Organic Farming

Mites are considered minor pests of coconuts as these are predominantly observed only in nurseries. However, an outbreak in the island of Camiguin in 1994 affected 90-98% of the coconut palms and reduced yield from 63% to 87%. Hence, from 1999 to 2005, as a pioneering work on the pest, Gallego (PCA) studied its biology and ecology and developed an integrated pest management scheme against the false spider mites.

In 1996, the mite was identified and recorded as a new genus and species (Rarosiella cocosae Rimando) under Family Tenuipalpidae, Order Acarina.
Mites were found in large numbers on the undersurface of the leaflets. Both nymphs and adults were destructive as these sucked the plant sap. In young palms, the damage started from the tip of leaflets as tiny lesions, which later discolored and dried up the leaf surface from the tip downwards.
On mature bearing palms, the damage started from the lowest matured fronds and progressed upward. Closer examination of infested leaflets showed irregular lesions with necrotic centers and water-soaked borders that later coalesced and formed blights. In severe cases, both young and mature mite-infested palms appeared as burnt from a distance.
Quarterly monitoring of R. cocosea Rimando populations showed that the mites were present throughout the year in coastal and inland zones in Camiguin Island. Mite population declined when average rainfall increased, but there was no correlation with relative humidity and temperature.
Eggs of the false spider mites were minute, oval, and reddish measuring 0.07 mm wide and 0.10 mm long. Incubation period ranged from 3 to 10 days. The nymph has three instar stages with a total nymphal period of 10-25 days. Adults lived from 13 to 54 days. Both female and male had similar bodies-broadly oval or round and magenta red, except that the female was larger than the male.
The total development cycle from egg laying to death of R. cocosea Rimando ranged from 35 days to 78 days, with an average of 49.84 days. About 10-27 eggs were laid in the entire life of the mite with 95% hatchability. The destructive stages were from first nymphal instar to adult, implying that each individual mite fed on the leaf for 42.71 days.
Three natural enemies were observed to prey o the false spider mites. These were voracious feeders of the mite’s eggs, nymphs, and adults. These natural enemies were: Amblyseius largoensis (Muma), and Armascirus Taurus (Kramer), both mite species, and Telsimia ephippiger Chapin, a coccinelid beetle. The role of the two predatory mites still needs to be further investigated.
Based on the survey, alternate hosts of the mites were the red palm, ivory palm, phoenix palm, ordinary palmera, coffee, cacao, papaya, banana, mahogany, Flemingia macrophylla, and ‘kamias.’

The following were the integrated control strategies developed and recommended for adoption:

Biological. Studies on the biology of the beetle, T. ephippiger, showed that it voraciously fed on different stages of the mites for 59.83 days. Its total development period from egg laying to death was 72.95 days. This meant that the predator was still in the field even with the second generation of mites. The predator devoured on average of 56.68 mites/day or a total of 3,470 mites throughout the predatory beetle’s lifespan. Thus, the beetle was a potential biological control agent ideal for its short life cycle, ease in handling, high predatory capacity, and availability of the hosts.

Mechanical. As a preventive measure, pruning of severely infested leaves in coconut seedlings or young plants was done every quarter. Mite population was lower in pruned palms than in unpruned ones. However, pruning was only feasible in coconut seedlings and in young plants, and not economically feasible.

Chemical. Among four commercially available pesticides tested in the laboratory, Triazophos and Dimethoate proved highly effective with total knockdown-effect in all dilutions 48 hours after treatment. Standard dilution of lamdacyhalothrin was also effective 72 hours after application.

Botanical. As an alternative to the commercially available chemical pesticides, Derris sp. (‘tubli’) and Azadirachta sp. (neem) were also tested in the laboratory . Pure tubli root extract proved to be the most effective at 24, 48, 72, 96, and 240 hours after spraying. Neem seed extract showed significant effect against mites only at 24 hours after application. These botanical pesticides can be used in young plantings and seedlings in the nursery.

The use of chemical pesticides may also have adverse effect on the natural enemies and thus result in recurrence of mite population outbreak. Hence, the use of biological control was a more sustainable option.

Today is May 17, 2006
	Controlling the false spider mites
	Mites are considered minor pests of coconuts as these are predominantly observed only in nurseries. However, an outbreak in the island of Camiguin in 1994 affected 90-98% of the coconut palms and reduced yield from 63% to 87%. Hence, from 1999 to 2005, as a pioneering work on the pest, Gallego (PCA) studied its biology and ecology and developed an integrated pest management scheme against the false spider mites. Findings In 1996, the mite was identified and recorded as a new genus and species (Rarosiella cocosae Rimando) under Family Tenuipalpidae, Order Acarina. Mites were found in large numbers on the undersurface of the leaflets. Both nymphs and adults were destructive as these sucked the plant sap. In young palms, the damage started from the tip of leaflets as tiny lesions, which later discolored and dried up the leaf surface from the tip downwards. On mature bearing palms, the damage started from the lowest matured fronds and progressed upward. Closer examination of infested leaflets showed irregular lesions with necrotic centers and water-soaked borders that later coalesced and formed blights. In severe cases, both young and mature mite-infested palms appeared as burnt from a distance. Quarterly monitoring of R. cocosea Rimando populations showed that the mites were present throughout the year in coastal and inland zones in Camiguin Island. Mite population declined when average rainfall increased, but there was no correlation with relative humidity and temperature. Eggs of the false spider mites were minute, oval, and reddish measuring 0.07 mm wide and 0.10 mm long. Incubation period ranged from 3 to 10 days. The nymph has three instar stages with a total nymphal period of 10-25 days. Adults lived from 13 to 54 days. Both female and male had similar bodies-broadly oval or round and magenta red, except that the female was larger than the male. The total development cycle from egg laying to death of R. cocosea Rimando ranged from 35 days to 78 days, with an average of 49.84 days. About 10-27 eggs were laid in the entire life of the mite with 95% hatchability. The destructive stages were from first nymphal instar to adult, implying that each individual mite fed on the leaf for 42.71 days. Three natural enemies were observed to prey o the false spider mites. These were voracious feeders of the mite’s eggs, nymphs, and adults. These natural enemies were: Amblyseius largoensis (Muma), and Armascirus Taurus (Kramer), both mite species, and Telsimia ephippiger Chapin, a coccinelid beetle. The role of the two predatory mites still needs to be further investigated. Based on the survey, alternate hosts of the mites were the red palm, ivory palm, phoenix palm, ordinary palmera, coffee, cacao, papaya, banana, mahogany, Flemingia macrophylla, and ‘kamias.’ The following were the integrated control strategies developed and recommended for adoption: Biological. Studies on the biology of the beetle, T. ephippiger, showed that it voraciously fed on different stages of the mites for 59.83 days. Its total development period from egg laying to death was 72.95 days. This meant that the predator was still in the field even with the second generation of mites. The predator devoured on average of 56.68 mites/day or a total of 3,470 mites throughout the predatory beetle’s lifespan. Thus, the beetle was a potential biological control agent ideal for its short life cycle, ease in handling, high predatory capacity, and availability of the hosts. Mechanical. As a preventive measure, pruning of severely infested leaves in coconut seedlings or young plants was done every quarter. Mite population was lower in pruned palms than in unpruned ones. However, pruning was only feasible in coconut seedlings and in young plants, and not economically feasible. Chemical. Among four commercially available pesticides tested in the laboratory, Triazophos and Dimethoate proved highly effective with total knockdown-effect in all dilutions 48 hours after treatment. Standard dilution of lamdacyhalothrin was also effective 72 hours after application. Botanical. As an alternative to the commercially available chemical pesticides, Derris sp. (‘tubli’) and Azadirachta sp. (neem) were also tested in the laboratory . Pure tubli root extract proved to be the most effective at 24, 48, 72, 96, and 240 hours after spraying. Neem seed extract showed significant effect against mites only at 24 hours after application. These botanical pesticides can be used in young plantings and seedlings in the nursery. The use of chemical pesticides may also have adverse effect on the natural enemies and thus result in recurrence of mite population outbreak. Hence, the use of biological control was a more sustainable option. Source: PCARRD, 2006. Highlights 2005, Los Banos, Laguna
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Controlling the false spider mites