Orius albidipennis (Reuter, 1884) (Hemiptera, Anthocoridae) preys on a diverse range of soft-bodied arthropods, including thrips such as Thrips tabaci Lindeman, 1889 and Frankliniella occidentalis (Pergande, 1895), whiteflies (Bemisia tabaci (Gennadius, 1889); eggs and nymphs), spider mites (Tetranychus spp.), and lepidopteran eggs such as those of Spodoptera frugiperda (J.E. Smith, 1797) (Sobhy et al. 2006). Both nymphs and adults exhibit high predation capacity; nymphs consume 6.8–26.5 first-instar thrips daily depending on prey density, while adults achieve consumption rates of up to 33.2 nymphs/day (Tavella et al. 1996; Amer et al. 2021). This polyphagy enables rearing on factitious prey (Ephestia kuehniella Zeller, 1879 eggs) or pollen supplements, facilitating commercial mass production for augmentative biological control programs (Cocuzza et al. 1997a).

As global temperatures rise, understanding temperature-driven developmental responses becomes critical for optimizing mass-rearing protocols and predicting field efficacy under climate change scenarios. In Mediterranean climates such as Egypt, where greenhouse cultivation predominates for vegetable production, thermal biology data enable precise release timing and habitat manipulation to maximize predator establishment (Sobhy et al. 2006; Waite 2012; El Kenawy et al. 2021). Antho­corid predators typically exhibit thermal optima between 24–28°C, where developmental rates accelerate, survival peaks, and reproductive output maximizes (Cocuzza et al. 1997b; Musolin et al. 2004; Tommasini 2004; Ballal et al. 2017). Below lower developmental thresholds (~12–15°C), prolonged immature stages increase mortality risk from fungal epizootics and nutritional deficits, while supraoptimal temperatures (>32°C) trigger reproductive senescence, reduced fecundity, and sex ratio distortion (Isenhour and Yeargan 1981; Madadi et al. 2009; De Oliveira et al. 2024). Stage-specific responses vary markedly: eggs and early instars show narrower thermal tolerances than late nymphs or adults, reflecting differential metabolic sensitivities and cuticular permeability (Logan et al. 2006; Bahşi and Tunç 2008; Lundgren et al. 2009). Orius albidipennis can complete its development and reproduce on Spodoptera frugiperda eggs, indicating its potential as a biological control agent against fall armyworm (Abd El-Rahman and Gaber 2023).

In Egypt, O. albidipennis demonstrates exceptional promise against F. occidentalis and T. tabaci in onion, tomato, and cucumber systems, consuming up to 15 first-instar thrips daily under peak conditions (Adly 2016; El-Kenawy et al. 2021). Temperature significantly modulates these traits: developmental time decreases from ~28 days at 20°C to 11 days at 30°C, with optimal fecundity (76 eggs/female) and lowest nymphal mortality (38%) at 25°C (El Arnaouty et al. 2018). Despite O. albidipennis’s demonstrated efficacy in achieving 75–85% thrips suppression during spring months (20–25°C) in Egyptian greenhouses, field efficacy drops precipitously to <40% during summer heatwaves (>32°C mean daily temperature; El Arnaouty et al. 2018). This seasonal collapse correlates with undocumented thermal thresholds for reproductive failure in locally adapted Egyptian strains. Critically, existing thermal biology studies for O. albidipennis derive primarily from European or Asian populations (Bonte et al. 2012; Hasanzadeh 2015), which may exhibit different thermal optima than North African strains subjected to intense selection pressure in Egypt’s arid climate. Furthermore, no published study has quantified instar-specific developmental durations with sufficient replication (≥15 cohorts) to parameterize stochastic population models for greenhouse microclimate forecasting, a critical gap for predicting establishment success under climate change scenarios.

Recent studies confirm linear relationships between temperature and developmental rates for O. albidipennis, yielding lower thermal thresholds of 12.5–15.0°C across instars and degree-day requirements averaging 26–51 days per stage (Bonte et al. 2012). Functional responses shift from Type II at 20–25°C to Type III at 30°C, with handling times dropping from 0.92 h (males) to 0.28 h (females) as temperatures rise, enhancing predation efficiency against high-density thrips cohorts (Rehman et al. 2020; El-Kenawy et al. 2021; Khamis and Jabbar 2021). Reproductive parameters follow suit: preoviposition shortens from 6–8 days at 15°C to 2–3 days at 30°C, while oviposition peaks (~12–15 days) and total longevity decline above 28°C due to accelerated senescence (Nagai and Yano 1999).

Life table analyses using age-stage, two-sex models reveal peak intrinsic rates of increase (r = 0.20 day⁻¹) at 25–30°C for O. albidipennis, surpassing temperate Orius species such as O. laevigatus (Fieber, 1860) (r = 0.105) under identical regimes (Bonte et al. 2012; Helgadóttir et al. 2017; Ali et al. 2020). Egyptian field trials corroborate laboratory optima, with 75–85% nymphal survival and 80–90% fertility on UV-killed E. kuehniella eggs at 25 ± 2°C (De Lima 2020). Yet critical gaps persist: (1) few studies incorporate stage-specific mortality into age-specific survival (l_x) calculations per Chi’s methodology, leading to inflated population growth estimates; (2) comprehensive stage-specific life tables across the 15–30°C rearing range remain limited for Egyptian strains, hindering commercial production standardization (Parker 1981; Ghoneim et al. 2021); and (3) the decoupling of r (intrinsic rate) and R₀ (net reproductive rate) under heat stress has not been quantified for IPM decision-making.

This study aims to (1) quantify temperature-driven stage-specific developmental patterns of an Egyptian O. albidipennis strain across 20, 25, and 30°C using rigorous age-stage, two-sex life table methodology with 15 replicates per temperature; (2) identify thermal optima for mass rearing by integrating mortality sources (egg hatch failure, nymphal mortality, sex ratio bias) into population parameter calculations; and (3) resolve the r–R₀ paradox under heat stress to provide actionable guidance for timing augmentative releases in Egyptian greenhouse systems under current and future climate scenarios.

Temperature exerted profound effects on the developmental biology and population dynamics of Orius albidipennis, with 25°C emerging as the unequivocal thermal optimum for mass-rearing applications in Egyptian greenhouse systems. Our life table analysis, rigorously implementing Chi’s age-stage, two-sex methodology (Chi 1988, 2020) with l_x incorporating all sources of pre-adult mortality—reveals that ignoring stage-specific mortality (egg hatch failure: 13.6–25.1%; nymphal mortality: 7.5–17.5%; sex ratio bias: female proportion 0.41–0.52) would artificially inflate R₀ estimates by 11–24%. This methodological rigor is critical for predictive accuracy in field establishment scenarios; a mass-rearing facility operating at 30°C that erroneously assumed 100% survival during development would project 29.7 offspring/female but produce only 25.6 reproductive females—a 14% underestimation of required founder populations for successful field releases.

Nymphal development accelerated nonlinearly with temperature, decreasing from 18.05 ± 0.35 days at 20°C to 9.62 ± 0.14 days at 30°C—a 47% reduction. This thermal sensitivity exceeded predictions from prior studies (Gitonga et al. 2002; Hasanzadeh 2015), likely reflecting our precise instar-specific measurements using daily exuviae tracking rather than periodic observations. Developmental time decreased consistently with increasing temperature across all nymphal instars.

All instars responded to warming, but the magnitude of reduction differed slightly among stages. N1 decreased from 3.50 to 1.81 days, representing a 48.3% reduction across 20–30°C. N5 declined from 4.44 to 2.53 days, corresponding to a 43.0% reduction. Intermediate instars showed comparable patterns, with N4 decreasing from 4.06 to 2.03 days (50.0% reduction). These results indicate strong thermal sensitivity throughout development rather than a disproportionate response restricted to later instars. The acceleration of N4–N5 at higher temperatures likely reflects increased metabolic rate and faster tissue growth under warming conditions, contributing substantially to the overall shortening of total nymphal duration (El-Kenawy et al. 2021), suggesting thermal manipulation during late nymphal stages could optimize pest suppression during vulnerable crop phenological windows.

Female fecundity peaked at 25°C (114.3 ± 2.5 eggs/female) with optimal egg hatch (86.4 ± 0.8%), yielding the highest net reproductive rate (R₀ = 49.4 ± 3.8 female offspring/female). This optimum reflects balanced physiological processes: sufficient metabolic rate for vitellogenesis without thermal stress on oogenesis or chorion formation. At 30°C, despite accelerated development (egg–adult = 15.0 days) and an elevated intrinsic rate (r = 0.145 day⁻¹), reproductive output collapsed (R₀ = 25.6)—a 48% decline from 25°C—due to synergistic effects of reduced fecundity (79.1 eggs), impaired egg viability (74.9% hatch), and a male-biased sex ratio (0.41 females). This decoupling of r and R₀ reveals a critical limitation with profound IPM implications: short generation times at supra-optimal temperatures cannot compensate for reproductive failure in sustaining populations long-term. While O. albidipennis may achieve rapid initial population growth during heatwaves (high r = 0.145 day⁻¹), sustained efficacy requires temperatures ≤28°C to maintain reproductive output (high R₀ = 49.4). Population models prioritizing r alone would dangerously overestimate field persistence during Egyptian summer conditions (Kahya 2023).

Temperature strongly affects the predatory performance of Orius similis Zheng, 1982 against Bemisia tabaci, with a Type II functional response across 19–31°C and peak efficiency at 28°C, where attack rate is highest and handling time is shortest. For optimal field control, O. similis should be released at 25–28°C, targeting early nymph stages while carefully managing predator density to reduce interference and maximize biocontrol efficacy (Zhang et al. 2024). Our study’s restriction to three constant temperatures precludes precise estimation of lower developmental thresholds (LDT) and optimal thermal ranges using nonlinear models (Sharpe and DeMichele 1977). Degree-day models require ≥5 temperature points spanning the full developmental range; future work should test 15, 20, 25, 28, and 32°C to calculate instar-specific LDTs and thermal constants. Furthermore, constant-temperature regimes poorly represent greenhouse microclimates where diurnal fluctuations of ±5°C occur daily. Fluctuating temperatures often enhance fitness relative to constant means through thermal summation effects and recovery periods during cooler phases (Kingsolver et al. 2015), potentially elevating the true thermal optimum above 25°C. Critically, we measured life history parameters without concurrent predation assays; functional response data at each temperature would reveal whether accelerated development at 30°C translates to enhanced pest suppression despite reduced fecundity—a key question for IPM implementation.

For commercial mass-rearing facilities targeting Egyptian greenhouse operations, maintaining 25 ± 1°C maximizes production efficiency, with 49.4 reproductive females produced per founder female and ~12 generations annually. Operations at 30°C require 92% more founder females to achieve equivalent output due to the 48% reduction in R₀ (25.6 vs. 49.4), rendering this temperature economically nonviable despite faster generation turnover (22.3 vs. 29.8 days). For field release timing, augmentative releases should target periods when 14-day mean greenhouse temperatures remain within 23–27°C to permit ≥2 complete generations before heat stress impairs reproduction. During summer months, when temperatures exceed 30°C for >5 consecutive days, supplemental evaporative cooling or 50% shade cloth deployment becomes essential to maintain predator efficacy against T. tabaci and F. occidentalis. Under climate change projections for Egypt (+2.5°C by 2050), greenhouse operators should prioritize installation of passive cooling systems to maintain thermal refugia for O. albidipennis during peak summer months.

Orius albidipennis exhibits optimal population growth at 25°C when mortality is properly incorporated into life table analysis using Chi’s age-stage, two-sex methodology. While development accelerates at 30°C (total nymphal duration = 9.62 days vs. 18.05 days at 20°C), reproductive collapse, evidenced by a 48% reduction in R₀ (25.6 vs. 49.4 female offspring/female), a 31% decline in fecundity (79.1 vs. 114.3 eggs/female), and a male-biased sex ratio (0.41 females), severely limits long-term population sustainability despite an elevated intrinsic rate (r = 0.145 day⁻¹). Critically, the decoupling of r and R₀ under heat stress reveals that rapid generation turnover cannot compensate for reproductive failure in sustaining populations, a finding with profound implications for climate-resilient biological control.

For Egyptian greenhouse operations, these findings provide actionable guidance: (1) mass-rearing facilities should maintain 25 ± 1°C to maximize female production efficiency (49.4 offspring/female) with a manageable generation time (29.8 days), enabling ~12 generations annually; (2) augmentative releases should target periods when 14-day mean temperatures remain within 23–27°C to ensure ≥2 complete generations establish before heat stress impairs reproduction; and (3) during summer months (>30°C), supplemental cooling or 50% shade cloth deployment is essential to maintain predator efficacy. Future research should integrate fluctuating temperature regimes with functional response assays to bridge the gap between laboratory life tables and field efficacy predictions under realistic greenhouse microclimates.

Regarding the use of AI in the preparation of this manuscript, the authors declare the following:

AI assistance was used exclusively for editorial refinement and structural enhancement of this manuscript. Specifically, AI tools supported: (1) language polishing and grammar correction. All scientific content, experimental design, data analysis, statistical interpretation, and authorship decisions were performed solely by the human authors. AI did not generate original scientific content or interpret experimental results.