Arun Baitha

Growth rate differences of wild vs laboratory reared sugarcane adapted strains oftrichogramma chilonis ishii (hymenoptera: trichogrammatidae)

Sugarcane adapted wild strains of egg parasitoid,Trichogramma chilonis Ishii was collected from sugarcane agro ecosystem of Paedegaon (Maharashtra) and Lucknow (U.P). Growth rate of wild strain ofT. chilonis Ishii was compared with laboratory strains of Lucknow and Paedegaon under laboratory condition at 28 ± 2 o C and 60 ± 5 percent relative humidity. The mean longevity (4.8 and 4.4 days) of wildT.chilonis strain was more than laboratory strains (3.5 & 2.6 day) of Lko &Pgn, respectively. Female progeny production was observed to be intensive for the first day (except Lko) after which it reduced drastically of wild as well as laboratory strain. The net reproduction rate (Ro) showed that a female parasitoid produced 50.15 and 47.88 females’ offspring during its life span of wild strain ofT.chilonis than laboratory strain (32.36 and 39.81) of Pgn&Lko strains, respectively. The intrinsic rate of natural increase (rm) for wild strain of T.chilonis (Pgn & Lko) were 0.3701; 0.3598 than laboratory reared strain (0.3389; 0.3535), respectively. The finite rate of increase of wild strain (1.448 and 1.433) was more than laboratory strain (1.40 &1.420) of Pgn&Lko, respectively. It can be concluded that identifiedTrichogramma chilonis strain with favourable sex ratios and scope for further enhancement of ratio of female through manipulation in the rearing conditions and the laboratory strain need to be augmented fortnightly with wild strain.

Soil Arthropods in Maintaining Soil Health: Thrust Areas for Sugarcane Production Systems

Maintaining high agricultural production on a sustainable basis requires conservation of natural resources, including soil quality. Nowadays global interest is growing for improvement in soil quality on the one hand and adoption of sustainable land management system, including farming systems on the other. Since the physical and chemical properties of soil respond slower to change in soil use and its management, the soil biological and biochemical properties along with soil organisms have emerged as indicators of soil quality. In particular, the soil arthropods are now used as indicators of soil quality and also in comparing various land-use systems as they are regulated by anthropogenic impacts. The availability and type of food primarily govern their community structure, abundance and dynamics. Although the interactions between soil invertebrates and land-use management are fundamental for soil quality assessment, such aspects are largely unaddressed in India. Like any other intensive agriculture system, sugarcane cultivation may have negative impacts on soil in terms of loss of quality and soil biodiversity. So there is a need to evaluate such systems from the angle of sensitivity of soil fauna to soil management practices like tillage, fertilizer use, land-use changes, etc. Such an understanding will be of value in designing production system that is sustainably productive. In the paper, present knowledge on soil arthropods, their function and available reports from sugarcane production system are reviewed and approaches to enhance soil biodiversity are discussed. Strategies for designing sustainable sugarcane production system and future thrusts are also presented.

Effect of female vs. male pupa of Scirpophaga excerptalis Walker on reproductive potential of Tetrastichus howardi (Olliff) (Hynenoptera: Eulophidae)

Tetrastichus howardi (Olliff) (Eulophidae: Hymenoptera) is gregarious and polyphagous endopupal parasitoid associated with sugarcane stem borers. It is adapted in its host-searching strategy to penetrate tunnels excavated by stem borers which is a prerequisite for a good biological control agent of stem borers. The experiment was conducted at 25 ± 2°C and 65 ± 5% relative humidity in BOD with ten replications at Biological in Division of Crop Protection, ICAR, Lucknow. The number of adult emerged (81.29) from female pupa (81.29) was more than male pupa (65.30). The smaller host pupae (i.e. male pupa) gave rise to small number of parasitoids whereas larger ones (i.e. female pupa) supported development of more parasitoids. The parasitoid completed development in 19.5 days on both pupae. There was no significant difference of development period in male vs. female pupa. The female emergence (%) on female and male pupa was 86.94 and 74.23, respectively. The number and sex ratio of adult progeny emerging from host pupa depends on the size. The large host size is more beneficial to the fitness of daughters than to sons and selection would then favor wasps to lay more daughters in large hosts and more sons in small hosts. It is concluded that parasitoid had high reproductive potential, more female biasesd sex ratio and its gregarious development make possible to multiply on sugarcane top borer in the laboratory.

Utility of Trichogramma for Biocontrol of Sugarcane Borers

Sugarcane tissue borers are an important constraint to sugarcane productivity and juice quality. There are several species of borers occurring in varying intensities across the country. The mass production and release of Trichogramma species for biocontrol of sugarcane borers in India have been recommended by researchers over several decades starting from early work in Mandya in the 1930s. The focus of RD targeting the major borers in different agro-climatic regions; selectively deploying locally adapted strains/populations; timing and frequency of releases for maximum control; improving storage, packing and delivery systems; and local refinement of Trichogramma release under individual factory R&D, besides undertaking on-farm validation of the economic benefits to the farmer and the factory, is discussed.

Interaction ofLixophaga diatraeae (towns.) andTetrastichus howardi (Olliff.) for management ofDiatraea saccharallis (Fab.) in Cuba

Interaction of larval parasitoid, Cuban fly,Lixophaga diatraeae and pupal parasitoid,Tetrastichus howardi for management of sugarcane borer,Diatraea saccharallis was studied. The total parasitism ofD. saccharallis pupae byT. howardi was 15.93% and of larvae was 29.05% byL.diatraeae, however, 35.85% of combined parasitism was recorded (during December 97 and June 98) in the area whereT. howardi was reported first time. The parasitism ofT. howardi showed its maximum in December 1997.It oscillated around 15% until the sampling of June, reduced to 9.09% in August 98. The combined parasitism (55% in June 98) was higher than the sole with L. diatraeae in all the samplings. The indirect competition or interference in the use of certain resources of the niche that can take place betweenL. diatraeae andT. howardi as consequence of the vicinity of their microhabitat didn’t significantly affect the effectiveness of the parasitoids. Pupae ofL. diatraeae were not parasitised byT. howardi; it is important evidences that there are the scarce possibilities thatT. howardi hyperparasitise on the Cuban fly under field conditions. It can be suggested that a complementation in working of both parasitoids can be exploited in programme of management of sugarcane borer,D. saccharallis.

Young and Fast Growing Plants as Better Feeding Material forDeltocephalus vulgaris, a Leafhopper Vector of Sugarcane Grassy Shoot Phytoplasma

Deltocephalus vulgaris Dash & Viraktamath has recently been established as a vector of sugarcane grassy shoot phytoplasma. Germinating (single bud settlings of CoS 95255) under glass house were transplanted in 12” size pots. These were covered with cages of fibreglass sheet. The leafhoppers were released in cages. The increase in population was to the tune of 3–5 times on young settlings of 1–2 weeks, but was lower (0.5 times) on 60 days plants. The young and fast growing tender sprouts with small succulent leaves were better for sucking the juice by leafhopper and also provided nutritionally better feeding material. The mortality of nymphs was lower in 7 days young plants (26%) than 60 days old plants (90%). The transmission trials of sugarcane grassy shoot disease byD. vulgaris Dash & Viraktamath were successful on young tender plants.