Maintaining <Emphasis Type="Italic">Bactrocera oleae</Emphasis> (Gmelin.) (Diptera: Tephritidae) colony on its natural host in the laboratory

The olive fruit fly, Bactrocera oleae (Gmelin.) (Diptera:Tephritidae) is a pest on olives (Olea europea) in the Mediterranean basin. An olive fruit fly colony was maintained on olives at 24 ± 1°C, 60% RH, and 16:8 h (light:dark) photoperiod with fluorescent lighting. We investigated oviposition behavior, developmental duration and weights of the biological stages, and adult longevity. A single female laid an average of 19 eggs/day and 200–350 eggs in her lifetime. The maximum number of oviposition stings in a single olive was 156.0 ± 5.77, and 28.00 ± 3.62 larvae out of it completed their development, all pupated, and all emergence successfully. Although the development period was similar for larvae and pupae, adult longevity varied. Male and female emergence percentages ranged as 38.7–52.8, and 32–39.9%, respectively. The results are presented in relation to published studies on olive fruit fly rearing.     

Effects of processed kaolin on pests and non-target arthropods in a Spanish olive grove

The particle film technology based on processed kaolin sprays has been recently introduced for the control of the olive fruit fly Bactrocera oleae (Rossi), the key pest of olive groves. A 3-year field experiment was conducted from 2005 to 2007 at Villarejo de Salvanés, Spain to assess the efficacy of a kaolin-based product (Surround WP) for controlling B. oleae and two other olive insect pests: the olive black scale Saissetia oleae (Olivier) and the olive psyllid Euphyllura olivina (Costa). The effects of Surround WP on the arthropod community of olive trees and on natural enemies were also evaluated. In a high olive fruit fly pressure year (2007), Surround WP sprays significantly reduced the incidence of B. oleae and that of S. oleae. However, Surround WP treatments did not have any effect on E. olivina populations. Both the abundance and the diversity of arthropods were reduced by Surround WP treatment. The principal response curve (PRC) analysis revealed a significant deleterious effect of Surround WP on the natural enemy arthropod community of the olive grove. The most affected taxa were the following: the coccinellids Scymnus mediterraneus Iablokoff-Khnzorian, Stethorus punctillum Weise and Hyperaspis reppensis (Hbst.); the mirid Brachynotocoris ferreri n. sp. Baena (in litteris); different species of Orius and the families of Philodromidae, Scelionidae, Pteromalidae, Chrysopidae and Aphelinidae. Processed kaolin is proposed as an alternative to chemical control of the olive fruit fly. However, the effect of processed kaolin treatments on natural enemies should be taken into account in a rational pest control programme.     

The use of ethylene diffusers is comparable to treatments with sprayed ethylene to reduce the damage caused by the olive moth (<Emphasis Type="Italic">Prays oleae</Emphasis> Bern.)

In 2002 and 2003, six field experiments were conducted at three olive groves of southern Spain in order to compare the effects of two types of ethylene treatments (sprayed and diffusers) on the olive losses caused by the olive moth (Prays oleae Bern.) as well as on the activity and effectiveness of oofagous predators. Both treatments showed to be effective to control the pest; in the two years studied the mean reduction in final infestation due to ethylene was of 35% with respect to the controls trees, and none affected negatively the action of natural predators of P. oleae. In addition, the use of diffusers set on the trees at the end of flowering period will help the farmers to overcome the problems of determination of optimum time for sprayed treatments of ethylene.     

Identification of predator–prey relationships between coccinellids and <Emphasis Type="Italic">Saissetia oleae</Emphasis> (Hemiptera: Coccidae), in olive groves,using an enzyme-linked immunosorbent assay

A polyclonal antiserum (AS) was developed and characterized for the detection of immature stages of the black-scale, Saissetia oleae, in whole body homogenized field-collected coccinellid species, using an indirect enzyme-linked immunosorbent assay (ELISA). The indirect ELISA showed to be sensitive to the S. oleae AS, detecting a protein content between 0.118 and 0.0374 μg mL⁻¹. The specificity of the ELISA was tested by assaying a range of sympatric predators and alternative preys with the S. oleae AS. Coccinellid larvae obtained the highest cross-reaction and a positive–negative threshold was established at 0.674 μg mL⁻¹ protein. A total of 1,322 coccinellids were field-collected in three olive groves located in Trás-os-Montes (northeast of Portugal) by the beating technique and were analyzed to detect S. oleae proteins in their guts. Field-collected coccinellids which attained a S. oleae protein concentration equivalent higher than the threshold were considered as a positive reaction. In the overall collected coccinellids, 21.2% reacted positively with the S. oleae AS. Chilocorus bipustulatus and coccinellid larvae obtained the highest percentages of positives with 43.4 and 40.8%, respectively. The greatest frequency of positive responses occurred at the beginning of July, mid-August, and mid-October coinciding with the occurrence of the first, second and third instar nymphs of S. oleae, respectively. Thus, in this study, the role of coccinellids as natural control agents of S. oleae was highlighted by the number of individuals and species that tested positive for S. oleae AS.     

Effects of cereal cover crops on the main insect pests in Spanish olive orchards

In olive orchards, which are very common in the Mediterranean region, cover crops are becoming increasingly used to counter problems of erosion. Although such plant covers can provide food and shelter for beneficial insects, mites, and spiders, they may also attract pests. In order to determine their relationships with the main pests in olive orchards, an analysis was made of adult population levels and damage caused in five olive-cultivation zones, in olive orchards with cereal-crop covers and in olive orchards with conventional tillage. The effects of the cereal cover crops on insect pest populations were different and in some cases in opposite direction. Thus cereal cover crops had no impact on the different studied pests, including all those that spend part of their development cycle in the soil, such as Bactrocera oleae, Prays oleae, or Otiorrhynchus cribicollis. However, under certain conditions some pests did show an increase in abundance. Diverse trophic relationships should be investigated in this agroecosystem in future studies in order to develop appropriate crop-management policies.     

For sex and more: attraction of the tephritid parasitoid Psyttalia concolor (Hymenoptera: Braconidae) to male sex pheromone of the olive fruit fly,Bactrocera oleae

The braconid parasitoid Psyttalia concolor foraging for larvae of Bactrocera oleae (Diptera: Tephritidae) uses olfactory cues from the larval microhabitat. However, it could rely on the sex pheromones of adults of its host, since B. oleae mating leks usually occur on olive plants and a high number of infested fruits can be easily located in their close proximity. We quantified the behavioural responses of P. concolor towards different doses of the two major sex pheromone components of B. oleae, the female-borne 1,7-dioxaspiro[5.5]undecane (DSU) and the male-borne (Z)-9-tricosene (ZT). Results showed that P. concolor females and males were attracted only to the highest amounts of ZT (10 B. oleae male equivalents), regardless of the mating status. Wasps remained longer on the surfaces treated with high ZT amounts over the control. P. concolor females could exploit the ZT produced by lekking olive fruit fly males as a foraging kairomone. This could allow them to rapidly track B. oleae-infested olive plants, thus raising their chances to locate host larvae during their lifespan. On the other hand, the perception of ZT by P. concolor males could raise their chances to locate receptive females emerging from parasitised B. oleae pupae or also ovipositing in olive fruits. This study increases the knowledge of the reproductive biology of P. concolor, highlighting a case of chemical espionage in which a sex pheromone component from adult stages of the host is exploited both as a foraging kairomone by female parasitoids and as a sexual kairomone by male wasps.     

Using degree-day accumulations and host phenology for predicting larval emergence patterns of the olive psyllid, <Emphasis Type="Italic">Euphyllura phillyreae</Emphasis>

The olive psyllid, Euphyllura phillyreae Foerster is one of the most destructive pests on buds and flowers of olive tree (Olea europaea L.) in May when the olive growers cannot apply any insecticides against the pest. Temperature-dependent development of the psyllid was studied at constant temperatures ranged 16–26°C. A degree-day (DD) model was developed to predict the larval emergence using the weekly cumulative larval counts and daily mean temperatures. Linear regression analysis estimated a lower developmental threshold of 4.1 and 4.3°C and a thermal constant of 164.17 and 466.13 DD for development of egg and larva, respectively. The cumulative larval counts of E. phillyreae approximated by probit transformation were plotted against time, expressed as the sum of DD above 4.3°C, the starting date when the olive tree phenology was the period of flower cluster initiation. A linear model was used to describe the relationship of DDs and probit values of larval emergence patterns of E. phillyreae and predicted that 10, 50 and 95% emergence of the larvae required 235.81, 360.22 and 519.93 DD, respectively, with errors of 1–3 days compared to observed values. Based on biofix depends the development of olive tree phenology; the DD model can be used as a forecasting method for proper timing of insecticide applications against E. phillyreae larvae in olive groves.     

Effective accumulated temperature and developmental threshold temperature for Semanotus bifasciatus （Motschulsky） in Beijing

In order to understand the occurrence and development of Semanotus bifasciatus （Motschulsky）, a borer insect of Platycladus orientalis in parts of northern and eastern China and to improve its prediction, the developmental threshold temperature （C1） and effective accumulated temperature （K） of S. bifasciatus were determined under conditions of constant and variable temperatures. The results show that under constant temperatures the value of C1 has a range of 8.90±1.77℃and the value of K lies between 95.19±13.14 degree-day for eggs; the values for larvae are C1= 13.26±3.06℃ and the number of degree-day is K 2,885.07±187.87 degree-day; for pupae the ranges are C1 = 8.93±2.49℃ and K= 131.20±25.63 degree-day. Under the condition of ambient temperatures, the values for eggs are C1= 17.33±1.24℃ and K= 70.79±8.99 degree-day. It is suggested that S. bifasciatus adults over-winter in a state of dormancy, not at a diapause. Warm winter may accelerate the life cycle ofS. bifasciatus. Equations can be used to predict an early occurrence ofS. bifasciatus.     

Are wild flowers and insect honeydews potential food resources for adults of the olive moth, <Emphasis Type="Italic">Prays oleae</Emphasis>?

The use of non-crop resources by natural enemies and their potentialities to enhance their effectiveness as pest control agents is increasing as a method for conservation biological control. Nevertheless, the effect of consumption of non-crop resources by pests has been generally overlooked being this knowledge crucial to favor natural enemies but not pests. In the present work, insect honeydews and flowers suitability as food resources for the olive tree key-pest Prays oleae were analyzed under laboratory conditions. The selected honeydews were excreted by Saissetia oleae and Euphyllura olivina, two olive pests, and the selected plants were seven abundant species in the olive grove agroecosystem that bloom simultaneously with the flight period of the anthophagous generation of P. oleae. In this work, some of these resources were identified as potential food sources for P. oleae. Despite the general findings, which indicate that honeydews have less nutritional value for insects than nectar, P. oleae reached the best survival and reproduction performance with the insects’ honeydews. Several of the tested flowers were identified as potential food resources for P. oleae, being Malva sylvestris the one that originated the best performance. Moreover, our results suggest that P. oleae females are synovigenic and emerge with nutritional reserves for reproduction. We highly recommend accomplishing further research before establishing these resources in biological control methods in order to confirm their effect on pests in fields.     

Development and population growth of <Emphasis Type="Italic">Stephanitis pyri</Emphasis> (F.) (Heteroptera: Tingidae) at five temperatures

Pear lace bug, Stephanitis pyri (F.) (Heteroptera: Tingidae) is a pest of apple and pear trees and ornamental Rosaceae plants in Mediterranean countries and palearctic region. The aim of this study is to determine the effects of temperatures on S. pyri in the laboratory. Development and fecundity of S. pyri reared on apple leaves (Pyrus malus L.) were investigated at five constant temperatures (20, 23, 26, 29 and 32 ± 1°C) and a 16L:8D photoperiod. Longevity was determined to be 12.6 days at 32°C and 58.7 days at 20°C for females, and 9.7 and 37.7 days for males. Females laid 186.9 eggs per female with the highest number achieved during 28.5 days of oviposition period at 26°C. Female lifetime fecundity was reduced at 32°C (40.0 eggs per female). While the net reproductive rate (R ₀) was highest at 26°C, the intrinsic rate of natural increase (r _m ) was highest at both 26 and 32°C. The mean generation time (G) was estimated to be 27.2–78.4 days at 20 and 32°C, respectively. The longest development times for egg and total nymph stages were obtained as 22.0 and 24.9 days, respectively, at 20°C. S. pyri developed fastest from egg to egg in 24.3 days at 32°C. The lower developmental threshold (T ₀) was 9.7°C and the thermal constant (K) was 517.3 degree-days for S. pyri. Thus, S. pyri is calculated to have 3.8 theoretical generations in Tekirdag. The optimum developmental temperature for S. pyri was 26°C.     

Threshold temperatures and degree-day estimates for development of post-dormancy larvae of <Emphasis Type="Italic">Monochamus galloprovincialis</Emphasis> (Coleoptera: Cerambycidae)

Developmental thresholds and thermal requirements for development of post-dormancy larvae of Monochamus galloprovincialis (Olivier) (Cerambycidae; Monochamini) were studied at ten constant temperatures ranging from 7 to 35°C. The relationship between temperature and development duration in days was linear between 15 and 30°C (r ²  = 0.98). The lower threshold for development was determined to be 12.2 ± 0.8°C and an average of 822 degree-days (DD) above that value was required for 50% adult emergence under laboratory conditions. The rate of larval development decreased above 30°C and the lethal upper threshold was between 32 and 35°C. Degree-day rate summation was initiated in the first of March and model predictions were validated with records of field emergence for the years 2001 to 2004. The modified sine wave predicted median emergence with an average error of 3.8 days from emergences in the field and a zero-day difference for two of the years. Model predictions were always within 10% of actual observed emergences. Predictions for early emergences (cumulative percentiles 1 and 10) were less accurate than predictions for median and late emergencies. The results suggest that a simple linear method driven by air temperatures can predict the emergence of M. galloprovincialis with sufficient accuracy to improve the pest management programmes currently implemented on the pine wilt disease affected zone in Portugal.     

Insecticidal properties of <Emphasis Type="Italic">Thymus persicus</Emphasis> essential oil against <Emphasis Type="Italic">Tribolium castaneum</Emphasis> and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis>

Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT₅₀) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT₅₀ values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC₅₀ values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.     

Assessing the potential for biological control of potato field pests in Ardabil,Iran: functional responses of <Emphasis Type="Italic">Orius niger</Emphasis> (Wolf.) and <Emphasis Type="Italic">O. minutus</Emphasis> (L.) (Hemiptera: Anthocoridae)

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), and the onion thrips, Thrips tabaci Lind. (Thysanoptera: Thripidae), are significant field pests of potato in the Ardabil region of Iran. Orius niger (Wolf.) and O. minutus (L.) (Hemiptera: Anthocoridae) are locally the predominant natural enemies of these pests. This study compared the functional responses of O. niger and O. minutus to female mites and second instar thrips larvae across a range of prey densities (5, 10, 20, and 40 prey/arena) under controlled conditions of 24 ± 1°C, 50 ± 5% RH and 16:8 h (L:D). The resulting data were appropriately fit to Type II functional response models in four predator–prey interactions, including: (1) O. niger to second instar thrips larvae (a = 0.009 h⁻¹; and T _h = 1.62 h); (2) O. niger to females mites (a = 0.006 h⁻¹ and T _h = 1.28 h); (3) O. minutus to second instar thrips larvae (a = 0.008 h⁻¹ and T _h = 1.93 h) and (4) O. minutus to females mites (a = 0.01 h⁻¹ and T _h = 1.1 h). The number of second instar thrips larvae attacked by O. niger was greater than that by O. minutus (P ≤ 0.01); conversely, the number of females mites attacked by O. minutus was greater than that by O. niger (P ≤ 0.01). These results confirm the potential for both O. niger and O. minutus to make valuable contributions to a biological control program against onion thrips and the two-spotted spider mites infesting potato fields in this region.     

Phytophthora ×alni and Phytophthora lacustris associated with common alder decline in Central Portugal

Since the early 1990s, an emerging disease induced by the highly aggressive oomycete Phytophthora ×alni has caused widespread alder decline across Europe. In parallel, P. lacustris, a recently described species associated with riparian habitats, has been subject of increasing interest. A field survey conducted in 2014 showed high mortality rates in alder stands located in the riparian gallery along two rivers in Central Portugal. The pathogens isolated from necrotic alder stem base during this study were identified as P. ×alni and P. lacustris. This paper is the first to report the occurrence of P. lacustris in Portugal and presents the first finding of P. ×alni affecting mature trees in natural ecosystems located in Central Portugal.     

Mini-cuttings: an effective technique for the propagation of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait.

Pinus pinaster Ait. is one of the main forest tree species planted in Spain, Portugal and France. Due to its high economic relevance, there is considerable interest in developing techniques for vegetative breeding aimed at mass propagation. In this study we present a mini-propagation protocol in order to define an efficient method to propagate families or clones of P. pinaster. We carried out three experiments using mini-cuttings of 3–5 cm in length with the aim of evaluating the effects of temperature (4°C vs. 25°C), plant growth regulator (IBA) and shoot age on rooting ability. Percentage of rooted cuttings and morphological root variables were recorded. The percentage of rooted cuttings per treatment ranged from 68 to 97%. Treatment with IBA significantly influenced the rooting process at 25°C but not at 4°C. The number of apexes, length, area and volume of roots were all positively affected by temperature treatment. Shoot age also had a positive effect on rooting capacity of cuttings, with the cuttings from the youngest shoots (70 days after pruning) having higher rooting percentages, ranging from 84.7 to 98.3%. The use of juvenile material, good environmental conditions and IBA all benefited the rooting of clonal material, resulting in high rooting capacity. This study presents an innovative propagation protocol for P. pinaster that can be used as a tool in breeding programs.     

Preference and performance of <Emphasis Type="Italic">Plutella xylostella</Emphasis> (L.) (Lepidoptera: Plutellidae) on canola cultivars

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important insect pest of canola, Brassica napus L., in Ardabil, Iran. Host plant resistance is an essential component of integrated management of P. xylostella. We investigated the preferences and performance of P. xylostella on nine commercial cultivars of canola, namely Zarfam, RGS003, Adder, Okapi, Opera, Hyola401, Ebonite Option500 and Elite under greenhouse conditions at 23 ± 1°C, 50 ± 5% RH and 14L:10D. In free-choice situation, oviposition was lowest on Opera (23.5) and highest on Zarfam (44.7). In the life table study, fecundity of new generation female moths was lowest on Opera (95.4) and highest on Adder (145.7). Survival from egg to adult was significantly lower on Opera, Option500 and Hyola401 than on other tested cultivars. The intrinsic rate of natural increase (r _m) and population growth rate (λ) were lowest on Opera and highest on Zarfam. The generation time (T) was shortest on Zarfam (17.2 days) and longest on Hyola401 (19.9 days) whereas doubling time (DT) was longest on Opera (3.9 days) and shortest on Zarfam (3.0 days). Our results clearly suggest that Opera was the most resistant host among the tested cultivars and has the potential to be used in the integrated management of P. xylostella.     

Effect of soybean cultivar on life history parameters of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> Koch (Acari: Tetranychidae)

The two-spotted spider mite, Tetranychus urticae Koch, is a very polyphagous pest with a worldwide distribution. In order to appraise population growth parameters of this pest, samples of two-spotted spider mites were taken from soybean (Glycine max) fields of Moghan region, Iran in June 2007 and are reared on bean plants var. Derakhshan (Phaseolus vulgaris) in a growth chamber. The life table parameters of this pest were calculated on three commercial soybean cultivars (Zane, Hach, and L17) and one hybrid (Hob × Will) at 25 ± 1°C, 60 ± 10%RH, and 16 h photophase. The developmental times of immature stages varied from 9.69 on Hach to 9.82 days on L17, whereas the immature survival was 57–79% on Hach and Hob × Will, respectively. On average, there were 65.5, 40.8, 38.8 and 34 eggs produced per female on L17, Hach, Hob × Will and Zane, respectively. The intrinsic rate of natural increase (r _m ) for T. urticae on Hob × Will was the highest, whereas the values for r _m ranged from 0.211 (females/female/day) on Zane to 0.292 on Hob × Will. Also, jackknife values of other life table parameters such as net reproductive rate (R ₀), generation times (T), doubling time (DT), and finite rate of increase (λ) on these cultivars were estimated. Overall, the two-spotted spider mite indicated a better performance on Hob × Will than on the other soybean cultivars.     

Insecticidal effects of the powdery formulation based on clay and essential oil from the leaves of <Emphasis Type="Italic">Clausena anisata</Emphasis> (Willd.) J. D. Hook ex. Benth. (Rutaceae) against <Emphasis Type="Italic">Acanthoscelides obtectus</Emphasis> (Say) (Coleoptera: Bruchidae)

The bioefficacies of essential oil and aromatized clay powder based on the mixture of clay and essential oil extracted from Clausena anisata were evaluated for their insecticidal activities and their effects on progeny production of Acanthoscelides obtectus. Contact toxicity assayed by coating on bean grains showed that these chemicals caused significant mortality of the test insect. Beetle mortality was dose dependant and after 2-day exposure the aromatized clay powder was more toxic (LD₅₀ = 0.069 μl/g grain) than the pure essential oil (LD₅₀ = 0.081 μl/g grain). There was, however, a highly significant loss of toxicity after 24 and 36 h following treatment with essential oil and aromatized powder, respectively. Both aromatized clay powder and pure essential oil considerably reduced the F₁ progeny insect production. The essential oil evoked moderated repellent action and high fumigant toxicity (LC₅₀ = 0.093 μl/cm³) against adults of A. obtectus. These results suggest that the clay powder could be used to stabilize the essential oil to increase its efficacy for use as an alternative to synthetic insecticides.     

Modeling leaf maximum net photosynthetic rate of <Emphasis Type="Italic">Festuca pallescens</Emphasis>, the dominant perennial grass of Patagonian pine-based silvopastoral systems

The integrated relationship in a simple mechanistic model between the critical environmental factors controlling leaf photosynthesis of understory species would be a useful tool to optimize the management of the silvopastoral systems. Individual effect of leaf temperature, water stress and light environment over net maximum photosynthetic rate (Pmax) was evaluated on Festuca pallescens leaves grown in a silvopastoral system of two Pinus ponderosa canopy covers (350 and 500 trees ha⁻¹) and natural grassland. The aim was to integrate individual functions for Pmax against these environmental factors into a multiplicative model. We measured pre-dawn water potential (ψ _pd), leaf temperature and net photosynthetic rate (Pn), stomatal conductance (gs) and intercellular CO₂ concentration (Ci) as a function of photosynthetic photon flux density (PPFD). The highest Pmax under non-limiting conditions was 20.4 μmol CO₂ m⁻² s⁻¹ and was defined as standardized dimensionless Pmax _s  = 1 for comparison of environmental factors. The leaf temperature function showed an optimum range between 20.2 and 21.8°C where Pmax _s  = 1. Then, Pmax _s declined by an average 1 μmol CO₂ m⁻² s⁻¹ C⁻¹ from the optimum to 4.7 and 38.5°C. Pmax _s decreased at a rate of 9.49 μmol CO₂ m⁻² s⁻¹ MPa⁻¹ as water potential reaches −1.9 MPa and showed a lower slope as water potential decreased down to −4.3 MPa. The light environment was estimated from hemispherical photograph analysis. Pmax _s was 20% higher in leaves of open control plants than under the maximum tree canopy cover. The simple multiplicative model accounted for 0.82 of the variation in Pmax. Such a simple mechanistic model is the first step towards a more effective decision support tool.     

Insecticidal efficacy of <Emphasis Type="Italic">Isaria farinosa</Emphasis> in different life stages of <Emphasis Type="Italic">Pissodes punctatus</Emphasis> (Coleoptera: Curculionidae)

The insecticidal activity of an entomopathogenic fungus, Isaria farinosa on pine bark-weevil (Pissodes punctatus) at different life stages underwent laboratory testing. Larvae, pupae and adults of Pissodes punctatus were exposed to a range of concentrations of fungal conidia in suspension for 5 s; mean mortality and LC₅₀ values were calculated. The results showed I. farinosa can effectively infect larvae, pupae and adult pine bark-weevils, and the highest mean mortalities at each life stage can exceed 88%. The mean mortalities increased with higher concentrations of I. farinosa. Larvae were most susceptible with LC₅₀ 1.2 × 10⁶ conidia ml⁻¹ (15 days), pupae (30 days) exhibited the second largest effects, and adults (15 days) with LC₅₀ 1.72 × 10⁶ and 1.99 × 10⁶ conidia ml⁻¹, respectively, at end of the experiments. This suggests that I. farinosa could be a potential bio-control agent against the pine bark-weevil.