Evaluation of selective insecticides efficacy against diamondback moth, Plutella xylostella (Linn.) on cabbage

Introduction

Cabbage, Brassica oleracea L. var. capitata (Brassicaceae), is economically important cruciferous vegetable. This crop is mooted to have cancer-preventing properties (Brooks et al., 2001) [4] and rich source of Ca, P, Na, K, S, vitamin A, vitamin C, carbohydrates and dietary fibre. Major cabbage growing states are in the country are Uttar Pradesh, Orissa, Bihar, Assam, West Bengal, Maharashtra, Tamil Nadu (Nilgiris) and Karnataka, it is grown on area of 10,490 hectares with a production of 2.212 lakh MT (Anon., 2015) [2] . The diamondback moth, Plutella xylostella (L.), is considered the most destructive pest of Brassicaceae in several regions of the world (Talekar & Shelton 1993) [3] . Lepidopteron larvae are the most destructive pests of cabbage and are often controlled with insecticide. Cabbage comprises intensive plant protection measures involving use of a large quantity of different insecticides. These applications are calendar-based rather than need-based. In spite of large scale and repeated applications of insecticides, the pest has been found to occur in severe form in all cabbage growing areas. Most of these applications may be unwanted or may not be timely. This practice not only results in increase in production cost but also lead to considerable complications in the ecosystem. Although several insecticides are available in market, the crop failures are very common in cabbage due to severity of the defoliator pests and the resistance developed by them especially diamondback moth. It was subsequently established that P. xylostella had developed multiple resistance to carbamates, synthetic pyrethroids and organophosphates (Sereda et al., 1997) [5] , yet these chemicals are still on the list of recommended insecticides for use against it (Anonymous, 2007) [1] . In addition to the development of resistance in pests, indiscriminate and injudicious use of pesticides has grossly poisoned almost each component of the biosphere, caused resurgence of pests and reduction in natural enemies in agro-ecosystems allowing rapid rebound of target and minor pest. Therefore, it is found necessary to evaluate new insecticides for the control of diamond back moth of cabbage.

Materials and Methods

The field studies were conducted at the experimental area of Indira Gandhi Agricultural University, Raipur (C.G.). The experiment was conducted during rabi season of years, 2015-16 and 2016-17 to assess the efficacy of selective insecticides against diamondback moth population at different intervals. Total three sprays of selective insecticides were applied during both the years. Control -

Results and Discussion

Total three sprays were applied during both the years to assess the efficacy of selective insecticides against diamondback moth population through field experiment.

First spray

On the basis of pooled evaluation of insecticides treatment during years, 2015-16 and 2016-17 after first spray, spinosad and chlorantraniliprole were found more effective and comparable. Considering least difference in efficacy, indoxacarb also have resulted as effective treatment during first spray. The order of effectiveness of selective insecticides on the basis of pooled mean reduction in diamondback moth larval population in first spray was found as spinosad (1.86 larvae/plant) > chlorantraniliprole (1.99 larvae/plant) > indoxacarb (2.18 larvae/plant) > flubendamide (2.29 larvae/plant) (fig. 1).

Similarly, the impact of insecticides treatments on the infestation of DBM larvae was also assessed and its order of effectiveness were arranged on the basis of pooled percent reduction over control for first spray as spinosad (58.10%) > chlorantraniliprole (55.18%) > indoxacarb (50.90%) > flubendamide (48.42%) (Table no. 2).

Second spray

The order of effectiveness of selective insecticides on the basis of pooled mean reduction in diamondback moth larval population in second spray was found as spinosad (2.01 larvae/plant) > chlorantraniliprole (2.36 larvae/plant) > indoxacarb (2.43 larvae/plant) > flubendamide (2.62 larvae/plant) (fig. 1).

Similarly, the impact of insecticides treatments on the infestation of DBM larvae was also assessed and its order of effectiveness were arranged on the basis of pooled percent reduction over control for first spray as spinosad (63.71%) > chlorantraniliprole (57.40%) > indoxacarb (56.13%) > flubendamide (52.70%) (Table no. 3).

Third spray

On the basis of pooled evaluation of insecticides treatment for third spray, spinosad was found best insecticide for DBM management. The order of effectiveness of selective insecticides on the basis of pooled mean reduction in diamondback moth larval population in third spray was found as spinosad (1.09 larvae/plant) > chlorantraniliprole

References

1. Anonymous. A guide for the control of plant pests. 14th ed. Department of Agriculture; 2007. South Africa.
2. Anonymous. National horticulture database [Internet]. 2015 [cited 2025 Mar 21]. Available from: www.nhb.gov.in
3. Talekar NS, Shelton AM. Biology, ecology, and management of the diamondback moth. Annu Rev Entomol. 1993;38:275-301.
4. Brooks DM, Pando VL, Ocmin PA, Tejada RJ. Resource separation in a Napo-Amazonian gamebird community. In: Brooks DM, Gonzalez F, editors. Biology and conservation of cracids in the new millennium. Misc. Publ. No. 2. Houston: Houston Museum of Natural Sciences; 2001. p. 213-225.
5. Sereda B, Basson NCJ, Marais P. Bioassay of insecticide resistance in Plutella xylostella (L.) in South Africa. Afr Plant Prot. 1997;3:67-72.