RESUMEN
Twenty-five RAPD loci and 6 isozyme loci were studied to characterize the genetic variability of natural populations of Anthonomus grandis from two agroecosystems of Brazil. The random-amplified polymorphic DNA data disclosed a polymorphism thatvaried from 52 to 84% and a heterozygosity of 0.189 to 0.347. The index of genetic differentiation (GST) among the six populations was 0.258. The analysis of isozymes showed a polymorphism and a heterozygosity ranging from 25 to 100% and 0.174 to 0.277, respectively. The genetic differentiation (FST) among the populations obtained by isozyme data was 0.544. It was possible to observe rare alleles in the populations fromthe Northeast region. The markers examined allowed us to distinguish populations from large-scale, intensive farming region (cotton belts) versus populations from areas of small-scale farming.
Asunto(s)
Animales , Gorgojos/genética , Variación Genética , Brasil , Isoenzimas/genética , Técnica del ADN Polimorfo Amplificado Aleatorio , Gorgojos/enzimologíaRESUMEN
Foram estudados, em câmara climatizada, a 30°C, umidade relativa de 60 ± 10 por cento e fotofase de 14h, os efeitos dos hospedeiros alternativos Euscepes postfasciatus (Fairmaire) e Callosobruchus maculatus (Fabricius) na reprodução e ataque de Catolaccus grandis (Burks), parasitóide do bicudo-do-algodoeiro. Os hospedeiros alternativos C. maculatus e E. postfasciatus, proporcionaram ao parasitóide, taxas de desenvolvimento superiores às apresentadas por A. grandis. As taxas de parasitismo variaram de 44,3 por cento no hospedeiro alternativo E. postfasciatus a 39,9 por cento em A. grandis. O hospedeiro natural (bicudo) foi o que originou a maior porcentagem de pupas fêmeas (73,7 por cento). C. grandis apresentou a mesma aceitação para oviposição em ambos hospedeiros alternativos, porém a maior produção de ovos foi obtida sobre E. postfasciatus. A oogênese do parasitóide foi estimulada de forma semelhante na presença dos hospedeiros A. grandis e E. postfasciatus, e ambos superaram o hospedeiro alternativo C. maculatus em número de ovos depositados nos cinco primeiros dias. A qualidade do hospedeiro afetou o período de oviposição e a longevidade do parasitóide, sendo o hospedeiro A. grandis responsável por menor expectativa de vida e menor período de oviposição. Larvas de E. postfasciatus ou C. maculatus podem ser usadas como hospedeiros alternativos de C. grandis e estimulam a oogênese em fêmeas de C. grandis.
The effects of the factitious hosts Euscepes postfasciatus (Fairmaire) and Callosobruchus maculatus (Fabricius) on the reproduction and attack rates of Catolaccus grandis (Burks), parasitoid of the cotton boll weevil, were studied in bioclimate chambers, at 30°C, relative humidity of 60 ± 10 percent, and a 14L:10D photoperiod. The factitious hosts C. maculatus and E. postfasciatus provided higher development rates than A. grandis. The parasitism rates ranged from 44.3 percent in E. postfasciatus to 39.9 percent in A. grandis. The natural host (cotton boll weevil) originated the highest female pupae percentage (73.7 percent). C. grandis showed the same acceptance for oviposition in both factitious hosts; however, the highest production of eggs was obtained on E. postfasciatus. The parasitoid oogenesis was stimulated in a similar way in the presence of the host A. grandis and factitious host E. postfasciatus, and both overcame the factitious host C. maculatus in number of eggs deposited in the first five days. The host quality affected the oviposition period and the longevity of the parasitoid, being the host A. grandis responsible for smallest life expectation and oviposition period. Larvae of E. postfasciatus and C. maculatus might be used as factitious hosts of C. grandis. These factitious hosts serve as hosts for parasitoid females of C. grandis to stimulate oogenesis.
RESUMEN
Host feeding plants of adult boll weevils (Anthonomus grandis Boheman) were determined within the period: January 1997 - December 1999. This took place through the identification of pollen grains, isolated from the digestive tracts of boll weevils captured in pheromone traps placed in a transect line which passes through the localities of Montecarlo, San Ignacio, Candelaria and the Capital in the province of Misiones. Cotton has not been cultivated for five years in that province, nevertheless important populations of weevils still remain during the whole year. About 1,360 weevils were dissected and 5,325 pollen grains were found; these were assigned to 28 species. Only those that presented percentages above 1%, which were 20 (4,183 pollen grains), were used. They belonged to five botanical families: Malvaceae, Compositae, Solanaceae, Euphorbiaceae and Leguminosae. Pollen of alternative plants provides the necessary energy for the survival of adult weevil in the absence of cotton pollen. The variation in the levels of relative abundance of pollen was analyzed with the study of the time of capture, sex, color, type of corporal fat, and reproductive status, using a log linear model (P<0.01).The following third order significant interactions were observed: time of capture x sex x reproductive status; color x corporal fat x reproductive status; levels of pollinic abundance x corporal fat x reproductive status. The ingesta level varied significantly with the corporal fat and the reproductive status, which are some determinants of the physiologic status of adult weevils. The grouping and ordering analyses showed the period of time, selectivity and use of the availability of pollen, since gender and species varied in the different seasons of the year, but they always belonged to the five mentioned families.
Se determinaron las plantas hospedantes alimenticias del picudo del algodonero adulto (Anthonomus grandis Boheman) en el período enero 1997- diciembre 1999. La misma se llevó a cabo mediante la identificación de los granos de polen aislados de los tractos digestivos de picudos capturados en trampas con feromonas ubicadas en una transecta que atraviesa los departamentos de Montecarlo, San Martín, San Ignacio, Candelaria y Capital de la provincia de Misiones, Argentina. Esta provincia no cultiva algodón desde hace cinco años, pero mantiene importantes poblaciones de picudo durante todo el año. Se disecaron 1360 picudos y se hallaron 5325 granos de polen asignados a 28 especies. Solo se utilizaron las que presentaron porcentajes superiores al 1%, que fueron 20 (4183 granos de polen), pertenecientes a cinco familias: Malvaceae, Compositae, Solanaceae, Euphorbiaceae y Leguminosae. El polen de plantas alternativas provee de la energía necesaria para la sobrevivencia del picudo adulto en ausencia de polen de algodón. Se analizó la variación en los niveles de abundancia relativa de polen, a través del estudio de la estacionalidad, sexo, color, tipo de grasa acumulada, y estado reproductivo, usando un modelo loglinear (P< 0,01). Se observaron las siguientes interacciones significativas de tercer orden: época de captura x sexo x estado reproductivo; color x grasa corporal x estado reproductivo; nivel de abundancia polínica x grasa corporal x estado reproductivo. El nivel de ingesta varió significativamente con la grasa corporal y el estado reproductivo, que son algunas determinantes del estado fisiológico de los picudos adultos. Los análisis de agrupamiento y ordenamiento demostraron la estacionalidad, selectividad y aprovechamiento de la disponibilidad de polen, ya que variaron géneros y especies en las diferentes estaciones del año, pero siempre pertenecientes a las cinco familias citadas.