Agriculture has been a very important sector in the economic development of countries for a very long time. The importance of agriculture lies in its ability to be a source of employment, raw material for industrial production, income to governments and most importantly as a source of food (Tiffen, 2003) [1] . In developing countries, the role of agriculture to poor families which spend less than a dollar a day is the only source of income and food; unlike in developed countries that have a variety of income generating options. Over 70 percent of poor families in developing countries are located in rural parts that have adequate land for crop production and pasture land for feeding livestock, but also spend their valuable working time in various agricultural activities (Hertel and Rosch, 2010) [2] . Despite the importance of agriculture to the rural poor population in developing countries, there have been various concerns in the ability of agriculture being reliable to the poor families to offer the required income and even food for the families. The poor families have consistently found agriculture to be unreliable because of low crop yields that are experienced every growing season. A lot of the farmers in developing countries often do not produce enough to feed their own families. The low crop yields in Madagascar, a poor African country, have been attributed to many factors that include loss of soil fertility, poor farming practices, climate change and use of unimproved crop varieties. However in South and Southwest regions of Madagascar, which are heavily infested by locusts, the most important factor leading to low yields is insects (Lecoq et al., 2011) [3] .

In Madagascar, the South and Southwest regions have for decades had locust outbreaks that have devastated crop fields (Lecoq et al., 2011) [3] . The locust species dominant in this area are the red locust (Nomadacris septemfasciata) and the Migratory Locust (Locusta migratoria capito), both of which have geographically restricted outbreaks (African Development Bank, 2001 [4] ; Magor et al., 2008 [5] ). The geographical restriction for the locusts is associated with the perfect environmental conditions in the region that allow them to go through the various stages of reproduction and also successfully survive. The solitarious and gregarious phases are the two main phases of locust population that represent the low population stage and the swarm population stage respectively (Sánchez-Zapata et al., 2007) [6] . However, the gregarious phase is associated with crop destruction, because of the increased locust population that causes significant harm to crops and other types of vegetation. The behavior of locusts has led to them being categorized as pests because they are organisms that interfere with the goals and activities of humans (Lomer et al., 2001) [7] . In the context of agricultural production, a pest can be defined as an organism which negatively influences the production of food and fiber (Shelton, AM, Badenes- Perez, 2006) [8] .

Pest control has exited ever since humans started growing crops and rearing livestock as a source of food. In agricultural production, there is always a competition between humans and pests for limited resources required for growth of crops and survival of pests. In view of this, there has always been the need in agriculture production to control and mitigate the negative effects of pests through the use of various pest control practices. In Madagascar the use of chemicals as a control practice has been preferred and overused for a long period of time, but it is both expensive and leads to environmental pollution. Despite the focus on chemical control of locusts in Madagascar, there are three other options and include biological controls, cultural controls and physical controls. Biological controls generally include the use of predators and disease causing organisms for the control of pests (Kar et al., 2012) [9] . A combination of these four categories of pest control is referred to as integrated pest management (IPM). The IPM approach is considered a better option because individual pest control initiatives do not have an effective outcome when compared to an integrated approach.

Many studies have been conducted to assess the beneficial direct interactions that exist between birds and plants (Meehan et al., 2005) [10] . Birds are known to play important roles as pollinators (Meffe, 1998) [11] , seed dispersers (Stiles, 2000) [12] , seed predators (Castro et al., 1999 [13] , Howe and Brown, 1999 [14] ), and herbivores (Noordhuis et al., 2002) [15] . These direct interactions have been shown to affect plant population dynamics and community structure, as well as the evolution and expression of plant life histories and morphologies (Meehan et al., 2005) [10] . Many bird species feed on locusts, but their ability to keep the locust population in check so as to avoid economic damage is not clearly known (Kirk et al., 1996) [16] . M. m. parasitus is widely distributed in sub-Saharan Africa, Comoros, and Madagascar and has strong intra-continental movements (Cramp & Simmons, 1980 [17] ; Fergusson-lees & Christie, 2001 [18] ). It is a migratory bird that flies to Madagascar every year at around the time when the weather and food competition is suitable for its survival and reproduction. This migratory behavior brings the bird species in large numbers making them a menace to the locust populations. Associated to the migratory behavior the bird occupies the study area (South and Southwest of Madagascar) in the period ranging from November to March, which is a time that coincides with high locust swarm development and propagation period. In this study, we considered the Black Kite (Milvus migrans parasitus) bird species in the area as a natural enemy for locusts; hence act as a biological preventive control method. However, questions existed on the locust feeding capability of the Black Kite (Milvus migrans parasitus) bird species to be considered as an effective biological preventive option that can form part of an IPM program. This paper aimed at determining the predation values from the Black Kite (Milvus migrans parasitus) bird species as a measure of effectiveness for locust outbreak preventive control. Furthermore, the study determined the predation values during both solitarious and gregarious phases.

Ecosystems are known for their roles in supporting their various members with resources for survival and other services that are crucial for individual organisms, but also their species as a whole. In the ecosystems, the food web is an interaction of organisms at different trophic levels that controls the performance of the general ecosystem, in terms of numbers. Two main approaches are central to the determination of the food web in an ecosystem and they include the top-down and bottom-up approaches (Hunter and Price, 1992 [19] ; Polis et al., 1997 [20] ). The top-down approach is a type of mechanism that is controlled by the organisms up the food web, which are the main consumers; while the bottom-up approach is the opposite of its counterpart as it is resource driven, which means it is controlled by organisms that are at lower levels in the food chain (Mantyla et al., 2011 [21] ). These approaches have formed the basis for this study, where plants are the producers fed on by locusts that in turn are preyed on by insectivorous birds. However, locusts’ swarms have been responsible for unsustainable consumption of plants, particularly crops in this case, to warrant the need for their predators in the ecosystem to control them. If an ecosystem is productive enough to facilitate the existence of vertebrate predators, the “ecosystem exploitation hypothesis” predicts that predators keep the population sizes of the notorious prey low, thus enabling plants to grow and reproduce (Oksanen and Oksanen, 2000) [22] .

Observed predation (OP) of the Black Kite (Milvus migrans parasitus) bird was done by examining the bird’s stomach contents to determine the number of locusts that were eaten. In performing this particular observation, this study predicted if the birds were able to enforce the ecosystem exploitation hypothesis in order to control gregarious phase of locusts. The results of the OP have shown the effect of vegetation on the ability of the Black Kite to feed on the locusts. Locust’s reproduction involves laying of eggs in the soil and the larvae that don’t have wings hop in vegetation that is close to the ground (Ambar, 2003 [23] ; Massey et al., 2007 [24] ). The Heteropogon contortus vegetation hosted a large number of locust larvae that were highly fed on by the birds. Similarly the wastelands, which are abandoned agriculture lands that were undergoing natural vegetation re-growth, had a large number of locust larvae. However, in areas with taller vegetation, the adults’ locust were dominant type found in the Black Kite bird stomach, which supported the observation that vegetation was associated to the size of locust found. The type of vegetation plays a role in attracting the birds to feed on insects that feed on it (Jones and Sieving, 2006) [25] . It was normal to observe in our study that birds caught in savannah and partly dry forest had a high number of locusts in their stomachs, maybe because the birds were attracted to this area.

Care in interpreting the results of stomach contents in birds was considered in this study, specifically on the number of adults and hoppers. In terms of numbers, the adult locusts were found in fewer numbers because they are larger in size hence the birds had to capture more hoppers than the adult locusts. This led to the experimental predation to assess if the Black Kite preferred eating hoppers or the adult locusts. A total of 1079 larval and 2083 fledglings were fed to the caged birds. The results showed that almost 100 percent of the larval and 97 percent of the fledglings were fed on during this duration. The EP for the larvae was calculated to be 77, while for the fledglings it was 65. Most avian species have opportunistic traits in their feeding habits, switching food types to take advantage of readily available food sources. For instance, during an insect outbreak in a Polish forest, predation of passerine nests declined, as predators switched to feeding on caterpillars (Tomialojc and Wesolowski, 1990) [26] . This indicates that the Black Kite bird generally feeds on the readily available locust that can easily be caught by the bird. Since the adult locusts are difficult to capture than the hoppers, then it would be no surprise that the fledglings were mostly captured in both experiments.

This study showed that the Black Kite birds can effectively control locust population in an outbreak when they are easy to predate on. Furthermore, the birds can be used as part of an IPM approach that can be used with other strategies. Despite the positive observation of this study, 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 and make an effective contribution to an integrated locust control approach. Such an assessment would correlate between the population of Black Kite and the role they can play in an IPM initiative. The role of parasites and predators, as a factor in the regulation of locust populations, has been thoroughly investigated and widely debated in the literature (Kirk et al., 1996 [16] ; Szabo, 2005 [27] ; Fildes et al., 2006 [28] ; Whelan et al., 2008 [29] ). The effects of predators and parasites are suggested to be modified by environmental conditions and by the stage of the outbreak (Wenny et al., 2011) [30] . Few natural enemies are associated with locust populations during the build-up phase, as parasites and predators depend on stable or declining populations (Lomer et al., 1999) [31] .

Mahitandrainy Jules Andriatsirevombola,Jiwen Ge,  Raholijaona, (2016) Predation Capability of Black Kite (Milvus migrans parasitus) on Locust as a Biological Control Option in Madagascar. Open Journal of Ecology,06,254-263. doi: 10.4236/oje.2016.65026