Subscribe Now Subscribe Today
Abstract
Fulltext PDF
References
Research Article
 

Abundance of Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae) in the Natural Herbaceous Fallow and Planted Forest: Effect of Chromolaena odorata (Asteraceae)



Sevilor Kekeunou, Stephan Weise and Jean Messi
 
ABSTRACT

This study assesses the abundance of Zonocerus variegatus in 2 natural herbaceous fallow and 2 planted forest types of the forest reserve of Mbalmayo (Cameroon) with the aim of testing the hypothesis that the high abundance of the grasshopper is linked to the presence of C. odorata. In each of 3 replications of each treatment, we carried out once every 14 days (from February, 2002 to December, 2003), regular collection and observation with sweep netting for a period of 30 mn. The results showed that, Z. variegatus is found in herbaceous fallows, but is extremely rare in the Inga edulis planted fallow. Within natural herbaceous fallows, it is significantly more abundant in those with, than in those without C. odorata, only in the dry season. No individuals were observed in the type I planted forest (without C. odorata) while 0.29 individuals were captured in the type II (with C. odorata). These data suggest that the type of vegetation has an important effect on Z. variegatus abundance.

Services
Related Articles in ASCI
Similar Articles in this Journal
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

Sevilor Kekeunou, Stephan Weise and Jean Messi , 2007. Abundance of Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae) in the Natural Herbaceous Fallow and Planted Forest: Effect of Chromolaena odorata (Asteraceae). Journal of Entomology, 4: 457-462.

DOI: 10.3923/je.2007.457.462

URL: https://scialert.net/abstract/?doi=je.2007.457.462

INTRODUCTION

The exclusively African variegated grasshopper Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae) is the main grasshopper crop pest in over twenty countries, which occupy the extensive forest and savanna areas of West and Central Africa (Modder, 1994). Z. variegatus is a non-migratory grasshopper, which may avoids the pure forest (Modder, 1994); cleared forest areas seem particularly suitable for the grasshopper (Modder, 1994; Kekeunou et al., 2005). There is no quantitative data to support these suggestions. In its natural habitat, Z. variegatus has six larvae stages; stage 1-3 larvae are gregarious while stage 4-6 larvae and adults are solitaries (Chiffaud and Mestre, 1990). In Southern Cameroon, Z. variegatus is present throughout the year in the undegraded and degraded zones in two univoltine populations, which has unequal abundance and durations (Messi et al., 2006). Z. variegatus live and feed on about 300 host plant species, including a wide range of plantation and subsistence crops (Chiffaud and Mestre, 1990; De Gregorio, 1989a,b). Chromolaena odorata (Asteraceae) is a most dominant herbaceous species in newly cleared areas in forest and along roadsides (Chapman et al., 1986). It is known to be one of the most important host plants of Z. variegatus, because it is consumed by all the post embryonic stages, it provides sites for laying and shelters and also serve as a source of Pyrrolyzidine Alkaloids for Z. variegatus (De Grégorio 1989b; Chiffaud and Mestre, 1990; Timbilla et al., 2007). From the southern Cameroon farmers’ point of view, the damage caused by Z. variegatus is higher in fields adjacent to C. odorata and herbaceous fallows than in those adjacent to forests and shrubby fallow (Kekeunou et al., 2006). In this study, we testing the hypothesis that the high abundance of the grasshopper is linked to the presence of C. odorata (Toye-Afolabi, 1974). It is generally established that the occurrence of acridid species primarily depends on the presence of host plant species (Kemp In Joshi et al., 1999). In Cameroon, short fallow systems (1-5 years) are dominated by Chromolaena odorata (Asteraceae). Because of the lack of adequate fertility, some leguminous species like Inga edulis are used for their improvement (IITA, 1998).

This paper evaluates the abundance of Z. variegatus (L.) (Orthoptera: Pyrgomorphidae) in natural herbaceous fallows and planted forests, with the aim to understand the effect of Chromolaena odorata presence on Z. variegatus population.

MATERIALS AND METHODS

Study Site
The study was carried out in the experimental station of the International Institute of Tropical Agriculture (IITA) located in the forest reserve of Mbalmayo (3°27’- 4°10’N and 11°32’-11°49’E, elevation = 600-1042 m asl), which covers approximately 109.3 km2 surface (Holland et al., 1992). Approximately 94.5% of this area is occupied by dense humid forest characterized by an abundance of Sterculiaceae and Ulmaceae (Holland et al., 1992). In the forest reserve, the forest canopy is irregular with towering emergent trees overtopping the main stratum of dominants, with smaller shade-dwelling trees below (Holland et al., 1992). In the undisturbed areas, the forest floor is relatively free of herbs, but there are many tree seedlings and saplings living in the shade below the canopy. This seedling bank is ready to compete for the increased light in a canopy gap when a decayed specimen collapses or a tree is brought down by lightning (Holland et al., 1992). The experimental station is an open area of approximately 400x400 m in which, the natural vegetation, consists of Chromolaena odorata, Mucuna sp., Triumfeta cordifolia. The rainfall pattern is bimodal, characteristic of equatorial climate. The small rainy season (March to June) is followed by the small dry season (July to August), and the great rainy season (September to November) is followed by the great dry season (November to March). The mean annual rainfall total for Mbalmayo from 35 years of data is 1513 mm, with a maximum of 1990 mm (1950) and minimum of 1017 mm (1946) (Holland et al., 1992). Overall there are six months in which average maximum temperature exceeds 30°C, December through to May. The monthly average minimum temperature is very stable, between 16.5 and 17.5°C (Holland et al., 1992).

Experimental Design
The observations were carried out in 4 types of existing fallows: two planted I. edulis forest (about 8 years old) and two natural bush fallows (4 years old) (one with C. odorata and another without C. odorata). The planted forest. Based on C. odorata presence, specific richness, presence and structure of herbaceous and shrubby layers, two types of I. edulis planted forest can be distinguished (type I and II). The trees of these two forests have heights of approximately 8 m; these trees are equidistant approximately 1 m (Table 1). These two forests installed on a surface of approximately 1500 m2 and separated by a distance of about 20 m. In type I, the herbaceous layer was weak and poor and deprived of C. odorata. The shrubby layer was absent. Type II, consists of an herbaceous layer dominated by C. odorata. In these two types of I. edulis forest, many plant species were found in Z. variegatus diet (Chiffaud and Mestre, 1990). In type I, specific richness (S = 28) is higher than that of type II (S = 24). Only 6 species were simultaneously present in the two types (Ficus exasperata, Lavigeria macrocarpa, Mallotus opasitifolium, Manihot esculenta, Rhinoria dentata and Terminalia sp.,). In each of these planted forests, captures were done in three selected 11.5x10.5 m plots.

Table 1: Main characteristics of two types of planted Inga edulis forests

The herbaceous fallows. Three replicates (11.5x10.5 m) of each of two herbaceous fallow types (with C. odorata and without C. odorata) were selected in the existing natural vegetation, surrounding the planted forest (in a distance of about 20 m). The natural herbaceous fallows were entirely dominated by C. odorata. Therefore, monthly mechanical extirpation was needed to remove C. odorata in order to create the without C. odorata treatment.

Sampling Procedure
Samples of Z. variegatus were collected by sweep netting for a period of 30 min in each plot (11.5x10.5 m) (Duranton et al., 1987; Dent, 1999). We carried out regular collection and observation once every 14 days in each fallow. Initially, we started the capture in the I. edulis forest type I, from February 2002 to February 2003. To confirm observed absence of Z. variegatus in this planted forest (without C. odorata), sampling was extended from June 2003 to December 2003 into the 4 types of fallow (herbaceous and forest with and whitout C. odorata). All the collections were started from a fixed point (chosen alternatively from the four corners) and extended across the entire plot. The collected individuals were kept in aerated bags and the individual numbers were counted by stage (larval and adult stages) and sex in the field. Thereafter, they were released at the plot where they were collected.

Statistical Analysis
Statistical analysis was carried out using SAS ver. eight (SAS Inc., Chicago, Illinois, USA). The averages were calculated by the MEANS procedure’ and compared by the Fisher ANOVA test using the GLM procedure. A pair of data was compared with Student Newman-Keuls test. All probabilities were appreciated at 5%.

RESULTS AND DISCUSSION

The levels of Z. variegatus population in the fallow vegetation depended on the vegetation type available (Table 2). The highest abundance was observed in natural herbaceous fallows and Z. variegatus is extremely rare in the planted I. edulis forest. This results confirm the assumptions of Modder (1994) that herbaceous fallows are an ideal habitat for Z. variegatus population. In fact, the majority of species consumed by Z. variegatus are found in the herbaceous fallows (Chiffaud and Mestre, 1990). Most grasshoppers including Z. variegatus live on or near their host plants. The ratio of host to non-host plants in an ecosystem plays an important role in determining the herbivore abundance (Rao et al., 2000). The abundance in the planted forest (I. edulis) was very weak because, Z. variegatus is an heliophilous insect (De Gregorio, 1989a,b). The herbaceous vegetation is sunny than forest under story. Forests under story maintain a shade and humidity hostile to the presence of Z. variegatus. Within closed forest, high humidity always favors Entomophaga grylli, which induces high mortality of Z. variegatus (Chapman et al., 1986; Modder, 1994).

The present study also showed that, within the herbaceous fallows the abundance was two fold greater in the fallows with (48 individuals) than those without (24 individuals) C. odorata. No individuals were observed in the type I planted forest (without C. odorata) while 0.29 individuals were captured in the type II (with C. odorata) (Table 2).

Table 2: Number of Zonocerus variegatus captured in 30 min in 2 herbaceous fallows and 2 planted forest types
p-value is the significance level of Fischer test-ANOVA (GLM). Similar letter(s) indicate non-significant differences

Table 3: Number of Zonocerus variegatus captured in 30 min during the rainy season in 2 herbaceous and 2-planted forest types
p-value is the significance level of Fischer test-ANOVA (GLM). Similar letter(s) indicate non-significant differences. Rainy season = Great and small rainy season

Table 4: Number of Zonocerus variegatus captured in 30 min during the dry season in 2 herbaceous and 2-planted forest types
p-value is the significance level of Fischer test-ANOVA (GLM). Similar letter(s) indicate non-significant differences. Dry season = Great and small dry season

This absence of C. odorata in the fallows induce a significant fall of Z. variegatus abundance only in the dry season (Table 3 and 4). This results confirm the Toye-Afolabi (1974) assumption that, increase in the dry season populations of Z. variegatus is linked to the spread of C. odorata. This result is explained by the fact that, in the dry season, most of C. odorata plants are in bloom (Mbarga, 1985). Z. variegatus is strongly attracted to flowers of C. odorata and grasshopper consumes the flowers in large numbers (Modder, 1984; Marks and Seddon, 1985). Z. variegatus consumes the pyrrolizidic alkaloids rinderine and intermedine from the flowers of C. odorata and transforms them into lycospamine and echinatine, respectively (Robins, 1995). Z. variegatus would use these pyrrolizidic alkaloids in the manufacture of the secretions of the repellent glands. These information’s could be useful in est management strategies. But, before final conclusion, complementaries studies need to be carried out on the effect of the non nutritional relationship between Z. variegatus and C. odorata.

ACKNOWLEDGMENTS

This study was financed by a grant from the weed and vegetation program of the International Institute of Tropical Agriculture (IITA) - Humid Forest Ecoregional Centre. We thank Mr. Sulem Steeve of ICLARM-Cameroon and Dr. Omer Njajou (University of California, San Francisco) for commenting on the manuscript.

REFERENCES
Chapman, R.F., W.W. Page and A.R. McCaffery, 1986. Bionomics of the variegated grasshopper (Zonocerus variegatus) in West and Central Africa.. Ann. Rev. Entomol., 31: 479-505.
CrossRef  |  Direct Link  |  

Chiffaud, J. and J. Mestre, 1990. The variegated grasshopper Zonocerus variegatus (Linne, 1758): Bibliographical synthesis. CIRAD-PRIFAS.

De-Gregorio, R., 1989. List commented on the work devoted to morphology, biology, ethology, food and seasonal polymorphism of Zonocerus variegatus I: Morphology, biology and ethology (Orthoptera Pyrgomorphidae). Bull. Societe Entomologique France, 94: 1-2.

De-Gregorio, R., 1989. List commented on the work devoted to morphology, biology, ethology, food and seasonal polymorphism of Zonocerus variegatus II: Food and seasonal polymorphism (Orthoptera Pyrgomorphidae). Bull. Societe Entomologique France, 94: 5-6.

Dent, D.R., 1999. Quantifying Insect Populations: Estimates and Parameters. In: Methods in Ecological and Agricultural Entomology, Dent, D.R. and M.P. Walton (Eds.). CAB International, New York, pp: 57-98.

Duranton, J.F., M. Launois, M.H. Launois-Luong, M. Lecoq and T. Rachadi, 1987. Anti-acridian guide of the Sahel. CIRAD-PRIFAS.

Holland, M.D., P.K.G. Allen, K. Campbell, R.J. Grimble and J.C. Stickings, 1992. Natural and human resource studies and land use options. Department of Nyong and so'o Cameroun. Main Report and Appendices, NRI.

IITA, 1998. Short fallow system to arrest resource degradation due to land use intensification. Project 1. Annual Report.

Kekeunou, S., J. Messi, B. Foahom and S. Weise, 2005. Impact of forest covers degradation on diversity and pest status of grasshoppers in Africa. Int. For. Rev., 7: 391-391.

Kekeunou, S., S. Weise, J. Messi and M. Tamo, 2006. Farmers perception on the importance of variegated grasshopper (Zonocerus variegatus (L.) in the agricultural production systems of the humid forest zone of Southern Cameroon. J. Ethnobiol. Ethnomed., 2: 17-17.
Direct Link  |  

Marks, M.K. and A.M. Seddon, 1985. Interaction between Chromolaena odorata (Compositae) and Zonocerus variegatus (Orthoptera: Pyrgomorphidae) with enphasis on achene predation. Afr. J. Agric. Sci., 12: 29-37.

Mbarga, M.A.C., 1985. Monographic study of Eupatorium odoratum (Asteraceae). M.Sc. Thesis. University of Yaounde.

Messi, J., S. Kekeunou and S. Weise, 2006. Abundance and life cycle of Zonocerus variegatus (Orthoptera: Pyrgomorphidae) in the humid forest zone of Southern Cameroon. Entomol. Sci., 9: 23-30.
Direct Link  |  

Modder, W.W.D., 1984. The attraction of the weed Chromolaena odorata and associated feeding behavior. Bull. Entomol. Res., 74: 239-247.

Modder, W.W.D., 1994. Control of the variegated grasshopper Zonocerus variegatus (L.) on Cassava. Afr. Crop Sci. J., 2: 391-406.
Direct Link  |  

Rao, M.R., M.P. Singh and R. Day, 2000. Insect pest problem in tropical agroforestry systems. Contributory factors and strategies for management. Agrofor. Syst., 50: 243-277.
Direct Link  |  

Robbins, D.J., 1995. Pyrrolizidine alkaloids. Natural Products Reports.

Timbilla, J.A., K. Yeboah-Gyan, B.W. Lawson and E. Woode, 2007. Screening of chemical insecticides for the development of pyrrolizidine alkaloid-based attracticides for the management of Zonocerus variegatus. J. Entomol., 4: 218-224.
CrossRef  |  Direct Link  |  

Toye-Afolabi, S., 1974. Feeding locomotry activities of Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae). Revue de Pathologie Agricole, pp: 205-210

©  2019 Science Alert. All Rights Reserved
Fulltext PDF References Abstract