Evaluating The Predation Impact Of Cattle Egret (Bubulcus Ibis) And Yellow-Billed Kite (Milvus Aegyptius) On Migratory Locust (Locusta Migratoria Capito) And Red Locust (Nomadacris Septemfasciata) In South And Southwest Region Of Madagascar

In Madagascar, the South and Southwest regions have for decades had locust outbreaks that have devastated crop fields. The locust species dominant in this area are the red locust (Nomadacris septemfasciata) and the Migratory Locust (Locusta migratoria capito). Control of locust outbreaks in Madagascar has proven to be very difficult; the control methods of locust outbreaks in Madagascar have leaned towards use of chemicals that are expensive and lead to environmental pollution. The locust behavior in South and Southwest regions of Madagascar follows the observed trends of locust plagues that breed successfully from solitarious to gregarious phase. Furthermore, the locust plagues are geographically restricted, which means the plagues have always occurred in the same region. To control locust plagues that have a geographical restriction, preventive control against pre-plague swarms has been widely recommended. Biological control of locust is deemed as a cheap and environmental friendly method, because it uses the pest’s natural enemies as a population control mechanism. Many bird species feed on locusts, but their ability to keep the locust population in check so as to avoid economic damage was not clearly known. In this study, we considered the Bubulcus ibis (Cattle Egret) and the Milvus aegyptius (Yellow-billed Kite) two bird’s species in the area as a main natural enemy for locusts.This study was mainly devoted to provide a great understanding on the effectiveness of Bubulcus ibis (Ardeidae) and Milvus aegyptius (Accipitridae) predation on locusts as a biological control method for locust outbreaks in the south and southwestern parts of Madagascar. Specifically the study aimed to (1) highlight the bird population capacity on the predation; (2) determine the predation values of the Bubulcus ibis ibis and Milvus aegyptius on locusts during the outbreak and remission periods; (3) determine the pecking frequency of the Bubulcus ibis ibis on locusts during the outbreak and remission periods; (4) determine the factors that influence successful predation of Bubulcus ibis and Milvus aegyptius on locusts. The research contents of this thesis are summarized as follows:Influence of Environment on Birds-An Inventory of Birds in Madagascar:The main objective of this chapter was to explore the existing relationship between bird population and the environment they exist in and how it would affect their predation on locusts. The population was observed from two main locust research stations of Antsakoaky (An open station devoid of net forest formations) and Ilempo (a closed station that consisted of a natural clearing, surrounded by xerophytic forest formations). The presence-absence method was applied and used the signs (+) and (0) to represent presence and absence of a bird respectively. The principle was based on the counting method on birds seen for a fixed duration and fixed hours. The results found that there were four main groups of birds based on their feeding preference and they included insectivorous, piscivorous, granivorous and carnivorous bird species. The insectivorous species were the most abundant group as represented by 37% of the total species identified. The piscivorous bird species had a proportion of about 28% and the carnivorous bird species were the third most abundant group with 20% of the species types. The most important group of species were the acridophagus and included Acridotheres tristis, Aviceda madagascariensis, Bubulus ibis, Corvus albus, Dicrurus forficatus, Eurystomus glaucurus, Falco concolor, Leptosomus discolor, Merops superciliosus, Milvus aegyptius and Numida maleagris. The five (5) species important to control of locusts included Bubulcus ibis, Milvus aegyptius, Corvus albus, Falco concolor and Meropssu perciliosus. Furthermore there were more birds in the 2012/2013 growing season than the 2013/2014 season. Additionally, the Corvus albus (CAL) and the Bubulcus ibis (BIB) were the most abundant bird species in the two years. The Bulbulcus ibis was the most populated when the total from all the sites is combined as it recorded a population of 10226 birds and compared to the Milvus aegyptius that had 1990 birds.Milvus aegyptius Predation Capability:This chapter aimed at determining the predation values from the Yellow-billed Kite (Milvus aegyptius), a natural enemy for locusts, as a biological measure for locust outbreak control. Two types of experiments were done that included observed predation (OP) and experimental predation (EP). It was observed, in the observed predation, that a higher number of locusts were found in the bird’s stomach during the afternoon session (mean= 66) than during the morning session (mean= 21). The high peak observed during the afternoon session was also associated with the feeding of Nymphs of the Migratory Locust. The experimental predation results showed that almost 100 percent of the nymphs and 97 percent of the fledglings were fed on. The experimental predation results also showed that there was no preference for nymphs or fledglings in the cage and that the bird’s fed on the different combinations equally. This study showed that the Yellow-billed Kite birds can effectively control locust population in an outbreak when they are easy to predate on. However, there is a need to assess the population of birds in locust infested areas to determine if the bird population is enough to predate on a locust outbreak.Predation Impact of Bubulcus ibis:This chapter determined the predation values of Bubulcus ibis bird species as a measure of effectiveness for locust outbreak preventive control. Three types of experiments were done that included observed predation, potential predation and pecking frequency. The observed predation was 19 locusts per day in the outbreak period higher than remission period with a value of 3 locusts per day. The experimental predation was 54 locusts per day, and was higher than the observed predation in the outbreak period. The highest pecking frequencies were observed in Isoanala (mean= 20.34) followed by Bekily (mean= 8.34) and Tulear (mean= 5.75). The observations from Bekily and Tulear were significantly different (t (56)= 2.49, p= 0.000), because of vegetation type. In Tulear the vegetation was bushy and thick, which provided canopy for the locust unlike the savannah environment in Bekily. The use of birds in prevention of locust outbreak during remission was found to be interfered by other insects that were fed on by birds. Thus locusts can best be controlled by birds when their population increases in an outbreak. However, there is a need to assess the population of birds to determine if they were enough to predate on a locust outbreak.Conclusion:This study determined the role of both native and migrant bird species on their ability to be used as natural predators of locust during both outbreak and remission period. The identification of these birds ability as predators will be considered in the broader efforts of its effectiveness as a biological control in a broader locust control approach of integrated pest management. Specifically the study is innovative as (1) the study has, for the first time, used the Bubulcus ibis and Milvus aegyptius bird species in Madagascar as natural biological controls for locust outbreaks; and (2) this research was a regional study in southern and southwestern parts of Madagascar, which has contributed valid information on the locust swarm control using economically sound and ecological friendly methods.