Pigeon-Pea Pod Borers and Their Natural Enemies

 in Barbados, West Indies

 M. M. Alam I. H. Gibbs
 CARDI/Sugar Technology Research Unit
 Edgehill, St. Thomas, Barbados, W.I.


In Barbados, three pests, Heliothis virescens (F.), Fundella
cistipennis (Dyar) and Callosbruchus chinensis (L.) inflict
serious damage to pigeon-pea pods. Over the years it was
estimated that some 60% pods were destroyed annually.
 Although a number of indigenous natural enemies were
recorded attacking eggs, larvae and pupae of these pests, their
populations were usually too low for adequate control.
 Between 1968 and 1983, a number of parasite species were
introduced from India, Pakistan, Uruguay, U.S.A. and the


Eastern Caribbean islands; 17 for the control of H. virescens,
seven for F. cistipennis and two for C. chinensis. Of these, two
species, Bracon hebetor (Say), from India and Bracon sp.
prob. hebetor (Say) (close to Bracon brevicornis [Wesmeal]),
from St. Vincent, became established against Heliothis and
Fundella. The levels of parasitism by the latter species ranged
from 2.1 70%, avg. 16.4%, between April and December
1983.


 The pigeon-pea (Cajanus cajan) is a cultivated annual or peren-
 nial shrub grown in many tropical and sub-tropical countries for
 its green or dry seeds. In the Caribbean in general and in Bar-
 bados in particular, it is planted on the borders of sugarcane
 fields. In recent years, because of the greater demand for this
 commodity, pure stands are also grown.
 In Barbados, the most important pests are the pod-borers, a
noctuid, Heliothis virescens (F.), a pyralid, Fundella cistipennis
(Dyar) and a bruchid, Callosobruchus chinensis (L.).
 Between 1968 and 1976, several parasites and predators were
introduced by the Ministry of Agriculture, Food and Consumer
Affairs, from India, Pakistan, Uruguay and the United States of
America, through the Commonwealth Institute of Biological
Control (CIBC), West Indian Station, Trinidad (see Appendix 1
-3). Some of these became established, but their populations re-
mained low.
 Since 1977, a search was carried out by the Caribbean
Agricultural Research and Development Institute (CARDI) for
natural enemies of pigeon-pea pod borers, H. virescens and F.
cistipennis; the bruchid, C. chinensis and certain other important
pests throughout the region.
 From a number of egg, larval and pupal parasites recorded in
the Eastern Caribbean islands, a Bracon sp. (solitary) attacking F.
cistipennis, and a Bracon sp. prob. hebetor (Say) (close to Bracon
brevicornis [Wesmeal]) a gregarious ecto-larval parasite attacking
H. virescens and F. cistipennis in St. Vincent; a Bracon sp.
(gregarious ecto-larval parasite) on F. cistipennis and An-
cylostomia stercorea (Zell.) in Antigua, St. Kitts, Nevis, Montser-
rat and St. Lucia; and Apanteles etiellae (Viereck) (solitary) at-
tacking F. cistipennis and A. stercorea in St. Kitts, Nevis and
Montserrat, were of greater importance for the control of these
pests, in the countries where these were absent. Of these, Bracon
sp. prob. hebetor and Bracon sp. (gregarious) were mass bred in
the laboratory on Trachylepidia fructicassiella (Rag.) larvae.
These two species were released in pigeon-pea plots throughout
the island, and recoveries were made in the field. It appears that
at present the former species is the most effective, attacking up to
44% Heliothis and up to 70% Fundella larvae in the field.
Observations on the permanent establishment of these two
parasites and their effect on the pod-borer populations are conti-
nuing. Bracon sp. prob. hebetor has also been introduced into
Antigua, St. Kitts, Dominica and St. Lucia.


38


 Trichospilus diatraeae (Cherian and Margabandhu), a pupal
 parasite of various pests in India, was introduced into Barbados
 against Fundella and Heliothis spp. The parasite seems to prefer
 pests pupating on the leaves of their host plants, and attacked
 Pseudoplusia includes (Walker) on tomato, Diaphania
 (= Margaronia) hyalinata (L.) on cucurbits and Palpita hyalinata
 (L.) on French Willow. Heliothis spp., which pupate in the soil,
 and Fundella in pigeon-pea pods, thus escaped parasitism.

 Pod-Borers and Their Natural Enemies
 Heliothis virescens (F.) (Lepidoptera : Noctuidae) is a serious
 pest of pigeon-pea in Barbados and other Eastern Caribbean
 islands.
 The larvae bore into the pods and destroy the developing
seeds. In addition to H. virescens, Fundella cistipennis (Dyar)
also attacks the pods. The average pod damage recorded between
1969 76 ranged from 27.8 90.5%, average 61%.
 H. virescens is always more abundant than F. cistipennir,
although the latter becomes more prevalent during January to
March.
 The egg of H. virescens is creamy-white, dome shaped, with a
small conical micropile at its apex. The sides are grooved with
long and short ridges. They are laid singly on buds, flowers and
young pods. Initially the newly hatched larva feeds on the leaf
surface, flowers, buds and pods, and later bores into the pod. A
single larva can damage most of the seeds in a pod. The full-
grown larva leaves the pod and pupates in the soil.
 The life-cycle was studied in the laboratory at 26.3C + 0.2C
and 88% relative humidity. The incubation period lasts three
days. Generally there are five or six larval instars and in a few in-
stances, seven. During these studies, 57.1% larvae moulted six
times; 38.1%, seven times and 4.8% eight times. The time taken
by various instars is given in Table 1.
 The pest has been recorded on a wide range of cultivated and
wild plants, including cotton (Gossypium barbadense), tomato
(Lycopersicon esculentum) and sweet potato (Ipomoea batatas).
 During these studies, the natural enemies were recorded in
Barbados as listed in Table 2.
 Because of inadequate control by indigenous natural enemies,
some seventeen species of parasites and one predator were ob-
tained from India, Pakistan, Uruguay, Arizona (U.S.A.), St.
Vincent and Antigua, W.I. (see Appendix 1).

 PROCEEDINGS of the CARIBBEAN FOOD CROPS SOCIETY-VOL. XX