Verificou-se o comportamento de cultivares de girassol em relação ao ataque de C. lacinia saundersii em condições de campo, avaliando-se o número de lagartas por planta, número de lagartas por metro linear porcentagem de plantas atacadas e de desfolha. Determinou-se ainda o efeito dessas cultivares sobre o desenvolvimento e alimentação do inseto em laboratório visando com isso determinar possíveis fontes e mecanismos de resistência envolvidos no laboratório, estudou-se a biologia do inseto em nove cultivares e realizou-se ainda um teste de não preferência para alimentação com chance de escolha em seis cultivares. Concluiu-se: as cultivares menos infestadas pela praga são Cargill-33, Contissol, Issanka-F, PIGB, Uruguai e Contissol-621, enquanto Contissol-711, Contissol-112 e Rumano-P₄ são as mais infestadas; cultivares testadas afetam a duração da fase larval o peso de lagartas a viabilidade pupal e a longevidade de adultos; entre os materiais testados as cultivares Uruguai Contissol-112 e Contissol -711 são as menos adequadas ao desenvolvimento da praga enquanto que PIGB, Issanka-F e Contissol-621 são as menos adequadas em testes com chance escolha, as lagartas apresentaram não-preferência para alimentação pela cultivar Uruguai, sendo as cultivares Contissol-112 e Contissol-711 as mais preferidas

This research deals with the behavior of sunflower cultivars in field condition. The following parameters were evaluated: number of larvae per plant, number of larvae per linear meter of plants, percentage of attacked plants and percentage of defoliation. In laboratory, the biology of the insect was evaluated on nine cultivars wich were previosly selected through field experiments. From this study six cultivars were selected to test the non-preference for feeding with free choice by using newly hatched and 4th instar larvae. The results were as follows: the most suitable methods for evaluating the insect infestation were the percentage of attacked plants and the number of larvae per linear meter of plants; the lesser infested sunflower cultivars were Cargill-33, Contissol, Issanka-F, PIGB, Uruguai, and Contissol - 621, while Contissol-711, Contissol-112, and Rumano-P₄ were the most infested ones; the occurrence of the insect was higher in the second period of planting (February to June) than in the first period (October to February); the cultivars tested affected several biological aspects of the insect; the cultivars Uruguai, Contissol-112, and Contissol-711 were the less suitable for the insect development, were as the cultivars PIGB, Issanka-F, and Contissol-621, were the more suitable ones; concerning the free choice tests, newly-hatched and 4th instar larvae showed non-preference for feeding on the cultivar Uruguai, on the other hand the cultivars|Contissol-112 and Contissol-711 were the most preferred ones