Daniel Blumberg

REVIEW: Date Palm Arthropod Pests and Their Management in Israel

This review summarizes the current knowledge on the distribution, natural history, economic importance and management of 16 major species of date palm pests in Israel. Another 15, rarely occurring, pest species are also identified. Research on the date palm pests in Israel was initiated against a background of severe outbreaks of scale insects in the late 1950s. These outbreaks were caused mainly by unrestrained use of organophosphates. This situation led to the gradual development of an Integrated Pest Management (IPM) program, which was implemented first against scale insects and later against fruit pests. The IMP approach resulted in successful control of the scale insects, up to the present, whereas agrotechnical and crop management procedures, including covering the fruit bunches with plastic nets and early harvesting of several date cultivars, were successfully applied to achieve efficient control of the fruit moths. In addition, the use of chemical compounds in date plantations was drastically reduced and restricted to heavy foci of pest infestation. In time, microbial control, mainly application ofBacillus thuringiensis products against the lesser date moth, and the use of pheromone traps for monitoring and controlling red palm weevil, enabled further reductions in the use of synthetic insecticides. The overall change in pest management also significantly improved the preservation of natural enemies of the pests in the plantations. Whereas in the 1950s the major problems were caused by the parlatoria date scale and the green scale, in the early 2000s the key pests in date plantations in Israel are the lesser date moth and sap beetles in most of the date-growing areas, and spider mites which are restricted to the Arava Valley. Future management of the first two of these pests should rely on an improved monitoring system and integration of pheromone application for reduction of the population and damage. Efforst should be made to prevent the red palm weevil, which currently is a potential pest, from becoming an actual key pest in date plantations.

Management strategies of mealybug pests of citrus in mediterranean countries

Six mealybug species have been reported as citrus pests in the Mediterranean Basin: the citrus mealybugPlanococcus citri (Risso), the citriculus mealybugPseudococcus cryptus Hempel, the longtailed mealybugPseudococcus longispinus (Targioni-Tozzetti), the citrophilus mealybugPseudococcus calceolariae (Maskell), the obscure mealybugPseudococcus viburni (Signoret) and the spherical mealybugNipaecoccus viridis (Newstead). Some of these species,e.g. N. viridis, have recently been introduced into the region and are still spreading. Mealybugs are usually occasional or minor pests of citrus, but some species can reach key pest status. Mealybug management strategies in citrus have been based mostly on classical biological control and, to a lesser extent, on augmentative releases. However, chemical control is widely used, mainly because of the poor adaptation of the principal natural enemies to the climatic conditions of the Mediterranean. The application of pheromones is still restricted to monitoring the citrus mealybug, whose sex pheromone is commercially available. Mass trapping and mating disruption should be considered for possible use in IPM programs as an alternative method to supplementary chemical treatments. Enhancement of biological control through management of ant populations is another promising tactic for control of mealybugs. Strategies for managing mealybug pests of citrus, and possible levels of integration of different tactics according to the pest status, are discussed.

IDENTIFICATION OF HOST-RELATED VOLATILES ATTRACTIVE TO PINEAPPLE BEETLE Carpophilus humeralis

Volatiles collected from oranges fed upon by Carpophilus humeralis of either sex were consistently more attractive than volatiles from beetle-free oranges in wind-tunnel bioassays. Three compounds were identified as attractants from this system: 4-ethyl-2-methoxyphenol (1), 2,5-diisopropylpyrazine (2) (a new natural product), and 2-phenylethanol (3). Identifications were confirmed with synthetic compounds that had matching chromatographic and spectral properties. Compounds 1, 2, and 3 had only slight activity alone, but were highly synergistic with each other and with propyl acetate (PA), a fruity ester that is mildly attractive to Carpophilus beetles. Compound 2 was the most active in the wind tunnel; its threshold dose was 0.5 ng when PA was present. The structural specificity for these compounds was high. Twelve phenol analogs of 1 were tested, but only one of these, 2-methoxyphenol, was more attractive than the control. Similarly, the analogs of 2, 2-isopropylpyrazine and 2,6-diisopropylpyrazine, were completely inactive. In the field, a combination of 1, 2, and 3 was not attractive by itself, but it strongly synergized attraction to fermentation volatiles, Carpophilus pheromones, or both. Compounds 1, 2, and 3 apparently have a microbial origin because all three were detected when the host fruit was pineapples instead of oranges, because they could occur in the absence of beetles, and because autoclaved pineapple began to produce the compounds after inoculation from an attractive piece of fruit. The study demonstrated that host location for this generalist species can be far more complex than responding simply to the bouquet of low-molecular-weight volatiles normally associated with fermentation.

Seasonal variations in the encapsulation of eggs of the encyrtid parasitoid Metaphycus stanleyi by the pyriform scale, Protopulvinaria pyriformis

Encapsulation of eggs of the introduced parasitoid Metaphycus stanleyi Compere (Hymenoptera: Encyrtidae) by the pyriform scale, Protopulvinaria pyriformis (Cockerel!) (Homoptera: Coccidae) under both greenhouse and field conditions, at Bet Dagan, was found to occur almost all year round (1986–1988). However, encapsulation rates varied considerably during the different seasons and were correlated with the ambient temperatures. The rates of efficient encapsulation (i) in scales infesting Hedera helix and Schefflera arboricola under greenhouse conditions, were lowest during December to May (6–17%) and highest during July to September (78–100%); (ii) in scales infesting avocado in the orchard, were lowest during October to May (0–11%) and highest during June to August (54–57%). Under greenhouse conditions, encapsulation rates did not differ in scales grown on H. helix and on S. arboricola, but were significantly lower in scales grown on avocado. Encapsulation by scales infesting S. arboricola was more frequent at temperatures ranging from 20–28 °C, than from 7–23 °C.

Encapsulation of parasitoid eggs in soft scales (Homoptera: Coccidae)*

Abstract. 1. The Mediterranean black scale Saissetia oleae (Olivier) was the most suitable host for the imported Metaphycus aff. stanleyi Compere and Metaphycus helvolus (Compere) and for the local Metaphycus flavus (Howard).

Colonization trials with Cryptochetum iceryae and Rodolia iceryae for improved biological control of Icerya purchasi in Israel.

Abstract Colonization of additional natural enemies of Icerya purchasi Maskell (Homoptera: Margarodidae) in Israel was considered because of the frequent outbreaks of the scale during the 1980s and the chronic severe injuries to certain ornamental plants whose toxic effects through the scale reduce the effectiveness of Rodolia cardinalis Mulsant (Coleoptera: Coccinellidae). Colonization trials were conducted with the parasitic fly Cryptochetum iceryae Williston (Diptera: Cryptochetidae) collected in southern California and with Rodolia iceryae Jenson sent from South Africa. Rearing experiments of both natural enemies were conducted using I. purchasi and I. aegyptiaca (Douglas) infesting different plant species. C. iceryae developed on I. purchasi growing on 17 host plant species. I. aegyptiaca was not affected by the fly. R. iceryae could not complete its development on either I. purchasi or I. aegyptiaca. C. iceryae was released at nine sites planted with Erythrina corallodendrum, Spartium junceum, or Retama raetam infested with I. purchasi. In citrus groves, after 2 years and following several releases, it is still uncertain whether C. iceryae has become established. C. iceryae was acclimatized at all sites planted with E. corallodendrum, S. junceum, and R. raetam and suppression of the scale was achieved in 2 years, probably because of the lack of significant competition with Rodolia cardinalis. I. purchasi populations were very sparse in the sampled citrus groves. Only in one site did we observe a rapid switch from the latent epidemic phase. This outbreak resulted in serious damage to the trees and was followed by a rapid breakdown of the scale population due to a sharp increase in the R. cardinalis population.

FURTHER STUDIES OF THE ENCAPSULATION OF METAPHYCUS SWIRSKII BY SOFT SCALES

Encapsulation of eggs of the encyrtid parasite Metaphycus swirskii Annecke & Mynhardt (= M. aff. stanleyi Compere) (Hymenoptera: Encyrtidae) in the Mediterranean black scale Saissetia oleae (Olivier), was more frequent in the rubber stage of the host than in the young female. Encapsulation frequency in young females did not differ at 24° or at 28°, but increased considerably at 32°. In the rubber stage of S. oleae. the % scales wherein encapsulation completely prevented parasite development increased from 20.5 at 24° to 96.7 at 32°. Intentionally weakened Coccus hesperidum L., as opposed to healthy hosts, allowed the development of M. swirskii due to a reduction in the hosts encapsulation capacity and, as a result, the mass rearing of the parasite on such a host was made possible. Egg encapsulation in the weakened C. hesperidum was more frequent in mature scales than in younger stages of the host. None of the eggs of M. swirskii, deposited in Coccophagus − parasitized C. hesperidum, became encapsulated.

Encapsulation of eggs of the encyrtid wasp, Metaphycus swirskii, by the hemispherical scale, Saissetia coffeae: Effects of host age and rearing temperature

The combined effects of host age and rearing temperature upon the encapsulation of eggs of Metaphycus swirskii Annecke & Mynhardt (Hymenoptera: Encyrtidae) by the hemispherical scale, Saissetia coffeae (Walker) (Homoptera: Coccidae), were determined. Encapsulation incidence at 16, 20, 24 and 28 °C increased with the age of the host, being 5.5–19.6% in 3rd instar nymphs, 45.4–74.2% in young female scales and 88.8–100% in preovipositing female scales. Within each host physiological age range, encapsulation frequency was not materially influenced by most of the temperatures. At 32 °C, regardless of host age, S. coffeae encapsulated 99.5 to 100% of parasitoid eggs. Complete immunity to successful parasitism by M. swirskii occurred at 20, 24, 28 and 32 °C in preovipositing female scales and at 32 °C in 3rd‐instar nymphs and young female scales of S. coffeae.

Effect of Buprofezin onIcerya Purchasi andPlanococcus Citri

The effectiveness of buprofezin (aqueous suspensions from 25% wettable powder) on cumulative nymph mortality and reproduction of two homopterous pests,Icerya purchasi Maskell (Margarodidae) andPlanococcus citri (Risso) (Pseudococcidae), was investigated under laboratory conditions. Buprofezin was very effective against crawlers of both species. Dipping in concentrations of 0.002%, 0.01% and 0.05% (a. i.) resulted in 91–99% nymph mortality ofP. citri, whereas 100% mortality was recorded whenI. purchasi was treated at 0.05% (a. i.); the 3rd-instar nymphs ofI. purchasi were less susceptible to the chemical. Death of the larval stages occurred mainly during the molting process to the 2nd-instar nymphs. At 0.05%, buprofezin sprayed on adults slightly reduced fecundity and decreased egg hatch to 31% forI. purchasi and, depending on the exposure period of the females, to 49-7% forP. citri. Buprofezin at 0.05% exhibited strong ovicidal activity onP. citri, resulting in inhibition of over 80% egg hatch.

The hymenopterous parasites of Nitidulidae

The known information on hymenopterous parasites of Nitidulidae was consolidated in this article. Species of parasites, nitidulid hosts and, where possible, plant host of the nitidulids are provided along with citations to sources of information. Thirty-three species of hymenopterous parasites are recorded in nine different families. Since nomenclature of several of the parasites has changed, it was updated with the assistance of specialists.