Biology of Anticarsia gemmatalis on soybean genotypes with different degrees of resistance to insects

• Published in: Scientia agricola 2005-01, Vol.62 (1), p.31-35
• Main Authors: Fugi, Cristina Gomes Quevedo, Lourenção, André Luiz, Parra, José Roberto Postali
• Format: Article
• Language: English
• Subjects: AGRICULTURE, MULTIDISCIPLINARY
• ISSN: 0103-9016; 1678-992X; 0103-9016
• DOI: 10.1590/S0103-90162005000100006

A knowledge of the mechanisms of resistance present in genetic materials should help breeding programs in developing cultivars resistant to insects. The biology of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) was studied on leaves of four soybean genotypes with different degrees of resistance to insects. The genotypes evaluated were cultivars IAC 17 and IAC 24, resistant to defoliators and stink bugs, line PI 229358, a source of multiple resistance to insects and used as parent in various lines selected for resistance to A. gemmatalis, and 'IAC PL-1', the susceptible control. The experiments were carried out in the laboratory, under controlled conditions of temperature (25 ± 2ºC), relative humidity (60 ± 10%) and photoperiod (14h). First instar larvae were placed in Petri dishes and fed leaves of each genotype, detached from plants at the R1 and R2 stages (beginning and full bloom). Later on, insect couples were maintained in 25 PVC cages to evaluate parameters of the adult stage. 'IAC 17' and 'IAC 24' promoted low viability of the larval, pupal, and egg stages, causing adult deformation and a reduction of the number of eggs per female. PI 229358 prolonged the immature stage and reduced pupal weight, egg viability, and adult longevity. Considering all tests, 'IAC 17' and 'IAC 24' were characterized as having antibiosis-type resistance, and 'IAC PL-1' demonstrated to be a genotype suitable for insect development. O conhecimento do tipo de resistência presente em genótipos pode dinamizar programas de melhoramento que tenham essa finalidade. Assim, estudaram-se aspectos biológicos de Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) em folhas de quatro genótipos de soja, sendo três com diferentes níveis de resistência e um suscetível a insetos. Avaliaram-se os cultivares IAC 17 e IAC 24, portadores de resistência a desfolhadores e sugadores, a linhagem PI 229358, progenitora de diversas linhagens resistentes a A. gemmatalis, e 'IAC PL-1' padrão de suscetibilidade. Os experimentos foram conduzidos em laboratório, sob condições controladas de temperatura (25 ± 2ºC), umidade relativa (60 ± 10%), e fotofase (14h). Larvas de primeiro ínstar foram acondicionadas em placas de Petri e alimentadas com folhas de cada um dos genótipos, retiradas de plantas nos estádios R1 e R2 (início e pleno florescimento). Posteriormente, casais foram mantidos em 25 gaiolas (tubo de PVC) para avaliar parâmetros da fase adulta. 'IAC 17' e 'IAC 24' proporcionaram baixa viab