Introduction
The bagworm, Oiketicus kirbyi is a polyphagous insect feeding on several crops: Musaceae (Musa spp.), cacao (Theobroma cacao L.), oil palm (Elaeis guineensis Jacquin), peach palm (Bactris gasipaes Kunth), coconut (Cocos nucifera L.), citrus (Citrus spp.), teek (Tectona grandis L.), eucaliptus (Eucalyptus spp.), Eryobothria japónica, Terminalia catappa L) and many more.
The insect became a serious problem in some commercial banana plantations on Costa Rica's Atlantic coast during the period 1962-1964. The start of the problem was associated with the irrational use of broad-spectrum, long-residuality insecticides such as Dieldrin, originally used to control an aphid (Lara 1970).
O. kirbyi was present in oil palm in Central America but was of no concern (Chinchilla 1989), until an outbreak was observed in an oil palm plantation in Puerto Armuelles, Panama, in 1990. The outbreak appeared to originate in a nearby plantain plantation. Early the following year, an outbreak occurred in another nearby oil palm plantation, this time located in Costa Rica. Initially, the insect was confined to two harvesting lots, but the area affected rapidly increased to comprise several hundred hectares. Several outbreaks fallowed during which control was attempted through the use of Bacillus thuringiensis (generally Dipel: 0.8 to 1.5 l/ha). From 1996 onwards, the population of the pest declined, apparently controlled by its numerous natural enemies. In September of 1998, a new outbreak occurred in a small area (less than 100 ha) but did not spread. From that moment on, the population of this pest has been very low.
O. kirbyi has also caused problems in oil palm in other countries. In Colombia, the pest was observed in El Cesar during 1973 and 1985, when it caused three defoliations in Palmeras de la Costa S.A (up to 353 larvae /leaf) (Villanueva and Avila 1987). It also caused damage in the Cauca Valley, in about 150 ha of plantains in 1975-1976 (García 1987).
This review summarizes part of the knowledge obtained on O. kirbyi originating in tropical America, particularly that learned in Costa Rica during outbreaks in the early nineties.
The Psychidae family
The larvae of the Psychidae family are hypognathous, measure between 8 and 50 mm, and build protective bags made from silk and fragments of plant tissue. They are cylindrical, with well-developed thoracic legs and four pairs of pseudo-legs in the abdomen and a pair at the anal extreme.
Pupation occurs within the bag; the final larval stage attaches the bag to the stratum and pupates up side down. In some more evolved genera, females do not abandon the bag, except after laying the eggs, when they drop to die on the ground. Depending on species, 200- 13 000 eggs remain within the bag. The larval stage is fairly long, but adult life is ephemeral. Sexual dimorphism is marked: adult females are neotenic with larval appearance and remain inside the bag. Males are free living moths (Stehr 1987).
There are about 600 species in the family; 500 are Old World species and 26 are found in Canada and the US. The genus Oiketicus is represented by three species in tropical America. O. kirbyi is found in lowlands from Brazil to Mexico and in the Caribbean islands.
Integrated pest management
The integrated management of the pest is based on sampling leaf 17 looking for larvae (healthy, parasitized, diseased…) and predators. Natural enemies are also looked for on the associated flora.
Chemical control. Aerial applications of broad-spectrum, long-residuality insecticides in both bananas and oil palm in the past disrupted natural control. The protection afforded the larva by its bag and its ability to fast make this pest difficult to control with most insecticides. Trunk injection of monocrotophos (14-18 cc/palm) has been used with success (up to 98% larval mortality in two weeks) in some occasions. However, the use of this technique is laborious, costly and not risk-free in terms of its affects on the natural enemies of the pest.
Results obtained with the use of Bacillus thuringiensis (2-3 kg/ha:Thuricide, Dipel…) have been variable (up to 70 % larval mortality), depending on several factors, including climatic conditions. Normally, effective control requires at least two applications of the product spaced 3-4 weeks. Chitin inhibitors (triflumuron: 0.45- 0.75 g a.i./ha) and the nereistoxin (Padan) have also been used with relative success.
Cultural control. Given that larvae tend to concentrate toward the tip of leaves, they can be collected manually on young palms. Cutting the tips of leaves is not a good idea since defoliation can be greater than that caused by the larvae. Manual removal of larvae can be costly and most of bags taken could be males, since many females tend to position themselves toward the tips of the youngest taller leaves where a normal person can not reach them.
Weed control should be selective (or suspended) during an outbreak of this or any other defoliator: patches or bands of known beneficial plants can be left to provide refuge and food to parasitoids and predators. Nurseries of these plants can be prepared and planted in areas where they can be protected without interfering with normal agronomic practices (Table 6).
Biological control. Parasitized larvae can be collected and placed in containers that allow the adult parasitoids to leave. However, protecting and planting those plants that harbor these natural enemies of the pest is more effective.
Pheromones. The main blend of pheromones produced by the female to attract males has been identified and can be used to monitor male population or even in mating disruption. Light traps do not attract many males, and no trap with food will work since adult males do not feed.
The bagworm, Oiketicus kirbyi is a polyphagous insect feeding on several crops: Musaceae (Musa spp.), cacao (Theobroma cacao L.), oil palm (Elaeis guineensis Jacquin), peach palm (Bactris gasipaes Kunth), coconut (Cocos nucifera L.), citrus (Citrus spp.), teek (Tectona grandis L.), eucaliptus (Eucalyptus spp.), Eryobothria japónica, Terminalia catappa L) and many more.
The insect became a serious problem in some commercial banana plantations on Costa Rica's Atlantic coast during the period 1962-1964. The start of the problem was associated with the irrational use of broad-spectrum, long-residuality insecticides such as Dieldrin, originally used to control an aphid (Lara 1970).
O. kirbyi was present in oil palm in Central America but was of no concern (Chinchilla 1989), until an outbreak was observed in an oil palm plantation in Puerto Armuelles, Panama, in 1990. The outbreak appeared to originate in a nearby plantain plantation. Early the following year, an outbreak occurred in another nearby oil palm plantation, this time located in Costa Rica. Initially, the insect was confined to two harvesting lots, but the area affected rapidly increased to comprise several hundred hectares. Several outbreaks fallowed during which control was attempted through the use of Bacillus thuringiensis (generally Dipel: 0.8 to 1.5 l/ha). From 1996 onwards, the population of the pest declined, apparently controlled by its numerous natural enemies. In September of 1998, a new outbreak occurred in a small area (less than 100 ha) but did not spread. From that moment on, the population of this pest has been very low.
O. kirbyi has also caused problems in oil palm in other countries. In Colombia, the pest was observed in El Cesar during 1973 and 1985, when it caused three defoliations in Palmeras de la Costa S.A (up to 353 larvae /leaf) (Villanueva and Avila 1987). It also caused damage in the Cauca Valley, in about 150 ha of plantains in 1975-1976 (García 1987).
This review summarizes part of the knowledge obtained on O. kirbyi originating in tropical America, particularly that learned in Costa Rica during outbreaks in the early nineties.
The Psychidae family
The larvae of the Psychidae family are hypognathous, measure between 8 and 50 mm, and build protective bags made from silk and fragments of plant tissue. They are cylindrical, with well-developed thoracic legs and four pairs of pseudo-legs in the abdomen and a pair at the anal extreme.
Pupation occurs within the bag; the final larval stage attaches the bag to the stratum and pupates up side down. In some more evolved genera, females do not abandon the bag, except after laying the eggs, when they drop to die on the ground. Depending on species, 200- 13 000 eggs remain within the bag. The larval stage is fairly long, but adult life is ephemeral. Sexual dimorphism is marked: adult females are neotenic with larval appearance and remain inside the bag. Males are free living moths (Stehr 1987).
There are about 600 species in the family; 500 are Old World species and 26 are found in Canada and the US. The genus Oiketicus is represented by three species in tropical America. O. kirbyi is found in lowlands from Brazil to Mexico and in the Caribbean islands.
Integrated pest management
The integrated management of the pest is based on sampling leaf 17 looking for larvae (healthy, parasitized, diseased…) and predators. Natural enemies are also looked for on the associated flora.
Chemical control. Aerial applications of broad-spectrum, long-residuality insecticides in both bananas and oil palm in the past disrupted natural control. The protection afforded the larva by its bag and its ability to fast make this pest difficult to control with most insecticides. Trunk injection of monocrotophos (14-18 cc/palm) has been used with success (up to 98% larval mortality in two weeks) in some occasions. However, the use of this technique is laborious, costly and not risk-free in terms of its affects on the natural enemies of the pest.
Results obtained with the use of Bacillus thuringiensis (2-3 kg/ha:Thuricide, Dipel…) have been variable (up to 70 % larval mortality), depending on several factors, including climatic conditions. Normally, effective control requires at least two applications of the product spaced 3-4 weeks. Chitin inhibitors (triflumuron: 0.45- 0.75 g a.i./ha) and the nereistoxin (Padan) have also been used with relative success.
Cultural control. Given that larvae tend to concentrate toward the tip of leaves, they can be collected manually on young palms. Cutting the tips of leaves is not a good idea since defoliation can be greater than that caused by the larvae. Manual removal of larvae can be costly and most of bags taken could be males, since many females tend to position themselves toward the tips of the youngest taller leaves where a normal person can not reach them.
Weed control should be selective (or suspended) during an outbreak of this or any other defoliator: patches or bands of known beneficial plants can be left to provide refuge and food to parasitoids and predators. Nurseries of these plants can be prepared and planted in areas where they can be protected without interfering with normal agronomic practices (Table 6).
Biological control. Parasitized larvae can be collected and placed in containers that allow the adult parasitoids to leave. However, protecting and planting those plants that harbor these natural enemies of the pest is more effective.
Pheromones. The main blend of pheromones produced by the female to attract males has been identified and can be used to monitor male population or even in mating disruption. Light traps do not attract many males, and no trap with food will work since adult males do not feed.
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