handbook on seed insects of Prosopis species
Cover: Mesquite pods with bruchid exit holes, a pentatomid bug and an adult bruchid (C.D. Johnson)
Ecology, Control, and
Identification of Seed-infesting
Insects of New World Prosopis (Leguminosae)
Clarence D. Johnson
Department of Biological Sciences
Northern Arizona University
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The importance of conserving and utilizing existing genetic variation is recognized as fundamental in most tree species used in large-scale industrial plantations. However little or no information is yet available on intra-specific variation in a large number of tropical species which today are receiving increased attention as providers of goods and services for rural communities.
Following the recommendations made by the FAO Panel of Experts on Forest Gene Resources and with financial support from the international Board for Plant Genetic Resources (IBPGR), FAO's Forestry Department initiated in 1979 a project on the conservation and better utilization of genetic resources of arboreal species for the improvement of rural living. Based on a list of species drawn up by the FAO Panel and in accordance with the wishes expressed by the future cooperators, priority has been initially given to a few selected species mainly in the genera Acacia and Prosopis.
The general objectives of the project are the conservation and improved utilization of genetic resources of multi-purpose arboreal species growing in arid and semi-arid areas. The means of achieving these objectives are exploration, collection of reproductive material (mainly seed) and evaluation of genetic variability and adaptability to varying environmental conditions of the species included. These activities will enable appropriate action to be taken in conservation in situ and ex situ and in planting well-adapted and otherwise suitable species and provenances in village woodlots, firewood plantations, for food and fodder, and for shade, shelter and land amelioration.
As the species included in the project have not in the past received much attention, little information and experience are available on fundamentally important aspects such as taxonomy and seed collection, handling, storage and treatment. Where such information exists, it is often scattered and difficult to obtain. Yet, the species present a number of serious problems in these specific fields: their taxonomy is often confused and a number of inter-breeding species complexes are thought to exist, making proper identification difficult and predictability of performance in subsequent generations impossible; seed collection and handling are difficult because of the scattered, often remote stands in which the trees occur, irregularity of good seed years, difficulty of extraction and uncertainties on safe but efficient methods of breaking the seed dormancy. Last, but not least there are the problems caused by insects in all stages of development and storage of the seeds.
In order to remedy at least in part these identified information gaps it was decided to prepare a series of handbooks within the framework of the FAO/IBPGR project. Such handbooks, aimed at professional staff involved in actual field operations, have been prepared on taxonomy; seed collection, handling, treatment and storage; and seed insects of the two main genera, Acacia and Prosopis. The handbooks are published in English, French and Spanish to help bridge-language barriers between countries and continents.
We are aware of the fact that much more work is still needed in this field: the species covered are only a small fraction of those which merit urgent attention, the topics covered in these handbooks are but a few of the numerous ones which need to be systematically tackled. However, through this and related work we hope to catalyze action elsewhere in the world, to show one of the ways of going about the problems which we all should be determined to solve: the conservation of our heritage of genetic resources and the utilization of these resources for the betterment of life particularly of rural communities dependent on these resources.
Fruits and seeds of species of Prosopis (mesquite, algarrobo) are fed upon mostly by insects in the orders Hemiptera, Lepidoptera and Coleoptera from the time the fruits start to form until after the fruits are mature. Although different species of insects vary in the amount of fruits and seeds that they destroy in time and space, most scientists agree that bruchid beetles cause the most damage to the seeds of Prosopis.
Few insecticides have been used to control fruit pests of Prosopis. Those insecticides that have been used are discussed, as are traditional methods of control and biological control.
The most important priority research needs are to conduct intensive studies of the life histories and ecology of the seed-infesting insects of Prosopis, to determine the best modern insecticides to control these insects, to determine their host preferences, and to conduct intensive studies on their taxonomy.
Means of identifying seed-infesting insects of Prosopis are included.
The author thanks M. Johnson and M. Bronson for preparation of the manuscript and D. Maier for drawing the figures; R. Kistler for assisting in the accumulation of references pertaining to seed-infesting insects of Prosopis; and John M. Kingsolver who made available unpublished manuscripts so that they might be included in this handbook. Most of the ecological data were gathered and analyzed by graduate students G. Forister, T. Center, S. Swier, G. Pfaffenberger and R. Conway, under various grants from the U.S. Department of Agriculture and the U.S. National Science Foundation.
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Insects that feed on pods and seeds of Prosopis
Prosopis bruchids in North America
Prosopis bruchids in South America
Other potential bruchid pests of Prosopis
Life histories of other bruchids and possible significance to Prosopis pods
Bruchid - plant interactions
Control of seed-feeding insects of Prosopis
Insecticidal control prior to harvest
Insecticides to control Prosopis seed-feeding insects in storage
Unique (traditional) methods to control bruchid seed pests in storage
Potential biological control agents for bruchids and other pests of Prosopis
Priority research needs in countries
Identification of the Bruchidae
Identification of Hemiptera
Table 1. Genera of Bruchidae whose species feed in seeds of Prosopis
Table 2. Prosopis bruchids and their host plants
Table 3. North and South American Prosopis species and the species of Bruchidae that feed in their seeds
Table 4. Possible insecticides to control Prosopis seed-feeding insects prior to harvest
Table 5. Insecticides that have been used to control various stored-products bruchids
Table 6. Unique (traditional) methods for controlling bruchid pests in stored seeds
Table 7. Potential biological control agents for bruchids and other pests of Prosopis
Table 8. Priority research needs for controlling seed-infesting insects of Prosopis (listed in order of importance)