High dispersal of Lepidoptera larvae between non-Bt and Bt cotton plants can favour the evolution of insect resistance; however, information on host acceptance of neonates in tropical transgenic crops is scarce. Therefore, the purposes of this study were as follows: (i) to investigate the feeding behaviour of susceptible and Cry1F-resistant strains ofSpodoptera frugiperda(J.E. Smith) on Bt and non-Bt cotton (Gossypium hirsutumL.) varieties and (ii) to understand the possible effects of cotton field contamination on the dispersal and infestation capacity ofS.frugiperdalarvae by using an individual-based model. The main results of this paper are as follows: (1) the highest post-feeding larval dispersal of the Cry1F-resistant strain occurred at an exposure time of 18–24 h; (2) via video tracking assays, we found that the least distance moved was by larvae resistant to Cry1F on non-Bt cotton; and (3) the model indicated differences in mobility capacity between Bt and non-Bt cotton. We conclude that resistant neonates exhibit sedentary behaviour. Our report represents the first findings concerning the fitness cost of larval behaviour traits ofS.frugiperdaassociated with Cry1F resistance in Brazilian populations.

Ecological modeling is an important tool for investigating dynamic behavior patterns in populations, trophic interactions, and behavioral ecology. However, the ecological patterns that reflect population oscillation trends are often not clearly visible without analytical instruments such as ecological models. Thus, ecological modeling plays a fundamental role in describing demographic processes that are important for population dynamics. Ecological models, besides making possible the visualization of ecological patterns, may also reveal patterns of population persistence in many trophic systems, including prey-predator or host-parasitoid relationships, interactions that are commonly present in integrated pest management programs. In this forum, we present the main ecological aspects important for model building and implementation of integrated pest management programs for insects. Particularly, in this study, we analyze the combination between host-parasitoid models and the concept of economic threshold level on a spatio-temporal scale. As a conclusion about the model combination, spatial structure is essential for models of this nature, since its introduction into the system significantly alters the economic threshold-level values.

In drosophilids, competition and coexistence can impact survivorship, growth, and reproductive output. Here, we evaluated direct competition between two co-occurring fruit flies, the spotted-wing drosophilaDrosophila suzukiiand the African fig flyZaprionus indianus, comparing results from field collections with laboratory experiments. Field collections were conducted to evaluate co-occurrence between species. In the laboratory, different densities of eggs of each species were provided an artificial diet, and intra- and interspecific densities were evaluated regarding biological traits such as development and fecundity. Field collections showed a prevalence ofZ.indianus, followed by other drosophilid species, includingD.suzukii. Pupal survival and adult emergence were higher inD.suzukiithan inZ.indianusat both intra- and interspecific densities, with decreasing values in response to increased densities. Fecundity did not differ significantly for either species at different intraspecific densities, but when reared together at different densities,Z.indianuswas significantly more fecund thanD.suzukii. Development time showed no significant difference at intraspecific densities, but when reared together,Z.indianushad longer development times thanD.suzukii. Leslie Matrix projections indicated thatD.suzukiishowed practically the same dynamics at intraspecific and interspecific densities, with increasing oscillations at low and intermediate densities and decreasing oscillations at high densities.Zaprionus indianusshowed a similar oscillation toD.suzukii, except at intermediate intraspecific densities, when the pattern was cyclic. Low interspecific densities resulted in decreasing oscillations. In the two-choice oviposition bioassays,D.suzukiifemales showed no significant preference for diets previously infested or not with either conspecific or heterospecific eggs at different densities. Understanding competitive interactions between co-occurring heterospecific species should be considered when establishing management tactics for spotted-wing drosophila.