Alternative hosts refer to plant species that are not grown for other types of agricultural products but can be used as replacements for insects’ food sources or habitats, specifically parasitoids and predators (Denys & Tscharntke, 2002). These host plants have a significant impact on the biology and population dynamics of plant pests. Alternative hosts provide shelter and resources for arthropods during unfavorable seasons, enabling them to survive and thrive so that they can complete their entire life cycle on alternative hosts even when their preferred host is absent. Alternative hosts can also serve as breeding grounds, supporting the reproduction and population expansion of arthropods (Kumar et al., 2021). Hence, to develop more effective pest control tactics, it is crucial to comprehend the relationship between arthropods and alternative hosts (Sudbrink et al., 1998). By identifying and implementing strategies to manage alternative hosts, farmers can reduce pest populations in rice fields effectively and minimize crop damage. Common pest management strategies include suppressing weeds and employing trap plants to target pests on different hosts (Pasini et al., 2018).

Some alternative hosts discovered in rice farming areas are Ageratum conyzoides L., Spermacoce verticillata L., Euphorbia heterophylla L., and Chloris barbata L. Ageratum conyzoides is commonly referred to as wild goat weed. These plants may be employed as trap plants within a push-pull strategy for pest management in cereal harvests. They have been successfully reported to repel pests while simultaneously attracting natural enemies, thereby diminishing pest populations when intercropped with cereals such as wheat, maize, and barley (Huss et al., 2022). In addition, A. conyzoides can serve as a valuable source of livestock feed and generate multiple streams of supplementary income for farmers (Khan et al., 2014). The weed survey investigation identified S. verticillata, also known as Shrubby False Buttonwood, as one of the predominant species observed in cassava plants. According to Miléo et al. (2016), S. verticillata can be an alternative host plant in agricultural settings.

Furthermore, an investigation into the foraging habits of the Larra bicolor F. stinger, a parasitic insect that preys on Scapteriscus grasshoppers, revealed that S. verticillata is the favored choice of food for the stinger when compared to other nearby plant species (Portman et al., 2010). The data indicate that S. verticillata can be a beneficial resource for multiple kinds of parasitoid insects. Euphorbia heterophylla has been identified as a potentially beneficial plant for enhancing the population of parasitoids, such as Goryphus bunoh Gauld, Dolichogenidea metesae Nixon, and Brachymeria carinata Joseph, Narendran and Joy, to manage the bagworm Metisa plana Walker infestations in oil palm (Ahmad Ali et al., 2007; Sahari et al., 2023). Meanwhile, on C. barbata, Coccinella transversalis F. was recorded feeding on Sitobion sp. in a rice field during harvest (Chitra et al., 2018). As a result, diverse plant species can promote a wider range of insect species. The inclusion of various plant species, such as weeds, contributes to the overall biodiversity of the ecosystem, benefiting both animal and plant lives. This, in turn, reinforces the ecosystem’s ability to withstand disturbances and offers a range of valuable ecosystem services (Berg et al., 2016).

Nevertheless, observers sometimes consider alternative host plants as unsightly and undesirable weeds. The lack of precise knowledge regarding the impact of alternative hosts on insect diversity in rice-growing areas contributes to the damage to rice crops. Therefore, this study aims to determine the number of insect species on various alternative hosts and evaluate the ecological diversity of insects on each alternative host plant. Additionally, this study seeks to clarify the beneficial role that rice farmers could exploit by incorporating these alternative host plants in their paddy fields.

This study has revealed that the insect orders Hemiptera, Hymenoptera, and Diptera have the highest documented population sizes among all other orders, with 1,191, 369, and 268 total individuals, respectively. This finding aligns with prior research indicating that Hemiptera (Razali et al., 2015; Yaakop et al., 2022; Khalid et al., 2024), along with Lepidoptera (Sulaiman et al., 2013), exhibit a greater presence in Malaysian rice fields. Lepidoptera exhibited the greatest richness among the organisms studied, comprising 10 species. However, it is worth noting that Chilo auricilius Ddgn. was reported to be the most commonly found species in the study conducted by Yaakop et al. (2020). However, the research results may deviate from the actual perspective of species abundance due to climate change considerations that would impact the rice fields in Malaysia (Tang, 2019), influencing both species richness and abundance.

The two pest species with the largest population in this study were S. furcifera and R. dorsalis, both of which were found in every host examined in this investigation. S. furcifera, also known as the white-back planthopper, is a significant Asian rice pest (Li et al., 2016; Yaakop et al., 2022). On the other hand, R. dorsalis serves as the primary carrier for transmitting rice dwarf virus (RGDV), playing a significant role in agriculture (Chen et al., 2013). Therefore, understanding these interactions is crucial for developing strategies to control RGDV and protect rice crops from reduced output.

Arthropods were found to be more diverse and uniform on S. verticillata compared to other host species. The diversity of host plant species is an important factor in arthropod diversity, which provides more ecological niches to support a wider range of arthropod species (Jaworski et al., 2023). Diverse arthropod species can be promoted through the provision of diverse food resources, such as varied prey or host species. This suggests that having a variety of host plants can support more diverse arthropod communities (Schowalter, 2017; Jaworski et al., 2023). Engel et al. (2020) also found that alternative host plants, specifically Eustachys retusa K., Andropogon bicornis L., and Saccharum angustifolium N., play a significant role in supporting predatory arthropods in areas surrounding soybean-corn succession systems. The diversity and abundance of these predatory species are also influenced by environmental factors such as the clump diameter of the plants and air temperature during the off-season (Engel et al., 2020). Maintaining diverse plant habitats to enhance the presence of beneficial predatory arthropods is important, which contributes to sustainable pest management in agricultural settings. Integrating alternative host plants into farming practices could improve pest control and promote biodiversity within agroecosystems (Ebeling et al., 2018). Alternative host plants could also play a crucial role in maintaining arthropods when the main crops are absent.

Different growth stages of plants can attract various arthropod communities. Young plants may support different species compared to mature plants, influencing the overall diversity present at different times (Ali et al., 2022). The structural complexity of rice plants at different growth stages provides various niches for arthropods. For example, taller and denser vegetation during the vegetative and reproductive stages can support a wider array of species, including both pests and beneficial insects (Norazliza et al., 2014; Jauharlina et al., 2019). As rice plants grow, they produce different types of foliage and reproductive structures, which can attract a variety of arthropods. The flowering stage, in particular, is critical for pollinators and beneficial insects while also supporting pest species that may increase in number during this time.

The diversity of arthropods can also be affected by the presence of pest species that thrive during certain growth stages. For example, the reproductive stage often sees an increase in pest populations, which can influence the dynamics of predator-prey relationships and overall arthropod diversity in the ecosystem (Thei et al., 2020). The interactions between different arthropod species, including competition and predation, are influenced by the growth stage of the rice plants. This can lead to shifts in community composition, with some species thriving in certain stages while others decline (Ali et al., 2022).

Although there was a correlation between the alternative hosts with predatory insects and parasitoids, their effectiveness in doing so is relatively low compared to pest insects. The most frequently collected parasitoid species was T. schoenobii, which plays a significant role in the rice ecosystem by parasitizing the eggs of the stem borer, S. incertulas (Sitepu et al., 2018). Therefore, it can help manage insect populations and minimize damage to rice plants (Wilyus et al., 2012). However, in this study, T. schoenobii has shown a non-significant correlation among the tested alternative hosts. T. schoenobii has been observed to be attracted to certain types of flowering plants, including Tagetes erecta L. This attraction is probably triggered by specific chemicals found in plant extracts, such as benzaldehyde, limonene, linalool, and phenylacetaldehyde (Sharma et al., 2019). Alternative hosts may provide essential resources, such as nectar and pollen, which support beneficial insects like pollinators and natural enemies of pests. This can enhance the overall balance of the ecosystem. The attraction of insects to weeds can also lead to increased biodiversity within agricultural ecosystems (Kleiman & Koptur, 2023). While alternative hosts can attract beneficial insects, they may also attract pest species. This dual role suggests that managing weed populations carefully is essential for maximizing benefits while minimizing potential drawbacks, such as increased pest pressure (Madden et al., 2021). For example, specific chemicals like methyl salicylate and other fatty acids have been shown to lure natural enemies and pests alike, indicating that the chemical composition of weeds can influence the diversity and abundance of insect populations in agricultural settings (Jakubska-Busse et al., 2023).

Micraspis discolor is a prominent predator that plays a vital role in managing harmful organisms and minimizing crop damage. Its presence and distribution in paddy fields fluctuate throughout various stages of rice growth. For instance, Mukherjee and Khan (2017) revealed that the population of M. discolor peaked during the rice growth stage, aligning with optimal harvest conditions. Although their population trend showed an overall increase during the planting season, there was no significant difference, with slightly higher numbers observed during the mature stage. This species tends to emerge later in rice fields, likely influenced by factors such as food availability. In the early growth stages, when pest populations are generally lower, M. discolor may not be as abundant. However, as pest populations surge, especially during the reproductive phase of rice, M. discolor populations also rise in response to increased food resources. Similar observations have been reported by several researchers, who suggest that the presence and behavior of these beetles are influenced by prey availability and suitable habitats during specific phases of rice cultivation (Woïn et al., 2006; Yudha et al., 2022). M. discolor is particularly effective at preying on aphids such as Aphis fabae Scopoli and Aphis craccivora Koch, which are commonly found in crops (Islam et al., 2016; Rain et al., 2016). However, it is noteworthy that during the flowering period, the abundance of adult M. discolor may indicate a preference for pollen consumption over entomophagy (Chitra et al., 2013).

Plants use a combination of floral scents, colors, and nectar rewards to attract insects (Garbuzov & Ratnieks, 2013). Plants produce several volatile organic compounds in their flowers that act as semiochemicals, mediating interactions with insects (Kong et al., 2005; Bouwmeester et al., 2019). Certain colors are particularly attractive to specific insect pollinators. Nectar, which is mainly composed of sugars, amino acids, lipids, and sometimes toxins, serves as a crucial factor in attracting insects to flowers (Jakubska-Busse et al., 2023). The study suggests that S. verticillata blooms have a significant capacity to attract insects, as evidenced by the increased uniformity and diversity observed in the S. verticillata compared to other hosts. Furthermore, Procheş et al. (2009) suggested a positive association between the diversity of plant phylogeny, the number of plant genera in each area, and the diversity of insect species.

The population of insect species is higher during the reproductive and mature stages of rice growth. This could be due to the many seedlings and a larger canopy area compared to the vegetative stage. Multiple studies have supported this finding, particularly in the Hemiptera species (Yaakop et al., 2022). Similar patterns have been observed in rice stem borer caterpillars (Lepidoptera; Yaakop et al., 2020), as well as in paddy areas implementing the System of Rice Intensification (SRI) for rice cultivation (Sulaiman et al., 2013). Bambaradeniya et al. (2004) also noted that variations in the richness and abundance of these species result from differences in the phenology of rice growth. This is influenced by variations in the fertilizer used, water level, and insecticide application. According to (Su et al. 2015), the Hemiptera species have abundant food supplies and exhibit the greatest abundance during the mature stage of the rice plant.

This study found a strong correlation between pests, predators, and other insects with alternative hosts. These findings indicate that alternative hosts have specific preferences for insects, probably serving as reliable food sources and providing protection from adverse weather conditions (Afun et al., 1999). Kohli et al. (2006) reported that A. conyzoides exhibited rapid growth, a short life cycle, significant reproductive capacity, and strong competitive ability. These characteristics make it an ideal alternative host for insects, especially pests. A. conyzoides grows quickly and completes its life cycle in a short period. The short life cycle coupled with high reproductive capacity means that A. conyzoides can produce numerous seeds in a short time, allowing it to spread rapidly and colonize large areas, further intensifying competition. With continuous seed production, this weed can maintain a persistent presence in agricultural fields, requiring consistent and costly management efforts (Kaur et al., 2023). Additionally, A. conyzoides might also attract natural enemies of pests, potentially aiding in biological control. However, this benefit depends on the specific ecological interactions and the management practices in place (Rioba & Stevenson, 2017).

On the contrary, A. conyzoides can harbor insect pests, providing them with a continuous food source and habitat, especially during periods when rice is not in its most vulnerable stages. This can lead to a buildup of pest populations that may subsequently move to rice plants, causing damage and potentially reducing yields if not managed properly (Kaur et al., 2023). However, this investigation showed a significant decline in the pest population of A. conyzoides and S. verticillata hosts. It is likely that while rice plants are growing and able to provide ample food and protection from favorable weather conditions, most pests have shifted their focus to rice plants. This has resulted in a decrease in insect pests on A. conyzoides, as confirmed by the sampling conducted in this study. The host plant S. verticillata is more attractive to parasitoids (Portman et al., 2010) than to insect pests because it releases nectar, which serves as a food supply for the parasitoids. Parasitoids have indirectly contributed to reducing pests on alternative hosts of S. verticillata. However, the observed trend of parasitoids was not statistically significant.

It has been observed that parasitoids have a limited association with alternative hosts when the number of individuals on those hosts is low. Previous research has indicated that S. verticillata is the main source of nectar for parasitoids, particularly the L. bicolor species, compared to other native plants such as Spermacoce remota Lamarck or Spermacoce prostrata Aubl. The abundance of immature wasps parasitizing mole crickets was found to increase with host density but decrease with distance from S. verticillata plots. The findings also imply that establishing patches of S. verticillata at least 400 m apart could potentially help reduce mole cricket populations when L. bicolor wasps are present in the area (Portman et al., 2010). On the other hand, this study has shown that S. verticillata does not appear as a preferred host plant for a wide variety of parasitoid species. The absence of parasitoid species in this study can be attributed to the lack of nectar sources provided by alternative hosts for adult parasitoids. During the adult phase, predators and parasitoids frequently consume nectar from plant blossoms. Therefore, the presence of plant food (such as nectar) enhances survival and also other parameters that contribute to increasing its intrinsic growth rate (r_m; Russell, 1989; Capinera, 2005). This would serve as a food source and alternative habitat for parasitoids and other biological control agents, consequently increasing their population (Ali et al., 2019, 2021). This ecological engineering approach is highly effective in promoting the implementation of Integrated Pest Management (IPM) on rice crops, which is known for its ecologically friendly and sustainable practices (Badrulhadza et al., 2018).

The specific alternative hosts displayed higher levels of consistency and variety in the arthropod population inside the rice farming environment. Although it has the potential to improve insect control and soil quality, its invasive characteristics and toxicity necessitate cautious evaluation. Efficient management strategies and more research are crucial for optimizing the benefits and minimizing the drawbacks of rice cultivation. Alternative hosts possess the ability to rapidly develop, reproduce, and compete, enabling them to outperform rice growth in agricultural areas by acquiring vital resources. Additionally, they can also facilitate the rapid growth of arthropod populations that may subsequently target rice and cause harm to crops. The growth of rice plants and the diversity of arthropods have a significant impact on ecological interactions, ecosystem services, and the composition of arthropod populations in different contexts. Comprehending the impact of different stages of plant growth on the diversity of arthropods is essential for developing efficient strategies for managing pests. Farmers could synchronize their actions, such as applying pesticides, with stages of growth in order to reduce the negative impact on helpful arthropods and improve the effectiveness of natural pest control methods. Thus, it is recommended to promote these naturally growing alternative host plants as well as cultivating different types of nectar-rich plants, such as T. erecta (marigold), Cosmos sp. (cosmos), Helianthus annuus L. (sunflower), and Sesamum indicum L. (sesame), along the banks and borders of rice farming areas to encourage the presence of indigenous predatory insects. This aligns with the objectives specified in the Integrated Pest Management (IPM) approach, which is currently being embraced by rice producers.