Saurbh Soni ¹, P. K. Mehta ¹, R. S. Chandel ¹

Affiliations
1 Department of Entomology, CSK Himachal Pradesh Krishi Vishvavidyalya, Palampur - 176062, Himachal Pradesh, IN

Abstract

Brahmina coriacea (Hope) is the most widely distributed and destructive species of white grubs having potential to inflict 40-50 per cent yield losses to potato in Himachal Pradesh. The efficacy of two local isolates of Beauveria brongniartii (KH I and KH II) was evaluated against grubs of B. coriacea by dip treatment and oral feeding methods. Against first and second instar grubs, KH I in dip treatment proved to be highly effective, whereas for third instar grubs, KH I through oral feeding showed higher virulence. The LC₅₀ values for first instar grubs for KH I and KH II were 2.55×10⁵ conidia/ml and 2.80×10⁵ conidia/ml in dip treatment, whereas in oral feeding method, the LC₅₀ values were 7.27×10⁵ conidia/ml and 9.69×10⁵ conidia/ml, respectively. Against second instar grubs, LC₅₀ values calculated were 2.91×10⁵ conidia/ml and 3.98×10⁵ conidia/ml for KH I and KH II in dip treatment, whereas corresponding values through oral feeding method were 5.36×10⁵ conidia/ml and 8.82×10⁵ conidia/ml. LC₅₀ values for third instar grubs were 4.47×10⁵ conidia/ ml and 4.88×10⁵ conidia/ml for KH I and KH II in dip treatment, whereas through oral feeding, LC₅₀ values were 3.03×105 conidia/ml and 5.14×10⁵ conidia/ml for KH I and KH II, respectively.

Keywords

Brahmina coriacea, Beauveria brongniartii, Himachal Pradesh, Potato, Susceptibility.

Full Text

   

Sarswati Negi ¹, P. L. Sharma ¹, S. C. Verma ¹, R. S. Chandel ¹

Affiliations
1 Department of Entomology, Dr YSP University of Horticulture and Forestry, Nauni, Solan - 173230, Himachal Pradesh, IN

Abstract

The present study deals with the impact of temperature on development, survival, reproduction and population growth of a recently invaded and the most destructive pest of tomato, Tuta absoluta (Meyrick) with the aim to understand its possible expansion in different agro-climatic zones. Though T. absoluta was able to develop between 15° and 35°C, temperature around 25°-30°C was more suitable. Survival and fecundity were highest at 25°C and lowest at 35°C. Developmental threshold for different developmental stages of the pest varied from 6.2 to 9.5°C, while the thermal constant required by the insect to complete the development from egg to adult emergence was 500 degree-days. Population growth parameters were also influenced significantly by the rearing temperature. Intrinsic rate of increase, net reproductive rate and finite rate of increase was higher at 25° and 30°C as compared to other temperature regimes. The study concludes that T. absoluta can be a serious pest of tomato in mid-hills of north-western Himalayan region and the southern plains of India where temperatures varies between 15-35°C. Furthermore, the developmental threshold values indicate that the pest can develop and survive at temperatures as low as 6-9°C without entering the diapause as long as the food is available.

Keywords

Fecundity, Reproduction, Survival, Temperature, Tuta absoluta.

Full Text

   

PRIYANKA SHARMA ¹, SUBHASH CHANDER VERMA ¹, PREM LAL SHARMA ¹, R. S. CHANDEL ²

Affiliations
1 Department of Entomology, Dr. Y S Parmar University of Horticulture and Forestry, Nauni, Solan (HP) 173230, India ., IN
2 Krishi Bhawan, Govt. of HP, Shimla – 171005, Himachal Pradesh, India ., IN

Abstract

The spatial distribution of Aphidius matricariae and Myzus persicae was studied in bell pepper under polyhouse conditions. In the present study, M. persicae and its parasitoid, A. matricariae populations followed negative binomial distribution throughout the season. The variance to mean ratio (σ2 /X), mean crowding (X*), ratio of mean crowding to mean (X*/X), ‘k’ of negative binomial, Taylor’s power equation for M. persicae and A. matricariae were σ² = 6.97X1.531 (R2 = 0.931), and σ² = 4.29X1.282 (R2 = 0.90) during 2018-2019, respectively. Iwao’s patchiness regression was X* = 45.12 + 1.333X (R2 = 0.853), and X* = 5.406 + 1.195X (R2 = 0.767) during 2018-2019, respectively. Optimum number of samples required for the green peach aphid, M. persicae and A. matricariae were 261.1 and 474 at 20% precision level. The present study will be useful for developing a sampling plan of M. persicae and its parasitoid, A. matricariae in bell pepper for its monitoring and management.

Keywords

Aphidius matricariae, green peach aphid, parasitoid, spatial distribution .

Full Text