International Journal of Tropical Insect Science (2021) 41, 2733-2738

Aaron Y. Mbogho, Robert Mwashimaha, Omary Mbwambo, Simon B. Boni, Jacob Yarro, Bruno Nyundo, Myron P. Zalucki and Srinivasan Ramasamy (2021)
Comparative effects of Plutella xylostella (L.) (Lepidoptera: Plutellidae) and Crocidolomia pavonana (F.) (Lepidoptera: Crambidae) on cabbage yield in Tanzania
International Journal of Tropical Insect Science 41 (4), 2733-2738
Abstract: In a series of open field experiments, we studied the effects of two lepidopteran pests (Plutella xylostella and Crocidolomia pavonana) at equal population density on cabbage yield. Completely randomised plots were assigned to four treatments, replicated four times. Treatments were P. xylostella only, C. pavonana only, or P. xylostella and C. pavonana at 1:1 ratio at different phenological stages of cabbages and a control (without any caterpillars). The growth stages and applied densities were pre-heading, cupping and heading, with densities of 2, 4 and 6 larvae/plant, compared with control. The effects of the two species differed significantly in terms of both yield (P < 0.0001) and injury score (P < 0.0001) compared to the control, which produced 67.4 ± 5.79 t/ha of clean, marketable cabbage. Crocidolomia pavonana reduced yield by 68% (21.8 ± 0.82 t/ha) with no market value at a cumulative injury score of 5, while P. xylostella reduced the yield by 40% (40.4 ± 2.38 t/ha at a cumulative injury score of 3.5). The sequential infestation of cabbage by P. xylostella and C. pavonana reduced yield by 41%, with 39.4 ± 3.48 t/ha of marketable yield at a cumulative injury score of 4.4. Thus, C. pavonana is more damaging than P. xylostella under the same growing conditions. Hence, zero infestation is recommended during the seedling and transplanting stages of the cabbages. The findings can serve as a basis to establish an economic threshold for C. pavonana and modify a two-decade-old economic threshold for P. xylostella in Tanzania.
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Link to article at publishers website
Database assignments for author(s): Myron P. Zalucki

Research topic(s) for pests/diseases/weeds:
damage/losses/economics

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plutella xylostella	Cabbage (Brassica oleracea)	Tanzania
	Crocidolomia pavonana	Cabbage (Brassica oleracea)	Tanzania