Natural Crop Protection in the Tropics: Storage-Pest controlling Plants

Many insecticidal plants are useful for pest control in the field as well as for stored products. According to their main use the general description is found either in the chapter on "Insect-controlling plants" under "Methods of Field Protection" or in this chapter.

There is a tremendous wealth of traditional local knowledge on the use of plant materials in storage protection. Some of this knowledge has been neglected over the past decades. However, there is an increasing interest and necessity to reactivate this knowledge.

Generally, plants with storage pest-controlling properties act through the following mechanisms:

• Toxicity to adults

• Reduction of egg-laying

• Toxicity to eggs

• Toxicity to the larvae prior to or directly after entering a grain

Each plant species protecting stored products possesses some of these four properties. Knowledge of these properties assists in employing them in an appropriate way in order to achieve the best control effects.

In a first step, if one wants to validate local knowledge or interesting external information e.g. from a newsletter, a simple bioassay can be employed. This does not differentiate between the 4 major mechanisms, but does provide information on whether it is worthwhile to proceed with deepening the knowledge on the plant species tested with the aim of making its use more precise and effective.

The following plants are described in detail:

Basil

Hoary Basil (Ocimum canum), Holy Basil (O. sanctum)

_Chilli

Capsicum frutescens

_{Fish bean plant}

Tephrosia candida, Tephrosia vogelii

_{Hyptis spicigera, Cassia nigrans}

_Muña

Minthostachys glabrescens, M. mollis

_Neem

Azadirachta indica

_{Velvet
leaf}

Cissampelos owariensis

_{Sweet flag}

Acorus calamus

The printed version of the book contains the summary of 20 other plants