The oriental fruit fly, Bactrocera dorsalis (Hendel), poses a significant threat to the global fruit industry, causing damage to diverse fruits like citrus, mango, and guava. Chemical pesticides have limited effectiveness, and pesticide residues and pesticide resistance are pressing issues. Therefore, it is essential to develop environmentally friendly pest control methods to address this problem. Behavior-modifying chemicals, including male attractants and intersex protein baits, play a critical role in the control of B. dorsalis. The mature host fruit serves as both an oviposition site and food source under natural conditions, making it a potential attraction source for oriental fruit flies. Orange, Citrus sinensis, is a main host of B. dorsalis, and commercial orange juice is a common attractant for the egg laying of B. dorsalis. Although it can both attract and elicit oviposition behaviors in B. dorsalis adults, its active components are still unclear. This study utilized analytical chemistry, behavioral tests, and electrophysiology to identify the active components of commercial orange juice that attract B. dorsalis, with the aim of providing a reference for the development of behavior-modifying chemical-based techniques to control B. dorsalis. Five compounds with a high abundance were identified via a GC-MS, including D-Limonene, butanoic acid ethyl ester, β-myrcene, linalool, and α-terpineol. Behavioral and electrophysiological experiments uncovered that D-Limonene was the active substance that was the main attractant in the mixture of these five substances, evoking a strong electrophysiological response in adult B. dorsalis. D-Limonene strongly attracts adult B. dorsalis only when they are sexually mature, and the attraction is not rhythmic. Olfaction plays a leading role in the attraction of D-Limonene to adult B. dorsalis, and Orco^−/− mediates the perception of D-Limonene by B. dorsalis. Overall, D-Limonene is one of the key attractant compounds for B. dorsalis in the volatile compounds of commercial orange juice, offering possible support for the development of behavior-modifying chemical-based technology to control B. dorsalis in the future.

Megalurothrips usitatus (Bagnall) is a major pest of cowpeas that severely affects their yield and quality. Spinetoram (a semi-synthetic derivative of natural spinosyns, modified to improve potency, residual activity, and stability) is currently one of the primary insecticides used for its control; however, prolonged or repeated exposure to this insecticide may lead to sublethal effects and the development of resistance. This study aimed to clarify the transgenerational effects of sublethal spinetoram stress on the development, reproduction, and population parameters of M. usitatus, with F₄ offspring reared on untreated pods to assess maternal effects. The LC₂₅ of spinetoram against M. usitatus was determined using an improved leaf-tube residual film method, and the thrips were successively selected for three generations (F₁–F₃) at this concentration. An age-stage, two-sex life table was constructed to systematically analyze the developmental duration, adult longevity, fecundity, and population life table parameters of the F₄ generation. The results showed that after three consecutive generations of LC₂₅ stress, the resistance ratio of M. usitatus to spinetoram reached 2.7. Compared with the water control, the F₄ generation from the treated group exhibited significantly shortened 1st and 2nd instar nymphal durations, as well as the total egg-to-adult period, while the prepupal duration was significantly prolonged. Adult longevity in females decreased from 23.65 ± 1.05 days to 16.07 ± 1.40 days (32.1% reduction), and male longevity decreased from 18.78 ± 0.96 days to 15.40 ± 0.82 days (18.0% reduction). Mean fecundity per female decreased from 247.15 ± 30.47 to 34.53 ± 6.02 eggs (86.0% decrease). Regarding population parameters, the net reproductive rate (R₀) decreased from 98.80 ± 0.07 to 10.36 ± 0.01 (89.5% decrease), the intrinsic rate of increase (r) decreased from 0.2506 ± 0.0001 to 0.1452 ± 0.0001 (40.0% decrease), the finite rate of increase (λ) decreased from 1.2849 ± 0.0001 to 1.1564 ± 0.0001 (10.1% decrease), and the mean generation time (T) was shortened from 18.24 ± 0.001 days to 15.84 ± 0.001 days (13.2% reduction). Age-stage-specific life expectancy (e_xj) was significantly reduced across all developmental stages, indicating a shorter survival time. The peak age stage-specific reproductive value (v_xj) was significantly lower and occurred earlier. The peak values of the age-specific survival rate (l_x) and fecundity (f_x, m_x) curves were significantly lower in the treated group. These findings indicate that multigenerational sublethal exposure to spinetoram can induce low-level resistance in M. usitatus and suppress the population growth potential by shortening developmental duration, reducing life expectancy, and reproductive contribution, and significantly inhibiting fecundity and survival. These results reveal the transgenerational sublethal effects of spinetoram and provide a theoretical basis for the integrated pest management (IPM) and resistance control of M. usitatus.

Frankliniella intonsa (Thysanoptera: Thripidae) is a polyphagous pest that causes significant economic agricultural losses by damaging flowers, vegetables, and fruit trees. We performed an age-stage two-sex life table analysis to evaluate the performance and adaptability of F. intonsa against nine common vegetable crops cultivated in Guangxi: cowpea (Vigna unguiculata) (Fabales: Leguminosae), green beans (Phaseolus vulgaris) (Fabales: Leguminosae), soybean (Glycine max) (Fabales: Leguminosae), catjang cowpea (Vigna cylindrica) (Fabales: Leguminosae), courgette (Cucurbita pepo) (Cucurbitales: Cucurbitaceae), wax gourd (Benincasa hispida) (Cucurbitales: Cucurbitaceae), bitter gourd (Momordica charantia) (Cucurbitales: Cucurbitaceae), cucumber (Cucumis sativus) (Cucurbitales: Cucurbitaceae), and chieh-qua (Benincasa hispida) (Cucurbitales: Cucurbitaceae). Among the tested host crops, green beans, cowpea, and courgette significantly accelerated the growth rate and favored the reproductive success of F. intonsa. Green beans, cowpea, and courgette facilitated rapid growth and reproductive success. The mean generation times (T) and net reproductive rates (R₀) were as follows: 14.90 d, 17.09 d, 21.03 d, and 104.04, 45.51, 32.61. Bitter gourd and chieh-qua significantly suppressed population growth (T: 49.49 d, 0 d; R₀: 0.73, 0). Wax gourd, catjang cowpea, cucumber, and soybean exhibited moderate effects characterized by delayed development and lower reproductive output (T: 22.30 d, 20.30 d, 19.51 d, 32.73 d; R₀: 7.17, 25.22, 13.74, and 12.54). These findings highlight the critical role of crop type in F. intonsa population dynamics. Therefore, the agricultural production of green beans, cowpea, and courgette crops necessitates improved control measures and monitoring. Similar measures are needed for cucumber, catjang cowpea, soybeans, and wax gourds because they pose risks as potential hosts.