Meeta Sharma , S. T. Ahmed

Abstract

A naturally occurring entomogenous fungus , Beauveria bassiana (Balsamo) Vuillemin has been isolated from the dead diseased weevils of Marwar teak defoliator , Patialus tecomella Pajni , Kumar & Rose from Rajasthan. The mortality of adult Patialus tecomella exposed to a series of spore dilutions from 3.5 × 10⁷ to 8.5 × 10⁴ spores/ml , decreased with decreasing amounts of inoculum. At spore concentrations of 3.5 × 10⁴ spores/ml , the mortality of the treated weevils was significantly greater than of the uninoculated controls. Experiments carried out using microbial controlling agent against P. tecomella gave 70% mortality of the grown up weevils. When applied in a spore concentration of 3.5 × 10⁷ , the pathogens is proved to be highly effective and very promising as a microbial agent to check the pest populations.

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S. I. Ahmed , K. K. Chaudhuri , Meeta Sharma , Shivesh Kumar

Abstract

Insect pests are amongst the most important detrimental factors in the successful establishment and growth of Prosopis cineraria (Linn) (Khejri) and Tecomella undulata (Sm.) Seem (Rohida) in arid and semi arid zone of Rajasthan. P. cineraria, the 'king tree' of Indian arid region, is revered for its range of products and services rendered to desert inhabitants. Khejri has a unique distinction of being referred in a variety of contexts, besides being a tree of socio-economic importance, it bears religious legends. T. undulata (Sm.) Seem, is one of the co-dominating tree species in the desert forests of western Rajasthan and adjoining lands of Haryana and Punjab. Twenty six potential pests on P. cineraria and P. juliflora have been recorded from arid and semi-arid areas. Of them, 18 species have been recorded as new pest records on P. cineraria including four species of long horned beetles viz., Derolus iranensis (=descicollis) Pic, Aeolesthes holosericea Fab, Hypoeschrus indicus Gahan and Acanthophorus serraticornis (Oliver) which have been recorded to exhibit severe damage to Prosopis cineraria in four north western districts of Rajasthan. In all 64 insect species have been recorded on T.undulata in the form of pests. Of them, 24 insect species were observed for the first time to cause mild to severe damage to marwar teak in arid and semi arid areas. Seedlings and young plantations of T. undulata are frequently severely attacked by a serious curculionid pest, Patialus tecomella throughout the tract of its distribution in arid and semi-arid areas. Natural enemy complex recorded on the insect pests of Prosopis cineraria and Tecomella undulata during the course of these investigations play an important role in controlling the outbreaks of insect pests of these economically important tree species in arid and semi-arid regions. Twenty species of parasites, thirteen species of predators and three species of entomopathogens were found associated with the potential insect pests of Khejri and Rohida A potential pupal parasite, Billeae atkinsoni has been recorded to keep the pest populations below the level of economic threshold. Integrated management strategy has been discussed to save the Khejri trees from large scale drying.

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Meeta Sharma , S. I. Ahmed

Abstract

Tecomella undulata (Sm.) Seem, commonly known, as 'Marwar teak' is an important agroforestry tree species of arid and semi-arid region. The distribution pattern of T. undulata in desert area of India is quite obvious because of its sparking features of drought tolerant, high quality of timber, fuel wood and fodder etc.T. undulata is frequently severely attacked by a curculionid pest, patialus tecomella. In the present paper an attempt has been made to study the orientation of adult weevils to different colour. Besides, the tactic response of the weevils towards two varieties of T. undulata is also studied as the knowledge of feeding preference may lead towards possible means of reducing damage level in the field. There was a significant difference in the attraction of weevils towards different colours when tested simultaneously. White colour attracted the maximum number of weevils (64.66 ♂ and 51.32 ♀) that was highly significant over the three other colours tested. Yellow colour was the second to attract both the sexes as being 21.32% males and 29.32% females respectively. Minimum numbers of weevils were attracted towards blue and green colours when tested simultaneously (10 ♂ 14 ♀ and 4 ♂ 5.32 ♀ respectively). The attraction of P. tecomella towards white colour was proved to be highly useful in evolving the effective devices for mechanical control. Out of both the host varieties (T. undulata var., yellow flower and T. undulata var., orange flower) that were offered to the adult weevils at threee different temperatures viz., 15°,25° and 35°C, yellow flower variety was the most preferred food source when compared to orange flower variety. Maximum feeding activity (37.80 mm2 ) has been recorded to occur at 35°C on orange flower variety of T. undulata.

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Meeta Sharma , S. I. Ahmed

Abstract

Tecomella undulata (Sm.) Seem, a member of the family Bignoniaceae, is one of the co-dominating tree species in the desert forests of Western Rajasthan and adjoining lands of Haryana and Punjab. It is commonly known as "Rohida" or "Marwar Teak" due to its sparking features of drought tolerant and high quality of timber. Seedlings and young plantations of T. undulata are frequently severely attacked by a serious curculionid pest, Patialus tecomella throughout the tract of its distribution in arid and semi-arid areas. A potential pupal parasite, Billeae atkinsoni has been recorded to keep the pest populations below the level of economic threshold. Biology of Billeae atkinsoni has been carried out in the laboratory under three constant temperatures of 25, 30 and 35°C as well as in the outdoor wire-meshed cages of insectary. Oviposition takes place in the anterior half of the host pupa preferably in the mesoor meta-thorax. The act takes 3.30 ± 0.21 m. The egg is whitish-pale, spindle shaped, measuring about 0.30 ± 0.01 mm in length and 0.65 ± 0.01 mm in breadth at the broadest end. Incubation period vary greatly from 18 to 30 hrs., during July to September in the field conditions whereas in laboratory under different levels of temperature, it ranges from 26.38 ± 2.25 to 41.96 ± 2.34 hrs. Larval stages last in 216.15± 11.56 to 336.46± 36.38 hrs.; pupal stage takes 63.65 ± 2.75 to 86.35 hrs. under three constant temperatures. Adult parasites takes 5.50 ± 0.315 minutes for emergence. Mating process lasts in 35.00 ± 2.53 seconds. Sex ratio in the males and females is recorded as 1:2. The maximum percentage of pupal parasitism was observed during the month of September (54.35% and 50.20% during 1995 and 1996 respectively), while minimum was recorded in the month of January (1.65% and 0.50% in 1995 and 1996 respectively). It is concluded that this parasite will have capability of a promising and potential biological controlling agent of P. tecomella in arid and semi arid areas.

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Meeta Sharma , S. I. Ahmed

Abstract

Tecomella undulata (Sm.) Seem, a member of the family Bignoniaceae, is one of the codominating tree species in the desert forests of Western Rajasthan and adjoining lands of Haryana and Punjab. It is commonly known as" Rohida" or" Marwar teak " due to its sparking features of drought tolerant and high quality of timber. Seedlings and young plantations of T. undulata are frequently severely attacked by a serious curculionid pest, Patialus tecomella throughout the tract of its distribution in arid and semi-arid areas. The objectives of the experiment conducted and reported in this paper are to examine the influence of selected constant temperatures and relative humidities on the longevity of starved larvae and adult weevils and to determine the threshold temperature and humidity ranges for the optimum longevity of P. tecomella, when kept as isolated single individuals and in different group sizes viz., groups of 5, 10 and 20 individuals, under the same experimental conditions. The adults and larvae of P. tecomella survived for a maximum period in groups as well as in isolated individuals at a temperature of 35° ± 0.5°C and 74 ± 5% relative humidity. Minimum survival periods are observed under the temperature of 45° ± 0.5°C and a relative humidity of 10 ± 5% in both the cases. The larvae and the adults (both in groups and as isolated individuals) can tolerate minor desiccation. Both the adults and larvae of P. tecomella survived for a longer period in groups than as isolated individuals.

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