Insect pests incidence of peanut (Arachis hypogaea L.) in the dryland of Kupang District, East Nusa Tenggara, Indonesia

The presence of insect pests is one of the obstacles in efforts to increase peanut production in Kupang District. This study aimed to evaluate farmers’ knowledge of peanut insect pests and assess their adopted control measures and to identify the types of insect pests and their respective incidence rates in peanut crops. Within each sub-district, two villages were selected on the advice of the local extension agents; five farmers were interviewed using predefined checklists. The checklists were designed to gather information about the farmers’ awareness of various pests affecting their peanut crops and the measures they employed to safeguard their crops. The second part of the study involved examining peanut fields in the chosen locations to assess pest infestation. The results revealed that farmers demonstrated a comprehensive understanding of the insect pests frequently linked to peanut cultivation, but the majority of farmers (64.3%) did not try to control insect pests on their peanut plants. Five insect pests were identified on peanut plants: Aphis craccivora, Anoplocnemis phasiana, Aulacophora indica, Chrysodeixis chalcites, and Lamprosema indicata. The incidences of the identified pests varied between 14.1% to 26.8%. Lamprosema indicata exhibited the lowest incidence, while Aphis craccivora had the highest.


Introduction
Peanuts, also known as groundnuts in some regions, are the edible seeds of a leguminous plant.The peanut, scientifically labelled as Arachis hypogaea L., is classified as a type of pea and is part of the legume family (Fabaceae).Despite being a legume, it is often categorized as an oilseed due to its high oil content.In addition to its oil, peanuts have a wide range of uses, including producing peanut butter, confectionary items, roasted peanuts, and snack products, as well as their incorporation as extenders in meat product recipes, soups, and desserts [1].Peanut seeds provide valuable protein, lipids, and essential fatty acids and are a good source of many bioactive compounds with recognized health benefits, such as tocopherols, vitamins, and phenolic compounds [2].Peanuts are enjoyed globally in diverse preparations, many deeply rooted in traditional culinary practices.
In Indonesia, peanut is the second most significant legume, following soybeans, in terms of importance [3].There are approximately 7.7 million hectares of drylands with a semi-arid climate suitable for agricultural occupations, of which 3 million hectares can be found in East Nusa Tenggara (ENT) Province, Indonesia, as reported by Dariah and Heryani [4].Within ENT Province, the drylands with semi-arid climates offer the potential for cultivating various food crops, such as maize, mungbeans, and peanuts.Nationally, ENT Province ranks 6th in peanut production in Indonesia, and one of the primary peanut production areas in ENT is Kupang District in Timor Island.The peanut productivity data in the ENT Province for 2019 to 2021 were 0.941 ton ha-1, 0.889 ton ha-1, and 1.003 ton ha-1, respectively.Similarly, in the Kupang District, for the same years, the peanut productivity was recorded 1346 (2024) 012029 IOP Publishing doi:10.1088/1755-1315/1346/1/012029 2 as 0.932 ton ha-1, 0.930 ton ha-1, and 0.812 ton ha-1 [5,6].These productivity figures are considered low, as full implementation of technological innovations for productivity enhancement could raise peanut yields to over 4.8 tons per hectare of dried pods [7].
Peanuts are vulnerable to various living organisms and environmental stresses, which can negatively impact their yield and quality and raise concerns about food safety [8,9,10].The key pests in peanut are the pod borer (Etiella zinckenella), peanut planthopper (Empoasca fascialin), leaf borer (Stomopteryx subscevivella), spanworm (Plusia chalcites), armyworm (Spodoptera litura) [11], and aphids [12].Aphids exhibit a particular affinity for young shoots and petioles.Notably, aphids also function as virus vectors responsible for inducing peanut stripe disease, characterized by leaf symptoms such as dark green and light stripes, chlorosis, and stunted growth [12].Regrettably, information concerning the presence, symptomatic expressions, and resultant damage caused by these insect pests is currently unavailable to peanut farmers in Kupang.Contrarily, survey findings reveal pest-induced symptoms in multiple peanut plants across diverse locations within Kupang District.
An effective and environmentally friendly pest involves implementing an integrated pest control system.A pivotal strategy supporting integrated pest control is comprehensively monitoring various plant pest organisms.Therefore, farmers' knowledge about types of pests in peanut plants, coupled with their initiative to control them, is necessary as a basis for carrying out control measures.Hence, this research was carried out to achieve the following aims: (a) evaluate farmers 'knowledge of peanut insect pests and assess their adopted pest control measures, and (b) identify the types of insect pests and their respective incidence rates.

Materials and Methods
The research, spanning a one-year duration, comprised two distinct components: farmer perception surveys and practical field assessment involving diagnosis and sample collection.Surveys were conducted in five sub-districts, specifically Amarasi, West Fatuleu, East Kupang, Semau, and Takari (Figure 1).

Farmers 'knowledge regarding the insect pests on peanuts and control measures
In each sub-district, two villages were chosen based on recommendations from local extension agents.Subsequently, interviews were conducted with 10 -15 farmers in each village using predefined checklists.The checklists aimed to gather insights regarding the farmers' awareness of different pests affecting their peanut crops, their assessment of the damage caused, and the preventive measures they employed to safeguard their crops against these issues.During the interview, farmers were also provided with a picture list containing pest insects and the symptoms of their damage, making it easier for farmers to explain the pests affecting their peanuts (Table 1).These interviews took place immediately after the harvest, ensuring that respondents' experiences from the recent growing season were still vivid in their recollections.The second component of the study encompassed sampling of peanut fields in the chosen locations to assess the presence of pests.Five farmers, each located at a minimum distance of 3 kilometres apart, were randomly chosen and subjected to pest sampling within each sub-district.The utilization of insect nets for sampling was mainly directed toward pre-adult stages characterized by enhanced flying mobility.

Whitefringed weevil
Imago of G. leucoloma [14] Attack symptoms of whitefringed weevil on peanut pod [14] 2.2 Types of insect pests and their respective incidence rates Direct observation techniques were done to collect samples from stages with diminished mobility, such as larvae, nymphs, and imago of the aphid group, and to observe symptoms indicative of pest attacks.Pests were identified directly in the field, but if not identified, pest samples were brought to the laboratory for precise classification based on Kalshoven [23].The data collected consisted of damage symptoms and the intensity of attacks from each identified pest.The intensity of peanut plant attacks was calculated using absolute and non-absolute damage formulas.Absolute damage observations involved counting the shoots/offshoots/clumps/other parts of the plant affected by insect pests.Nonabsolute damage observations were conducted by determining a damage scale (score) resulting from insect pest attacks.The formula for absolute damage is I= a/ (a + b) x 100%, where I= the intensity of damage, a= the number of plants/parts of plants affected, and b= the number of plants/parts of plants unaffected.The formula for non-absolute damage is I = ∑ (n x v)/N x V x 100%, where I = the intensity of damage, n = the number of peanut leaves of each attack category, v the scale value for each attack category, Z= the scale value for this highest attack category, N = the number of peanut leaves observed for each plant.The attack category scores and criteria are presented in Tables 2 and 3

Farmers 'knowledge regarding the types of insect pests affecting peanuts
Farmers were familiar with various pests and diseases commonly associated with peanuts, as indicated in Table 4. Notably, aphids Aphis craccivora (Hemiptera: Aphididae), cucurbit beetle Aulacophora indica (Coleoptera: Chrysomelidae)), and golden twin spot moth Chrysodeixis chalcites (Lepidoptera: Noctuidae) emerged as the most easily recognizable among these.Moreover, over 70% of the respondents exhibited the capability to elucidate the characteristics of these pests and articulate the nature of the harm they inflict upon peanut crops.
Despite a general awareness among most farmers (80%) regarding the damage wrought by pests to their crops, a notable finding in Table 5 reveals that most of them needed to undertake deliberate measures for their control.In cases where farmers take action against pests, farmers primarily resort to physical methods, most notably handpicking (22.38%).A minority of respondents (10.52%) also mentioned applying pesticides as a control measure.

Types of insect pests and their respective incidence rates
Surveillance and sampling of peanut fields revealed the incidence of some insect pests recorded on peanut crops in Indonesia (Table 6).Foliar pests included sap-suckers, notably aphids (Aphis craccivora), tip-withering bugs Anophlocnemis phasiana (Hemiptera: Coriodae), cucurbit beetle Aulacophora indica, golden twin spot moth (Chrysodeixis chalcites) leaf roller caterpillars Lamprosema indicata (Lepidoptera: Pyralide).The incidence of the identified pests varied between 14.1% and 26.8%.Lamprosema indicata exhibited the lowest incidence, while Aphis craccivora exhibited the highest incidence.

Discussion
Aphis craccivora is recognized as one of the most harmful sucking pests in peanut cultivation, responsible for inducing yield losses and acting as a vector for transmitting viral diseases [11,12].Severe infestations of aphids give rise to a range of adverse effects, including the inhibition of plant growth, deformation and distortion of leaves, and delayed onset of flowering, ultimately leading to a decrease in overall crop yield.Significantly populous aphid populations exude substantial volumes of honeydew, creating a favorable environment for the proliferation of sooty mold on plant foliage.This, in turn, hampers the photosynthetic efficiency of the affected plants [8,23].
Several research findings have also reported the presence of attacks by Anophlocnemis phasiana, Aulacophora indica, Chrysodeixis chalcites, and Lamprosema indicata in various peanut cultivation locations in Indonesia [28,29,30].Anophlocnemis phasiana infests the tender leaf buds of peanut plants, leading to wilting, desiccation, and a browning effect resembling burn damage.The telltale signs of Aulacophora indica infestation are leaves riddled with holes or reduced to mere leaf veins due to their feeding and tissue consumption.In severe infestations, all leaf tissues are consumed, and the larvae of these beetles also burrow into the plant's roots and stems.Chrysodeixis chalcites, on the other hand, primarily affects the young leaves of peanut plants by feeding on the leaf margins, causing them to appear torn and, in severe cases, resulting in extensive leaf perforations and the complete denudation of the plant's growing tips.Subsequently, when the young leaves and growing dividends are entirely depleted, this pest intensifies its assault on the older leaves beneath.Lamprosema indicata infestations manifest in the form of rolled leaves.Upon unrolling these leaves, one may encounter larvae or larval excreta characterized by a dark brown-black coloration.The adult stage of this pest, represented by a small, brownish-yellow moth, can be observed.
The findings also demonstrated that the incidence of peanut pests in the tropical Kupang District is low to moderate (Table 5).However, attention is still required to stop the spread of pests.When considering pest control methods for the future, the first thing that should come to mind is the array of tools already available to growers.Integrated pest management, IPM or IDM, is the overarching principle underpinning all pest and disease management strategies.The four primary components of IPM are biological, cultural, mechanical/physical, and chemical.Each pest or disease control tactic attempts to bring these elements together to develop a strategy that is both economically beneficial and sustainable [31].In a peanut system, for example, it is necessary to investigate the impact of microclimate, soil types, fungicide programs, and irrigation schedules on pest and disease development.This data could help researchers better understand the variation associated with a management technique and target more effective strategies in areas where pest or disease is more likely to occur or be more severe.The impacts on rural communities should be assessed to increase the successful integration of these new strategies into production agriculture [32][33][34].

Conclusion
A noteworthy majority of farmers, constituting 64.3%, were observed to refrain from implementing proactive measures to control insect pests on their peanut plants.Five insect pests were identified on peanut plants: Aphis craccivora, Anoplocnemis phasiana, Aulacophora indica, Chrysodeixis chalcites, and Lamprosema indicata.The incidence of the identified pests varied between 14.1% to 26.8%.Lamprosema indicata exhibited the lowest incidence, while Aphis craccivora had the highest.Farmers demonstrated a comprehensive understanding of insect pests frequently linked to peanut cultivation.Notably, the accorded paramount importance to insect pests as a significant impediment to peanut production.

Table 1 .
List of common pests found on peanut plant

Table 4 .
Pests and diseases mentioned by 120 farmers of peanut crops in Kupang District

Table 5 .
Control measures adopted by 120 farmers of peanut crops in Kupang District

Table 6 .
Mean pests incidence of peanut crops in Kupang District (%)