Variation in Wing Length of the African Armyworm, Spodoptera exempta in East Africa During 1973-74

AbstractThe association between weather and light-trap catches of Spodoptera exempta (Wlk.) was examined for four traps in East Africa, using whole–night catches and several years' data. Large increases in trap catch were found to be (1) significantly associated with rain at all four traps for the period December–March, but not for later in the season; (2) significantly associated with light wind periods at Muguga for December–May, but not later in the year, and not at Nakuru, due to the very high overall frequency of light winds there; and (3) not significantly associated with windshifts at either Muguga or Nakuru. These results suggest that high densities of flying moths, which may give rise to caterpillar outbreaks early in the year, often occur where the rather infrequent early–season rains fall.

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Predicting the severity of Spodoptera exempta (Lepidoptera: Noctuidae) outbreak seasons in Tanzania

Bulletin of Entomological Research ◽

10.1017/s0007485300032958 ◽

1995 ◽

Vol 85 (4) ◽

pp. 479-487 ◽

Cited By ~ 7

Author(s):

A.W. Harvey ◽

G.A. Mallya

Keyword(s):

East Africa ◽

Negative Correlation ◽

Seasonal Pattern ◽

Light Trap ◽

Spodoptera Exempta ◽

Convergence Zone ◽

Light Traps ◽

Inter Tropical Convergence Zone ◽

African Armyworm ◽

Lepidoptera Noctuidae

AbstractOutbreaks of the African armyworm, Spodoptera exempta (Walker), in East Africa follow a seasonal pattern related to the movement of the inter-tropical convergence zone. The season typically begins in central Tanzania with primary outbreaks that coincide with the arrival of the rains. An analysis of 27 years' light trap records shows a high negative correlation between the total number of moths caught by light traps during the season over the whole country and the number of rain days during November in central Tanzania. Out of the 27 seasons, 22 could have been correctly predicted as ‘light’ or ‘severe’, using the November rainfall at one station, Dodoma, in time to give two months' warning before the peak of the season.

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New evidence on the migration of moths of the African armyworm, Spodoptera exempta (Wlk.) (Lepidoptera, Noctuidae)

Bulletin of Entomological Research ◽

10.1017/s0007485300056674 ◽

1966 ◽

Vol 56 (4) ◽

pp. 671-684 ◽

Cited By ~ 48

Author(s):

E. S. Brown ◽

G. Swaine

Keyword(s):

East Africa ◽

Adult Stage ◽

Sex Ratios ◽

Spodoptera Exempta ◽

Light Traps ◽

African Armyworm ◽

New Evidence ◽

Lepidoptera Noctuidae

Fresh evidence is described which supports the theory that moths of the Noctuid Spodoptera exempta (Wlk.) (the adult stage of the African armyworm) are migratory. The evidence comes from four main sources: a study of fluctuations in numbers of moths caught in a network of light-traps operated in East Africa; the fertilisation rates in samples of females as shown by dissection; the sex ratios in samples of moths caught in light-traps; and a study of the behaviour of moths in the field during the period immediately following emergence. In certain of these features S. exempta is compared and contrasted with the related S. triturata (Wlk.), in which the evidence points against extensive migration.It is concluded that migration occurs in S. exempta, probably on an extensive scale, and that it therefore has an important bearing on the occurrence and distribution of outbreaks of the larvae.

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Rainfall and outbreaks of the African armyworm, Spodoptera exempta (Walker) (Lepidoptera: Noctuidae)

Bulletin of Entomological Research ◽

10.1017/s0007485300008804 ◽

1983 ◽

Vol 73 (2) ◽

pp. 195-199 ◽

Cited By ~ 28

Author(s):

M. R Tucker ◽

D. E Pedgley

Keyword(s):

East Africa ◽

Egg Laying ◽

Spodoptera Exempta ◽

African Armyworm ◽

Grass Growth ◽

Lepidoptera Noctuidae

AbstractFrom estimates of the most likely egg–laying dates of 53 outbreaks of Spodoptera exempta (Wlk.) in East Africa, and from estimates of the likelihood of rainstorms (20 mm or more a day) at the outbreak sites around those dates, it is shown that concentrated laying by moths leading to outbreaks early in the season (January to March) in 1974–75 was associated with rainstorms at the time of oviposition. However, there was no such association in April and May. The mechanism of association is unknown; moths may be concentrated whilst airborne, or they may reach and stay in limited areas wetted by rain, where new grass growth might be expected.

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