July 2010. Help was sought on the identification and control of crickets attacking Jatropha plantations in Mali. A Jatropha plantation in Kita, Mali, was totally defoliated by a ‘green’ cricket attack last week.
Some nurseries and isolated Jatropha trees are attacked by ‘yellow striped’ crickets.
Are there non-chemical ways to limit cricket populations? Farmers are presently using lambda cyhalothrin or carbofuran, when they can afford it, or nothing most of the time. The writer said that the crickets are not very damaging at present, but was concerned whether these isolated attacks which are becoming quite frequent may be the sign of an impeding wider attacks.
A member identified the crickets as Pyrgomorpha vignaudii (photo, top), and 2) and Zonocerus variegatus (photo, below). These are grasshoppers (Orthoptera: Pyrgomorphidae).
Locusts of West Africa and especially the Sahel zone are very well documented in the works published by CIRAD/PRIFAS/GERDAT (Uvarov's and coworker's work in this area of science is a bit old, though still of good value).
The relevant publications are ‘Les Acridiens des Formations herbeuses d'Afrique de l'Ouest’ (1988, 330 pp.) describing all pest (and some other) species of Acrididae for that region, and ‘Le Criquet puant Zonocerus variegatus (Linne, 1758)’ (1990, 138 pp.), which is one of the common and devastating species.
These books were published by Ministere de la Cooperation de France/CIRAD Dept GERDAT/PRIFAS; these and the other publications of PRIFAS/GERDAT would answer the questions posed by the member from Mali.
As for control, Green Muscle could be tried; this contains Metarrhizium and seems to have good specificity to locusts. Many of these species are migratory, but at least the striped one is a nymph and, therefore, must have emerged from an egg capsule locally. A member from Senegal confirmed the usefulness of Green Muscle against grasshoppers and some lepidopteran larvae. Other suggestions were PDPs (plant-derived products) for:
Crickets: Stemona (Stemona tuberosa - Roxburghiaceae family).
Grasshoppers: Tephrosia (Vogels tephrosia, purple tephrosia, white tephrosia) (Tephrosia
spp. Leguminaceae family).
There was also mention of the Online Information Service for Non-chemical Pest Management in the Tropics: www.oisat.org. It has extensive information on control measures against pests and diseases. It also includes specific Field Guides for the major crops.