The study was conducted in mango orchards across two agroecological zones (AEZs) of Cameroon: the Sudano-Sahelian Savannah (AEZ 1) and the High Guinea Savannah (AEZ 2) [7] . These AEZs differ significantly in terms of altitude, climate, and dominant vegetation as documented in previously studies [7] , thus providing a relevant ecological context for assessing the biological and ecological diversity of parasitoids and the biogeographic host-parasitoid associations.

AEZ 1 is characterized by a dry climate, with an average annual temperature of 28˚C, a prolonged dry season lasting seven months (from mid-November to mid-May), annual rainfall ranging from 500 to 900 mm, and altitudes between 250 and 500 meters above sea level [35] . The orchards studied in this zone included Mbé (E 13˚36'949"; N 7˚50'743"; 590 m), Ngong (E 13˚31'956"; N 9˚03'149"; 290 m), Lagdo (E 13˚40'985"; N 9˚04'138"; 200 m), and Djefatou (E 13˚31'452"; N 9˚09'434"; 260 m). All these orchards are located near areas of intensive cucurbit cultivation. At the time of the study, the vicinity of Mbé orchard experienced frequent pesticide use. The Djefatou and Ngong orchards were subjected to high anthropogenic pressure, particularly due to the systematic collection of attacked fruits for livestock feed.

AEZ 2 has a humid climate, with an average annual temperature of 23˚C, a prolonged rainy season from April to November, annual rainfall ranging from 1,500 to 1,800 mm, and altitudes between 500 and 1,500 meters above sea level [35] . The orchards selected in this zone included Malang (E 13˚32'948"; N 7˚27'233"; 1110 m) and Manwi (E 13˚32'835"; N 7˚22'760"; 1100 m), both characterized by semi-natural vegetation and low pesticide use in the surrounding areas, as well as Marza (E 13˚35'227"; N 7˚16'290"; 1100 m), which presented conditions similar to those observed in Mbé. Orchard selection was based on mango production intensity, the absence of pesticide use, cultivar diversity, and documented history of tephritid infestation.

Biweekly sampling was conducted during two mango fruiting seasons (2021-2022). A total of 2,795 fruits were collected from 26 cultivars, including 17 commercial cultivars: Alphonso, Alphonso Hawai, Amélie, Brooks late, Eldon, Ruby, Sabot, Julie, Valencia, Smith, Palmer, Kent, Keitt, Ifack 1, Ifack 5 Haden, Tommy Atkins and 9 local cultivars.

Fruits showing signs of tephritid infestation, such as oviposition punctures, larval exit holes, or premature fruit drop, were randomly sampled both from tree branches and the ground. To ensure cultivar representativity, 5 to 10 fruits per cultivar were collected during each sampling date, depending on fruit availability. Each fruit was labeled, assigned a reference code, and transported to the Laboratory at the Applied Zoology (LAZOA) at the University of Ngaoundéré for incubation and further analysis.

Each sampled fruit was placed in a transparent plastic incubation box containing oven-sterilized sand, to facilitate larval pupation, and covered with a fine mesh screen to allow gas exchange while preventing the escape of emerging insects. One week after incubation, the pupae formed in each box were regularly collected, transferred to new incubation containers, and monitored until adult emergence [36] . Emerging tephritids and parasitoids were counted, sorted into morphospecies, and preserved in 70% ethanol for identification.

The tephritid specimens obtained were identified to the species level using morphological keys appropriate for economically important species [37] . These identifications were confirmed by Dr. Marc De Meyer of the Royal Museum for Central Africa (RMCA) in Tervuren, Belgium.

The parasitoids were identified, some to the species level, using a dichotomous key [38] and the online database by Wharton and Yoder, available at: http://paroffit.org . Identifications were verified by experts from the French Agency for Food, Environmental and Occupational Health and Safety (ANSES) in Montpellier, France.

Voucher specimens are preserved in 70% ethanol at LAZOA.

Parasitoid species abundance was assessed using the index of Dajoz [39] , based on the relative abundance (p_i), calculated as follows:

$p_i=\frac{n_i}{{\displaystyle \sum n_i}}$

where n_i is the number of individuals of a given parasitoid species or hymenopteran wasp family, and ${\displaystyle \sum n_i}$ is the total number of individuals in the community. The value of p_i was classified as follows:

This classification was visualized using a heatmap. Color gradients (YlOrRd palette) were scaled from 0% to 100% to reflect dominance within the parasitoid community across the surveyed orchards.

Parasitoid species richness and diversity were assessed using three commonly applied ecological indices: the Shannon-Wiener index (H'), the Simpson index (1 − D), and Pielou’s Evenness index (J').

The Shannon-Wiener index measures species diversity by incorporating both species richness and relative abundance. It is calculated as:

$H^{\prime }=-{\displaystyle {\sum }_{i=1}^{N}pilnpi}$

The Shannon index ranges from 0 (low diversity) to ln(S) (maximum diversity); 0  ≤   $H^{\prime }$ ≤  ln(S).

The Simpson index measures the probability that two individuals randomly selected from a sample belong to different species. It is calculated as:

$D=\frac{1}{{\displaystyle \sum p_i^2}}$

and expressed as 1 − D, where higher values indicate greater diversity, while values closer to 0 reflect dominance by one or a few species.

Pielou’s Evenness index quantifies the uniformity of individual distribution across species. It is derived from the Shannon-Wiener index and calculated as:

$J^{\prime }=\frac{H^{\prime }}{\text{ln}S}$

where H′ is the Shannon-Wiener index and S is species richness. Values of J' range from 0 to 1, with values near 1 indicating a more even species distribution.

Community similarity between AEZs and orchards was assessed using the Jaccard similarity index, which quantifies the proportion of species shared between two sites. The index was calculated as follows:

$J\left(A,B\right)=\frac{a}{a+b+c};$

where:

Jaccard values range from 0 (no shared species) to 1 (identical species composition). The resulting similarity matrix was visualized as a heatmap to reveal patterns of community clustering. Color gradients (YlOrRd palette) were scaled from 0% (low similarity) to 100% (high similarity).

Parasitism rate, expressed as a percentage (%), was calculated as the proportion of parasitoids that emerged from a fruit relative to the total number of emerged individuals (parasitoids + tephritids) [40] . Parasitism rates were compared across AEZs, orchards, and cultivars. Means were separated using Tukey’s HSD post hoc test at a significance level of α = 0.05.

Host-parasitoid associations were recorded when individuals of a single parasitoid species and a tephritid host emerged from the same incubation box. These associations were visualized using heatmaps generated with Python libraries (matplotlib and seaborn), where relative parasitoid abundance (pi) was standardized by host species. Color gradients (YlOrRd palette) were scaled from 0% to 100% to reflect the intensity of parasitism. These visualizations highlighted the ecological dominance of parasitoid species across AEZs and tephritid hosts.

All analyses were performed using both R (version 4.3.0) for statistical and ecological computations (vegan, ggplot2, agricolae) and Python (v3.9) for data manipulation and visualization (pandas, scipy).

From a total of 2,795 attacked mango fruits, collected from 26 cultivars across seven orchards located in agroecological zones (AEZs) 1 and 2, yielded 27,654 tephritids and 1,008 parasitoids (Supplementary Materials 1 and 2).

The tephritid community comprised four species, with Ceratitis cosyra being dominant in AEZ 1 and Bactrocera dorsalis in AEZ 2 (Supplementary Materials 1 and 2).

The parasitoids recovered belonged to three hymenopteran families: Braconidae, Figitidae, and Diapriidae, and represented a total of six species ( Figure 1 ).

In the orchards of Lagdo (AEZ 1) and Malang (AEZ 2), three parasitoid species emerged from mango fruits infested by tephritis. The orchard of Manwi (AEZ 2) yielded two species, while only one species was recorded at Marza (AEZ 2) and Mbé (AEZ 1) ( Figure 1 ). In contrast, at Djefatou and Ngong (AEZ 1), premature harvesting of fruits for livestock feeding resulted in a complete absence of tephritid parasitism, despite high levels of fruit fly emergence (Supplementary Material 1).

Marked differences were observed between the parasitoid communities of the two AEZs. AEZ 1 was dominated by the Braconidae family, with the exclusive presence in Lagdo of Fopius caudatus ( Figure 2(a) ), Diachasmimorpha fullawayi ( Figure 2(b) ), and Psyttalia concolor ( Figure 2(c) ). In contrast, AEZ 2 was characterized by the presence of Figitidae, represented by Ganaspis sp. ( Figure 2(d) ) and Ealata saba ( Figure 2(e) ), as well as Diapriidae (Trichopria sp., Figure 2(f) ). According to the Dajoz index, Ganaspis sp. emerged as the most abundant and broadly distributed parasitoid species across both AEZs.

The orchards of Lagdo and Malang exhibited the highest species diversity, reflecting a balanced abundance among the collected parasitoid species ( Figure 3 ). Furthermore, in these orchards, evenness values were close to 1, while Shannon-Wiener index values approached maximum diversity ( Figure 3 ), indicating an equitable distribution of parasitoid species. In contrast, the orchards of Marza and Mbé showed near-zero diversity ( Figure 3 ), due to extreme dominance (100% of the abundance) by Trichopria sp. and Ganaspis sp., respectively ( Figure 1 ).

The Jaccard similarity index between the two agroecological zones was low (> 0.5), indicating distinct community compositions between AEZs ( Figure 4 ).

Overall parasitism rates did not vary significantly between AEZs ( Figure 5(A) ) or between orchards ( Figure 5(B) ). However, notable differences were observed depending on the mango cultivar.

At Lagdo, the Palmer cultivar, characterized by a thin and soft pericarp, exhibited the highest parasitism rate (F = 3.14; df = 3; p = 0.04), which may be explained by greater accessibility of tephritid larvae to the parasitoid ovipositor. In contrast, cultivars with a thick pericarp, such as Kent and Smith, recorded the lowest parasitism rates ( Figure 6(A) ). In the Malang and Manwi orchards, no significant differences in parasitism rates were observed ( Figure 6(B) and Figure 6(C) ).

Heatmap analysis revealed distinct host preferences. Generalist species Ganaspis sp. and Trichopria sp., parasitized multiple hosts, primarily B. dorsalis and, to a lesser extent, Ceratitis species, particularly at Malang and Manwi ( Figure 7 ). Ealata saba showed a strong association with C. cosyra and a low occurrence on B. dorsalis at Malang ( Figure 7 ), suggesting a higher level of host specificity. Additionally, F. caudatus, D. fullawayi, and P. concolor were predominantly associated with C. cosyra and, to a lesser extent, with B. dorsalis at Lagdo.