Journal of Biological Control

7-17

Authors: Anna L. N. Varela, Ilka M. Vasconcelos, Rodolpho G. G. Silva, Hudson F. N. Moura, Thiago F. Martins, Darcy M. F. Gondim, Nagila M. P. S. Ricardo, Francisco C. O. Freire, Jose T. A. Oliveira

This work was conducted to assess whether or not a natural occurring polysaccharide from Adenanthera pavonina seeds (PLSAp) and its chemically sulfated derivative galactomannan (SPLSAp), which did not act as fungicides, induce defense proteins and protect a susceptible cowpea (Vigna unguiculata) genotype (BR3-Tracuateua) against the phytopathogenic fungus Colletotrichum gloeosporioides. Twelve-day-old plants were sprayed to run-off with PLSAp or SPLSAp, both at 100 and 200 mg L-1, dissolved in 0.01% Triton X-100, which served as control. The primary leaves were collected at 0, 6, 12, 24, and 48 h after the carbohydrate treatments and the activities of guaiacol peroxidase (POX), β-1,3-glucanase (βGLU), and chitinase (CHI) were determined to verify the ability of the studied galactomannans to induce alterations in their kinetics. In addition, the primary leaves of a plant group previously sprayed with SPLSAp and 6 h later inoculated with C. gloeosporioides were collected at 0, 6, 12, 24, and 48 h after the polysaccharide treatment, the enzyme activities measured, and the severity of the fungal disease evaluated. SPLSAp induced more prominently POX, βGLU, and CHI activity than PLSAp. Importantly, the combined treatment of SPLSAp and C. gloeosporioides was even more effective as enzyme inductor than SPLSAp alone, and the necrotic lesions of the anthracnose disease caused by the fungus were much less severe compared to control plants. The results indicate that SPLSAp induces plant defense proteins and increases the cowpea tolerance to C. gloeosporioides. These findings indicate that SPLSAp merits further investigation as a promising alternative or a supplemental environmentally friendly protector agent against anthracnose.

27-35

Authors: V. S. L. Saranya, K. Samiayyan, M. Shanmuga Prema

Investigations conducted on the identification of predatory spider fauna in maize ecosystem throughout the crop growth, in Tamil Nadu Agricultural University, Coimbatore during 2013-2014 yielded around 2821 spiders, belonging to 16 species under 10 genera of 6 families from seedling to maturity stage. Majority of the spiders collected belonged to the families Lycosidae (1671 individuals), Salticidae (459 individuals), Oxyopidae (352 individuals), Gnaphosidae (178 individuals), Corinnidae (96 individuals) and Clubionidae (65 individuals). The predatory spider species dominating in the maize ecosystem included the species Lycosa barnesi, L. pseudoannulata, Pardosa birmanica, Salticus sp. and Hippasa lycosina. Dendrogram analysis of spiders revealed that the families, Clubionidae and Gnaphosidae were closely related when compared to other predatory spider families. Correlation analysis with the weather parameters showed that the predatory spider population had non-significant positive correlation with relative humidity at 14:22 hrs and negative correlation with all other weather parameters viz., maximum temperature, minimum temperature, relative humidity at 07:22 hrs, rainfall, sunshine hours and rainy days.

48-52

Authors: Neena Lenin, Haseena Bhaskar

Cucumber is one of the most preferred crops grown in polyhouses of Kerala. However, incidence of spider mite, Tetranychus urticae Koch, 1836 as emerged as an important limiting factor for cucumber cultivation in the polyhouses. Increasing concern over the abuse of acaricides for mite management in polyhouses has necessitated development of alternative strategy with emphasis on biological control. The phytoseiid mite, Neoseiulus longispinosus (Evans, 1952) which has a wide distribution and has the ability to adapt to warm temperatures can be a potent candidate against tetranychid mites. To identify the optimum predator: prey ratio of N. longispinosus to T. urticae for effective management of spider mites, experiments were conducted both in the laboratory as well as polyhouse using a range of ratios. In the laboratory, the experiment was carried out on excised cucumber leaves maintained on moist sponge in plastic trays. Gravid females of N. longispinosus were released to 100 mixed stages including eggs, nymphal stages and adults of prey on cucumber leaves at predator: prey ratios of 1:5, 1:10, 1:20, 1:25, 1:33, 1:50 and 1:100. In the polyhouse, hundred mixed stages of T. urticae were released on four leaf stage of twenty days old cucumber plants at the rate of 25 mites/leaf, followed by the release of gravid females of N. longispinosus at predator: prey ratios of 1: 20, 1: 25, 1: 33 and 1:50. Laboratory studies showed that, at ratios of 1:5 and 1:10, the prey population was significantly reduced by third day. The prey was completely eliminated by seventh and tenth day at ratios 1:5 and 1:10 respectively. Ten days after the release, the prey population at ratios, 1 20, 1:25 and 1:33 were on par with that of 1:5 and 1:10. In the polyhouse, the predator: prey ratios of 1:20 and 1:25 were significantly superior in reducing the population of T. urticae on cucumber. The present study has revealed the potential of the predatory mite, N. longispinosus as a biocontrol agent against T. urticae on cucumber in polyhouse.

57-62

Authors: Arbind Kumar Rai, Rajendra Prasad

The management of spotted stem borer of maize Chilo partellus through augmentative releases of the parasitoid Cotesia flavipes was conducted at Dr Rajendra Prasad. Central Agricultural University, Pusa, Bihar during Kharif 2014, 2015 and 2016. Cotesia flavipes (Cameron) was the dominant natural enemy of Chilo partellus (Swinhoe) in maize fields of Bihar agro - climatic condition and its maximum parasitization was 57 per cent. In the augmented experimentation lay out, the maximum natural infestation of Chilo partellus and its parasitoid was as 41.21 per cent during last week of September and 42.30 per cent during second week of November, respectively. In the augmented maize field, the maximum infestation and parasitization were found as 11.36 and 51 per cent, respectively.

70-75

Authors: R. Gandhi Gracy, K. Srinivasa Murthy, T. Venkatesan

Specimens of the aphid hunting wasp Carinostigmus Tsuneki (Hymenoptera: Crabronidae: Pemphredoninae) were collected from South India. Morphological identification revealed three species, and one of them, C. griphus Krombein, is new for India. Identification of the species is supported through COI partial gene-DNA Barcoding.