In this issue of the Newsletter, a report by Dr. Stein Holden urges that edible caterpillars become an active focus of agroforestry research in Zambia, and Dan Turk reviews Tango Muyay’s book which emphasizes the increasing importance of edible insects in Zaire, particularly some of the edible caterpillars. As brief backgrounding for their contributions, attention is called to two earlier and very valuable studies, one by Malaisse and Parent (1980) on the specific identity of caterpillars used as food in southern Zaire, and one by Leleup and Daems (1969) on the timing of bush fires in relation to the survival of edible caterpillars.
Numerous reports make it evident that scores of species of caterpillars (mostly larvae of the giant silk moths, Family Saturniidae) are important items of food throughout much of sub-Saharan Africa. Unfortunately for scientific progress, the caterpillars have usually been referred to only by their vernacular names. Malaisse and Parent (1980), however, not only determined that at least 35 species of caterpillars are used as food in the southern Shaba region of southern Zaire, but they determined the taxonomic identity of 26 of the species. They further reported the host trees and the seasonal occurrence of harvesting for each species. In their analyses of the nutritional value of 22 species of these caterpillars, kcal/100 grams dry weight averaged 457, ranging from 397 to 543, and crude protein content averaged 63.5%, ranging from 45.6% to 79.6%. Most species proved an excellent source of iron, 100 g averaging 335% of the recommended daily allowance. Their study stands as a model for the kinds of species-specific basic information which is needed, but not available, in most parts of Africa.
The study by Leleup and Daems (1969) in the Kwango District of northern Zaire (one of the poorest regions of the country from the standpoint of protein reserves) was commissioned by the territorial administration of Feschi to investigate whether recent fluctuations and reduced tonnage of the most economically important caterpillars might be due to badly timed brush-burning. The authors state (translation, p. 1): “Large game having become very scarce, it is fish, and especially caterpillars, of which certain species abound, that constitute the most important sources of protein for local consumption …. Caterpillars are not only an important source of protein for local consumption, but they also bring in a substantial income to these disadvantaged regions …. Commercialized dried caterpillars in the Kwango district averaged 185 tons per year for the five-year period, 1954-1958. To this must be added tonnage, sold privately to Bapende retailers, as well as local consumption, bringing the dried caterpillar production to an estimated 280-300 tons per year.”
We cite the work of Leleup and Daems here because it explains why, when the biology of the insects is considered, the timing of bushburning is of critical importance. Of the more than 30 species of caterpillars consumed in the Kwango and Kwilu districts, only three (all saturniid larvae) account for most of the exports. Cirina forda forda larvae, called ‘Makoso” by both the Kipende and the Kitshok people, are found in wooded savannah where they feed on the tree ‘Mikoso’ (Kipende) or “Mikwatshi” (Kitshok) (Erythrophleum africanum?). The larvae are abundant and are harvested in September. Pupation is underground.
“Masese” larvae (scientific name not specified) feed on the “Masese” tree. (Burkea afrikana?) in wooded savannah and are harvested in February. Pupation is underground. These larvae are very abundant and together with the “Makoso” are collectively known as “Mangola.”
The third most important species for export is Bunaeopsis aurantiaca. The larvae are known as “Mambula” (Kipende) or “Makunga” (Kitshok) and feed on a low perennial woody plant known as ‘Mikia” (Kipende) or “Mitongo” (Kitshok), which occurs in the steppes biotope (open high plateau). Harvest is in October. Pupation is underground.
Fires can be set only in the dry season which, in the region studied, extends from the beginning of May to the end of August(Fig. 1). The authors conclude that, in wooded savannah, the optimum dates for setting brush fires are June 5 in areas where “Makoso” predominates, and June 10 where “Masese” predominates. Fire setting should be banned after June 15. The underground pupae, about 5 cm deep, are somewhat protected from fire if (1) the ground surface is relatively denuded, which is usually the case at the base of the trees where the pupae are located, and (2) if the heat is not too great. This is why, according to the authors, in the wooded savannah where fires have much stronger intensity than on the high plains, fires in July-August when the undergrowth is very dry must be outlawed. This is all the more urgent because this is the time when the “Makoso” are in the egg or young caterpillar stage (Fig. 1) and they are subject to destruction en masse. Because the adults appear in the second half of June, this justifies the ban on setting fires in the wooded savannah after 15 June.
Figure 1: Recommended bush-burning dates in relation to seasonal occurrence of the life stages of the three edible caterpillars of greatest nutritional and commercial
importance (adapted from Leleup and Daems 1969)
The situation is different in the high plains where the vegetation is lower, the fire moves more rapidly, and the ground does not heat up as much. The optimum date for setting fires in the steppes, relative to “Makunga,” is July 10 with a leeway of 10 days earlier or later. Bush fires in the steppes must be banned (1) from July 20 to August 31 in order not to destroy the freshly emerged adults or their eggs, and (2) from May 11 to June 30, so that foliation after the fire is not too advanced (host leaves get too tough) when the young caterpillars emerge.
Leaf toughness is also a factor relative to the “Makoso.” To burn in the month of May would make the reconstituted foliage of the “Mikoso”‘ too tough by the time the young caterpillars emerge during the second half of July. The “Masese” are much less sensitive to fire
because they spend the entire dry season in the pupal stage. They would suffer from fires in July and August, however, because of the high heat intensity of fire in wooded savannah during those driest months.
In addition to optimum times for burning, Leleup and Daems made several other recommendations aimed at avoiding the dwindling of the “Mangolo” biologic stock: (1) to enforce the ban on felling trees in order to harvest the caterpillars; (2) to forbid the increasing practice of harvesting pupae; (3) to encourage resowing attempts on a massive scale by collection of eggs prior to burning; and (4) to create “reserves” of some small wooded savannahs, in which all harvest for purposes of consumption would be forbidden.
Space limitations prevent more than passing mention of two other pertinent papers. Malaisse et al (1969), noting that the notodontid caterpillar, Elaphrodes lactea (Gaede), is an important protein/fat source for the rural people, questioned on biological and social grounds the necessity of foresters’ campaigns aimed at destroying the caterpillars which annually cause massive (but not lethal) defoliation of Brachystegia boehinii and other Caesalpiniacees in parts of Zaire and Zambia. Turk (1990) lists 42 species of leguminous trees that are fed upon by edible caterpillars in Africa, and suggests preservation or development of management practices that would help preserve caterpillar production.
Gene DeFoliart, Editor.
Leleup, N.; Daems, H. 1969. Les chenilles alimentaires du Kwango. Causes de leur rarefaction et mesures preconisees pour y remedier. J. Agric. Trop. &Botany Appl. 16:1-21.
Malaisse, F.; Malaisse-Mousset, M.; Evrard, A. 1969. Aspects forestiers et sociaux des pullulations de Tunkubiu. Faut-il détruire ou protdger Elaphrodes lactea (Gaede) (Notodontidae)? Problémes sociaux congolaise, Bull.trim.C-E.P.SJ.No.86:27-36.
Malaisse, F.; Parent, G. 1980. Les chenilles comestibles due Shaba meridional (Zaire). Les Nat. Belges 61(l):2-24.
Turk, D. 1990. Leguminous trees as forage for edible caterpillars. Niftal Project [Nitrogen Fixing Tree Research] Reports 8:75-77.