The thoracic morphology of cave-dwelling and free-living ground beetles from China (Coleoptera, Carabidae, Trechinae).

External and internal thoracic structures of two carabid species (Trechini) were examined and documented with different techniques. The study has a main focus on the eyeless cave-dwelling specialist Sinaphaenops wangorum, but detailed information is also provided for a species occurring in cave entrances. The phylogenetic background of the structural features of the thoracic skeletomuscular system was addressed. The thoracic morphology of the examined species was compared to conditions observed in previously studied carabids and non-related subterranean leiodids (Staphylinoidea) in order to identify cave adaptations. Main thoracic character complexes linked with cavernicolous habits in Trechini are elongation of the pro- and mesothorax and the legs, and a complete and irreversible reduction of the flight apparatus. The lost flight capacity is linked with a far reaching modification of skeletal elements of the metathorax including a strongly shortened and simplified metanotum, a shortened metaventrite, and completely reduced wings and sclerites of the wing base. The elongate prothorax together with the long and slender head and elongated legs distinctly increases the activity range in the subterranean lightless environment, which likely facilitates foraging of the carnivorous beetles. Some of the observed features like wing loss and elongation of the anterior thorax and legs are also found in some cave-dwelling Leiodidae (Leptodirini), whereas some other subterranean members of the staphylinoid family have a compact body and legs of normal length. In contrast to the predaceous Trechini, Leptodirini are scavengers.

Exploring the Caste-Specific Multi-Layer Defense Mechanism of Formosan Subterranean Termites, Coptotermes formosanus Shiraki.

The survival and foraging of Coptotermesformosanus Shiraki in a microbe-rich environment reflect the adaptation of an extraordinary, sophisticated defense mechanism by the nest-mates. We aimed to explore the host pathogen interaction by studying caste-specific volatile chemistry and genes encoding the antioxidant defense of winged imagoes, nymphs, soldiers and workers of Formosan subterranean termites. Qualitative analyses of C.formosanus Shiraki performed by HS-SPME/GC-MS showed considerable variations in the chemical composition of volatile organic compounds (VOCs) and their proportions among all the castes. Winged imagoes produced the most important compounds such as naphthalene and n-hexanoic acid. The antifungal activity of these compounds along with nonanal, n-pentadecane, n-tetradecane, n-heptadecane and methyl octanoate against the conidial suspensions of Metarhiziumanisopliae and Beauveriabassiana isolates enable us to suggest that the failure of natural fungal infection in the nest is due to the antiseptic environment of the nest, which is mainly controlled by the VOCs of nest-mates. In addition, conidial germination of M.anisopliae and B.bassiana isolates evaluated on the cuticle of each caste showed significant variations among isolates and different castes. Our results showed that the conidia of M.anisopliae 02049 exhibited the highest germination on the cuticle of all the inoculated castes. Moreover, we recorded the lowest germination of the conidia of B.bassiana 200436. Caste-specific germination variations enabled us to report for the first time that the cuticle of winged imagoes was found to be the most resistant cuticle. The analysis of the transcriptome of C.formosanus Shiraki revealed the identification of 17 genes directly involved in antioxidant defense. Expression patterns of the identified antioxidant genes by quantitative real-time PCR (qPCR) revealed the significantly highest upregulation of CAT, GST, PRXSL, Cu/Zn-SOD2, TXN1, TXN2, TXNL1, TXNL2, TXNL4A and TPx genes among winged imagoes upon infection with the most virulent isolate, M.anisopliae 02049. Furthermore, soldiers showed the least expression of genes encoding antioxidant defense. Our findings indicated that the volatile chemistry of nest-mates and genes encoding antioxidant defense greatly contribute to the survival and foraging of Formosan subterranean termites in a microbe-rich habitat.

Reproductive traits of Glenea cantor (Coleoptera: Cerambycidae: Lamiinae).

Glenea cantor (F.) is a cerambycid species that attacks living trees of at least seven plant families in Asia, and has the potential to become an invasive pest. Here we investigated its reproductive biology in the laboratory to provide vital information for the development of pest control measures and preparation of pest risk analysis. Both sexes required a period of maturation feeding before mating, with the mean premating period of males (5.87 +/- 1.68 d) being significantly longer than that of females (4.59 +/- 2.34 d). This was a synovigenic species with the mean preoviposition and oviposition period being 13.50 +/- 3.15 d and 49.46 +/- 16.16 d, respectively. If no food was available after emergence, adult males died before reaching sexual maturation and females vanished before oviposition. Paired couples mated an average of 15.12 +/- 7.02 times; 28- to 53-d-old beetles mated significantly more frequently than younger and older ones. The mean fecundity was 133.24 +/- 9.67 eggs. The oviposition rate significantly increased in the first 5 wk of the oviposition period, peaking when females were 40- to 54-d-old, and then significantly decreased in the following weeks. Reproductive activities occurred almost exclusively during the day, with most ovipositions taking place in the morning and matings in the afternoon with some overlaps.

Phenology and laboratory rearing procedures of an Asian longicorn beetle, Glenea cantor (Coleoptera: Cerambycidae: Lamiinae).

Clenea cantor (F.) (Coleoptera: Cerambycidae: Lamiinae) is an Asian longicorn beetle whose larvae bore under the bark of living trees of at least seven plant families and enter the wood for pupation. Here, we determined the phenology of this beetle on its natural host, kapok [Bombax ceiba L. = Cossampinus malabaricus (DC.) Merr], in an uncontrolled insectary at ambient environmental conditions, and we compared the efficiency of four larval rearing procedures at 25 +/- 2 degrees C, 75 +/- 5% RH, and a photoperiod of 14:10 (L:D) h in the laboratory. It had five generations, including an overwintering generation, a year in southern China, with overlaps between generations and no diapause. Adults were present in early March-early December; eggs in early April-early December; larvae almost year-round, and pupae in mid-February-mid-April as well as mid-May-late November. All larvae of the overwintering generation and the larvae of the fourth generation that hatched in and after mid-November overwintered. The longevity of females and males was 71.94 +/- 1.21 d and 46.87 +/- 1.11 d, respectively, and mean fecundity was 106.65 +/- 3.61 eggs. Four larval rearing procedures using kapok twigs were tested: (1) 10 neonate larvae were left in the original host twig, (2) 10 neonate larvae were removed from the original bark and transferred to a new host twig, 3) 10 neonate larvae embedded in the original bark were transferred to a new host twig, and 4) a single neonate larva embedded in the original bark was transferred to a new host twig. We observed the survival of 300 neonate larvae for each rearing procedure. Approximately 81-85% of neonate larvae successfully developed to adult stage when neonate larvae were transferred together with the original bark to new host twigs; when neonate larvae were transferred without the original bark, only approximately 38% of the inoculants became adults, and when larvae were left in original twigs, approximately 52% of them reached adult stage. Resulting adults from different rearing methods and collected from the field had similar body weight and sex ratio. In terms of time, labor, and the number of resulting adults, procedure 3 is the most effective method for maintaining a laboratory colony.

Host selection and colonization strategies with evidence for a female-produced oviposition attractant in a longhorn beetle.

In longhorn beetles and many other internally feeding insects, oviposition choice by females is critical to the survival of their offspring because their larvae are incapable of moving between hosts. Here we report on the complex host selection and colonization strategies of a longhorn beetle, Glenea cantor (F.) (Coleoptera: Cerambycidae), which is an important pest of kapok trees [Bombax ceiba L.=Gossampinus malabaricus (DC.) Merr.] in southern Asia. It attacks weakened trees, eventually killing them. The typical oviposition behavioral sequence in the laboratory includes the following: oviposition site search and recognition using antennae and palpi, oviposition slit preparation with mandibles, turning body direction 180°, egg deposition with the ovipositor, and oviposition wound covering with a jelly-like material from the ovipositor. Bark moisture content significantly increases from the upper to lower sections in kapok trees. In accordance with this variation female adults select the upper section of trees first for oviposition. As infestation continues and the host becomes more weakened, ovipositing females move further down the tree for oviposition. Consequently, the larvae kill the hosts from the top down. We show that the jelly-like material or eggs or both have an olfactory role in attracting females to oviposit nearby. Our findings are important in terms of increasing our understanding of host selection and colonization mechanisms of internally feeding insects, particularly cerambycids, and the development of environmentally friendly pest management measures.

Differential fluctuation in virulence and VOC profiles among different cultures of entomopathogenic fungi.

Insect-passaged cultures of entomopathogenic fungi grown on potato dextrose agar media have been shown to have altered virulence and profiles of volatile compounds. The present study demonstrated the pathogenic status of FS(0) (in vitro) and FS(1) and FS(2) (insect-passaged cultures grown on PDA) cultures of Metarhizium anisopliae (strains 406 and 02049) and Beauveria bassiana by a non-choice assay, in which filter paper was inoculated with fungal spores at a concentration of 1 x 10(7) spores/ml. The FS(1) and FS(2) cultures of M. anisopliae strain 02049 and B. bassiana produced conidia with high virulence, and the volatile profiles of these conidia comprised relatively lower percentages of branched-alkanes than conidia from the FS(0) cultures. In contrast, the conidia from an FS(0) culture of M. anisopliae strain 406 had somewhat elevated virulence levels, but their volatile profile had <2% branched-alkanes. The FS(1) and FS(2) cultures of M. anisopliae strain 406 did not gain virulence, and these cultures showed a decline in virulence along with major alteration of their volatile profiles. Their volatile profiles mainly comprised branched-alkanes. The volatile profiles of the FS(1) and FS(2) cultures lacked n-tetradecane, which was an important component of all the virulent cultures. Four compounds, 2-phenylpropenal, 2,5,5-trimethyl-1-hexene, n-tetradecane and 2,6-dimethylheptadecane, were detected only from the virulent cultures, suggesting that low LT(50) values were probably due to the production of these compounds. This is the first report to characterize volatiles from FS(0), FS(1) and FS(2) cultures of entomopathogenic fungi; its utility in different aspects opens an interesting area for further investigations.

Mate location and recognition in Glenea cantor (Fabr.) (Coleoptera: Cerambycidae: Lamiinae): roles of host plant health, female sex pheromone, and vision.

Glenea cantor (Fabricius) is an important pest of kapok trees [Bombax ceiba L.=Gossampinus malabaricus (DC.) Merr.] in southern China and Vietnam, and its adults are diurnally active. We carried out both field and laboratory experiments to examine the mechanisms that brought G. cantor sexes together from a long distance and facilitated mate location and recognition in a close range. Long-range sex pheromones are not involved in mate location. Mutual attraction of sexes to weakened kapok trees where adult feeding, mating, and oviposition occur plays the key role in mate location from a long distance. In a close range, vision and a female sex pheromone that operates over a short distance (3-3.5 cm) and/or by contact are major cues males use for mate location and recognition. Males seem to use combined chemical and visual cues to achieve mating. Male antennae, particularly the terminal five segments, are critical for males to detect and recognize females. Removal of male palpi has no significant effect on mate location and recognition by males.