3.3.5 - Guava

In South Africa C. destructor is a minor pest of guava, because its populations are curbed by parasites (de Villiers and van den Berg, 1987). It has one generation a year in South Africa (de Villiers and van den Berg, 1987).

According to Hempel (1920a), C. psidii does serious damage to guava trees in Brazil. We have no additional data on damage, life history or natural enemies.

In Egypt, C. floccifera is considered a minor pest of guava trees and only the leaves are infested (El-Minshawy and Moursi, 1976). See Section 3.3.7.

In Egypt and India, C. psidii is considered a serious pest of guava trees. Sooty mould may cover fruits and leaves; the value of fruits may decrease, and in cases of heavy infestations, the leaves may drop (El-Minshawy and Moursi, 1976; Salama and Saleh, 1970; Pawar et al., 1981; Gopalakrishnan and Narayanan, 1989). According to Steinweden (1946), in Florida, it is liable to cause serious damage to guava. In South Africa, the coccid is usually effectively suppressed by natural enemies but it may flare-up at times as a consequence of the action of ants, or due to the effect of broad-spectrum pesticides which disrupt biocontrol of the pest (Annecke and Moran, 1982; de Villiers and van den Berg, 1987).

Chloropulvinaria psidii reproduces parthenogenetically. In Egypt, it produces two generations a year and is most abundant in July and August. The first generation starts in April-May and the second in July-August. From April to October the populations of the coccid on the central core of sunny guava trees are higher than on the terminals but between November-December, the populations on both zones are almost equal, whilst in January-February the coccids tend to accumulate on the exposed terminals. In shady trees, the central core of the tree harbours a lower population than the terminals, between June and October and in February, but in November and December and again in March, the population in these two zones are almost equal, although by April/May the largest population is found on the central core. The insects are photopositive, but their spatial distribution is governed not only by light, but also by other factors, such as temperature and wind. During April-May, the khamsin winds (hot, dry desert winds) lead Ch. psidii to shelter in more protected zones of the tree. This is relevant also to the distribution of the insect during the hot summer months (Salama and Saleh, 1970). According to El-Minshawy and Moursi (1976), the total life cycle, from egg hatching to death lasts 31-43 days at between 22.5°C-28°C.

During 1953-1961, efforts were exerted to biocontrol Ch. psidii on ornamentals in Burma. Out of many imported natural enemies, only the four following species were reported as established: the Coccinellidae, Azya luteipes Mulsant and Cryptolaemus montrouzieri Mulsant and the Encyrtidae Metaphycus stanleyi Compere and Microterys kotinskyi (Fullaway) (Encyrtidae). The rate of parasitism by M. kotinskyi has been high in some areas and indeed this parasitoid is considered an important factor in the biocontrol of Ch. psidii. The predators A. luteipes and C. montrouzieri were at times effective (Bennett and Hughes, 1959). The efficacious activity of C. montrouzieri against the coccid was also recorded in Puerto Rico by Bartlett (1978). However, according to Simmonds (1959), several imported coccinellids were indeed established in Bermuda, but none were efficient enough to curb populations of Ch. psidii on oleanders. Zimmermann (1948) lists the following natural enemies in Hawaii: Microterys kotinskyi and M. flavus (Howard) (Encyrtidae) and the coccinellid Cryptolaemus montrouzieri. Singh (1989) records the following natural enemies of Ch. psidii on guava in India: Bothriophryne pulvinaria Agarwal, Agarwal and Khan, B. tachikawaii Agarwal, Agarwal and Khan, (Encyrtidae); Coccophagus bogoriensis Kon, C. cowperi Girault (Aphelinidae) and the predators Chilocorus nigritus (Fabricius) and Menochilus sexmaculatus (Fabricius). In India, under laboratory trials, 1st- to 4th-instar larvae of C. montrouzieri consumed eggs of Ch. psidii. In a preliminary field trial, the release of 10 adults of this coccinellid per tree resulted in a reduction of adults, nymphs and ovisacs of Ch. psidii to a negligible size (Mani and Krishnamoorthy, 1990). In India, sprays of the fungus Verticillium lecanii (Zimmermann) did not effectively control Ch. psidii (Easwaramoorthy and Jayaraj, 1977), although Gapalakrishnan and Narayanan (1989) recorded that this coccid was fatally attacked by the fungus Fusarium oxysporum.

In India, acephate and demeton-S-methyl gave good control of Ch. psidii (Easwaramoorthy and Jayaraj, 1977; Pawar et al., 1981). In Florida in the 1950's, parathion or malathion were recommended against the pest (Butcher, 1954). In South Africa, malathion was used against Ch. psidii (de Villiers, 1978); but “the first sensible step should be to control ants and thus establish a favourable environment for natural enemies” (Annecke and Moran, 1982).

In South Africa, various species of natural enemies keep C. hesperidum populations under low levels; but, if the natural enemies are hindered by pesticides or ants, severe attacks of the pest may damage guava trees (de Villiers and van den Berg, 1987). See Section 3.3.7.

In Egypt, P. nigra was considered a serious pest of this crop in the 1960's and control trials were carried out with oil and organophosphorous compounds (El-Minshawy et al., 1971). See also Section 3.3.7.

In Florida and South Africa, P. pyriformis is considered a pest of guava (Ray and Williams, 1982; de Villiers and Myburgh, 1987). Although this species is common in Israel, it has so far not become a pest of guava. See Section 3.3.3.

In Egypt, S. coffeae is considered as a serious pest of guava trees (El-Minshawy and Moursi, 1976). The the percentage of parasitism of S. coffeae by Scutellista caerulea (Fonscolombe) (= S. cyanea Motschulsky) was quite high in the late summer and autumn, reaching its peak in August (43.2%). However, the synchronization of the parasitoid with its host was unsatisfactory during the winter, since S. coffeae overwinters in its 2nd instar and the adults of S. caerulea could not curb this stage of the scale. Therefore, the release of adult parasites in April-May is suggested in order to improve the biocontrol of the pest (El-Minshawy et al., 1978). See Section 3.3.7.