Development of Stegasta bosqueella (Chambers) (Lepidoptera: Gelechiidae) in Peanut Cultivars

Stegasta bosqueella (Chambers) (Lepidoptera: Gelechiidae) is a major peanut pest (Arachis hypogeae L.) in Brazil. The evaluation of peanut cultivars is fundamental for characterizing the levels of insect resistance, supporting their use in integrated pest management (IPM). This study evaluated possible sources of antibiosis-type resistance to S. bosqueella in selected peanut cultivars. Five cultivars were evaluated for constitutive resistance levels: IAC Caiapó, IAC Runner 886, IAC OL3, IAC 503, and Granoleico. The development of S. bosqueella was evaluated under laboratory conditions, where neonate larvae were kept in Petri dishes and fed leaves of the peanut cultivars until pupation. The evaluated biological parameters of S. bosqueella were larval and pupal weights; larval, prepupal, and pupal periods; adult longevity; sex ratio; and larval survival. Larvae fed leaves of the IAC 503 cultivar presented prolonged larval periods, lower weights and survival. In addition, larvae fed on this cultivar gave rise to pupae with lower weights, adults with shorter longevity, and those with the lowest fitness index. Thus, IAC 503 was classified as resistant to S. bosqueella through antibiosis, whereas the other cultivars presented different levels of susceptibility. The results obtained herein can support the use of resistant cultivars in IPM for peanut crops since IAC 503 is a commercial cultivar that is readily available for planting by farmers. Additionally, IAC 503 can be useful in peanut breeding programs targeting S. bosqueella resistance, serving as a resistance gene donor.