Biology and host preferences of Cryptorhynchus melastomae (Coleoptera: Curculionidae), a possible biocontrol agent for Miconia calvescens (Melastomataceae) in Hawaii

The introduced plant Miconia calvescens (Melastomataceae) poses a grave threat to Hawaii's native ecosystems and biodiversity. One potential candidate for classical biological control is Cryptorhynchus melastomae (Coleoptera: Curculionidae: Cryptorhynchinae), a stem-boring weevil from Central and South America. This weevil feeds on M. calvescens in its native Costa Rica and has been successfully reared under greenhouse conditions. Comparison of its environmental conditions in Costa Rica with those in the Miconia infested areas of Hawaii indicates the latter is a suitable habitat for C. melastomae. C. melastomae has one or two generations per year. Adults feed on new stems, petioles, leaf buds, veins, and lamina, whereas larvae mine the stem until pupation. Adults appear to prefer saplings for oviposition and feeding. Under greenhouse conditions both adults and larvae can seriously damage and kill small M. calvescens. Preliminary host testing indicates that C. melastomae may be family specific on Melastomataceae. However, because Hawaii lacks native melastomes and has many other serious melastome weeds, a family specific insect may be suitable as a biocontrol agent in this case.     

Pseudomonas protegens CS1 from the lemon phyllosphere as a candidate for citrus canker biocontrol agent

• Citrus canker is a worldwide‐distributed disease caused by Xanthomonas citri subsp. citri. One of the most used strategies to control the disease is centred on copper‐based compounds that cause environmental problems. Therefore, it is of interest to develop new strategies to manage the disease. Previously, we reported the ability of the siderophore pyochelin, produced by the opportunistic human pathogen Pseudomonas aeruginosa, to inhibit in vitro several bacterial species, including X. citri subsp. citri. The action mechanism, addressed with the model bacterium Escherichia coli, was connected to the generation of reactive oxygen species (ROS). This work aimed to find a non‐pathogenic strain from the lemon phyllosphere that would produce pyochelin and therefore serve in canker biocontrol.
• An isolate that retained its capacity to colonise the lemon phyllosphere and inhibit X. citri subsp. citri was selected and characterised as Pseudomonas protegens CS1. From a liquid culture of this strain, the active compound was purified and identified as the pyochelin enantiomer, enantio‐pyochelin.
• Using the producing strain and the pure compound, both in vitro and in vivo, we determined that the action mechanism of X. citri subsp. citri inhibition also involved the generation of ROS. Finally, the potential application of P. protegens CS1 was evaluated by spraying the bacterium in a model that mimics the natural X. citri subsp. citri infection.
• The ability of P. protegens CS1 to reduce canker formation makes this strain an interesting candidate as a biocontrol agent.

     

The biology of the predatory miteHypoaspis miles (Acari: Laelapidae), a potential biological control agent ofBradysia paupera (Dipt.: Sciaridae)

The following aspects ofHypoaspis miles' biology were investigated; development rate of egg to adult at different temperatures, fecundity, longevity and rate of predation on sciarids. With an increase in temperature the time taken for development decreased from 33.7 days at 15°C to 9.2 days at 28°C. The threshold temperature forH. miles to complete its life cycle was between 10° and 12°C. When fed onAcarus siro, H. miles laid 2–3 eggs a day and unfertilized eggs only developed into males. Adults ofH. miles (0–1 day old) survived for 24.0±1.4 days without food and if fed for 6 days and then starved, females lived for 65.4±2.6 days which was significantly longer than males (45.2±3.0 days). With food, 60% of males and females survived for 142 days. All larval instars of sciarids were attacked byH. miles although the numbers consumed were dependent on the size of the larvae. Egg predation was negligible and pupae were not attacked. In productivity studies ofH. miles in culture (fed onA. siro), the time taken for the mites to reach a density of 45–65,000/litre ranged from 76 to 23 days at 15° and 28°C respectively.

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Résumé Différents aspects de la biologied'Hypoaspis miles sont examinés: vitesse de développement de l'oeuf à l'adulte à différentes températures, fécondité, longévité et voracité sur les sciarides. Avec une augmentation de la température, la durée du développement passe de 33,7 jours à 15°C à 9,2 jours à 28°C. La température minimale qui permet le développement complet deH. miles est située entre 10 et 12°C. Quand il est nourri d'"itAcarus siro, H. miles pond 2 à 3 oeufs par jour et seuls les oeufs non fécondés donnent des males. Les adultes deH. miles (agés de 0 à 1 jour) survivent pendant 24±1,4 jours sans nourriture et si elles sont nourries pendant 6 jours puis privées de nourriture, les femelles vivent 65,4±2,6 jours, ce qui est significativement plus long que les males (45,2±3 jours). Avec de la nourriture, 60% des males et des femelles vivent pendant 142 jours. Toutes les larves de sciarides sont attaquées parH. miles, mais le nombre de proies consommées dépend de la taille des larves. La prédation des oeufs est négligeable et les pupes ne sont pas attaquées. Dans des études sur la productivité deH. miles en élevage (nourri deA. siro), la durée nécessaire aux acariens pour atteindre une densité de 45–65 000/1 est de 76 et 23 jours à 15°C et 28°C respectivement.

     

Population dynamics of Spalgis epius (Lepidoptera: Lycaenidae), a candidate biocontrol agent of mealybugs and its interaction with mealybug-attendant ants

Spalgis epius is an economically important hemipterophagous butterfly. Detailed information on the population dynamics, natural enemies, and prey range of S. epius and its association with mealybug-attendant ant species is lacking. Three years of field studies conducted at Bangalore University campus, Bengaluru, India on these aspects indicated that the population density of S. epius was greatest from June to December and least from February to May in the low land region. S. epius survived on eight prey species, which were present in different months, of which Phenacoccus indicus was recorded as a prey of S. epius for the first time. Different prey species occurred on 12 species of host plants. The occurrence of S. epius was negatively correlated with temperature and positively correlated with relative humidity and prey populations. Six mealybug-attendant ant species were associated with the larvae of S. epius. The seven general predators of S. epius adults were recorded. Knowledge on the population dynamics and a prey range of S. epius and its interaction with mealybug-attendant ant species could be helpful to using this predator as a major biocontrol agent of various species of mealybugs. This study contributed to our understanding of the population dynamics of a hemipterophagous butterfly.     

Field biology and control of Phytophthora parasitica on papaya (Carica papaya) in Hawaii

Epidemic attacks of Phytophthora parasitica on papaya fruits developed during wet, windy weather, but declined rapidly when the weather became dry. During rain, abundant sporangia were liberated from the mycelial mats on infected fruits, but none was trapped in dry air. Collar rots and tree collapse caused by root rot occur irrespective of spray treatments and previous aerial infections on the same tree: they are no more prevalent in blocks with abundant aerial infections than in blocks with none. Basal rots occurred earlier and more frequently on plantings near abandoned diseased fields: they were scattered randomly and appeared before aerial infections. It is suggested that new outbreaks might be initiated from seeds of infected fruit, in which chlamydospores have been found, or from infected nursery seedlings. Drosophila spp. were found to be occasional vectors of sporangia. Control of aerial infections was obtained with maneb, basic copper sulphate, captan or difolatan. Spraying only the upper half of the acropetally developing fruit cluster gave much better control than spraying only the lower fruits.     

The biology of Chrysopidae and Hemerobiidae (Neuroptera), with reference to their usage as biocontrol agents: a review

• 1 Many regions have well-developed faunas of Chrysopidae and Hemerobiidae, many of which are potential control agents, but only a few widely distributed species have been seriously considered as such.
• 2 Most of the biological information available concerns Chrysopa species in north temperate areas. C.carnea Stephens, in particular, has been utilised in many pest control programmes. Prepupal or adult diapause constitutes a well-defined stage in the life cycles of many temperate species.
• 3 Larval searching behaviour is efficient, and larvae of most species studied can utilise a wide range of prey organisms or sugar-based foods. The quality of the larval food can affect reproduction of the ensuing adults. Cannibalism is frequent, and may serve as the main food supply when other sources are scarce. Artificial diets for mass rearing are outlined.
• 4 Adult Hemerobiidae are predators. Adult Chrysopidae are either predators or honey-dew feeders, the latter possessing symbiotic yeasts which aid amino acid synthesis. Sprays based on sugar and yeast hydrolysates can be applied in the field as (i) attractants and (ii) alternative or additional food.
• 5 A wide range of predators and hymenopterous parasites attack all stages. Many widespread and non-specific parasites may attack lacewings introduced from other areas.
• 6 Potential use of Chrysopidae and Hemerobiidae in integrated control is enhanced by their tolerance to some insecticides.
• 7 Lacewings are potential control agents of pests in greenhouse, field crops, and orchards. Native species should be augmented rather than others introduced. It would probably be wise to encourage only one or few lacewing species against any given pest.

     

Effect of temperature on the susceptibility of Culiseta longiareolata (Macquart) (Dipt., Culicidae) to two standard strains of biocontrol bacteria

The susceptibility of fourth instar larvae of Culiseta longiareolata (Macq.) to two standard strains of biocontrol bacteria was investigated under laboratory conditions. Larvae were found to be more susceptible to Bacillus sphaericus (Bs-IPS88) than to Bacillus thuringiensis H14 (Bti-IPS82) at 25 ± 1°C at concentrations ranging from 0.003 to 0.004 ppm at 2 and 3 days post-treatment. Statistical regression analysis revealed a significant mortality–concentration relationship for the two bacteria. Larval mortality increased significantly as temperature increased from 20 ± 1°C to 28 ± 1°C.     

Field trial of an attractant mixture for dipterous, including the pest Ceratitis capitata (Wiedemann) (Dipt., Tephritidae), in Valencia, Spain

In field trials of tentative lures for female Ceratitis capitata , made in two areas of Valencia (Spain), it was observed that a mixture, not previously described, of ethyl acetate, acetic acid and ethanol attracted dipterous of different species, some of them being pests of economic importance (including C. capitata ). This mixture appears to be Diptera specific, and suitable for the monitoring or control of the identified species. Coboldia fuscipes Meigen, Drosophila funebris F. and Megaselia sp. are the most attracted.     

Parasitoids of Apiomyia bergenstammi (Wachtl) (Dipt., Cecidomyiidae), a new pest on pears, in Hatay province, Turkey

Abstract:  Studies were carried out on the galls formed by Apiomyia bergenstammi (Wa.) on buds and/or twigs of pear trees, in Yayladagi, Senköy, and Belen, Hatay province, Turkey in 2003. The pest was introduced into Hatay province at least 5 years ago. It produces one generation a year and hibernates as larvae in the galls. In Yayladagi, Senköy and Belen, 20, 18 and 5%, respectively, of buds/twigs of pear trees were attacked by A. bergenstammi . Each of the galls contained on average 9.6 ± 0.5 (range: 6–11) larval chambers. Adults were reared from galls collected at the beginning of spring, viz. A. bergenstammi emerged in the first half of April 2003, Oxyglypta rugosa Ruschka (Hym., Pteromalidae) and Torymus apiomyiae Boucek & Mihajlovic (Hym., Torymidae) (a new record for Turkey) emerged in the second half of April. Other chambers contained unemerged adults of Platygaster sp. (Hym., Platygasteridae). Natural parasitism rates obtained by dissecting 10 galls from Yayladagi and Senkoy in 2003 were: 26.6 ± 4.4% by O. rugosa and 10.0 ± 3.2% by Platygaster sp. The parasitism rate by T. apiomyiae was 16.6% as determined from the galls collected from Belen.     

Field evaluation of Medfly (Dipt., Tephritidae) female attractants in a Mediterranean agrosystem (Balearic Islands, Spain)

Field evaluation of female-targeted trapping systems for the Mediterranean fruit fly Ceratitis capitata (Wied.) was carried out in a Citrus orchard in Majorca (Spain). Traps and lures included: IPMT and Tephri traps, both baited with a three-component food-based synthetic attractant 3FA (composed of putrescine, ammonium acetate and Trimethylamine) as well as IPMT-baited with Nu-Lure, and Delta traps baited with Trimedlure. The 3FA food-based synthetic attractant was set up either wet (containing water) or dry (without water) in IPMT and Tephri traps. Two experiments were conducted, the first during autumn/winter conditions and high Medfly population levels, and the second during spring conditions and low population levels. The results obtained show that the 3FA was very effective at capturing females at high and low population levels. In the first experiment the best performance was shown by the Tephri trap baited with 3FA in combination with water, and in the second the best was also the Tephri trap but with dry treatment. The high number of non-targeted insects captured by the first treatment together with servicing difficulties would indicate that the 3FA/dry-baited Tephri trap is the best choice in the area of the study. On the other hand the 3FA captured a percentage of mated females equivalent to those obtained with Nu-Lure. The Trimedlure proved to be an adequate tool to detect the earliest Medfly males in increasing spring population. The implications and advantages of using the 3FA female attractants in sterile insect technique programmes and mass trapping approaches, are discussed.     

Biology and host preference of the planthopper Taosa longula (Hemiptera: Dictyopharidae), a candidate for biocontrol of water hyacinth

Taosa longula Remes Lenicov (Hemiptera: Dictyopharidae) is a planthopper from the South American tropics that feeds on water hyacinth, Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae). The biology of T. longula was studied in the laboratory and field to evaluate it as a potential biological control agent for this widespread aquatic weed. The developmental time of nymphs was recorded at different temperatures (15, 19, 23, 25, 27 and 30 °C), and developmental threshold temperatures were obtained for the different instars. The host range was evaluated in terms of development and feeding preference. Development from instar I to adult was recorded in two no-choice trials, one with cut leaves of Pontederiaceae, and a second with growing whole plants. In the cut-leaf tests, adults were obtained from Pontederia cordata var. cordata, P. rotundifolia and water hyacinth. In the whole plant test, T. longula adults were obtained only from water hyacinth. Feeding preference was evaluated by means of a paired-choice test with 10 T. longula first instars on whole plants of P. c. cordata, P. rotundifolia and water hyacinth. The number of insects that fed on water hyacinth was significantly higher than on P. c. cordata and P. rotundifolia. Taosa longula showed a clear preference for water hyacinth and exhibited warm climate requirements, making it an attractive candidate for water hyacinth biological control in tropical and subtropical areas.     

Multicellular behaviour and production of a wide variety of toxic substances support usage of Bacillus subtilis as a powerful biocontrol agent

Intensive cultivation of plants in the monoculture field system in order to feed the continuously growing human population creates a need for their protection from the variety of natural competitors such as: bacteria, fungi, insects as well as other plants. The increase in the use of chemical substances in the 20th century has brought many effective solutions for the agriculture. However, it was extremely difficult to obtain a substance, which would be directed solely against a specific plant pathogen and would not be harmful for the environment. In the late 1900's scientists began trying to use natural antagonisms between resident soil organism to protect plants. This phenomenon was named biocontrol. Biological control of plants by microorganisms is a very promising alternative to an extended use of pesticides, which are often expensive and accumulate in plants or soil, having adverse effects on humans. Nonpathogenic soil bacteria living in association with roots of higher plants enhance their adaptive potential and, moreover, they can be beneficial for their growth. Here, we present the current status of the use of Bacillus subtilis in biocontrol. This prevalent inhabitant of soil is widely recognized as a powerful biocontrol agent. Naturally present in the immediate vicinity of plant roots, B. subtilis is able to maintain stable contact with higher plants and promote their growth. In addition, due to its broad host range, its ability to form endospores and produce different biologically active compounds with a broad spectrum of activity, B. subtilis as well as other Bacilli are potentially useful as biocontrol agents.     

Polymorphic adaptive insecticidal resistance in Rhynocoris marginatus (Fabr.) (Het., Reduviidae) a non-target biocontrol agent

Rhynocoris marginatus (Fabr.) is a polymorphic reduviid predator inhabitating tropical rainforests, semi-arid zones, scrub jungles and agro-ecosystems and predates upon insect pests. It exists in three different morphs; (1) with black connexivum (niger); (2) with red connexivum (sanguineous); and (3) with black and red banded connexivum (nigrosanguineous). Insecticides used to manage insect pests affect non-target biocontrol agents such as R. marginatus . Hence laboratory experiments were conducted to evaluate the adaptive polymorphic resistance of the morphs of R. marginatus to the toxic effects of three insecticides, namely, dimethoate, methylparathion and quinalphos, with each in five concentrations. The 50% lethal concentration (LC₅₀) values clearly indicated that methylparathion was the most toxic insecticide followed by quinalphos and endosulfan to all three morphs. Among the three morphs, the niger was the most resistant and the sanguineous was the most sensitive.     

Silba capsicarum (Diptera: Lonchaeidae), a newly recognized pest of chilli pepper in Java

The lonchaeid fly Silba capsicarum is recorded for the first time from the island of Java where it is considered a potential pest of chilli pepper. The taxonomy and ecology of the species is reviewed and comparisons are drawn with Lonchaeidae attacking Capsicum spp. in the Neotropics. Initial results on the level of infestation in Java are provided.     

Seasonal biology and abundance of Psyllaephagus pistaciae,a biocontrol agent of the common pistachio psylla Agonoscena pistaciae

The solitary endoparasitoid Psyllaephagus pistaciae Ferrière (Hymenoptera: Encyrtidae), is the most widely distributed biological control agent of the common pistachio psyllid, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psylloidea), in Iran. The pupation and overwintering sites of diapausing parasitoids and the psyllid were studied for 2 years using emergence traps in pistachio orchards in Rafsanjan, Iran. The psyllid mummies containing the overwintering parasitoid adhered to pistachio leaves and were carried on these leaves away from the tree when they latter senesced. The present results verified that plant litter which included dried grasses and old pistachio leaves tended to support a greater population of adult winter-form psyllid and psyllid mummies during the winter through early spring than other options examined. Adult parasitoids appeared in the field in early April, about 30 days after the emergence of adult psyllids, but almost at the same time as the hatching of the first generation psyllid nymphs in early April. Rates of parasitism of CPP were generally low throughout most of the year, ranging from 1 to 5%, but rose in late autumn to about 11%. Results suggest that the density of P. pistaciae is not great enough to keep pace with the psyllid populations in these orchards. They explain why growers consider it necessary to apply pesticides for this pest. However, this parasitoid undoubtedly does play an important role in the natural control of A. pistaciae late in the growing season, particularly in non-sprayed orchards. Conservation of these natural enemies should be one of the objectives in the development of sustainable pest management programs.