybia sp.). Our study shows that the variation recorded in floral traits between accessions impacts the attraction of visiting insects, which demonstrates an important intraspecific variation in Cucurbita sp.

Insecticidal and antifeedant bioactivities of Melaleuca alternifolia essential oil on Ascia monuste orseis

Paulo Henrique Martins Da Silva — 2023-07-28

This study evaluated the bioactive effects of Melaleuca alternifolia essential oil on the behavior and mortality of Ascia monuste orseis caterpillars. The experiment was conducted at the laboratory under controlled conditions using a completely randomized design with six treatments, represented by A. monuste orseis caterpillars fed collard leaves treated with 0 (control), 5, 10, 20, 30, or 40 mg mL⁻¹ essential oil. Each treatment consisted of five replicates of four third-instar caterpillars. Mean daily intake of collard leaves, feces production, mortality, and behavioral changes were assessed for 15 days after the beginning of the experiment. Data on leaf intake and feces production were subjected to analysis of variance by the F-test; when significant differences were found, data were subjected to regression analysis. Corrected mortality rate was calculated and subjected to analysis of variance by the F-test followed by Tukey’s test at the 5% significance level for comparison of means. The median lethal dose (LD₅₀) was also evaluated. Two very clear feeding behaviors were observed, one in caterpillars exposed to essential oil concentrations of 5, 10, and 20 mg mL⁻¹, which showed little difference in feed intake from the control, and the other in caterpillars exposed to the highest concentrations (30 and 40 mg mL⁻¹), which showed a decrease of 76 to 93% in feed intake compared with the control. Lower leaf intake resulted in a decrease in feces production, and the negative effects increased linearly with essential oil concentration. The mortality curve showed a linear and positive response to essential oil concentration, reaching 100% in insects exposed to the highest concentrations. The LD₅₀ was 13.93 mg mL⁻¹.

Population fluctuation of Scolytinae (Coleoptera: Curculionidae) in avocado (Persea americana Mill.) orchards in Michoacán, México

Martha Olivia Lázaro-Dzul — 2023-09-01

This study aimed to determine the population fluctuation of Scolytinae (Coleoptera: Curculionidae) in orchards of avocado Persea americana var. Hass, located in the municipalities of Nuevo San Juan Parangaricutiro (SJ), Uruapan (UR), and Ziracuaretiro (ZR), Michoacán, México. The study was carried out from July 2016 to June 2018. The insects were captured using α-copaene, ethanol and querciverol + ethanol lures, which were placed in bottle traps. The population fluctuation of Scolytinae, during both years and sampling sites, presented its maximum peak during July and August. In ZR, the highest abundance of Scolytinae were recorded during July and October in the 2016-2017 cycle, and during September and October in the 2017-2018 cycle. The population abundance of Scolytinae was higher during the 2016-2017 cycle in SJ and UR, and in ZR the highest population abundance corresponded to the 2017-2018 cycle. The most abundant species of Scolytinae in SJ were Microcorthylus invalidus (43.28 %), Araptus schwarzi (28.68 %) and Corthylus detrimentosus (23.02 %), in UR, were A. schwarzi (41.40 %) and M. invalidus (14.75 %) and ZR were Premnobius cavipennis (26.04 %), Hypothenemus crudiae (17.75 %) and Corthylus flagellifer (16.17%). At the three sites, the maximum population coincided with the periods with higher rainfall and higher relative humidity percentages, conditions that favored a greater availability of food resources at the sites, which were used by the species for their establishment.

Synergists for agave weevil Scyphophorus acupunctatus (Coleoptera: Dryophthoridae) trapping on Agave angustifolia (Asparagaceae), in Guerrero, Mexico

Daniel Cuevas-López — 2023-08-16

Scyphophorus acupunctatus (Coleoptera: Dryophthoridae) attacks several species of native agaves and it is the most important insect pest of cultivated agaves in Mexico. The management of this insect is difficult due to its feeding habits on agave stems and leaves. Recently, a trapping system based on a synthetic aggregation pheromone and food bait has been developed to monitor and capture adult S. acupunctatus. However, it is important to know some alternatives that can synergize the response of S. acupunctatus to the synthetic pheromone. In this study, two consecutive field trials were carried out where diverse synergists were evaluated in traps placed in a plantation of Agave angustifolia (Asparagaceae), in Quetzalapa, Guerrero, Mexico. The synergists evaluated were the following: plant tissue of A. angustifolia, ripe fruits of pineapple (Ananas comosus), and banana (Musa paradisiaca) as well a synthetic synergist (Sinergium®). In all the experiments, a completely randomized design was used, with four repetitions for each treatment. The synergists evaluated had no effect on the captures of S. acupunctatus. The capture averages of S. acupunctatus/trap/day in the experiments did not differ, which is why it is suggested that in plantations with initial or low infestations (up to 5 weevils) it is not required to add synergists, while at high densities (more than 5 weevils) it is advisable to use a plant or synthetic synergist (Sinergium®) to make synergy with the synthetic pheromone. In addition, more female (192) than male (137) were captured in traps, which may impact future pest density populations of the weevil, plant health, and agave producer economics.