Biology and behavior of Spathius agrili, a parasitoid of the emerald ash borer, Agrilus planipennis, in China

Spathius agrili Yang (Hymenoptera: Braconidae) is a gregarious larval ectoparasitoid of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) and is a recently described species. Both pest and parasitoid are native to China. In Tianjin City, China, S. agrili typically exhibited 3-4 generations per year, overwintering as a prepupa in a cocoon inside the host gallery. The multiple generations of S. agrili overlapped with its host, as did the emergence dates of the overwintering generation. From a single host, 1-18 S. agrili successfully developed to the adult stage (average 8.4), but in all cases the host was killed. The sex ratio (female: male) of the parasitoid adults emerging from field-collected cocoons was 2:1, whereas the sex ratio of parasitoids reared from field collected eggs and larvae was greater than 3:1. On average, adult females lived 29.1 d, and males lived 23.6 d when fed with 20% honey solution, significantly longer than without a nutritional supplement. Sexual reproduction is the normal mode of reproduction, but in the laboratory females did reproduce parthenogenetically, producing only males. The average fecundity was 23.3 eggs per female in the laboratory. S. agrili developed through five larval instars, and the larvae fed gregariously on the host hemolymph. The generation time from egg to adult wasp was 27-28 d at 22-26 degrees C. Natural parasitism rates were as high as 60%, and in October they reached over 90% in some stands. This study showed that S. agrili is a promising agent for biocontrol of A. planipennis.

The species of Rhimphoctona (Xylophylax) (Hymenoptera: Ichneumonidae: Campopleginae) parasitizing woodborers in China

Four species of Rhimphoctona (Xylophylax) collected from P. R. China are reported. Two of them are new to science: Rhimphoctona (Xylophylax) maculifemoralis Luo and Sheng, sp.nov. reared from Tetropium castaneum (Linnaeus), and Rhimphoctona (Xylophylax) immaculata Luo and Sheng, sp.nov. One is a new record for China, R. (Xylophylax) rufocoxalis ( Clément 1924 ) reared from T. castaneum (Linnaeus). The other is R. (Xylophylax) lucida ( Clément 1924 ) reared from Monochamus saltuarius Gebier, Tetropium gabrieli Weise and Asemus sp. A key to species known in China is provided.

Reproductive capacities and development of a seed Bruchid beetle, Acanthoscelides macrophthalmus, a potential host for the mass rearing of the parasitoid, Dinarmus basalis

The reproductive capacities and development of the seed beetle Acanthoscelides macrophthalmus (Schaeffer) (Coleoptera: Bruchidae), found in Togo, were determined under natural conditions in a Guinean zone for its use as a substitute host for the mass rearing of the parasitoid Dinarmus basalts Rond (Hymenoptera: Pteromalidae), a biological agent for the control of beetles that are pests of cowpea, Vigna unguiculata (L.) Walpers (Fabales: Fabaceae). Population dynamics at the field level; and survival, fecundity and offspring production by A. macrophthalmus under laboratory conditions were measured when fed on its natural plant-host Leucaena leucocephala (Lamark) deWit (Fabales: Mimosaceae). The data resulting from the laboratory study were used to calculate the demographic parameters of A. macrophthalmus by establishing its fertility and life tables. Contrary to cultivated leguminous food plants, L. leucocephala is a perennial sub-spontaneous leguminous plant whose pods are available year round. Although A. macrophthalmus was present in nature throughout the year, its infestation rate of the pods fluctuated according to the phenology of the plant. The maximum infestation of L. leucocephala pods was observed between August and December. Four larval stages and one pupal stage of A. macrophthalmus were identified in the laboratory. The total mean development time varied on average 33.75 ± 2.87 days on the mature pods and 33.39 ± 2.02 days on seeds. The adult female lived from one to two weeks. During its life time, the female laid an average of 62.3 ± 19 and 43.1 ± 13 eggs on the mature pods and seeds respectively and produced an average of 36.7 ± 11.3 offspring on the mature pods and 21.8 ± 8.4 offspring on seeds. On seeds, the net reproduction rate was 5.88 females per female and the intrinsic rate of population increase 0.051 per day. The generation time was 34.59 days and the doubling time 13.59 days. The demographic parameters of A. macrophthalmus in this study are close to those of Callobruchus maculatus F. (Bruchidae), the natural host of D. basalts in a previous study. A. macrophthalmus could therefore be used as substitute host for the mass rearing of D. basalts and subsequently its release in farmers' storage containers. The data presented in this study provide some baseline information regarding the reproductive capacities of A. macrophthalmus that may be useful for its promotion as a substitute host for mass rearing of D. basalts.

[Morphogenesis of the Staphylocystis furcata cysticercoid (Cyclophyllidea, Hymenolepididae)]

The morphogenesis of the Staphylocystis furcata (Stieda, 1862) cysticercoids has been studied in the experimentally infected beetles Geotrupes stercorosus and their structural and ontogenetic features have been described. At the initial stage of its development metacestode of S. furcata forms lacuna primitiva. The primordium of scolex invaginates early into the posterior part of the larva, and then the scolex develops in the cyst cavity. There is only an anterior obturator valve developing in the cyst. Posterior obturator valve is absent, that results in the cyst remaining unlocked and the cercomer does not separate from the cyst. There is no lacuna primitiva in the cercomer. The tegument of metacestode gets covered with a solid fibrous layer at the final stage of morphogenesis. It makes the cyst partly or completely pressed in the anterior part of the cercomer when it grows. The similarity between S. furcata cysticercoids and morphologically related cysticercoids Hymenolepididae has been analysed.

Facultative hyperparasitism: extreme survival behaviour of the primary solitary ectoparasitoid, Dinarmus basalis

This study investigated the egg-laying behaviour of ectoparsitoid, Dinarmus basalis Rondani (Hymenoptera: Pteromalidae), females when faced with a prolonged deprivation of suitable hosts leading to extreme 'oviposition pressure'. The egg-laying behaviour of virgin D. basalis females was tested with Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) hosts previously parasitized by the conspecific females in which the developing larvae had reached the last larval instar (L5) or pupae. The hyperparasitism did not prevent the occurrence of superparasitism, but only one D. basalis egg from a hyperparasitized D. basalis L5 larvae reached the adult stage due to the solitary behaviour of the D. basalis larvae. Under these experimental conditions, 60.78% of the D. basalis adults emerging from larvae were miniaturized due to the depletion of host resources.

Insights to host discrimination and host acceptance behaviour in a parasitoid (Diptera: Asilidae): implications for fitness

The robber fly Mallophora ruficauda is one of the principal pests of apiculture in the Pampas region of Argentina. As adults they prey on honey bees and other insects, while as larvae they are solitary ectoparasitoids of third instar scarab beetle larvae. Females of M. ruficauda lay eggs away from the host in tall grasses. After being dispersed by the wind, larvae drop to the ground, where they dig in search of their hosts. It is known that second instar larvae of M. ruficauda exhibit active host searching behaviour towards its preferred host, third instar larva of Cyclocephala signaticollis. Although the means by which host location occurs has been studied and since superparasitism is a frequent scenario in the field, no information about host discrimination and host acceptance is available. We carried out studies in the field and behavioural experiments in the laboratory to determine if M. ruficauda is capable of quality host discrimination. We also studied if this parasitoid is capable of conspecific detection in order to avoid superparasitism. Finally, we analyzed the conditions under which superparasitism occurs in the field. We report here that the second instar larva of M. ruficauda is able to discriminate the parasitism status of the host by means of chemical cues, but is not capable of detecting conspecifics prior to attacking a host. We also found that the host cannot detect the presence of the parasitoid by means of chemical cues, so that no counter-defense against parasitism occurs. Furthermore, we determined that superparasitism occurs on the heavier hosts, i.e. those with more abundant resources which could harbor several parasitoid individuals. Finally, we discuss the possible implications of larval host location and host discrimination decisions on the fitness of this parasitoid.

Unikaryon phyllotretae sp. n. (Protista, Microspora), a new microsporidian pathogen of Phyllotreta undulata (Coleoptera; Chrysomelidae)

The microsporidium Unikaryon phyllotretae sp. n., a new pathogen of Phyllotreta undulata, is described based on light microscopic and ultrastructural characteristics. Microscopic examination of parasitized individuals revealed two types of spores. The majority of the spores were of the first type, which are oval and measured 2.74+/-0.17 x 1.93+/-0.17 microm when fresh. Fresh spores of the second type (very rare) are elongated and measured 4.39+/-0.18 x 1.61+/-0.20 microm. All life stages have single nuclei. Sporogony ends with uninucleate single sporoblasts and spores. The spores were only observed in Malpighian tubules. The isofilar polar filament of the parasite has six to eight coils, and a well-developed polaroplast was of the lamellated type, with closely packed anterior lamellae and loosely packed posterior lamellae.

Nontarget effect of entomopathogenic nematodes on larvae of twospotted lady beetle (Coleoptera: Coccinellidae) and green lacewing (Neuroptera: Chrysopidae) under laboratory conditions

The nontarget effect of Steinernema feltiae, Steinernema carpocapsae, Heterorhabditis bacteriophora, and three mixed suspensions of two species of entomopathogenic nematodes on the larvae of the twospotted lady beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), and on the larvae of the lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), were studied in a laboratory bioassay. The assay was performed at three temperature (15, 20, and 25 degrees C) and at three different concentrations of the suspension (500, 2,500, and 5,000 infective juveniles [IJs]/ml). The larvae of A. bipunctata were more susceptible to nematode attack than the larvae of C. carnea. Four days after treatment, significantly the lowest mortality of A. bipunctata and C. carnea larvae was recorded at 15 degrees C, whereas no significant differences were noted between 20 and 25 degrees C. At 500 IJs/ml, the nematodes had significantly the lowest nontarget effect on the larvae of both aphid predators, whereas no significant differences in this regard were established between 2,500 and 5,000 IJs/ml. We conclude that the entomopathogenic nematodes under investigation exhibit a pronounced nontarget effect on the larvae of both predators mentioned.

Could hosts considered as low quality for egg-laying be considered as high quality for host-feeding?

When parasitoid females encounter a host, they can either lay an egg and thus invest in current reproduction or feed on the host and thus invest in future reproduction. However, hosts could have different values according to their parasitized status. Whereas already parasitized hosts represent poor quality for egg-laying, they could have a high nutritive value for feeding. Moreover, the optimal strategy adopted generally depends on the females' physiological state. In this study, the impact of the females' physiological state on their reproductive strategies was investigated in the solitary parasitoid Anisopteromalus calandrae. We analysed how their age and diet influenced (i) the use of hosts (feeding vs. oviposition) and (ii) host selection (previously parasitized vs. unparasitized). Our results show that both age and diet influence the reproductive strategy of A. calandrae females: old females fed with the poorer diet laid fewer eggs and made more host-feeding than others. Females also showed a preference for already parasitized hosts for feeding. This strategy cannot be explained by the nutritive value of haemolymph, as parasitized hosts carry fewer lipids. However, as parasitized hosts are also paralyzed, it could be less costly to feed on them than on unparasitized hosts.

Reproduction in a variable environment: How does Eupelmus vuilleti, a parasitoid wasp, adjust oogenesis to host availability?

Oogenesis of the parasitoid wasp Eupelmus vuilleti is known to be dependent on host availability. However, examination of ovarian dynamics by microscopy showed that oogenesis and vitellogenesis are initiated before female eclosion and proceed 1-2 days after, independent of host presence. Oogenesis continued beyond the 2nd day only in the presence of hosts, otherwise it was replaced by egg resorption. It is thus possible to distinguish between host-independent and host-dependent periods of oogenesis. In the presence of host, each ovariole (three per ovary) contained generally three oocytes: a fully mature oocyte, a nearly mature one and an immature one. However, host deprived-females resorbed their most mature and their smallest oocytes, but kept one almost mature oocyte per ovariole. Comparison of zero, short and long host deprivation periods showed that females always had the ability to quickly lay eggs to exploit any new host. However, increased deprivation led to a reduction in the number and the viability of eggs. Enzymo-immunological measurements of ecdysteroids were made in whole females, in dissected ovaries and in newly laid eggs. Our results indicated that ecdysteroids play a major role as circulating hormones involved in the regulation of oogenesis.

Formulation and application of entomopathogenic nematode-infected cadavers for control of Hoplia philanthus in turfgrass

BACKGROUND

Commercially produced entomopathogenic nematodes (EPNs) are usually applied in an aqueous suspension. However, recent studies demonstrate that they can be successfully applied as infected cadavers. EPN-infected insect cadavers were formulated in various carrier/coating materials, but only infective juveniles (IJs) from kaolin-formulated and non-formulated cadavers were tested for survival, emergence and virulence. The efficacy of IJs from kaolin-formulated and non-formulated cadavers applied against Hoplia philanthus Füessly in greenhouse and field was also assessed.

RESULTS

The kaolin-based formulation (kaolin-starch combination) proved to be the most stable. Emergence of Heterorhabditis bacteriophora Poinar CLO51 from cadavers formulated in kaolin was significantly higher than from non-formulated cadavers. In greenhouse conditions, efficacy of freshly formulated (8 days post-infection) cadavers of H. bacteriophora provided significantly higher H. philanthus control (62%) than three-month-old cadavers (31%) or aqueous applications of the same EPN (39% and 43%). Similarly, under field conditions, significantly higher H. philanthus control was achieved with freshly formulated cadavers (39%) than with three-month-old cadavers (21%) or with aqueous applications (24% and 28%) of H. bacteriophora 2 weeks after application. Additionally, after 1 year, cadaver applications provided >90% H. philanthus control, while aqueous applications of H. bacteriophora gave only 55% control.

CONCLUSIONS

This study demonstrated that kaolin-starch coating provided superior protection and preservation of EPN-infected cadavers. Use of formulated cadavers may solve several current problems preventing the wider utilisation of EPNs in pest management.

Monitoring western corn rootworm (Diabrotica v. virgifera) adults: situation in Romania 2008

Romania is part of the southeast European expansion zone of the invasive rootworm species Diabrotica v. virgifera LeConte (Col.: Chrysomelidae) (WCR). The pest originated in North America and reached Belgrade airport with US foreign aid air shipments prior to 1992. Today, about 20 years after its introduction, WCR is a major maize pest which regionally causes economic damage to maize. However, it also can colonize secondary hosts which complicates IPM efforts. Basis for sound management is a reliable monitoring system. The easiest and cheapest way is to use Metcalf type monitoring traps for the mobile adults. Sex pheromones and plant kairomones for trapping are commercially available. Traps can be either bought or cheaply prepared. Metcalf traps with adhesive and lure cost about 15 cents per piece. So state-wide trapping is no longer a problem for less affluent countries. Results from two independent locations in 2008 report flight curves and attractively of secondary hosts like Sorghum spp. in relation to the principle host Zea mays. In addition, high capacity traps baited with pheromone are surprisingly effective, and, in combination with the chemically inert, absorptive silica powder AL 06, will be considered as future alternatives in cases where frequent monitoring is unfeasible and were a large holding capacity is indicated.

Seasonal phenology and management of Tomarus subtropicus (Coleoptera: Scarabaeidae) in St. Augustinegrass

The grub Tomarus subtropicus Blatchley (Coleoptera: Scarabaeidae) is one of the most destructive pests of turfgrass and sugarcane (Saccharum spp.) in southern Florida, but its life cycle has only been described in sugarcane production. Preventive insecticides applied against T. subtropicus in turfgrass when adult activity and oviposition were expected in sugarcane have necessitated subsequent curative treatments. Thus, the seasonal activity of T. subtropicus was monitored using UV blacklight traps and by sampling soil in infested St. Augustinegrass lawns in Cape Coral and Punta Gorda, FL, during 2005-2006. Several preventive and curative insecticides and entomopathogenic nematode species were evaluated in laboratory, greenhouse and field tests. T. subtropicus is univoltine in both sugarcane and St. Augustinegrass, but adult flight peaked approximately 1 mo later in St. Augustinegrass than in sugarcane. Halofenozide, clothianidin, and imidacloprid were effective preventive control products, and carbaryl and trichlorfon were satisfactory curative insecticides. The nematodes Steinernema scarabei (Stock & Koppenhöfer), S. glaseri (Steiner), and Heterorhabditis bacteriophora (Poinar) were most effective against T. subtropicus grubs, and second instars were more susceptible compared with third instars. Improved knowledge of the biology and effectiveness of different management options for T. subtropicus will help minimize excessive pesticide use, especially in coastal areas of Florida.

Effect of host plants on successful parasitism by Haeckeliania sperata (Hymenoptera: Trichogrammatidae) on Diaprepes abbreviatus (Coleoptera: Curculionidae) eggs

Diaprepes abbreviatus L. is a highly polyphagous root weevil that causes damage to several fruit crops, ornamental plants, and other naturally occurring plants in Florida. Haeckeliania sperata Pinto is a gregarious endoparasitoid that attacks D. abbreviatus eggs. We hypothesized that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus. Six host plants with varying degrees of pubescence were used to determine the effect of leaf trichomes on the searching behavior and success of parasitism by H. sperata. No-choice tests showed that H. sperata was able to parasitize Diaprepes eggs laid on the six host plants. However, the plants with a high trichome density on their leaves had a lower percent of parasitism than the plants with smoother leaves. Removing trichomes from a host plant showed that the presence of some leaf trichomes had a negative effect on the overall searching efficiency of H. sperata. The presence of trichomes decreased the total distance traveled and increased the total search time of H. sperata females, resulting in a lower searching speed. Multiple regression analysis was used to establish the relationship between percent parasitism and leaf trichome density, leaf thickness, and the searching speed of H. sperata. Searching speed was the best predictor of percent parasitism; this parameter could be used to predict the suitability of host plants for the establishment of H. sperata. Our findings suggest that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus.

Development of a strategy for selective collection of a parasitoid attacking one member of a large herbivore guild

Selectively collecting a single natural enemy species that parasitizes one member of a guild of herbivores that attack the same host plants can be a challenging problem during development of biological control programs. We present here a successful strategy for the collection of a strain of the egg parasitoid Avetianella longoi Siscaro (Hymenoptera: Encyrtidae), that parasitizes eggs of the longhorned borer Phoracantha recurva Newman (Coleoptera: Cerambycidae). This cerambycid is one member of a large guild of woodborers that simultaneously infest dying and fallen Eucalyptus in Australia, and it has become a major pest of Eucalyptus in many areas of the world where Eucalyptus has been introduced. Adult P. recurva of both sexes were caged on freshly cut Eucalyptus logs, and the resulting egg masses were marked and then left exposed to natural parasitization in the field. Parasitized egg masses were then harvested and held in the laboratory until adult parasitoids emerged. Parasitoids were identified as A. longoi by morphological comparisons with reference specimens, and with molecular markers. This strain of A. longoi readily accepted and had high survival rates in eggs of P. recurva. In contrast, the strain of A. longoi that has been used for biological control of P. semipunctata in California since the 1990s strongly prefers eggs of eucalyptus longhorned borer, Phoracantha semipunctata (F.) (Coleoptera: Cerambycidae), and has relatively low rates of survival to adulthood in eggs of P. recurva. The causes of these behavioral and physiological differences between the two strains are not yet known.

[Mites associated to the Coleopteran Passalus cognatus (Coleoptera:Passalidae) from Los Tuxtlas, Veracruz, Mexico]

There are few records of mites associated with the tropical coleopterans of Mexico. We examined 35 passalid beetles (bessbugs) Passalus cognatus from Los Tuxtlas region in Veracruz State, Mexico. Twenty of them had a total of 245 mites (representing eight species, eight genera, eight families and three suborders). The most abundant species were Uroobovella californiana Wisniewski & Hirschmann (35%), Euzercon hyatti Hunter & Rosario (20%), and Uropoda sp. (17.5%). The preferred attachment areas were the coxae; followed by the mesosternum and the humeri. Each beetle had 1 to 40 mites (average: 12); and we found 1-4 mite species per beetle.

Behavioural genetics: worms seek that old beetle smell

Some nematodes eavesdrop on pheromonal signals to sniff out their elderly beetle hosts. This turns out to be yet another behaviour regulated by cGMP/PKG signalling.

Multipartite symbioses among fungi, mites, nematodes, and the spruce beetle, Dendroctonus rufipennis

The spruce beetle, Dendroctonus rufipennis, is an eruptive forest pest of significant economic and ecological importance. D. rufipennis has symbiotic associations with a number of microorganisms, especially the ophiostomatoid fungus Leptographium abietinum. The nature of this interaction is only partially understood. Additionally, mite and nematode associates can mediate bark beetle-fungal interactions, but this has not yet been studied for spruce beetles. In this study, we found eight mite species associated with spruce beetles: Tarsonemus ips, T. endophloeus, Histiogaster arborsignis, Dendrolaelaps quadrisetus, Proctolaelaps hytricoides, Trichouropoda alascae, T. n. sp. nr dalarenaensis, and Urobovella n. sp 767. The most prevalent species was H. arborsignis. In addition, 75% of beetles examined carried nematodes, with six species represented. These included a new species of Parasitorhabditis, Ektaphelenchus obtusus, Bursaphelenchus n. sp. 727, Aphelenchoides n. sp., Panagrolaimus sp., and Mykoletzkya ruminis. H. arborsignis showed strong feeding and oviposition preferences for L. abietinum among four fungal species tested in laboratory assays. Information on our attempts to culture the various nematode species collected from D. rufipennis is also provided. Bursaphelenchus were cultured from D. rufipennis nematangia plated on agar containing L. abietinum but not sterile agar. Thus, L. abietinum plays an important role in these gallery communities, affecting the tree-killing bark beetle, its phoretic mites, and nematodes. These data add to our understanding of bark beetle-microorganism interactions.

Multipartite symbioses among fungi, mites, nematodes, and the spruce beetle, Dendroctonus rufipennis

The spruce beetle, Dendroctonus rufipennis, is an eruptive forest pest of significant economic and ecological importance. D. rufipennis has symbiotic associations with a number of microorganisms, especially the ophiostomatoid fungus Leptographium abietinum. The nature of this interaction is only partially understood. Additionally, mite and nematode associates can mediate bark beetle-fungal interactions, but this has not yet been studied for spruce beetles. In this study, we found eight mite species associated with spruce beetles: Tarsonemus ips, T. endophloeus, Histiogaster arborsignis, Dendrolaelaps quadrisetus, Proctolaelaps hytricoides, Trichouropoda alascae, T. n. sp. nr dalarenaensis, and Urobovella n. sp 767. The most prevalent species was H. arborsignis. In addition, 75% of beetles examined carried nematodes, with six species represented. These included a new species of Parasitorhabditis, Ektaphelenchus obtusus, Bursaphelenchus n. sp. 727, Aphelenchoides n. sp., Panagrolaimus sp., and Mykoletzkya ruminis. H. arborsignis showed strong feeding and oviposition preferences for L. abietinum among four fungal species tested in laboratory assays. Information on our attempts to culture the various nematode species collected from D. rufipennis is also provided. Bursaphelenchus were cultured from D. rufipennis nematangia plated on agar containing L. abietinum but not sterile agar. Thus, L. abietinum plays an important role in these gallery communities, affecting the tree-killing bark beetle, its phoretic mites, and nematodes. These data add to our understanding of bark beetle-microorganism interactions.

Pupation by Viburnum leaf beetle (coleoptera: chrysomelidae): behavioral description and impact of environmental variables and entomopathogenic nematodes

Pyrrhalta viburni (Paykull), a new landscape pest in the United States, feeds in both the larval and adult stages on foliage of plants in the genus Viburnum. The insect is univoltine, with larvae active in spring and adults throughout the summer months. Experiments were conducted to determine the depth of pupation in the soil; the impact of substrate texture, moisture content, and temperature on pupation success; and ability of entomopathogenic nematodes to kill larvae when they enter the substrate to pupate. Larvae burrowed only a short distance into the substrate when pupating; 97-100% were found within the top 3 cm of a column of soil or sand and soil mixture in the laboratory. Larval mortality before pupation was low at 22 degrees C but considerably higher at 30 degrees C; at both temperatures, pupation success was lowest on a mixed substrate and higher (and equivalent) on sand or soil alone. Survivorship to adult was influenced by both temperature and substrate moisture content; at 22 degrees C, 56% percent of pupating larvae emerged as adults at 75% moisture content compared with only 25 at 25% moisture content. Emergence of adults was negligible at 30 degrees C, regardless of moisture content. Heterorhabditis bacteriophora and Steinernema carpocapsae were very effective biocontrol agents in laboratory bioassays, reducing adult emergence by 76-100%, with nematode applications made before pupation being more effective than those made after pupation, and H. bacteriophora consistently (but not significantly) more effective than S. carpocapsae. Management methods that take advantage of pupation behaviors are discussed.

Early timing and new combinations to increase the efficacy of neonicotinoid-entomopathogenic nematode (Rhabditida: Heterorhabditidae) combinations against white grubs (Coleoptera: Scarabaeidae)

BACKGROUND

An investigation was carried out to determine whether new neonicotinoid-nematode combinations and earlier applications against younger larval stages could increase the efficacy of synergistic neonicotinoid-entomopathogenic nematode combinations against white grubs.

RESULTS

In the laboratory, combinations of the neonicotinoids imidacloprid and clothianidin and the nematodes Heterorhabditis bacteriophora Poinar and H. zealandica Poinar against third instars were compared. In Anomala orientalis (Waterhouse) and Popillia japonica Newman, H. bacteriophora-imidacloprid combinations showed the most consistent synergism but did not cause significantly higher mortality than H. zealandica-imidacloprid combinations. In Cyclocephala borealis Arrow, there was no clear trend as to which combinations caused the most consistent synergism, but H. zealandica-imidacloprid combinations tended to cause the highest mortalities. In the laboratory, imidacloprid-H. bacteriophora combinations provided more consistent synergism against third-instar than against second-instar A. orientalis, but mortality was higher in second instars. In field experiments, imidacloprid-H. bacteriophora combinations against A. orientalis and P. japonica provided more consistent synergism when applied in mid-September but more consistent control when applied in late August.

CONCLUSIONS

Imidacloprid is a better synergist for entomopathogenic nematodes than clothianidin. Imidacloprid-nematode combinations are more effective against second instars than against third instars, allowing rate reductions of both agents to make this approach more competitive with full-rate applications of neonicotinoid alone.

Studies on three species of the genus Cystocephalus Schneider, 1886 (Apicomplexa: Eugregarinida: Stylocephalidae) with special reference to host specificity and distribution of members of family Stylocephalidae in Egypt

Three species belonging to genus Cystocephalus, Schneider 1886 were found parasitizing three coleoptra hosts. Out of 105 Blaps polychresta, only one male was infected with C. algerianus and females were parasites free. Ten percent of examined Pimelia angulata Ten percent of examined Pimelia angulata (n = 30) were infected with the same parasite. Among are one male (5.56%) and 2 females (16.67%). Out of 126 of Trachyderma hispida 6 (4.76%) were parasitized by C. gabei. Only 3 males (5.1%) and 3 females (4.48%) were harbouring this parasite. Cystocephalus albrechti were found infecting 78 (61.9%) out of 126 of T. hispida. Forty six males (77.93%) and 32 females (47.76%) were infected. Males of the three tenebrionid hosts were more susceptible to infection rather than females. B. polychresta was considered a new host for C. algerianus in Egypt. Also, C. albrechti might be considered as specific host for T. hispida. Mid and hind gut appeared blackened in case of massive infection (> 240 parasites per host) of parasitized males of C. albrechti. The host specificity and the first biogeographical map fort distribution of stylocephalids and cystocephalids are provided here.

Cheating on a mutualism: indirect benefits of ant attendance to a coccidophagous coccinellid

Coccinellids (Coleoptera: Coccinellidae) are generally unable to prey on ant-tended prey. However, particular coccinellid species have morphological, behavioral, or chemical characteristics that render them immune to ant attacks, and some species are even restricted to ant-tending areas. The benefit gained from living in close association with ants can be twofold: (1) gaining access to high-density prey areas and (2) gaining enemy-free space. Here, the myrmecophily of Azya orbigera Mulsant (Coleoptera: Coccinellidae), an important predator of the green coffee scale, Coccus viridis (Green) (Hemiptera: Coccidae), is reported. In this paper, three main questions were studied. (1) Are the waxy filaments of A. orbigera larvae effective as defense against attacks of the mutualistic ant partner of C. viridis, Azteca instabilis F. Smith (Hymenoptera: Formicidae)? (2) Does A. instabilis reduce the rate at which A. orbigera larvae prey on scales? (3) Do A. orbigera larvae gain enemy-free space by living in close association with A. instabilis? Laboratory and field experiments were conducted to answer these questions. We found that, because of the sticky waxy filaments of A. orbigera larvae, A. instabilis is incapable of effectively attacking them and, therefore, the predation rate of A. orbigera on C. viridis does not decrease in the presence of ants. Furthermore, A. instabilis showed aggressive behavior toward A. orbigera's parasitoids, and the presence of ants reduced the parasitism suffered by A. orbigera. This is the first time that this kind of indirect positive effect is reported for an ant and a coccidophagous coccinellid. Furthermore, this indirect positive effect may be key to the persistence of A. orbigera's populations.

Parasites of Phyllotreta atra (Fabricius, 1775) (Coleoptera: Chrysomelidae) in Trabzon

In this study, the parasites of Pyllotreta atra (Coleoptera: Chrysomelidae) in Trabzon were investigated. Samples of P. atra were collected in different localities of Trabzon. Three different types of parasites from P. atra observed are as follows: Gre-garine (Apicomplexa), Nematode (Tylenchida: Allantonematidae) and larvae of certain parasitoids. The most abundant infection found in this study was gregarine infection followed by nematode infection with total infection rates 37.8% and 7.6%, respectively. The gre-garine and the nematode parasites were identified as Gregarina phyllotretae and Howardula phyllotretae, respectively.

First results on the distribution of Nosema chaetocnemae Yaman et Radek, 2003 (Microspora) in the populations of Chaetocnema tibialis Illiger, 1807 (Coleoptera: Chrysomelidae)

In the present study, the first report on the distribution of Nosema chaetocnemae infection of Chaetocnema tibialis populations in Turkey is given. Of the 1751 beetles collected from ten provinces, 193 were infected by the parasite. The infection average was 11.02% in Turkey. Nosema infection was found in C. tibialis adults from two (Samsun and Trabzon) of the ten provinces studied. In eight localities in different regions of Turkey, the infection was not observed. The highest percentage of beetles infected with a Nosema isolate was recorded in Samsun. The infection average in Samsun was 25.20%. The results showed that the infection level of N. chaetocnemae was relatively stable during the observation period between the years 2000-2006.