Intercycle pests

Nematodes, mealybugs and ants

In a monoculture pineapple production system, the fallow period or intercycle has historically ranged from years to as little as a

© CAB International 2003. The Pineapple: Botany, Production and Uses (eds D.P. Bartholomew, R.E. Paull and K.G. Rohrbach)

Fig. 9.1. Illustration showing typical frequencies of infestation of the most significant pineapple pests in relation to a plant-crop pineapple cycle. Darker area indicates higher frequencies.

_|_Ants_J

Bud moths |

Fruit mite | [ Red mite ] J Symphylids | _White grubs_|

Fig. 9.1. Illustration showing typical frequencies of infestation of the most significant pineapple pests in relation to a plant-crop pineapple cycle. Darker area indicates higher frequencies.

Mealybug wilt

Nematodes

Butt rot Heart rot

Root rot

Yellow spot Fusarium stem rot

Bacterial heart rot

Fig. 9.2. Illustration showing typical disease intensities of the most significant pineapple diseases in relation to a plant-crop pineapple cycle. Darker areas indicate higher intensities.

few weeks. Prior to the discovery of soil fumigants for nematode control, the fallow period was an important nematode-control strategy, particularly for the root-knot nematode. The fallow period is also important for the control of ants and mealybugs which are associated with mealybug wilt. Tillage must be thorough and frequent enough for the decomposition of the previous crop and its pests and for the elimination of weed growth

Fig. 9.3. Illustration showing typical pineapple fruit disease intensities of the most significant pineapple fruit diseases in relation to a plant-crop pineapple cycle. Darker areas indicate higher intensities.

Fig. 9.3. Illustration showing typical pineapple fruit disease intensities of the most significant pineapple fruit diseases in relation to a plant-crop pineapple cycle. Darker areas indicate higher intensities.

Fig. 9.4. Pineapple disease index used to measure external disease severity (e.g. black rot) based on the proportion of fruitlets per fruit that show symptoms.

Fig. 9.4. Pineapple disease index used to measure external disease severity (e.g. black rot) based on the proportion of fruitlets per fruit that show symptoms.

during the fallow period. Weeds present during the fallow period may provide a carryover host for nematodes and mealybugs. Thorough tillage can also eliminate ants within the fallowed field.

Ants present in intercycle fields are the big-headed ant, Pheidole megacephala (F.) (Plate 22), the Argentine ant, Iridomyrmex humilis (Mayer), and the fire ant, Solenopsis geminata (F.) (Rohrbach and Schmitt, 1994).

With deep, frequent intercycle tillage, most ant colonies can be eliminated.

Nematode populations during the fallow period will decline significantly if soil moisture is adequate. However, the presence of soil moisture increases the need for weed control. Dry fallow is not as effective at reducing the reniform nematode population as is wet fallow (Caswell and Apt, 1989).

Economic thresholds for nematodes are not well defined. Soil sampling is important because the qualitative occurrence of reni-form, root-knot or root-lesion nematodes is generally interpreted as a potential problem that requires control (Caswell et al., 1990; Stirling and Kopittke, 2000).

Souring beetles

Small nitidulid beetles (c. 4.5-8.0 mm), known as souring beetles, sap beetles or dried-fruit beetles, are attracted to decomposing pineapple plant material (termed pineapple trash) following knock-down of the previous crop. The adult beetles are hard-bodied and dark brown (Hinton, 1945).

Several different species may infest trash or overripe pineapple fruit, of which Carpophilus humeralis (F.), Carpophilus hemipterus (L.) (Fig. 9.6), and Haptoncus ocularis (Fairm) are the most common (Carter, 1967; Py et al., 1987). Fertile females may lay more than 1400 eggs and live as many as 115 days (Carter, 1967). Eggs usually hatch within 2 days after deposition. Hinton (1945) indicates that the life cycle of C. humeralis from egg to adult is about 21 days. While the larvae typically feed on decaying fruit, the adults may attack pineapple plants at every stage of growth (Hinton, 1945). They may congregate on seed plants placed in the field and feed on the exposed butts and starchy stalk material. However, the injury to the plant is not economically significant. Chang and Jensen (1974) have identified these beetles as being possible vectors of the fungus Chalara paradoxa (De Seynes) Sacc. (syn. Thielaviopsis paradoxa (De Seyn.) Hohn) (telemorph Ceratocystis paradoxa (Dade) C. Moreau) which causes black-rot disease.

Souring beetles are more of a social nuisance than an agricultural one, because they

Fig. 9.6. Souring beetle, Carpophilus hemipterus L.

often land on humans in the vicinity of knocked-down fields and fruiting pineapple plantings. This has been a problem in places such as Hawaii, where recreational and tourist activities (e.g. golf) are enjoyed near pineapple-production areas. It has been reported (R. Heu, personal communication) that a single Maui resort company lost $50,000 weekly due to problems stemming from swarms of adult souring beetles. Given that these beetles do not have a significant impact on pineapple production, it is not economically feasible or environmentally desirable to control them with pesticides. However, to reduce their nuisance factor, the parasitic wasp Cerchysiella (= Zeteticontus) utilis Noyes (Hymenoptera: Encyrtidae) was collected in Israel and released in Hawaii in 1977 to control the immature larval stages of the beetles that infest rotting pineapple trash and fruit (Funasaki et al., 1988). The wasp established populations on the Hawaiian Islands of Oahu, Maui and Lanai (C. Nagamine, personal communication). The adult female parasitoid deposits her eggs into beetle larvae and the parasitized larvae mummify (i.e. turn hard and stiff) after 9-11 days. Fifteen days after egg deposition, an adult C. utilis emerges from the parasitized beetle. Souring-beetle numbers have been reduced somewhat, but the beetles still remain a problem in some areas.

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