Agricultural pest management studies

Occurrence, biology, natural enemies and management of Tuta absoluta in Africa

International audience

THE BREEDING BIOLOGY OF THE BLACK‐FACED DIOCH <i>QUELEA QUELEA</i> IN NIGERIA

SUMMARY A study of the breeding biology of Quelea quelea in Nigeria, and particularly at a large breeding colony near Lake Chad, showed that losses of eggs and young were extremely small. 95% of eggs laid hatched successfully, and 87% give rise to fledglings. Nestling deaths were density‐dependent and apparently due to starvation. The incubation period was 10 days or less. By day, eggs were heated to 34°‐ 37° C. by the sun; at night the females incubated. The nestlings were initially fed mainly on insects, their diet gradually changing to one of seeds—mostly of the grass Echinochloa pyramidalis . The deep body temperatures of young birds were determined. It is suggested that the nestlings left the nest after, on average, 11 1 / 2 days to escape intolerable temperature conditions in the nest. Fat reserves were accumulated by nestlings and fledglings, and were utilized when the young became independent. The adults put on fat during the incubation period and lost it during the time spent feeding nestlings. It is concluded that the most common clutch‐size of Q. quelea , which is everywhere three, corresponds to the largest number of young the parents can normally nourish. This conforms to Lack's theory on the significance of clutch‐size, and gives no support to Skutch's opinion that the theory does not apply to tropical birds.

Some aspects of the biology of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), a pest of stored groundnuts in Nigeria

Biology ofEpidinocarsis [=Apoanagyrus] lopezi [Hymenoptera: Encyrtidae] an exotic parasite of cassava mealybug,Phenacoccus manihoti [Homoptera: Pseudococcidae] in Nigeria

Floral Biology and Pollination Ecology of Cowpea (Vigna Unguiculata L. Walp)

Studies on the floral biology and pollination ecology of three varieties of cowpea (Vigna unguiculata L. Walp) were carried out. The varieties studied were Var. Oloyin, Var. Sokoto, and Var. Drum. Cowpea is a self pollinated crop which is encouraged by the arrangements of the floral parts. However, Insects visiting cowpea flowers have been implicated in the movement of pollen from one cowpea plant to another. Flower opening of cowpea begins between 6:00am and 6:30am and closes between 11:30am and 12:00pm. Pollen analysis showed similarities in the pollen morphology of the cowpea varieties. Moreover Var. Drum produced the highest number of pollen grains per flower in terms of pollen productivity.

The Biology and Ecology of Busseola fusea and Sesamia Species in South-Western Nigeria. I. Distribution and Population Studies

The distribution of maize stem borers, Busseola fusca Fuller, Sesamia calamistis Hampson, and S. penniseti Bowden, throughout south-western Nigeria was studied between November and December 1964. The maize-sample survey revealed that B. fusca was more abundant than S. calamistis. While B. fusca was prevalent in the southerly, more humid lowland rainforest zones, S. calamistis was generally distributed and was more prevalent in the dry savanna zones of the region. S. penniseti was not abundant and was very sparsely distributed. There was a marked difference in the position of egg masses on the maize plants. All egg masses of B. fusca were laid within 30 inches of the maize whorl, while S. calamistis egg masses were spread over greater distances from the whorl. This distribution appears to be associated with the larval habits of both B. fusea and S. calamistis. Larval populations studies revealed that in lbadan (and probably south-western Nigeria) there are 4 generations of B. fusca in maize per annum. There are 2 generations between April and July, 1 in September-October, and another in November. It is the larvae of the November generation which go into the dry-season diapause and which later give rise to the 1st-generation adults the following year. S. calamistis,, although not so numerous as B. fusca, was observed to breed throughout the year.

Studies on the biology of <i>Acanthomia tomentosicollis</i> (Stål) (Hemiptera: Coreidae) in the field and insectary

Abstract Studies on the biology of Acanthomia tomentosicollis (Stål) at Ibadan, Nigeria, showed that the periods of development in the field and the insectary averaged 17 and 18 days, respectively. The hemispherical, hexagonally sculptured eggs were laid in batches of 2.99 (mean=7 eggs per batch in the insectary and 20 in the field). Preoviposition periods were 11–22 days in unmated and 6–9 days in mated females. The mean number of eggs deposited by mated females (202) was significantly higher than that deposited by unmated females (135), although the average oviposition period of 16 weeks in unmated females was three weeks longer than in mated females. Unmated males and females were longer-lived than their mated counterparts, and females generally lived longer than males. These results and other observations on 'the biology of A. tomentosicollis are discussed in the context of its seasonal biology and the pattern of infestation of pigeon pea ( Cajanus cajari ), its main host plant.