Line Weaving Spider As a Biological Component in Citrus Mite Integrated Control System

Cooperating agency for this topic:
Entomology and Zoology Group
Plant Protection Research and Development Office
Department of Agriculture,
Bangkok 10900, Thailand
Fax: 66-02-9405396
Email: ipada@doa.go.th, 2005-12-01

African red mite, Eutetranychus africanus (Fig. 1), and Citrus yellow mite, Eotetranychus cendanai (Fig. 2), are economically important citrus mite pests. They cause major damage and loss to pummelo and tangerine yields by sucking the sap from the leaves or fruits. Heavy infestations cause the citrus leaves and/or fruits to dry and drop. Both pests are likely to be more serious in dry weather condition. Control measures often involves application of acaricides which are very expensive and have negative impact on the environment.

The line weaving spider, Hylyphantes graminicola (Linyphiidae) (Fig. 3), is an important predator of these citrus mite pests. They have been recorded to be distributed in northern Asia such as China, Korea, and Japan.

In Thailand, H. graminicola was found distributed throughout the central part of the country where pummelo and tangerine are grown, and shares 11 percent of the total spider population found in citrus orchard. The male has a body length of 2.3-2.5 mm while that of the female is 2.5-3.0 mm; head and cephalothorax are brown, with shiny grey abdomen. They inhabit under citrus leaves and feed on citrus mite pests. Laboratory research on predation efficiency of H. gramminicola revealed its dominant role in keeping down the citrus mite population, as shown in Table 1. The study suggested that the population of H. graminicola can be managed and conserved in citrus orchard in order to bring down the citrus mite population. This can be done by modifying the citrus orchard ecosystem to be suitable or to provide some weedy areas for the line weaving spider when pesticides are applied in the orchard.

Technology

• Judiciously use pesticides in the orchards; especially, select those with the least or no impact on line weaving spider, or not broad spectrum insecticides, and select timing of application.
• Apply botanical insecticides such as neem as alternative to chemicals, as they have no impact on population of line weaving spider or other spiders.
• Provide or leave sparsely weedy areas of grasses around fruit trees and orchards as shelters for spiders.

Merit of Technology

• No impact on environment, with low or no cost.
• Benefit from spider predators, and their role as biological control component from modified environment of orchards in integrated control system.
• Based on the characteristics and behavior of line weaving spider, they are likely to be an ideal predator due to their high predation rate, especially the female, and to the adult longevity of about 80 days predating preys.

Index of Images

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  Figure 1 African Red Mite, <I>Eutetranychus Africanus</I>.

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  Figure 2 Citrus Yellow Mite, <I>Eotetranychus Cendanai</I>

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  Figure 3 Line Weaving Spider, <I>Hylyphantes Graminicola</I>.

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  Table 1 Comparison on Consumption Rates of Line Weaving Spider, <I>H. Graminicola,</I> of Different Stages or Sex of Mites, <I>Eutetranychus Africanus</I> and <I>Eotetranychus Cendanai</I>

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