Publisher Summary Salivary function is especially interesting in Hemiptera because of the effects the saliva has on the living and surviving organisms, on which many of these insects feed. The saliva of Hemiptera is by no means a simple secretion—in addition to the usual salivary functions of moistening food and mixing it with hydrolytic enzymes before ingestion, the saliva of phytophagous species plays an important physiochemical role during the mechanical penetration of plant tissues by the piercing and sucking mouthparts; in accomplishing this task, the saliva may vary in its chemical composition and physical consistency from one moment to the next. Moreover, deposits of solidifying components of the saliva of many species persist in the food plants, modifying the long term effects of feeding by the insects. This chapter compiles the various types of investigation on salivary functions in the Homoptera and Heteroptera, and suggests profitable lines of future investigation based on analogous functions in different taxonomic groups.

The Saliva of Hemiptera

The red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier), a concealed tissue borer, is a lethal pest of palms and is reported to attack 17 palm species worldwide. Although the weevil was first reported on coconut Cocos nucifera from South Asia, during the last two decades it has gained a foothold on date palm Phoenix dactylifera in several Middle Eastern countries from where it has moved to Africa and Europe, mainly due to the movement of infested planting material. In the Mediterranean region, RPW also severely damages Phoenix canariensis. Currently, the pest is reported in c. 15% of the coconut-growing countries and in nearly 50% of the date palm-growing countries. Infested palms, if not detected early and treated, often die. However, palms in the early stages of attack respond to chemical treatment with insecticide. RPW has been managed in several countries employing an integrated pest management (IPM) strategy including the use of food-baited pheromone traps. Early detection of infestation in the field is important for the success of any RPW-IPM programme. Ideally, movement of planting material from infested plantations within the country and also from one country to another needs to be stopped. Wherever this is not possible, it is essential to implement strict pre- and post-entry quarantine regimes, wherein only pest-free and certified planting material can be transported. The existing pheromone-based IPM programme can be strengthened by intensifying the search for effective natural enemies, coupled with the introduction of resistance in palms to RPW. This article reviews the work done during the last 100 years on various aspects of RPW viz. life history, damage and symptoms of attack, seasonal activity, spatial distribution, host range, IPM and its main components, including trapping adult weevils and chemical control, besides biological control, host plant resistance and male sterile technique.

A review of the issues and management of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Rhynchophoridae) in coconut and date palm during the last one hundred years

Publisher Summary The xylem and phloem tissues of plants represent substantial nutrient resources for biophages. The vascular plants, which parasitize xylem are in many respects nutritionally similar to the shoot of the host. Acquisition of xylem sap, containing the water needed for transpiration and growth and the soil-derived elements needed for growth, involves the parasite in having a more negative water potential than the host. Xylem-feeding insects obtain xylem sap by inserting their stylets into a xylem element and sucking out the sap. The thermodynamic limit on xylem sap extraction corresponds to a tension of 3 MPa. Phloem-feeding insects obtain phloem sap by inserting their stylets into the phloem—the phloem turgor pressure drives sap into the insect's gut. By contrast to xylem-feeding heterotrophs, the phloem-feeders have organic carbon in excess of other dietary requirements, such as nitrogen, in phloem the sap. A problem, which phloem-feeders share with less-specialized phytophages is that the nitrogen/carbon ratio is sub-optimal for their growth—they must ingest an excess of organic carbon to obtain sufficient nitrogen.

Phytophages of Xylem and Phloem: a Comparison of Animal and Plant Sap-feeders

Recent advances in the bio-remediation of persistent organic pollutants and its effect on environment

Because of their selectivity and safety, microbial control agents (MCAs) appear to be ready-made components of integrated pest management (IPM) systems that do not pose a threat to applica- tors or the environment and allow other natural enemies to func- tion. Control of several orchard pest insects using MCAs, including viruses, Bacillus thuringiensis, fungi, and entomopathogenic nema- todes (EPNs), have been demonstrated in apple, pear, stone fruits, citrus, and several nut crops. B. thuringiensis is the most used MCA for control of lepidopteran orchard pests. Significant use of EPNs in citrus for control of root weevils is also reported. The granulovirus of codling moth is used increasingly in apple and pear by organic growers, with interest also shown by conventional growers. Although some success has been achieved, in most orchard systems MCAs ac- count for a relatively small proportion of the pest control tactics employed, and in some systems they are not used at all. Research toward improving MCA efficacy and economic competitiveness is required to enhance the role of MCAs in IPM.

Microbial Control of Insect Pests in Temperate Orchard Systems: Potential for Incorporation into IPM ∗

The incidence of red ring disease was found to be highly correlated with the seasonal abundance of the palm weevil, Rhynchophorus palmarum (L.) Adult insects became contaminated with fragments of diseased tissue containing large numbers of nematodes after visiting diseased palms. The main source of contamination appeared to be the frass in tunnels excavated by the larvae during feeding, but adult weevils also became contaminated by bodily contact with diseased tissue and after walking through suspensions of worms in “pockets” in diseased palms. Internal contamination of the gut and body cavity also occurred following the feeding of insects on infected tissue. Virgin insects were found to be contaminated both externally and internally prior to emergence from their cocoons. The numbers of nematodes picked up by adult weevils was found to vary with the source of contamination, the density, stage, and activity of the worms present, and the age and feeding history of the insect. Longevity of the nematodes on the body surface of the insect varied between 2-6 days and was as long as 10 days in the gut and body cavity. External and internal contamination of the field population was found to be 38.5% and 9.8%, respectively. The incidence of red ring disease was significantly reduced following the application of endrin for palm weevil control.

The Role of the Palm Weevil, Rhynchophorus palmarum, as a Vector of Red Ring Disease of Coconuts. I. Results of Preliminary Investigations

In the laboratory, females deposited 245±155 eggs in an oviposition period of· 30.7±14.3 days, with maximum production of 48 eggs per day in the first 8–10 days of the period; maximum lifetime production was 718 eggs by a single female. The incubation period was 3.2±0.93 days at room temperature (70°–91°F) and humidity (62%–92%). There were 6–10 larval molts (most commonly 9), and the larval period averaged 52.0±10.0 days (as against 43.0±6.0 days for larvae reared in standing palms outdoors). Mature larvae spun cocoons in which they passed a prepupal stage of 4–17 days and a true pupal stage of 8–23 days (average for the two combined, 26.8±4.5 days), and in which the adults remained for 7.8±3.4 days before emerging. Feeding and mating normally began 12–24 hours after emergence, and oviposition commenced 5.6±3.7 days after the first mating; both sexes mated repeatedly and indiscriminately. The entire life cycle required 79.0±9.0 days in laboratory-reared insects, 72.0±13.0 days in insects reared in standing palms. The sex ratio was approximately 1:1, and adult longevity was 44.7±17.2 days for males, 40.7±15.5 days for females. Adults were most active at 5–7 PM and 7–11 AM. Both sexes were strong flyers, averaging about 20 ft per sec in the field, and were capable of rapid dissemination. Their rate of movement on coconut plantations varied from 85 yards to 1 mile in 24 hours, depending on conditions. Larval damage was most extensive in 3- to 7-year-old palms, whose “crowns” often fell over following excavation of the stem tissues by the larvae. Infestation was usually associated with red ring disease, of which the weevils were important vectors. Adult feeding and oviposition was observed in numerous palm species other than Cocos nucifera, as well as in several root and fruit crops.

On the Life History and Habits of the Palm Weevil, Rhynchophorus palmarium

Field surveys for estimating the seasonal abundance of the palm weevil, Rhynchophorus palmarum (L.), have been conducted in the past by field trapping with sections of the stem of 3 to 4-year-old coconut palms, Cocos nucifera L., as the attractant source. This method was laborious, and as a chemical might be used in the control of R. palmarum, several organic compounds were tested as attractants for this insect.

Tests of Attractants for the Palm Weevil

Efficacy of the entomopathogenic nematode Steinernema carpocapsae (Weiser) for the control of plum curculio, Conotrachelus nenuphar (Herbst), on apple was evaluated under laboratory conditions. When 50, 100, 200, or 400 nematodes per plum curculio larva were pipetted in 1 ml of water onto moistened filter paper in petri dishes containing 20 larvae, average larval mortality was 71.8, 80.6, 91.6, and 95.1%, respectively, after 3 d of incubation at 25 degrees C. In a comparison of four strains applied at 50, 100, and 200 nematodes per larva, S. carpocapsae strain All was more effective at the rate of 50 per larva than three other strains, and was equal to the effect of S. feltiae (Filipjev) (= S. bibionis, Biosys strain no. 27) applied at the rate of 100 and 200 per larva. Maximum mortality caused by the Mexican and Kapow strains of S. carpocapsae was only 50.0 and 27.5%, respectively, irrespective of rate. When S. carpocapsae All was sprayed on or mixed with a 5-cm layer of soil at a rate equivalent to 10 X 10(9)/ha, 90.8 and 87.6%, respectively, of the 12-15 plum curculio larvae added were killed after incubation for 3 d at 25 degrees C. Natural sods (25 by 30 by 5 cm) from an orchard floor were sprayed or drenched with S. carpocapsae All at the rate of 10 X 10(9)/ha in 600 ml of water 2 d before 25 plum curculio larvae were added. After 3 d, larval mortality was 73.4%. Reversal of the inoculation sequence by addition of plum curculio first, followed by nematodes, gave similar control (76.4%). In sods treated with nematodes, only four of the 55 nontarget insect larvae and adults contained nematodes; we found no infestation in nontarget insects from untreated sods. When Galleria mellonella (L.) larvae were used as bait, we showed that the sod soil contained naturally occurring entomopathogenic nematodes. These results show plum curculio is highly susceptible to entomopathogenic nematodes in the laboratory.

Laboratory Studies of the Efficacy of Steinemematid Nematodes Against the Plum Curculio (Coleoptera: Curculionidae)

The border parenchma cells were the primary feeding site of adult Aeneolamia varia saccharina (Distant) on sugarcane leaves. On the roots, nymphs were xylem-feeders, although the first and second instars also ingested the contents of parenchyma cells in the cortex of young roots. Cellular damage was extensive in all cases, and occlusion of the xylem elements often occurred following feeding by fourth and fifth instars.

Elmer A. C. Hagley

Papers

The Role of the Palm Weevil, Rhynchophorus palmarum, as a Vector of Red Ring Disease of Coconuts. I. Results of Preliminary Investigations

On the Life History and Habits of the Palm Weevil, Rhynchophorus palmarium

Tests of Attractants for the Palm Weevil

Laboratory Studies of the Efficacy of Steinemematid Nematodes Against the Plum Curculio (Coleoptera: Curculionidae)

Site of Feeding of the Sugarcane Froghopper, Aeneolamia varia saccharina (Homoptera: Cercopidae)