Survival and mortality of grasshopper egg pods in semi-arid cereal cropping areas of northern Benin

Abstract

Surveys of egg pods of agriculturally important grasshoppers were carried out in northern Benin between 1992 and 1995. Searches were made of oviposition sites under shrubs of the perennial legume Piliostigma thonningi along field margins. In 1993 and 1995, surveys were extended to include sorghum, Sorghum bicolor, and the perennial thatch grass Vetiveria nigritana. The four principal grasshopper species found at these oviposition sites were Hieroglyphus daganensis Krauss, Cataloipus fuscocoeruleipes Sjostedt, Kraussaria angulifera (Krauss) and Tylotropidius gracilipes Brancsik comprising 86% of 4545 identified egg pods while 651 egg pods could not be identified to species level. Predation by meloid beetles (Epicauta, Mylabris and Psalydolytta spp.) varied between 0 and 50% for the four dominant grasshopper species. From 1993 and 1994 data, nymphal eclosion from egg pods damaged by meloids was significantly lower than emergence from undamaged egg pods. The hymenopterous parasitoids Scelio africanus Risbec and S. mauriticanus Risbec were reared from the four dominant grasshopper species and parasitism levels of 0.0-3.3% were recorded from these hosts. There were significant differences in nymphaJ emergences between parasitized and unparasitized egg pods of H. daganensis.

Development of strategies for the incorporation of biological pesticides into the integrated management of locusts and grasshoppers

“…Early observations on the impact of egg parasitoids on desert locust populations are reported by Greathead (1963Greathead ( , 1992. Shah et al (1998) conducted extensive observations over four seasons on the natural enemies affecting egg pods in Malanville, north Benin. Meloid beetle predators accounted for up to 50% mortality (Epicauta sp., Mylabris (4 spp.)…”

Enumerative sampling plans for grasshopper egg pods in northern Benin

“…During surveys carried out between 1992 and 1995, a total of 3030 egg pods of H. daganensis and C. fuscocoeruleipes were collected, 88.2% were from P. thonningi , 9.8% from V. nigritana and 2.1% from S. bicolor (Shah et al, 1998). As a better comparison of the importance of the three vegetation types for oviposition, 1243 egg pods were found in 1993 and 1995 of which 71.1, 23.8 and 5.1% were from P. thonningi , V. nigritana and S. bicolor , respectively.…”

“…The present work forms part of a larger study being undertaken in northern Benin concerned with egg‐quiescent grasshopper pests (Shah et al, 1998). The objectives are to evaluate the impact of natural enemies, determine whether control measures are necessary on the basis of egg pod densities and to investigate whether mechanical destruction of egg pods by farmers, during the dry season, may cause long‐term reductions in grasshopper numbers.…”

Divergent Egg Physiologies in Two Closely Related Grasshopper Species:Taeniopoda equesversus Romalea microptera (Orthoptera: Romaleidae)

“…Furthermore, in the field, desert T. eques lay deeper egg pods than R. microptera (9.3 vs. 3.9 cm to the bottom of the pod) (Stauffer and Whitman 2007), which presumably keeps the eggs away from the hot and dry desert soil surface (Wardhaugh et al 1969). In contrast there may be advantages for marsh-inhabiting R. microptera to lay pods near the soil surface, because deep pods experience greater flooding, and flooding can kill grasshopper eggs (Popov 1959, Shulov and Pener 1961, Uvarov 1966, Farrow 1975, Shah et al 1998). Almost all grasshopper species oviposit underground, and it is well known that desert grasshoppers tend to lay deeper egg pods than do mesic or hydric species (Stauffer and Whitman 1997).…”