Compatibility of entomopathogenic fungi and botanicals against sucking pests of okra: an ecofriendly approach

Background Okra, Abelmoschus esculentus (Linn.) Moench, is one of the most important traditional vegetables in India. The crop is attacked severely by sucking pests, viz., jassid, Amrasca biguttula biguttula Ishida, and whitefly, Bemisia tabaci Genn., throughout its growth period. To control these sucking pests, different entomopathogenic fungi (EPF), viz., Beauveria bassiana, Metarhizium anisopliae, and Lecanicillium lecanii were tested alone and their 1:1 combinations with neem oil against these sucking pests and compared to Imidacloprid 17.8% SL as chemical control under field conditions during 2018 and 2019. Results Among the EPF tested, the lowest jassid (1.16, 1.27 leaf-1) and whitefly (1.33, 0.84 leaf-1) population was recorded in plots treated with L. lecanii during the two consecutive years. Combination of L. lecanii and neem oil at half of their recommended concentrations had the lowest jassid and whitefly population among all the treatments and maximum reduction over control and at par with chemical control, i.e., Imidacloprid 17.8 SL at 0.33 ml l−1. Moreover, all these biopesticides were found relatively safe to the polyphagous predators (Micraspis discolor, Menochilus sexmaculatus, and spiders) and at par with untreated control. In contrast, Imidacloprid 17.8 SL was the most toxic among all the treatments with the lowest numbers of spiders and ladybird beetles. Conclusion Combination of the EPF like B. bassiana, M. anisopliae, and L. lecanii with neem oil at half of their recommended concentrations could be a viable ecofriendly option in the management of the sucking pests of okra, along with the conservation of natural enemies.

DIVERSITY OF PREDACEOUS COCCINELLID BEETLES (COLEOPTERA: COCCINELLIDAE) IN UTTARAKHAND, NORTH INDIA

A field survey was conducted to explore the diversity of predaceous ladybird beetles (Coleoptera: Coccinellidae) by sampling adults and larvae from five geographical habitats of Uttarakhand, North India. As a result, eighteen predaceous ladybird beetle species were identified belonging to 15 genera and 3 subfamilies: Chilocorinae, Coccinellinae, and Scymninae. These species were: Platynaspis saundersi, Adalia hexaspilota, Alloneda dodecaspilota, Calvia albida, Menochilus sexmaculatus, Coccinella septempunctata, Coccinella transversalis, Harmonia eucharis, Harmonia sedecimnotata; Hippodamia variegata, Illeis cincta, Illeis confusa, Micraspis discolor, Oenopia sauzeti, Propylea dissecta; Propylea luteopustulata; Palaeoneda auriculata and Scymnus posticalis. Of these, six species ladybird beetles are the first time reported from Uttarakhand. Their distinctive characters, distribution, host plant-prey range, active period, and ecological importance have been described. A few of these species may be potentially utilized as biological agents to control many phytophagous insect pests of agriculture and horticulture crops. A disparity was observed in the ladybird-abundance, as both the number of individuals of ladybirds and their frequency in the population differed significantly. The dominance of a few ladybird beetles, particularly C. septempunctata, M. sexmaculatus, C. transversalis and H. variegata was confirmed by the low value of Simpson’s Dominance Index (0.1903) further indicating the disparity in the populations of different ladybird species in a community

Feeding Propensity and Cannibalism of Micraspis Discolor (Fab.) to Different Prey Species (Aphis craccivora and Nilaparbata lugens) under Laboratory

Feeding propensity and cannibalism of Micraspis discolor (Fab.) to different prey species (bean aphids and brown plant hopper ) was studied in the laboratory of the Department of Entomology, Bangladesh Agricultural University, Mymensingh, during January, 2007 to April, 2007. It was found that the highest pre-oviposition period was to 5.6±0.54 days when BPH were used and this period was lowest, 4.6±0.54 days using bean aphid. The oviposition period was maximum 40.20±1.78 days using bean aphid and minimum 29.00± 2.00 days were found using BPH. Maximum number of eggs 216.00±16.58 was laid when fed on bean aphid. The hatching percent was highest 88.71% using bean aphid and hatching percent was lowest 85.34% when fed on BPH. Incubation period varied from 2.40±0.54 to 3.80±0.44 days using different foods. However, the larvae passed through four larval instars and highest larval period was 10.00 ± 0.70 when BPH were used as food and lowest was 8.40 days feeding on bean aphid. Pupal period was 3.00±0.00 & 3.80±0.44 days when bean aphid & BPH were supplied as food. The average longevity of female was 38.60±3.78 and 31.40±2.96 days and that of male was 32.00±2.91 & 26.00±0.91 days when feeding on bean aphid and BPH respectively. It was significant at 1% level. The sex ratio of male and female was found (0.78:1.00) using different foods and these were not significant at 1% level. By this experiment, It was observed that feeding propensity of Micraspis discolor to different prey species during the total life cycle was as follows: bean aphid > BPH. It was also found that M. discolor had cannibalistic behavior and this was significant at 1% level.J. Environ. Sci. & Natural Resources, 9(1): 81-85 2016

Coccinellid Predators of Aphid and Their Phylogenetic Analysis Using COI Gene Sequences

An extensive survey of aphid predatory Coccinellid beetles (Coleoptera: Coccinellidae) was conducted in Jahangirnagar University campus, Savar during October 2014 to March 2016. Total nine ladybird beetles viz, Adalia bipunctata, Coccinella septempunctata, Coccinella transversalis, Cycloneda munda, Harmonia axyridis, Hippodamia convergens, Micraspis discolor, Scymnus nebulosus, Sticholotis sp. were identified as predators of aphid. Among them, Micraspis discolor was most abundant predator. Biology and bio-control potential of M. discolor was studied in laboratory condition on bean infesting aphid (Aphis fabae). The maximum predation was 102±1.83 observed in 4th instar larvae of M. discolor. Along with biological study, phylogenetic relationship of ladybird beetles was constructed based on mitochondrial COI gene. Out of nine identified coccinellids, five species showed more conserve region than the rest in alignment. The interspecific genetic distance ranges for nine beetles were very low (0.15-0.24). Higher interspecific genetic diversity recorded for H. axyridis. The phylogenetic tree was created and analyzed using both Neighbour Joining and Maximum likelihood methods to define the origin and evolutionary relationships of the species. Molecular analysis demonstrated that evolution of these species has been occurred from a common ancestor. Such study of ladybird beetles would be helpful in biological control program of aphid pest. Int J Appl Sci Biotechnol, Vol 4(3): 408-416

Control Strategies of Papaya Mealybug, Paracoccus marginatus Williams and Willink in the Laboratory Condition

The laboratory experiment was conducted at the laboratory of the Department of Entomology, Bangladesh Agricultural University to determine the effectiveness of polythene band, predatory ladybird beetles (available species found in Bangladesh viz. Coccinella transversalis (F.), Micraspis discolor (F.), Menochilus sexmaculatus (F.), Cyclonida sanguinea, Adalia bipunctata, Coccinella novemnotata and Illeis koebelei), four chemical insecticides and three botanical oils in controlling papaya mealybug, Paracoccus marginatus Williams and Granara de Willink. The chemical insecticides were Sevin 85 SP, Dimethoate 40 EC, Fipronil 50 EC, Deltamethrin 2.5 EC, and the botanical oils were Neem oil, Mahogany oil and Karanja oil. In the laboratory experiment, polythene banding failed to prevent the plant from the infestation of papaya mealybug. Seven commonly available species of ladybird beetles in Bangladesh did not provide any control to papaya mealybug. Among the chemical insecticides, Sevin 85 SP and Dimethoate 40 EC showed significant mortality of papaya mealybug. Deltamethrin 2.5 EC and Neem oil (2%) provided moderate control of the pest. The remaining insecticides and botanical oils were less effective to control papaya mealybug. Int J Appl Sci Biotechnol, Vol 3(4): 687-691