Search Results (35)

The gene encoding juvenile hormone transcription factor Krüppel homolog 1 (Kr-h1) was studied for its effects on ovary development and reproduction in the ladybug beetle, Coccinella septempunctata. Kr-h1 expression in C. septempunctata was evaluated in females supplied with a juvenile hormone (JH) amended diet using quantitative PCR, and the function of Kr-h1 in female reproduction was assessed using RNAi technology. Expression of Kr-h1 in females supplied with a JH diet was significantly higher at 5 and 10 d than in females not supplied with JH. At 5 and 10 d post-injection with Kr-h1-dsRNA, Kr-h1 expression levels were 30.97% and 38.32% lower, respectively, than expression in controls injected with GFP-dsRNA. Development of ovaries and vitellogenesis in ladybugs microinjected with Kr-h1-dsRNA was significantly delayed in comparison to controls. At 20 d post-injection, mean egg production decreased by 28.74% relative to controls. These results prove that Kr-h1 has a vital role in modulating ladybug fecundity by impacting ovary development and egg production. Full article

Ongoing climate change is increasing the frequency and magnitude of high-temperature events, and extreme weather events such as heatwaves are expected to become more common. The impacts of extreme temperatures are likely even more severe at higher trophic levels, which depend on the adaptive capacity of lower trophic levels. However, compared with parasitoids at the third trophic level, less is known about these effects on parasitoids at the fourth trophic level, which occupy the terminal end of food chains. This study investigates the effects of experimental heatwave duration variability on the development of two congeneric gregarious larval–pupal endoparasitoids, Oomyzus scaposus and O. spiraculus, parasitizing the seven-spot ladybird, Coccinella septempunctata L. Heatwave treatments negatively affected the brood size of both species. The heatwave also affected the sex ratio of O. scaposus, though it remained highly female-biased. Exposure to heatwaves for 1 h accelerated the development of O. scaposus. For O. scaposus, the body mass of both females and males was lowest under the 3 h heatwave treatment. In contrast, for O. spiraculus, heatwaves had a marginally negative effect on the body mass of both female and male adults, though this effect was not statistically significant. Our results indicate that both species respond similarly, and even daily heatwave exposure of a few hours can affect the performance of O. scaposus and O. spiraculus. Full article

Cauliflower, a widely cultivated vegetable crop valued for its edible curds, faces a persistent threat from insect pests, which are typically managed using synthetic insecticides. This study evaluated the benefits of intercropping practices as part of an ecological pest management strategy in cauliflower cultivation during the winter seasons of 2017–18 and 2021–22. Nine insect pests belonging to six families of three orders were recorded. The calendula intercropping system (IS) consistently showed the lowest infestation by Plutella xylostella and Pieris brassicae/plant. Calendula IS had attracted the highest numbers of syrphids, Cotesia glomerata, Diaeretiella rapae, Cotesia vestalis, and coccinellids such as Coccinella septempunctata and Cheilomenes sexmaculata. In candytuft IS, a strong tri-trophic interaction between the flower and D. rapae significantly reduced aphid populations, for each additional D. rapae, aphid numbers decreased by 48.53 in 2018. The marigold IS recorded the highest Shannon diversity index in 2021–22. The longest adult survival of C. septempunctata (8.67 ± 3.35 days), in the absence of aphids was recorded on candytuft flowers. The total sugars and protein in flowers positively influenced the longevity of the adult coccinellid beetles (R²-40.42 and 20.79%, respectively). Calendula intercropping yielded the highest revenue return of Indian rupee (₹) 11.33 per INR 1 invested, compared to the cauliflower monocrop (1.58). These findings demonstrate that, intercropping and habitat manipulation can enhance ecological pest control and reduce the dependence on synthetic chemicals. Full article

The effects of the gene encoding the ecdysone receptor (EcR) on the reproduction of the ladybug Coccinella septempunctata was evaluated. EcR transcription was measured by quantitative real-time PCR in ladybug adults reared on artificial diets with and without 20-hydroxyecdysone (20E). EcR expression levels in 5 d old male and female ladybugs supplied with the 20E-amended artificial diet were lower than expression levels in ladybugs reared on an artificial diet lacking 20E. However, EcR expression levels in 10 d old ladybugs supplied with the 20E artificial diet were higher than those lacking 20E supplementation. The regulatory effects of EcR were studied in female and male ladybugs by RNA interference. EcR expression in female ladybugs injected with EcR-dsRNA was significantly downregulated after 5 d but remained unaffected in 10 d old females. EcR expression levels in males microinjected with EcR-dsRNA were significantly lower at 5 and 10 d after microinjection than GFP-dsRNA-treated males. The ovary volume in females injected with EcR-dsRNA at 5 d was smaller than females microinjected with GFP-dsRNA, but volumes at 10 d were larger than in GFP-dsRNA-treated females. The testes of males injected with EcR-dsRNA were larger than those injected with GFP-dsRNA at 5 d but the testes at 10 d after injection with EcR-dsRNA were smaller than those injected with GFP-dsRNA. When females were microinjected with EcR-dsRNA and mated with noninjected males, egg production decreased by 34.80% for 20 days. When males were microinjected with EcR-dsRNA and mated with noninjected females, egg production decreased by 30.38% for 20 days. Injection of female and male ladybugs with EcR-dsRNA had no significant effect on egg hatching rates. Our results show that EcR plays an important role in the development of reproductive organs and egg development in C. septempunctata. Full article

Cotton aphids, Aphis gossypii, are an important pest worldwide and have evolved mutualistic relationships with the invasive fire ant Solenopsis invicta. Their body color varies from pale yellow to dark green, with an increase in body size and fecundity. The body color composition in a cotton aphid colony can be influenced by biotic interactions with mutualistic ants and predatory ladybugs. However, since the distribution of nutrients varies across host plant organs, there may exist special effects of biotic interactions on the body color composition of the aphids on different plant parts. In the present study, we found that, under constant laboratory conditions, the proportions of dark green morphs varied among the cotton aphids distributed on different parts of a cotton seedling, with significantly higher proportions on the stems, petioles, and sprouts (SPSs) than on leaves. The presence of mutualistic fire ants significantly increased the proportion of dark green morphs in the cotton aphid colony, but with a reduction in aphid body size, compared to the untended individuals. In contrast, the introduction of a predatory seven-spotted ladybug, Coccinella septempunctata, dramatically decreased the proportion of dark green morphs on SPSs, but not on leaves, leading to a reduction in the proportion of the whole colony. These results illustrate a spatial variation in the proportions of dark green morphs on host plants in cotton aphids, which may be an adaptive strategy used by the aphids to gain benefits and/or minimize costs in the interactions with mutualistic ants and predatory ladybugs. Full article

Coccinella septempunctata (Linnaeus, 1758) is a voracious predator all over the world where aphids have found a niche. Behavioral studies of C. septempunctata are very important to make them effective bio-controllers. Therefore, this study explains the functional response of C. septempunctata praying on two distinct aphid species, examined in this work at two different temperatures. Six different prey densities (4, 8, 16, 32, 64, and 128 aphids) and two different temperatures (15 and 25 °C) were used in the experiment. All of the development stages of the predator were used to perform the experiment. Every experiment was replicated five times. The type and parameters of functional response were ascertained by the application of Roger’s random predator models and logistic regression. Results showed that C. septempunctata adults and larvae both had a type II functional reaction against the tested aphids in both temperatures. When comparing the fourth instar to other predatory stages, the attack rate against both aphids was shown to be greater. As the temperature rose, so did the attack rate. Fourth instar larvae exhibited attack rates of 1.314 h⁻¹ on Aphis nerii Fonscolombe, 1758 (Hemiptera: Aphididae) and 1.959 h⁻¹ on Lipaphis erysimi Kaltenbach, 1843 (Hemiptera: Aphididae) at 15 °C, while at 25 °C, the rates were 1.747 h⁻¹ and 1.321 h⁻¹, respectively. Handling time was influenced by both temperature and predator stage. As the temperature increased, the handling time of the later predatory stages decreased. This study suggests that later predatory stages of C. septempunctatas actively hunt aphids at higher temperatures. Full article

The ladybirds Coccinella septempunctata and Harmonia axyridis are important biocontrol agents for the small walnut aphid Chromaphis juglandicola, a key walnut pest. C. juglandicola outbreaks occur in walnut orchards, and walnut yields have declined. Intraguild predation (IGP) is prevalent among natural enemies that coexist in shared habitats and prey upon the same extraguild prey. We designed laboratory experiments to evaluate the potential for IGP between these two ladybirds at different temperatures and extraguild (EG) prey densities, and the ability of IGP to control EG prey under different conditions. We measured IGP rates in first instar larvae, female adults, and male adults (both starved for 24 h) in the vulnerable immature life stages of two ladybird eggs. Intraguild (IG) prey (H. axyridis eggs or C. septempunctata eggs) and EG prey (C. juglandicola) consumption were tallied after 24 h. Temperature and EG prey density influenced IGP rates, with temperature contributing the most to the variance. IGP increased with increasing temperature (15–35 °C), with both factors interactively influencing the EG prey consumption rate and exhibiting highly significant effects. EG prey consumption increased with temperature and density. This research provides theoretical support for the rational use of H. axyridis and C. septempunctata in the joint biological control of C. juglandicola Full article

This study focuses on the regulatory effects of genes encoding the juvenile hormone (JH) receptor methoprene-tolerant (Met) and transcription factor krüppel homolog 1 (Kr-h1) on the reproductive capacity of Coccinella septempunctata male adults. Met and Kr-h1 expression levels were analyzed in males fed on artificial diets with and without JH by quantitative real-time PCR, and the effects of Met and Kr-h1 on male reproduction were analyzed by RNA interference technology. Met transcription levels in 5- and 10-day-old males fed with a JH-supplemented diet were lower than those without JH. Kr-h1 expression in 5-day-old adult males was lower in diets lacking JH but was higher in 10-day-old males fed on a diet lacking JH. There were no significant differences in the testes sizes of male ladybugs injected with Met-dsRNA when compared to GFP-dsRNA; however, the testis volume of ladybugs injected with Kr-h1-dsRNA was smaller than those injected with GFP-dsRNA. After males were injected with Met-dsRNA and Kr-h1-dsRNA, the mean egg production by females decreased by 12.75% and 23.10%, respectively, at 20 d postinjection. Our results show that Met and Kr-h1 have important roles in regulating reproduction by directly affecting testes development in males and egg production in females. Full article

Insulin-like peptides (ILPs) are important peptide hormones in insects, particularly involved in regulating physiological processes such as growth, development, and reproduction. However, the specific roles of ILPs in the reproduction of natural enemy insects remain unknown. In this study, two ILP genes, CsILP1 and CsILP2, were cloned and their functions were analyzed in female Coccinella septempunctata L. (Coleoptera: Coccinellidae). The open reading frames (ORFs) of CsILP1 and CsILP2 were 384 bp and 357 bp, respectively. The expression of CsILP1 increased on the 6th day after eclosion, reaching its peak on the 12th day, while CsILP2 levels showed a significant increase on the 6th day and then stabilized. In different tissues, CsILP1 was highly expressed in ovaries, while CsILP2 predominated in elytra. Injection of dsRNA targeting CsILP1 and CsILP2 resulted in the down-regulation of insulin pathway genes. The relative expression of ovarian development-related genes Vasa, G2/M, and Vg was reduced by 82.50%, 89.55%. and 96.98% in dsCsILP1-treated females, and by 42.55%, 91.36%, and 55.63% in dsCsILP2-treated females. Furthermore, substantial decreases in 14-day fecundity were observed, with reductions of 89.99% for dsCsILP1 and 83.45% for dsCsILP2. These results confirm the regulatory functions of CsILP1 and CsILP2 in female C. septempunctata reproduction. Full article

Many Coccinella septempunctata flights, with their precise positioning capabilities, have provided rich inspiration for designing insect-styled micro air vehicles. However, researchers have not widely studied their flight ability. In particular, research on the maneuverability of Coccinella septempunctata using integrated kinematics and aerodynamics is scarce. Using three orthogonally positioned high-speed cameras, we captured the Coccinella septempunctata’s banking turns in the climbing flight in the laboratory. We used the measured wing kinematics in a Navier–Stokes solver to compute the aerodynamic forces acting on the insects in five cycles. Coccinella septempunctata can rapidly climb and turn during phototaxis or avoidance of predators. During banked turning in climbing flight, the translational part of the body, and the distance flown forward and upward, is much greater than the distance flown to the right. The rotational part of the body, through banking and manipulating the amplitude of the insect flapping angle, the stroke deviation angle, and the rotation angle, actively creates the asymmetrical lift and drag coefficients of the left and right wings to generate right turns. By implementing banked turns during the climbing flight, the insect can adjust its flight path more flexibly to both change direction and maintain or increase altitude, enabling it to effectively avoid obstacles or track moving targets, thereby saving energy to a certain extent. This strategy is highly beneficial for insects flying freely in complex environments. Full article

Previous studies on the clap–fling mechanism have predominantly focused on the initial downward and forward phases of flight in miniature insects, either during hovering or forward flight. However, this study presents the first comprehensive kinematic data of Coccinella septempunctata during climbing flight. It reveals, for the first time, that a clap-and-fling mechanism occurs during the initial upward and backward phase of the hind wings’ motion. This discovery addresses the previously limited understanding of the clap-and-fling mechanism by demonstrating that, during the clap motion, the leading edges of beetle’s wings come into proximity to form a figure-eight shape before rotating around their trailing edge to open into a “V” shape. By employing numerical solutions to solve Navier–Stokes (N-S) equations, we simulated both single hind wings’ and double hind wings’ aerodynamic conditions. Our findings demonstrate that this fling mechanism not only significantly enhances the lift coefficient by approximately 9.65% but also reduces the drag coefficient by about 1.7%, indicating an extension of the applicability range of this clap-and-fling mechanism beyond minute insect flight. Consequently, these insights into insect flight mechanics deepen our understanding of their biological characteristics and inspire advancements in robotics and biomimetics. Full article

Many insects are able to walk vertically or upside down on both hard and soft surfaces. In beetles such as the ladybird (Coccinella septempunctata), intermolecular forces between tarsal setae on the footpads of the insects make this movement possible. In prior work, adhesion structures made from polydimethylsiloxane (PDMS) that mimic the action of the tarsal setae have been developed. It is proposed that these adhesion structures could be attached to a simplified version of the leg of a ladybird and used in practical applications. For example, the leg structures could potentially be employed in small surveillance drones to enable attachment to surfaces during flights, in order to preserve battery power. Alternatively, the structures could be used in small robotic devices to enable walking on steeply inclined surfaces. In this program of work, the morphology and movement of the leg of a ladybird were closely studied using a 3D X-ray microscope and a high-speed microscope. The positions of the tendons that facilitated movement were identified. From this knowledge, a simplified leg structure using pin-joints was designed and then fabricated using 3-D printing. The PDMS adhesion structures were then attached to the leg structure. The tendons in the actual insect leg were replicated using thread. Typical detachment forces of about 4 N indicated that the simplified leg structure was, in principle, more than capable of supporting the weight of a small device and then detach successfully. Attachment/detachment movement operations were performed using a linear actuator and controlled remotely. Therefore, proof of concept has been demonstrated for the use of such a simplified ladybird leg structure for the attachment/detachment of small robotic devices to horizontal, inclined, or vertical surfaces. Full article

Mosquitoes, as disease vectors causing global morbidity and mortality through diseases like malaria, dengue, and Zika, necessitate mosquito population control methods. This study investigated the efficacy of nano-formulated insecticide-based sugar baits in controlling Anopheles gambiae populations and assessed their potential non-target impact on Coccinella septempunctata. This laboratory-based study employed thiolated polymer-coated attractive toxic sugar bait (ATSB) nano-formulations, delivering pesticides via nano-carriers. Adult and larvae populations of insects were collected from rice and cotton fields subjected to bioassays with 0.5% and 1% concentrations of each nano-formulated and conventional insecticide within ATSB solution, alongside a control 100% attractive sugar bait (ASB). Mosquitoes interacted overnight with insecticide-treated baits, and mortality was assessed. Further observations up to 72 h were conducted for potential delayed toxic effects. Results highlighted nano-ATSB carbosulfan’s effectiveness, particularly among organophosphates and pyrethroids. Among pyrethroids, nano-ATSB cypermethrin exhibited high efficacy, while Deltamethrin displayed lower mortality. Among organophosphates, nano-ATSB chlorpyrifos induced substantial mortality. The nano-formulations of insecticide were harmless against C. septempunctata compared to their conventional form. Nano-formulations demonstrated enhanced mortality rates and prolonged efficacy against mosquitoes, having a benign impact on non-target beetles. We expect these results to aid in developing effective plant protection products suitable for IPM practices. Full article

The psyllid Bactericera gobica is a serious pest in goji berry orchards. The current primary psyllid control methods involve chemical pesticides, which pose potential risks to human health and the environment. The implementation and promotion of biological control agents should receive increased attention as an alternative approach to safeguarding goji berry orchards. To compare the predatory performance of three potential biocontrol agents of psyllids, including Harmonia axyridis, Coccinella septempunctata and Hippodamia variegata, the functional response and intraspecific interactions of adult ladybirds were studied under laboratory conditions. We observed a significantly higher searching efficiency (0.84 ± 0.09) in H. axyridis when preying on psyllids compared to H. variegata (0.55 ± 0.05), whereas the handling time for psyllids was considerably longer in H. axyridis (7.33 ± 0.83 min) than in H. variegata (5.67 ± 0.97 min). The impact of intraspecific interactions on H. variegata (0.44 ± 0.04) was significantly greater than that on C. septempunctata (0.29 ± 0.03), whereas the maximum consumption by C. septempunctata (223.35 ± 41.3) significantly exceeded that of H. variegata (133.4 ± 26.9). Our study suggests that each of these three ladybird species possesses distinct advantages as a potential predator of psyllids. However, further field studies are required to determine the most promising ladybird species for rapid impact through inundative biological control, taking into consideration the specific environmental adaptability of each ladybird species. The present study is expected to provide evidence that supports the potential of incorporating promising ladybird species as an effective biological control agent in goji berry orchard management programs. Full article

The aphid, Aphis gossypii Glover, is identified as a significant pest that causes severe damage to goji berries in China. To analyze the ladybird consumption of aphids, the functional responses of three ladybird species, Harmonia axyridis, Coccinella septempunctata, and Hippodamia variegata, and intraspecific competition among ladybird individuals were evaluated under laboratory conditions. Moreover, the practical impact of ladybirds on aphid population reduction was investigated in semi-field conditions. We found that all adult ladybirds of the three species exhibited a type II functional response toward aphids. According to Holling’s disc equation, H. axyridis exhibited the highest searching efficiency (a = 0.79), while C. septempunctata had the shortest handling time (T_h = 5.07 min) among the three ladybird species studied. Additionally, intraspecific competition had a greater impact on H. variegata (m = 0.41) compared to the other two ladybird species. The semi-field study demonstrated that H. axyridis (83.9% reduction) and C. septempunctata (78.7% reduction) exhibited higher efficacy in reducing aphid populations compared to H. variegata (27.3% reduction). This study suggests that H. axyridis and C. septempunctata exhibit potential as effective biological control agents against aphids on goji berry plants and highlights the importance of considering intraspecific competition. However, the results obtained from laboratory and semi-field studies cannot be directly extrapolated to field conditions due to the simplification of these experimental systems. Future field studies are crucial in ensuring the effective implementation of a biological control program. Full article