30 



THE AGKICULTLJRAL NEWS, 



January 22, 191Ch 



FUNGUS NOTES. 



FUNGI ATTACKING INSECTS. 



Several articles Lave appeared in the recent numbers of 

 the A<i)inilturnl Xcvg, in which reference has been made to 

 the fungoid parasites of scale insects; but many other insects, 

 belonging to widel)' different groups,' are liable to be attacked 

 by fungi, and it is thought that a brief account of some of these 

 parasites, and of the insects attacked, ma}- prove of interest. 



Flies are often attacked by a species of Emjmsa. Infected 

 Hies are frequently found on windows in a moribund condi- 

 tion. After death, the Hies remain sticking to the glass, their 

 bodies becoming dry and mummified, owing to the presence 

 of a mass of fungal hyphae within them. At a later stage, 

 the hyphae grow out from the body over the glass, and may 

 form a white ring around it. The fungus is of general 

 occurrence, and, in some seasons, large numbers of Hies are 

 killed by it. A closely allied fungus, belonging to the genus 

 Entijiiiophthora, has been found on spiders in Trinidad. 

 ilucor e.fitiosiis, like Eniptixa and Ento)noplillioru, one of the 

 lower fungi, has been considered to be the cause of a disease 

 of locusts that is of wide-spread occurrence in South Africa; 

 attempts to employ this fungus for controlling this pest have 

 unfortunately met with but little success, and it is .suggested 

 that the disease is in reality mainly due to some other fungus, 

 possibly Empusa grylli, which sometimes causes an epidemic 

 among grasshoppers in the United State"; and other parts of 

 the world. Grasshoppere attacked by Eiiipiisn ;/ri///> show 

 a tendency to crawl upwards, usually on the stalks of plants, 

 and cling tightly after death. The fungus also attacks cer- 

 tain caterpillars which exhibit the same .symptoms when 

 diseased. Cultures of this fungus have been used in the 

 United States as a means of artificial infection, and in some 

 cases they were very success! ul; a few insects were caught, 

 dipped in the cultures, and then permitted to go free 

 among the rest. Other members of the group Entomoph- 

 thoreae are to be found attacking gnats, midges, certain 

 mosquitos and scale insects. 



Grasshoppers in the Argentine Eepublic are also 

 attacked by a species of Sjiorotrichum {S. globnliferiim). 

 The dead insects are to be found in cool, damp places, 

 such as the roots of grasses. The fungus is the same 

 as that which kills chinch bugs in North America. The 

 species of this group form a white or creamy mycelium, which 

 eventually covers the infected insect, and then produces 

 masses of spores, giving it a powdery api)earance. The 

 spores are borne on short, simple or branched conidiophores 

 which arise as lateral outgrowths of the main hyphae. 

 They are very small, usually more or less oval, and quite 

 colourless. They may occur singly on the conidiophores, or 

 may be grouped into heads, owing to the spores which have 

 been formed adhering laterally to the conidiophores and to 

 one another, as they are pushed aside by the ue.xt younger 

 spore. AVhite grubs, wasps, ants, aphids and scale in.sects, 

 particularly those of the genus Lccmium, besides grasshop- 

 pers and chinch bugs, are attacked by members of this genus, 

 to which the shield scale fungus of these islands may possibly 

 belong. (See Aijiiniltiiyal A'eirs, Vol. VIII, p. 299.) 



Some of the .species of Spnrotricliuw very closely 

 resemble the simplest conidial stage in the life-history of the 

 genus Vordyccj^s, whose members attack all kinds of insects, 

 as the larva, the perfect insect, and probably as the pupa. 

 The fungi lorm a white or coloured mycelium in the insect, 

 which eventually covers the surface in many cases, and there 

 produces the first spore form, resembling that of a Sporo- 

 hic/ium. This spore form, however, varies considerably in 



the different species, and may have simple conidiophores 

 producing single spores or heads of spores, or branched 

 conidiophores sometimes bearing chains of spores, so that 

 the fructifications closely resemble those of the genus 

 Penicillium; the colour is also very variable. The next 

 stage in the life history is the formation of the Isaria, 

 fructification This consists of an upright, conical or cylin- 

 drical body, usually somewhat pointed, formed by the close 

 interweaving of the hyphae; the whole of its surface is- 

 covered with conidiophores bearing small conidia. The shape 

 of the conidiophores varies, as also does the colour of the 

 whole fructification. Finally, the perfect or ascigerous stage 

 is formed. The stalk of the Isaria fructification thickens,, 

 and a spherical or cylindrical top is formed in which the 

 perithecia are more or less sunken. The asci contained in 

 the perithecia produce eight long filamentous spores, which.' 

 frequently break up into numerous much smaller spores, and 

 these are extruded as a fine dust. 



The fungus is often found on dead caterpillars. These 

 keep their original shajjc, but become filled with the- 

 mycelium of the fungus, which forms a sclerotium inside the 

 skin. From this the fructifications arise, either direct!}-, as 

 the Cofdi/rcps stage, or more generally with the intervention- 

 of the Imi ia condition. Some species form the perfect 

 fructification rarely, and only arrive at the Isaria sta^e, and 

 some are most generally found in the first conidial form, only^ 



The insects attacked are very various, the most general 

 being caterpillars both of moths and butterflies. The Isaria 

 stage of Cordyc&ps Barheri is recorded as a useful parasite on 

 the larva of the moth "borer of the sugar-cane, Diatraea 

 saccharalis, in Martinique and elsewhere. {Agricultiiral 

 Kexrs^ Vol. Ill, p. 13.5; Vol. VI, p. 3.) Another species is of 

 common occurrence on the large Lecaniums. A specimen 

 of the perfect stage of a sphinx moth, probably Ani-ery.i; 

 fnsciata, is recorded as being attacked Ijy Isaria sphingum 

 whose mycelium is of a vellowish colour. (Aaricvltnral Xevs 

 Vol. V, p. 1.38.) 



Itecently, specimens of the 'Jack Spaniard', Fo/isfes 

 annularis, and of a cotton stainer, Di/sdcrcas sp., were 

 received from Mr.s. Patterson in St. Vincent. These showed 

 a cream-coloured, cottony mycelium between the scales of the 

 insects, accompanied by grey Isaria fructifications of some 

 species of Cordyreps. The occurrence of this fungus on the 

 cotton stainer is of interest, but it seems unlikely that it will 

 be possible to make use of it from a practical point of view. 



Another genus of fungi is known to attack insects, 

 namely Batrytis. One specie.s, B. hassiaiia, occurs on silk- 

 worms. Another, B. eriojJiyt-s. Mass., has recently been 

 described as occurringon the black currant mite, Eriophyes ribis. 

 {Journal oT Eronoiiiii: Biolo'jy, Vol. IV, Xo. 1.) The fungus 

 produces sterile, creeping hyphae, septate and vaguely branched. 

 On these arise erect fertile hyphae bearing at intervals clusters 

 of from three to six whorled conidiophores. Each conidio- 

 phore is acutely pointed at the tip and bears a single, erect,. 

 hyaline conidium. The fungus may be either parasitic on the 

 mites or .saprophytic on decaying leaves. It is of interest 

 because the black currant mite is allied to the leaf-blister 

 mite of cotton, Eriopliyes gossypii, and it is possible that it 

 might be successfully introduced into these islands. It is 

 also possible that the same, or some other fungus occurs 

 naturally here on the leaf-blister mite, but has been over- 

 looked up to the present. 



Any further observations with regard to the occurrence 

 of different species of entomogenous fungi, particularly of 

 the genus Cordyceps, would be of considerable value, and 

 a request is made by the Department for useful information 

 and specimens, from those who are interested in the subject. 



