Mustard aphid, Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae), is one of the major biotic constraints limiting the productivity of Indian mustard (Brassica juncea). Biological control using aphidophagous coccinellids forms one of the cornerstones of sustainable integrated pest management (IPM) in mustard ecosystems. The present laboratory study was conducted to evaluate the comparative feeding efficiency of seven coccinellid predators, namely Coccinella septempunctata, Cheilomenes sexmaculata, Coccinella transversalis, Hippodamia variegata, Harmonia octomaculata, Micraspis discolor, and Brumoides suturalis, against L. erysimi under controlled conditions during 2023-24 and 2024-25. Adult predators were offered a constant prey density of 100 aphids per day, and consumption was recorded at 24, 48, 72 and 96 h intervals. Feeding efficiency was assessed in terms of mean percentage consumption and relative efficiency. Results indicated a clear hierarchy among predators, with C. septempunctata consistently showing the highest predatory potential, with an overall mean consumption of 86.20 per cent and 100 per cent relative efficiency, closely followed by C. sexmaculata 83.30 per cent and 96.68 per cent. Medium-ranking species, C. transversalis, H. variegata, and H. octomaculata, showed the best feeding efficiency, while M. discolor and B. suturalis recorded a comparatively lower consumption rate. A gradual decline in feeding over time was evident in all species due to satiation and endurance. Findings from the present study strongly affirm the superior biocontrol potential of C. septempunctata and C. sexmaculata against mustard aphid, thus necessitating their prioritized utilization in augmentative biological control and IPM programs in mustard cultivation.
Effective cotton leaf worm management strategies are crucial to minimize the destructive effect of the cotton leaf worm, Spodoptera littoralis. Silver nanoparticles (Ag NPs) are promising in controlling the cotton leaf worm because they are effective and eco-friendly rather than synthetic insecticides. The current study was conducted to evaluate the larvicidal activity of gamma-assisted silver nanoparticles (Ag NPs-G) against the third instar larvae of S. littoralis through the histopathological effect. The accumulative mortality of S. littoralis larvae for synthesized Ag NPs at LC50 was 170.76 ppm. Additionally, ultrastructure studies of midgut epithelial cells in 3rd instar larvae treated with Ag NPs revealed cell lysis including destruction of the cell membrane, nuclear distortion of the epithelial cells, destruction of microvilli, lysis of the mitochondrial matrix, appearance of electron-dense vesicles and vacuolated cytoplasm compared to the control group. This study concluded that applying the phyto-radio synthesized Ag NPs is more effective for controlling the cotton leaf worm, S. littoralis.
The castor hairy caterpillar, Euproctis lunata Walker (Lepidoptera: Erebidae), a least-known defoliating pest of castor plants (Ricinus communis), has recently gained attention due to considerable losses of castor plants in Pakistan. Pakistan lacks a comprehensive investigation of this insect pest, resulting in a significant knowledge absence about its biology, effects on castor crops, and sustainable management strategies. We determined the developmental biology of E. lunata on castor plants and studied the potential of entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana to control larvae of this pest. Larvae were grow through six instars, with a total duration of 21.4 days. The pupal stage was completed in 12.4 days, and adult moths lived for 5.10 days. Pathogenicity trials showed higher virulence of B. bassiana against E. lunata larvae compared toM. anisopliae. At a concentration of 10(9) conidia/mL, B. bassiana caused 87.5% larval mortality up to 15 days, while M. anisopliae induced 80.0% mortality. Further, probit analysis confirmed B. bassiana as a potent pathogenic fungus, with a lower LC50 value of 1.4 & times; 10(5) conidia/mL and LC90 of 6.1 & times; 10(9) conidia/mL. The findings provide useful information aboutE. lunata biology and highlight the potential of B. bassiana fungus for eco-friendly and sustainable management of this pest. Future studies should include extensive field surveys to map the distribution and infestation levels of this pest on castor plants and nearby cropping systems across diverse agro-ecological zones of Pakistan.
Spodoptera litura and Sodoptera exigua are major devastating agricultural pests with a wide host range. The influence of different hosts on the life cycle of S. litura and S. exigua growth was investigated using the age-stage, two-sex life table method. The mean incubation period of S. litura and S. exigua on cabbage was 3.43 and 3.27 days and 3.43 +/- 0.09 and 3.43 +/- 9.08 days on maize. The mean total larval period of S. litura and S. exigua was a little longer on maize than on cabbage. The high net reproductive rates (R-0) of S. litura and S. exigua were recorded on cabbage rather than maize. R-0 of S. exigua on maize and cabbage were 216.8 and 269.96 offspring, respectively. The mean generation time (T) of both Spodoptera spp. ranged from the shortest on cabbage to the longest on maize. The lowest intrinsic rate of increase (r) and highest finite rate (lambda) of S. litura were recorded on both hosts in comparison to S. exigua. The significant differences in larval and pupal weight of the pest were recorded on each host. These findings show that the host plants have an impact on all of the biological characteristics of S. litura and S. exigua. The findings show that S. litura and S. exigua can grow and reproduce healthily on both hosts, while cabbage is a better choice. However, the information indicates that this pest is dangerous at high population densities or in rare shortages of the favored host.
Spinetoram, a semi-synthetic insecticide with a unique mode of action unlike traditional compounds was evaluated for its sublethal impacts on various life stages i.e., larvae, pupae and adults of fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Various sublethal concentrations (LC30 and LC50) of the spinetoram (0.0000189 % and 0.0000388 %) were determined after treating third instar larvae by employing leaf disc-dip bioassay method. Exposure to spinetoram notably prolonged larval development, with duration reaching 28.64 days at LC50 levels compared to 18.88 days in control. Pupal span was similarly extended to 10.24 days under higher dose as compared to 7.80 days in control. Interestingly, pupal weight was lowest (0.116 g) in treated lot, while untreated pupae weighed 0.208 g. Pupal dimensions i.e., length and breadth also showed significant reductions following treatment. Adult emergence dropped sharply from 93 per cent in control to just 52 per cent under LC50 exposure. Treated adults (LC50) exhibited smaller body size and shorter life span compared to those from LC30 and control group. Thus, spinetoram demonstrated significant detrimental effects on the development and survival of S. frugiperda, highlighting its potential as an effective tool for managing S. frugiperda.
