Spread Of Insects Research Articles

The Insects associated with Export Produce in Southern Nigeria

The problem of insect infestation of stored export food commodities in southern Nigeria is discussed, and a list of insects is given. At the ports there is considerable cross-infestation between commodities produced in northern and southern Nigeria awaiting shipment.Old sacks used for the storage and transit of groundnuts are responsible for the spread of insects to palm kernel and cocoa marketing centres in the south. After bulk shipments of a portion of the groundnut crop, sacks are repaired and distributed for the shipment of palm kernels and some of them may be used by fanners and brokers as service bags for the marketing of cocoa and local food commodities. The importance of disinfestation before distribution is realised, and a small fumigation plant is in operation at port.Ephestia cautella and Lasioderma serricorne are the major pests of stored cocoa beans. Both originate in farmers' and brokers' stores which are rarely cleaned, and in which small parcels of low-grade beans may be retained for mixing with a following crop to conform with an exportable grade. Ephestia cautella also infests palm kernels, and the early abundance of adult moths in cocoa stores up country during the marketing season is considered to be largely due to the storage of palm kernels in the vicinity. The development of Ephestia larvae can be completed on the outside of cocoa beans, only germinated or damaged beans being penetrated.

The Spread of Scale Insects and their Parasites

MANY years ago I was an industrious collector of scale insects and mealy-bugs, especially in Jamaica. I found them in great abundance on cultivated plants, and obtained many species. When recently travelling in the Oriental tropics, I was struck by the relative scarcity of these insects, and the occurrence of various well-known injurious forms only in small patches or isolated individuals. Perhaps the difference was partly due to the relative poorness of my eyesight, but I could not help speculating on the causes which might lead to a diminution of scale insects on cultivated plants, aside from the operations of economic entomologists. World-wide commerce has spread the injurious Coccidae over the earth, as they are so easily carried with plants. In their native countries they are efficiently controlled by parasitic and predatory enemies. In several well-known cases a plague has been abated by going to these countries and obtaining the natural enemies, which had failed to arrive with the first (accidental) importation of the coccids. Thus, following the modern expansion of trade and rapid transit, there has been in many regions a great increase in the damage done by scale insects, at times reaching the magnitude of a calamity. But by the same process, gradually but surely, the natural enemies will also spread. In the course of time, almost imperceptibly, they will gain the ascendancy, and the coccid plague will cease, never to return unless through the importation of a new sort of cocoid. Thus it may even happen in some cases that a rigid quarantine, after a pest has arrived, may be harmful, preventing natural enemies from following it. These latter may, however, be brought in by entomologists, through special permission, provided they have been found and recognised.

Balloons to Study The Spread of Insects

Balloons to Study The Spread of Insects

Balloons to Study The Spread of Insects

Balloons to Study The Spread of Insects

The Spread of Injurious Insects

IN 1898 Dr. L. O. Howard forwarded to me a scale insect discovered by Prof. Chaves at Ponta Delgada, Azores, attacking the foliage of the orange tree. The insect proved to be new, and was described as Lecanium perlatum. Since that time it has never been reported from any other place; but now I have received some large, flat, dark brown scales on orange leaves from Villa Encarnacion, Paraguay, collected by Mr. Schrottky, and they are this very same L. perlatum.1 This is only one new case to be added to the many already known of scale insects being transported from one side of the world to the other, evidently by human means. It is to be regretted that the British Government, with its numerous tropical colonies and excellent botanical gardens, has not done something to make known the scale insects within its domains. It is true that Mr. E. E. Green, the Government entomologist of Ceylon, is bringing out a magnificent work on the scale insects of that island; but he finds insufficient support, and it is divulging no secret to say that the publication of this useful book will involve him in very serious financial loss. There is no properly classified national collection of scale insects (the only good collection in England is that of Mr. Newstead at Liverpool), and we are still totally ignorant of the coccid fauna of many colonies. The reasons for regretting this condition of affairs are mainly two:—(1) because in ignorance pests of this group are continually being carried to new regions, where they are liable to become destructive; and (2) because man is so mixing up the distribution of these insects that every year makes it more difficult to ascertain their natural habitats. Having regard for the experiences of the past, it is surely safe to say that the annual expenditure of a few hundred pounds in the investigation of these pests would be far more than repaid in economic as well as scientific gains.