ABSTRACT
Insects of economic importance such as Leucoptera coffeella can cause high defoliation in plants and reduce crop yields. We aimed to identify changes in the ecological niche and potential zones of the invasion. Occurrence records were obtained from databases and bibliography. WorldClim V2.0 bioclimatic layers were used. For the modeling of the potential distribution, the kuenm R package was used by executing the Maxent algorithm. The potential distribution models suggested greatest environmental suitability extends from Europe, South Asia, and Central and South Africa, showing the "tropical and subtropical moist broadleaf forests" as the ecoregion that presents the greatest probability of the presence of L. coffeella. The potential distribution model projected in the invaded area agrees with the known distribution in the region (America), although the results show that it is occupying environmental spaces not present in the area of origin. This species presented a large proportion of the invaded niche that overlaps the native niche and is colonizing new environmental conditions in the invaded area relative to its native distribution (Africa). This information could be used in the planning of coffee crops on the American continent.
Subject(s)
Ecosystem , Introduced Species , Animals , Animal Distribution , Lepidoptera , Coffea , MothsABSTRACT
Coffee culture, one of the main agricultural activities in Brazil, has undergone recent negative impacts due to unfavorable climate conditions, with a subnormal rainy period and increased temperatures during the second half of 2015. The coffee berry borer Hypothenemus hampei (Ferrari, 1867) (Coleoptera: Curculionidae) is one of the main insect pests of coffee crops worldwide. The present research aimed to determine the climate zones for coffee berry borer in the state of São Paulo, based on its thermal requirements. The results showed that the mean biological development time of H. hampei was affected by temperature, completing its life cycle more rapidly in increased temperatures until the 30°C threshold temperature, and more slowly above this temperature. Development time (egg-adult) was inversely related to temperature in the range between 18 and 32°C. The temperature threshold (Tt) was 13.9°C and the thermal constant (K) was 299 degree-days. These laboratory estimates of thermal requirements and the Geographic Information System (GIS) were used to generate insect life span distribution maps for São Paulo. In this state, the coffee berry borer can produce 5.09-10.53 generations annually. Higher pest incidences should coincide with both temperature increases and the availability of coffee fruit for infestation. The data obtained can be used to estimate the monthly and yearly number of generations of this pest, for use in integrated pest management programs.
Subject(s)
Temperature , Weevils/growth & development , Animals , Brazil , Coffea , Female , Models, BiologicalABSTRACT
Vector-borne plant pathogenic bacteria can induce changes in infected plants favoring the insect vector behavior and biology. The study aimed to determine the effect of maize bushy stunt phytoplasma (MBSP) postinoculation period on the host plant preference and transmission efficiency by the corn leafhopper, Dalbulus maidis DeLong & Wolcott, 1923 (Hemiptera: Cicadellidae). In a series of choice tests, D. maidis preference was measured as settling and oviposition on healthy maize plants versus infected maize plants showing early disease symptoms, advanced symptoms, or no symptoms. Finally, transmission efficiency of D. maidis was measured when the vector previously acquired the phytoplasma from asymptomatic source plants at different postinoculation periods. D. maidis adults preferred to settle and to oviposit on healthy than on symptomatic infected plants with advanced disease symptoms, and preferred asymptomatic plants over symptomatic ones. MBSP transmission by D. maidis was positively correlated with the postinoculation period of the source plant. Results suggest an MBSP modulation for D. maidis preference on asymptomatic infected maize plants in the early stages of the crop, allowing the pathogen an undetected transmission.
