Effect of blue-stain fungi on the number of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) carried by Monochamus alternatus (Coleoptera: Cerambycidae)

Blue-stain fungi were mainly isolated from the wood of pine wilt-killed Pinus densiflora. Intense blue-stain on the pupal chamber walls of the Japanese pine sawyer (Monochamus alternatus) increased the number of pinewood nematodes (Bursaphelenchus xylophilus) aggregating around such chambers and the number carried by the beetles that emerged from the chambers. There were differences in the numbers of nematodes carried by beetles among individual trees from which the beetles emerged. The beetles emerging from dry chambers carried relatively few nematodes.

Schizolysis of dolipore–parenthesome septa in an arthroconidial fungus associated with Dendroctonus ponderosae and in similar anamorphic fungi

An arthroconidial anamorphic fungus occurred in pupal chambers of the mountain pine beetle (Dendroctonus ponderosae) in lodgepole pine. No teleomorph was found and no suitable form genus was available for its disposition. However, in cultural characteristics it closely resembled the group 1 arthroconidial fungi, defined by other researchers as probable basidiomycete anamorphs. Septa of the pupal-chamber fungus and several of the group 1 isolates were of the dolipore–parenthesome type. Conidial separation was by septum schizolysis. Cell separation was initiated by disintegration of the dolipore wall, followed by progressive shrinkage of the fused dolipore wall. The parenthesomes retracted towards the dolipore wall and the triangular areas of the cross wall dissolved. The cross wall then split centripetally along the median electron-light layer to complete cell separation. The pupal-chamber fungus was also compared with Phlebia radiata (group 2) and with groups 3 and 4 strains of other researchers. Mauginiella scaettae was confirmed to have simple septa; thus this genus fails to accommodate arthroconidial basidiomycete anamorphs. Key words: basidiomycete anamorphs, dolipore–parenthesome septa, septum schizolysis, arthroconidiogenesis, Phlebia radiata, Mauginiella scaettae.

ASSOCIATION OF DENDROCTONUS PONDEROSAE (COLEOPTERA: SCOLYTIDAE) WITH BLUE STAIN FUNGI AND YEASTS DURING BROOD DEVELOPMENT IN LODGEPOLE PINE

The physical association between Dendroctonus ponderosae Hopk. and its associated blue stain fungi Ceratocystis montia Rumb. and Europhium clavigerum Robinson and Davidson and the yeasts Pichia pini (Holst) Phaff, Hansenula capsulata Wickerham, and H. holstii Wickerham is described in single broods reared in bolts of lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm. Eggs just prior to hatch and first-instar larvae were always in contact with the microorganisms whereas newly laid eggs, second-, third-, and fourth-instar larvae were not. During pupation, blue stain fungi and yeasts colonized pupal chamber walls. Transfer of these microorganisms to the new generation of insects was ensured when tenerals contacted the microorganisms lining the pupal chamber. Ensured physical contact between these organisms supports the hypothesis of a symbiosis between them.

THE LIFE HISTORY OF "DIAPREPES ABBREVIATUS" L., AT RIO PIEDRAS, PUERTO RICO

1. The females of Diaprepes abbreviatus L. lay 5,000 or more (or less) eggs in as few as two months, May and June, or in as many as seven months at other times of the year, often living over twice as long as do the males after emergence from the soil. 2. The incubation period of all eggs is seven days. Larvae attain full size in two to four months. A diapause period is absolutely essential before pupation. The pupal period is about two weeks. Fully-formed adults remain within the pupal chamber for a variable period of weeks or months, the length of this period and that of the diapause period of the larva being subject to great variation. 3. The great variation in the duration of the diapause period of the larva and before the emergence of the adult from the pupal cell in the ground permits some individuals to complete their life-cycle (hatch ing of eggs to first egg-cluster laid by female, or to emergence of male from soil) in less than eight months, but for other individuals it may extend for eighteen months (hatching of egg to last egg-cluster laid by female, or to death of male). 4. Deviation from a one-year life-cycle is of tremendous value to Diaprepes abbreviatus L. in enabling its eggs to escape attack by a common parasitic wasp, Tetrastichus haitiensis Gahan, which is most abundant during the late spring, but very scarce during autumn and winter.

Bionomics of Agrilus acutus (Thnb.) (Col., Buprestidae) on mesta (Hibiscus cannabinus) in India

An account is given of the life-history of Agrilus acutus (Thnb.) (Buprestidae), a pest of ‘mesta’ (Hibiscus cannabinus) in india. The eggs are ovate and scale like, and are laid singly on the stem, usually near a leaf scar, and when kept at 31°C. and 73 per cent. relative humidity hatched on average in 12.4 days. The larva bores through the lower surface of the egg directly into the stem and feeds under the bark forming a sprial tunnel. A raised weal develops on the surface of the stem overlying the tunnel. Before each moult, the larva bores into the wood and makes a vertical chamber in which moulting occurs. There are normally three moults in the active feeding stages, but exceptionally four, and a prepupal moult. The rate of tunnelling is at first about 56 mm. per day and later eaches about 107 mm. The larval stage lests 26 days. The fully grown larva is 21 mm. long and bores into the wood to pupate, making a pupal chamber 11 mm. long into which it fits itself by adopting an asymmetrical U-shaped posture. After a prepupal stage of 2.5 days it pupates. The pupal period occupies about 11.7 days and a further seven days are spent by the adult in the pupal chamber. The adult female mates within a day of emergence from the stem. but does not oviposit until at least seven days have elapsed.

Observations on the biology of some members of the genus Tragocephala (Coleoptera, Lamiidae) associated with Theobroma cacao in West Africa

Members of the genus Tragocephala are widespread as pests of cocoa, and other tree crops, in West and also in East Africa. Those known to be associated with cocoa in West Africa are listed and observations are given on the biology of two of the more important, T. castitnia theobromae Entw. in Ghana and T. castnia cacaoensis Entw. in Nigeria, and a method of laboratory rearing and breeding is described.The egg is laid in an unhardened stem and the oviposition behaviour is complex; the stem is first girdled at a point where it is less than one centimetre in diameter and an oviposition slit excavated above the girdle. The ovipositor is inserted into this slit and the egg is concealed inside the stem; the adult finally closes the oviposition slit with her mandibles.The egg hatches after 11 days and the young larva bores upwards in the dead wood above the girdle. This phase appears obligatory and is followed by one in which the larva bores down into the living stem below the girdle. The mean larval period of T. castnia theobromae in the laboratory was 143 days (range, 70–228 days).A pupal chamber is made by severing the stem beyond about 10 cm. above the end of the gallery and filling the aperture with shreds of wood. The pupal period, in the last half of which adult coloration begins to show, is about 20 days for T. castnia theobromae and 23 days for T. castnia cacaocnsis.Laboratory evidence suggests that there is a post-pupal resting phase in the pupal chamber followed by a free-living non-feeding period; in T. castnia cacaocnsis these lasted on average 6·5 and 4·2 days, respectively, and were followed by intensive feeding on green unhardened stems. The length of life of caged adults varied greatly but the mean was 57·0 and 55·5 days for males and females, respectively, of T. castnia theobromae and 32·0 and 28·5 days for T. castnia cacaoensis. The least preoviposition period noted for T. castnia theobromae was 20 days and previously unmated males and females of this subspecies were still fertile up to at least 76 and 162 days, respectively. Mating normally initiated the bark-ringing behaviour of females and the maximum number of eggs laid by a female of T. castnia theobromae was 146. Considering only individuals that laid 25 or more eggs, an oviposition rate (number of eggs laid per day between first and last oviposition) of 0·51 was recorded for this subspecies. Host plants alternative to cocoa are listed for T. castnia theobromae and T, castnia cacaoensis.The oviposition activity of T. castnia theobromae was least in June, July, August, December and January, whilst for T. castnia cacaoensis very few eggs were laid in the main dry season (November to the following February).The eggs of T. nobilis (F.), T. castnia theobromae and T. castnia cacaoensis, and of another species in the Congo Eepublic, are attacked by the Encyrtid Aprostocetus lamiicidus Kerrich, which in Nigeria appears to undergo a larval diapause in the dry season. Whilst only 5·5 per cent, of eggs were attacked in Ghana, over 50·0 per cent, were attacked in Nigeria. There was an average of 11·7 individuals per egg and the ratio of males to females was 1:2·7.The Tachinid Billaea vanemdeni Fennah was parasitic on larvae of T. nobilis and T. castnia theobromae in Ghana, where its larval stage was in the region of 197 days and its pupal stage 23 days. Incidence of attack was highest from April to July and the two main adult emergence periods were June and September/ October.An Ichneumonid, Nadia sp., is parasitic on either larvae or pupae of T. castnia cacaoensis in Nigeria. Scolytid species incursive in wood dying after being girdled destroy many eggs in Nigeria, where geckoes and ants are thought to be responsible for loss of larvae.Tragocephala can be a locally important pest, especially of seedling cocoa and its numbers may increase considerably if unsuitable chemical control methods are used against other pests of cocoa.The bark-ringing habit in Cerambycidae is discussed.