Essential oils have emerged as promising alternatives for pest insect control. However, sublethal effects on insect reproduction and development are rarely explored, despite their relevance to integrated pest management (IPM). This study evaluated the sublethal effects of Piper hispidivervum C. DC. essential oil (EOPH) on the development and population growth of four populations of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), as well as the persistence of safrole residue in treated corn grains. Population development rates were determined using emergence curves and total emerged adults, while population growth was assessed by counting live insects in the feeding substrate at different storage intervals. Safrole residue persistence was analyzed using solid-phase microextraction in headspace mode (SPME-HS). Sublethal exposure to EOPH significantly reduced the development rate, total emergence, and growth in three of the four populations. The population from Crixás, GO, showed no significant reduction, with a population curve overlapping the control. The lethal dose was reduced by 98.20%, indicating low persistence and potential food safety. The EOPH exhibited sublethal effects on S. zeamais populations, reducing both development rates and population growth. This reduction varied among the populations studied. Further research is encouraged to explore its effects on different insect populations and under broader environmental conditions.

The two-spotted spider mite, Tetranychus urticae, is a global pest with increasing resistance to conventional acaricides, prompting the search for sustainable alternatives. Essential oils (EOs) are promising botanical biocides due to ecological safety and multitarget action. We evaluated lethal and sublethal effects of EOs from Alpinia zerumbet and Mesosphaerum suaveolens against T. urticae. Oils were obtained by hydrodistillation and characterized by GC–MS (major constituents: A. zerumbet—1,8-cineole 14.05%, sabinene 12.6%; M. suaveolens—β-sabinene (predominant), spathulenol 12.28%, 1,8-cineole 11.01%). In adult bioassays, M. suaveolens was more toxic (LC₅₀ = 4.24 µL mL⁻¹), whereas A. zerumbet showed LC₅₀ = 8.74 and LC₉₀ = 46.24 µL mL⁻¹. In ovicidal assays at LC₉₀, egg viability declined to 2% with A. zerumbet versus 57% with M. suaveolens. Repellency at sublethal concentrations (LC₂₀–LC₃₀) was high for both oils (≥75%) and exceeded 90% for M. suaveolens. Both oils suppressed population growth (instantaneous rate r_i reduced from 0.5848 in the control to 0.4746–0.5155 under treatments). PCA confirmed lethal concentration and repellency as the main discriminators among treatments. These data demonstrate the multitarget potential of A. zerumbet and M. suaveolens EOs as botanical acaricides for sustainable management of T. urticae.

O ácaro rajado Tetranychus urticae (Acari: Tetranychidae) é uma praga polífaga atacando diversas culturas, dentre estas são exemplos o feijão, algodão, soja, milho, tomate e entre outras. Seu controle

The black aphid Aphis craccivora Koch (Hemiptera: Aphididae) is pointed out as one of the main pests of cowpea, causing injuries through the suction of sap on the plants. Conventional control involves the use of systemic chemical pesticides, which, from indiscriminate use, can cause contamination of the environment, applicators and other people, causing the selection of resistant insect populations. In view of this scenario, this study proposes to evaluate the toxicity, repellency and impact on population growth of A. craccivora when exposed to neem and manipueira extract. Leaf discs of cowpea plants were made, which were immersed in the concentrations of extract and volume of cassava, using the residual effect methodology for these experiments. Toxicity tests were performed to determine the sublethal concentrations LC20 and LC30 of neem extract and manipueira volume. In addition, tests were conducted to evaluate the repellency of the treatments, observing the behavior of the insects in relation to the previously determined concentrations. The study also analyzed the impact of the lethal concentration (CL) of neem extract and cassava extract on the population growth of A. craccivora, calculating the growth rate of the insect. The results showed that neem has a higher lethal concentration, both in LC50 and LC90, showing to be more toxic, with 0.99 times and 1.69 times, compared to cassava, in relation to the repellent effect, only neem in CL30 was repellent, while in the other concentrations, LC20 of neem itself and CL20 and LC30 of manipueira, had a neutral classification. In the population growth the CL20 concentrations of neem and manipueira extracts there was no difference, however, it was evident that manipueira has a higher population growth rate in relation to neem.