Evaluation of commercial trap types and lures on the population dynamics of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) and its effects on non-targets insects

Abstract

The trapping efficacy and specificity of a commercially available two types of traps; funnel and delta traps, two types of lures; botrack (sex pheromone) and femtrack (floral attractant) were evaluated to determine the population dynamics of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) and its effects on non-target insects under field condition of Dandi district during 2018/2019. The result obtained indicates that the funnel-botrack was captured H. armigera moth more profoundly than the other treatments, followed by a femtrack with the same kinds of trap. Likely, funnel-botrack was less effect on non-target insects than the other treatment combinations. Funnel types were more effective than sticky traps in catching H. armigera. Delta traps captured the highest number of non-target insects and recorded the lowest capture of H. armigera moths. Significantly more non-target moths were captured in delta-femtrack and delta-botrack treatments. Across all traps and lure combinations, 6,332 non-target insects were collected, belonging to five major insect orders. The most commonly collected insect orders in descending order were Diptera -> Lepidoptera -> Coleoptera -> Hymenoptera or at a family level, Noctuidae -> Tachinidae -> Muscidae were common in traps baited with H. armigera lures. We noted that, two population peaks in Ethiopia. Our results suggest that the funnel-botrack combination was efficient and specific to capture H. armigera under the agro-ecology of the Dandi district in Ethiopia.

Keywords:

• lures
• traps
• population dynamics
• pheromone

PUBLIC INTEREST STATEMENT

The cotton bollworm, Helicoverpa armigera, is a polyphagous insect pest of many economically important crops worldwide. Insect pest monitoring using commercially available effective and specific trap and lures are alternative management for suppression and prediction of its occurrence through population dynamics study. Hence, two type of traps; funnel and delta, two types of lures; botrack (pheromone) and femtrack (floral attractant) were evaluated to determine its effectiveness and specificity on the population dynamics of H. armigera, and its effects on non-target insects during 2018/2019 at Dandi district, Oromiya, Ethiopia. Funnel-botrack was captured the H. armigera moth more profoundly than the other treatments and less effect on non-target insects than the other treatment combinations. More non-target moths were captured in delta-femtrack/botrack treatments. We noted that, two population peaks in Ethiopia. Our results suggest that the funnel-botrack pheromone trap was effective and specific to capture H. armigera under the agro-ecology of the area.

Competing interests

The authors declares no competing interests.

1. Introduction

The cotton bollworm, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), is among polyphagous insect pest of many economically important crops worldwide (Fitt, 1989). In Ethiopia, H. armigera is one of the most destructive insect pests, causing considerable economic loss to chickpea (Dagne et al., 2018; Damte & Ojiewo, 2017; Fite et al., 2018). In chickpea, it causes up to 33 % pod damage in Ethiopia (Tebkew, 2004) and 70 to 95 % in India (Prakash et al., 2007), which make it economically important insect pest of chickpea (Ali et al., 2012; Fite et al., 2018, 2020) elsewhere. The moths begin ovipositing on chickpea in the seedling stage but, this oviposition behavior is influenced by adverse climatic and geographical conditions (Tahhan et al., 1982). H. armigera starts devouring the young shoot leaves available soon after hatching. However, its severity increases during flowering and pod setting stages as larvae get maturity.

In many crops, including chickpea the major control methods for H. armigera is dominated by the use of conventional synthetic insecticides (Alvi et al., 2012; Vivan et al., 2017), which may have irreversible side effects to the environments and human health. Besides such side effects, such insecticide use on H. armigera has led to the development of resistance to many conventional insecticides and destruction of non-target beneficial natural enemies (Armes et al., 1996; Geremew & Surachate, 2005; Kranthi et al., 2002).

To overcome these problems, timely prediction of the occurrence of the H. armigera can be made using pheromone trap to detect its infestation early and to predict the need-based insecticide application program (Witzgall et al., 2010) so that the insect can be controlled at its initial stage before inflicting economic loss to the hosts. However, complementary strategies of pest management remain to be tested and assessing new or evaluating the existing pheromone traps are remained unknown in most parts of Africa. Lepidopteran pheromone has been successfully used for insect monitoring, mass trapping, and mating disruption of a diversity of insect pests (Guerrero et al., 2014; Keathley et al., 2013; Spears & Ramirez, 2015). More friendly, pheromone blends are species-specific which makes a meaningful decision making before pesticide application in pest management (Cruz et al., 2012). There have been many efforts to increase trap and pheromone specificity and decrease capture of non-target insects (Mori & Evenden, 2013; Panzavolta et al., 2014). Some trap and lure combinations are attractive to beneficial insects or/and non-target insects that they become unacceptable as pest management tools (Aurelian et al., 2015). For instance, non-target insects are attracted to some monitoring traps and pheromone blends (Guerrero et al., 2014; Keathley et al., 2013; Spears & Ramirez, 2015). Furthermore, some predators have also evolved to detect these pheromones and may use them to identify and locate prey (Verheggen et al., 2007). Thus, to improve the effectiveness of pheromone captures and make the traps a more reliable tool in pest management programs, it is necessary to determine the factors that affect their efficiency (Athanassiou et al., 2004; Boyd & Evenden, 2013). In Ethiopia, some studies on the population fluctuations of H. armigera on chickpea have demonstrated the occurrence of two population peaks of the moths after the main rainy season (Meher peak) and after the small rainy season (Belg peak) (Seid & Tebkew, 2002).

Hence, insect pest management strategies need to be based on sound knowledge of the materials used for population monitoing and detection of the insect infestation before cause economic damage and understanding of peak time of H. armigera. It is important to evaluate the commercially existing pheromone traps and lures on the population dynamics of H. armigera and its effects on non-target insects during chickpea growing season. The baseline information will help us to create a benchmark that could be used by the expertise in the area for efficient and effective H. armigera management in chickpea. Therefore, the objectives of the study were to evaluate commercially available pheromone traps and lures on the population dynamics of H. armigera and its effects on non-target insects, and to determine the relationships of weather conditions with populations of H. armigera moth captured under agro-ecologic conditions of Dandi district in Ethiopia.

2. Material and methods

2.1. Study sites

The study was conducted at Dandi district (located at 09°01.303ʹ N; 038°07.094E and 2285 m.a.s.l) (West Showa zone, Oromiya) of Holota Agricultural Research Centre station, evaluations of the commercial pheromone trap and lures were conducted during 2018 from October to November for eight standard weeks and for 12 months from April 2018 to March 2019 for population dynamics study.

2.2. Evaluations of trap and lures

Two commercial trap designs (delta and funnel traps) and two lure types (femtrack and botrack) were evaluated under field conditions. The test was designed as 2 × 2 factorial experiment replicated two times in a randomized complete block design. Traps without lures were used as a control. The traps were hung with the lure and erected on the field at 1.5 m from the ground. The replicated treatments were erected and arranged in parallel lines at a distance of 120 m intervals (between both treatmrnts and blocks). Details of the products (Table 1) and treatments (Table 2) were indicated below.

Table 1. Types of pheromone lures/floral attractant used and their active ingredients

Product name (Lures)	Active ingredient (a.i.)	Chemical family of a.i.	Manufacturer
Femtrack	Plant Volatile Blend: Phenaacetaldehhyde, 2-Phenylethanol, Limonene Methylmethaxybenzoate, Methyl salicilate	Aldehydes, alcohols, terpenes and acids SYNONYMS: Noctuid moth attractants	Kenya Biologics LTD
Botrack	(Z)-9-Hexadecenal (90%), (Z)-11-Hexadecenal (10%)	Additives: Antioxidant and binder SYNONYMS: Helicoverpa armigera moth attractants	Kenya Biologics LTD

Table 2. Treatments and treatment combinations used for the evaluations of pheromone trap and lure against H. armigera at Dandi district, Oromiya, Ethiopia during 2018/2019

Treatments (traps/lures)	Funnel	Delta
	Treatment combinations
Femtrack	Funnel—Femtrack	Delta—Femtrack
Botrack	Funnel—Botrack	Delta—Botrack

Lures for both were replaced every 30 days (Malik et al., 2002) depending on the manufacturer’s recommendations. Whereas, the sticky papers for delta traps were changed every two weeks. Lures including old lures were stored in a deep freezer. The evaluations were conducted weekly from the data collected every morning at 7: 00 am. The numbers of moth per trap per week were used to establish a score where higher than 3.0 H. armigera moths per trap per week indicates high infestation; moderate infestation, with captures between 0.5 and 3.0 H. armigera moths per trap per week; and low infestation, where the mean capture is lower than 0.5 H. armigera moths per trap per week (Grigolli et al., 2017). We assumed that this evaluation criterion will enable us to judge and identify efficient and specific treatment for the population dynamics study of H. armigera in the current experimental setup.

The collected moths (Figure 1(a)) were taken to Ambo university laboratory, after 24 hr adhesives to guarantee moth quality for confirmation that the catch moths are H. armigera. The moths were identified using identification keys for species-level identifications (Queiroz-Santos et al., 2018) of H. armigera (Figure 2(b,c)). Furthermore, all the catch non-insects were also collected for further order and family level identifications whenever possible.

Figure 1. H. armigera collected moths (a) and frontal view of H. armigera (b) lateral view of H. armigera (c).

Figure 2. Delta trap (a) and funnel trap (b) used to collect the moths for population dynamics study at Dandi district (April 2018 to March 2019).

Based upon their efficiencies and specificity, two treatments consisting of delta trap (Figure 2(a)) and funnel traps (Figure 2(b)) with femtrack and botrack lures were erected as procedures indicated above at the same site. A daily H. armigera moth capture taken data were pooled to gather as of monthly mean and summarized to monthly at the end of the data collection.

2.3. Meteorological data

Weather variables were monitored at the experimental station by an automated weather station. The weather conditions of the area were collected to determine the correlation of weather and populations of H. armigera. Weather data such as maximum temperature, temperature minimum and average temperature (^oC), average relative humidity (mm), rainfall (mm) and wind speed (m/g) were presented in Figure 3(a,b).

Figure 3. Monthly weather condition during the experimental period of Dandi district during 2018/2019. Mean, maximum and minimum temperature, and mean rainfall (a), Wind speed and average air humidity of the location (b).

3. Data analysis

Trap counts were Log10 transformed to meet analysis of variance (ANOVA) assumption whenever necessary. Then, subjected to two-way ANOVA analysis using R (Version 3.5.2) statistical software package (R Development Core Team, 2020). Treatment means were compared by Least Significant Difference (LSD) test at p = 0.05. The correlation between the population of H. armigera and weather parameters were analyzed using Simple Pearson Correlation using SPSS Statistics (version 20).

4. Results

4.1. Evaluations of trap and lures

All the treatments were attractant to moth of H. armigera capture (Table 3). Except for week four (F = 3.816; df = 4; p = 0.0592) and five (F = 3.321; df = 4; p = 0.0795) the number of moth capture per treatment/week was significantly different; such that, week one (F = 4.17; df = 4; p = 0.048), two (F = 4.35; df = 4; p = 0.044), three (F = 14.65; df = 4; p = 0.00164), six (F = 14.65; df = 4; p = 0.00162), seven (F = 8.88; df = 4; p = 0.0071) and eight (F = 5.393; df 4 =; p = 0.0265) standard weeks (Table 3). Funnel-botrack captured significantly more H. armigera moths in this study (F = 24.14; df = 4; p = 0.0003) (Figure 4). However, this value is on par with funnel-femtrack and delta-femtrack treatments (Figure 4).

Table 3. Overall weekly evaluation/captures of H. armigera moths (mean ± SE) by commercial pheromone traps and lure types for eight standard weeks during 2018 (January and February of 2018) under field condition at Dandi district, Oromiya, Ethiopia

Standard weeks/treatments	Week one	Week two	Week three	Week four	Week five	Week six	Week seven	Week eight
Funnel—femtrack	2.59 ± 1.22^abc	2.98 ± 0.47^a	4.24 ±.16^a	2.19 ± 0.65^a	2.36 ± 1.4^ab	2.82 ± 0.24^a	1.82 ± 0.6^b	0.0 ± 0.0^b
Funnel—botrack	4.72 ± 0.67^a	4.58 ± 0.00^a	4.2 ± 0.84^ab	2.64 ± 0.26^a	2.99 ± 0.23^a	2.28 ± 0.77^ab	3.44 ± 1.1^a	4.72 ± 1.2^a
Delta—femtrack	3.78 ± 0.65^ab	2.23 ± 3.16^ab	2.53 ± 0.41^bc	2.78 ± 0.76^a	2.08 ± 1.5^ab	1.36 ± 0.51^b	0.0 ± 0.0^c	2.2 ± 3.08^ab
Delta—botrack	1.73 ± 2.44^bc	1.98 ± 0.36^ab	1.82 ± 0.58^cd	1.22 ± 1.7^ab	0.5 ± 0.7^b	0.25 ± 0.5^c	1.5 ± 0.7^bc	0.0 ± 0.0^b
Control	0.78 ± 0.91^c	0.25 ± 0.50^b	0.43 ± 0.86^d	0.35 ± 0.7^b	0.6 ± 0.71^b	0.00 ± 0.00^c	0.5 ± 0.57^bc	0.25 ± 0.5^b

Note: Funnel and Delta; are types of commercial traps used in this experiment, Femtrack, and botrack; are types of commercial lures. High infestation: > 3 moths of H. armigera/trap/week; Moderate infestation: 0.5–3.0 moths of H. armigera/trap/week; and Low infestation: < 0.5 moths of H. armigera/trap/week. Since, femtrack is floral attractant it attracted both sex (male and female moths); therefore, the data presented for femtrack is the sum of both male and female H. armigera moths.

Figure 4. Overall Helicoverpa armigera moth captured during the evaluation of commercial pheromone traps and lures in the study at Dandi district.

4.2. Diversity of non-target insect captures

Across all traps and lure combinations, 6,332 non-target insects were collected, belonging to five major insect orders (Table 4). The most commonly collected insect order was Diptera, which comprised 33.24 % of the total non-target insects collected. Lepidopterans were the second most abundant non-target insect orders comprising 23.75 %, followed by Coleopterans (17.62 %) and Hymenoptera (14.98 %) captures (Table 4).

Table 4. Abundance and diversity of non-target insect captured during the evaluation of commercial pheromone traps and lures in H. armigera population dynamics study at Dandi district, Ethiopia

Order	Family	Abundance (%)
Hymenoptera^a	Formicidae/ants	580 (9.15 %)
	Apidae/bees	274 (4.32 %)
	Sphecidae/wasps	96 (1.51 %)
Hemiptera^b		651 (10.28 %)
Coleoptera^c	Coccinellidae/lady beetles	738 (11.65 %)
	Curculionidae/weevils	252 (3.97 %)
	Chysomelidae/leaf beetles	132 (2 %)
Lepidoptera^d	Noctuidae	1,504 (23.75 %)
Diptera^e	Tachinidae/Tachinid flies	1321 (20.86 %)
	Muscidae/house flies and stable flies	784 (12.38 %)

^aIncluding all caught of bees, ants, and wasps; ^bbugs; ^cbeetles; ^dFall armyworm and other unidentified microlepidopterans; ^eTachinids and house fly.

4.3. Non-target insects

The effects of the H. armigera pheromone traps on the captures of non-target insects were also compared (Figure 5(a)). The result indicated that several non-target insects also were captured in the H. armigera pheromone traps; there were also significantly different between the treatments in attracting non-target insects (F = 12.71; df = 4; p = 0.0025) (Figure 5(a)). Similarly, the results showing the effects of H. armigera traps and lures on the capture of non-target moths were presented in Figure 5(b). Significantly (F = 14.73; df = 4; p = 0.0016) more non-target moths were captured in delta-femtrack and delta-botrack combinations (Figure 5(b)), which is not the objective of our study, but we considered as a criterion to select specific and efficient pheromone trap combination that is less attractive to non-target insects and high specificity to H. armigera. Whereas, minimum non-target moths attraction was recorded from funnel-botrack on par with funnel-femtrack (Figure 5(a,b)).

Figure 5. Non-target insects captured during the evaluation of commercial pheromone traps and lures in H. armigera population dynamics study at Dandi district. (a) Mean number of overall non-target insects. (b) Mean number of non-target moths captured by the treatments.

Delta-femtrack and delta-botrack were characterized in attracting diverse insect’s orders mainly; dipterans and lepidopteran insect orders to which most of the natural enemies of H. armigera and other beneficial insects have belonged. Therefore, based upon moth H. armigera capture per trap per week and its effects on the non-target attraction, we selected funnel-botrack and funnel-femtrack for population dynamics study of H. armigera in Ethiopia at Dandi district for 12 months under field conditions.

4.4. Population dynamics of H. armigera

Here, we interested to report the results obtained from both funnel-botrack and funnel-femtrack lures because in the absence of one pheromone lures the other may work as an option at the particular district. We noted that two population peaks, the first peak was during June and the second was February for funnel-botrack (Figure 6(a)) while, during November was the first and February were the second maximum population peaks for funnel-femtrack (Figure 6(b)). For funnel-botrack, H. armigera moth capture was first observed during June and re-observed October, during which the moths have begun population built-up until it reached the second maximum population peaks and onward started to decline (Figure 6(a)). On the other hand, moth H. armigera population build-up begun during October and reached the first highest peaks in November and starts to decline in December and re-build-up until it reached the second-highest peak which is during February and declined in March (Figure 6(b)). Comparing both combinations, funnel-botrack was capturing more H. armigera moth, early detecting, more specific and has little effect on non-target insect orders than funnel-femtrack.

Figure 6. Monthly variations in the population of H. armigera moths with temperature and rainfall under field condition from April 2018 to March 2019 at Dandi district in Oromiya, Ethiopia. (a) Population dynamics of H. armigera by funnel-botrack. (b) Population dynamics of H. armigera by a funnel-femtrack.

The number of H. armigera moths showed different relationships with the various weather condition parameters (Figure 7). The population of H. armigera moths increased with increasing wind speed with a coefficient of determination R² values of 0.364 (Figure 7(a)), while the population of H. armigera moths decreased with increasing average air relative humidity (Figure 7(b)), mean air temperature (Figure 7(c)) and rainfall (Figure 7(d)) with a coefficient of determination R² values of 0.26, 0.52 and 0.38, respectively. Wind speed (r = 0.6, p < 0.05) were positively and significantly correlated with the number of captured H. armigera moths. Whereas, air relative humidity (r = −0.51), mean temperature (r = −0.72, p < 0.01), and rainfall (r = −0.62, p < 0.05) were showed a strong negatively correlated with the captured number of moths.

Figure 7. Correlations between captured H. armigera moths and (a) wind speed, (b) air relative humidity, (c) mean air temperature and (d) rainfall during 2018/2019 at Dandi district, Oromiya, Ethiopia. Circles in the figures represent H. armigera moths.

5. Discussion

In this study, we evaluated the effectiveness and specificity of commercial pheromone trap types and lures for H. armigera population dynamics and its effects on non-target insects, and the relationships of weather conditions with populations of H. armigera moth captured.

Funnel-botrack was the most effective in attracting the H. armigera moths and less effect on non-target insects. Perhaps, this variation was due to the properties of species-specific and highly selective of funnel-botrack lures to H. armigera. Performance differences is common among pheromone lures which may have been related to the type of dispenser used in pheromone load and release rates, lures longevity, formulation error, or some other unknown factors (Evenden & Gries, 2010; Roger et al., 1989). Similar studies were also conducted by Guerrero et al. (2014), who found that more male Helicoverpa moths were captured in a bucket than sticky traps, and that sticky traps required more processing time than bucket traps. The trap type we used in the present experiment was funnel and delta types which influenced the number of H. armigera moth captures. Trap type/design is known to impact adult capture of many insects (Reddy et al., 2005). Various pheromone trap designs are commercially available and have been tested against a variety of insect pests (Ávalos & Soto, 2015; Diego et al., 2018; Reddy et al., 2012). For instance, Reddy et al. (2018) demonstrated that pheromone-baited pitfall and ramp traps caught more adults than ground or delta traps in catching adults of pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae). Sex pheromones have been widely used for detection, monitoring, forecasting and control of the population of various moths (Santanu et al., 2017; Witzgall et al., 2010) and plant bugs (Katherine et al., 2017). Besides trap types, a large number of factors can influence the effectiveness of traps and lures such as; pheromone lure substrate, trap color, lure longevity, trap height, and field positions (Abdullah and Mohammad, 2012; Athanassiou et al., 2004; Boyd & Evenden, 2013; Reddy et al., 2009, 2012) in combinations or alone can affect its effectiveness.

The type of lures used within a pheromone type can be an important factor affecting trap capture in various insect orders. For examples, insect response to lure has been described in various insect species (Reddy et al., 2018; Malo et al., 2001) such as in fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) in which membrane lure is better than septa lure to attract the moths (Malo et al., 2001) and Tuta absoluta (Lepidoptera: Gelechiidae) (Roda et al., 2015). Similarly, Evenden and Gries (2010) reported that traps baited with sex pheromone lures from APTIV Inc. (Portland, OR) and ConTech Enterprises Inc. (Delta, BC, Canada) consistently captured more male diamondback moths, Plutella xylostella L. (Lepidoptera: Plutellidae) than traps baited with lures from the other sources tested.

At least five insect orders of non-target insects were responded to the pheromone traps and lures used for evaluation of the destructive H. armigera in the present study. Across the entire, 6,231 insects were captured. The most commonly collected insect orders in descending order were Diptera -> Lepidoptera -> Coleoptera -> Hymenoptera or at a family level, Noctuidae -> Tachinidae -> Muscidae were common in traps baited with H. armigera lures. Studies have revealed that chemical communication is an important component of lady beetle (Coleoptera) (Alhmedi et al., 2010), bee (Hymenoptera) (Howard & Blomquist, 2005), and other moth behavior (Li et al., 2005; Zhang et al., 2012).

The delta trap with either of the lures captured the highest number of non-target insects other than a closely related species; most being flies, beetles bees, and other lepidopterans and recorded the lowest capture of H. armigera moths. Perhaps, the sticky paper may also stick flying and passing various insect species evenly/incidental captures in addition to the specificity of the chemical lures composition. Several studies indicated that non-target insects are attracted to some monitoring traps and pheromone blends (Guerrero et al., 2014; Keathley et al., 2013; Roda et al., 2015; Spears & Ramirez, 2015).

Including some beneficial natural enemies such as ladybird beetles and the tachinids were also attracted to the pheromone blend combinations. It was postulated that some predators have also evolved to detect these pheromones and may use them to identify and locate prey (Verheggen et al., 2007). Although there have been many efforts to increase trap and pheromone specificity and decrease capture of non-target insects (Mori & Evenden, 2013; Panzavolta et al., 2014), some trap and lure combinations are so attractive to beneficial insects that they become unacceptable as pest management tools (Aurelian et al., 2015).

Particularly, Roger et al. (1989) reported that trap design as more influential than the choice of pheromone lures in the capture of non-target moths and others in his study on fall armyworm. For example, many non-target insects were captured in Spodoptera frugiperda pheromone traps even the traps captured more non-target insects than S. frugiperda male (Malo et al., 2001). The same author reported that some non-target insects can be attracted to pheromone-baited traps, including species that are closely related and not related to the target pest. Similarly, Sullivan and Molet (2007) and Spears et al. (2016) who reported that Helicoverpa Zea (Lepidoptera: Noctuidae), which is considered as a non-target insect is strongly attracted to the lures designed for the sibling species, H. armigera. It was evident that H. zea which was one of the invasive destructive and recently introduced insect species in Ethiopia and as a non-target in our study was seriously attracted to the pheromone trap types and lures, particularly delta-botrack. Therefore, it would be beneficial to recommend the funnel-botrack lures in monitoring H. armigera moths in chickpea at the Dandi district.

In our study, funnel-botrack and funnel-femtrack traps were selected for the population dynamics study of H. armigera at the study district. Two population peaks were recorded in the present field study at the site for both funnel-botrack and funnel-femtrack traps. Maximum peak catch moth of H. armigera per trap per month was during February. So, any management options have to be ready before the first peak before causing any economic damage to host plants mainly chickpea at the location. In Ethiopia, studies on the population fluctuations of H. armigera on chickpea have demonstrated the occurrence of population peaks of the moths after the main (Meher peak) and the small rainy season (Belg peak) (Seid & Tebkew, 2002). Whereas, in Egypt, up to four population peaks were reported in cotton by Al-Mezayyen and Ragab (2014) using light traps. Pheromone blends are species-specific which makes meaningful decision making before pesticide application in pest management (Cruz et al., 2012). Due to unknown reasons, except during June for botrack, no infestation was recorded from April until October in both lures. Population build up starts during November and reached it’s the highest peak during February and starts declining in March.

The result of correlation analysis indicated that the number of H. armigera moth capture with that of mean temperature, wind speed, and rainfall was the most weather conditions parameters, determining the number of H. armigera moth capture under Dandi district agro-ecological conditions. Régnière et al. (2012) reported that high-temperature threshold is the main factor governing insect population dynamics. It was reported that geographical variations and host strains alter sexual communication in several lepidopteran species (Groot et al., 2008, 2007). The population of H. armigera moths increased with increasing wind speed while decreased with increasing average air relative humidity, mean air temperature and rainfall. Climatic and geographical conditions are the main abiotic factors in influencing and affecting the biological performance of H. armigera, more particularly influencing the oviposition behavior of the moths (Tahhan et al., 1982). The present finding results are in agreement with those obtained by Potter et al. (1981) on Helicoverpa virescens, Taman (1990) on Spodoptera littoralis and Dahi (2007) on H. armigera who mentioned that the maximum and minimum daily temperature were responsible for the population density of insects under field conditions. It was postulated that temperature as the main influencing factor affecting the insect life history, activity and behavior of field populations and ultimately prediction of future generations (Al-Mezayyen & Ragab, 2014; Amer et al., 2009; Dahi, 2007; Ragab, 2009). Therefore, local evaluation of commercial trap types and lures on the population dynamics of H. armigera and its effects on non-target insects under Dandi agro-ecological conditions are important to develop local IPM packages and implementing information based strategies.

6. Conclusion

This study evaluated commercial traps and lure on H. armigera population dynamics and its effects on the non-target insects at Dandi district, Oromiya, Ethiopia. Funnel-botrack was effective in attracting high moths of H. armigera and relatively specific to the target insect than the other combination we used in this experiment. Comparing both, funnel-botrack has little effect on non-target insect orders than funnel-femtrack. Two population peaks were noted in Ethiopia at the site. The population of H. armigera moths increased with increasing wind speed while decreased with increasing average air relative humidity, mean air temperature and rainfall. Thus, this information may help in insecticide application timing using its specificity and effectiveness and its population peak densities in consideration for economic management and have a significant role in providing local and IPM-based management options to chickpea producers. However, there is a need for determining the economic threshold for better and effective insecticide applications for production profitability and environmental sustainability. Therefore, any management options have to be ready before any economic damage to major host plants at the Dandi district.

Author contributions

TF, TT, TD, and MN; conceived and designed the experiment; TF; conducted the field experiment, collected, and analyzed data; TF, and TD; interpreted the results; TF, TT, TD, and MN; Wrote and approved the manuscript.

Cover image

Source: Author.

Acknowledgements

This study was supported by the USAID Feed the Future IPM Innovation Lab, Virginia Tech, Cooperative Agreement No. AID-OAA-L-15-00001 under the provision of Rice, Maize, and Chickpea IPM Project for East Africa. We also gratefully acknowledge the financial support by the UK’s Department for International Development (DFID); Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); and the Kenyan Government. The views expressed herein do not necessarily reflect the official opinion of the donors. We also appreciate Holota and Debre Zeit Agricultural Research Centers.

Additional information

Funding

The authors received no direct funding for this research.

Notes on contributors

Tarekegn Fite

Tarekegn Fite is an icipe PhD DRIP fellowship student specializing on Agricultural Entomology. Currently, working on a research supported by USAID Feed the Future IPM Innovation Lab, Virginia Tech, under the provision of Rice, Maize, and Chickpea IPM Project for East Africa for his Dissertation research.