ABSTRACT The aim of this study was to evaluate the damages caused by Diceraeus (=Dichelops) melacanthus in maize plants subjected to bioinoculation with or without imidacloprid seed treatment. In this study, five different combinations of bioinoculants and imidacloprid seed treatment were applied to maize seeds in a completely randomized design. The bioinoculants used were Azospirillum brasilense and Bradyrhizobium japonicum. From emergence, the plants were subjected to infestation with the stink bug D. melacanthus (one stink bug/plant), with permanence up to 21 days after emergence. After this period, the phytotechnical parameters (shoot and root) of the corn plants were evaluated. In general, plant height was higher when imidacloprid was applied, suggesting compatibility with bioinoculants. The chlorophyll a content was higher when bioinoculants were applied, regardless of whether imidacloprid was present. Finally, the results indicate that the bacteria A. brasilense and B. japonicum do not induce resistance to the level of D. melacanthus infestation used in the present study. Therefore, these bacteria can be used in combination with imidacloprid, allowing for greater plant height, higher chlorophyll a content, and reduced damage caused by D. melacanthus.

RESUMO A lagarta Chloridea (Heliothis) virescens (F.) (Lepidoptera: Noctuidae) tem sido registrada recentemente em lavouras de milho. Apesar disso, não existem informações sobre a biologia dessa espécie alimentando-se de espigas de milho. Adicionalmente, a relação entre os hábitos alimentares da lagarta-do-fumo e a temperatura é importante para a projeção da adaptação da praga em lavouras de milho, em diferentes épocas e regiões. Objetivou-se investigar o desenvolvimento de C. virescens em espigas de milho, em condições controladas de laboratório, sob três temperaturas (25 ± 1 ºC, 28 ± 1 ºC e 31 ± 1 ºC). Embora os insetos tenham atingido a fase adulta em todas as temperaturas, a fase larval foi reduzida a 31 ± 1 ºC, resultando em menor consumo de grãos. Por outro lado, parâmetros biológicos como viabilidade larval e pupal, peso de pupa e razão sexual não foram influenciados pela temperatura. Durante a fase adulta, a fecundidade foi similar para todas as temperaturas; no entanto, a viabilidade de ovos foi nula. A temperatura adequada para o desenvolvimento de C. virescens foi entre 25 ± 1 ºC e 28 ± 1 ºC. A temperatura de 31 ± 1 ºC afeta o desenvolvimento dos ovos, não permitindo uma nova geração da praga.

ABSTRACT The tobacco budworm Chloridea (Heliothis) virescens (F.) (Lepidoptera: Noctuidae) has been recently reported in corn crops. However, there is no information regarding the biology of this species feeding on corn cobs. Additionally, the relationship between temperature and tobacco budworm feeding habits is important to project the adaptation of the insect in corn crops at different times and regions. This study aimed to investigate the development of C. virescens feeding on corn cobs, under controlled laboratory conditions, at three temperatures (25 ± 1 ºC, 28 ± 1 ºC and 31 ± 1 ºC). Although adult budworms were observed at all temperatures, the larval development period was reduced at 31 ± 1 ºC, resulting in a lower grain consumption. On the other hand, biological parameters such as larval and pupal viability, pupal weight and sex ratio did not vary with temperature. During the adult stage, a similar fecundity was recorded at all temperatures; however, the egg viability was zero. The optimal temperature for the C. virescens development was between 25 ± 1 ºC and 28 ± 1 ºC. The temperature of 31 ± 1 ºC affects the eggs development, preventing the next generation of tobacco budworms.