Nest Characteristic Features and Prey Selection of Mud Dauber Wasp Sceliphron madraspatanum “Fabricius, 1781”

INTRODUCTION

Wasps are social or solitary nest builders by natural or artificial materials as a substrate. There are 35 species described in the genus Sceliphron worldwide [1]. A few definite groups of sphecid and crabronid wasps construct the characteristic nests with unique architectural patterns to lay their eggs and nurture their larvae. These nests are built out of mud unruffled from nearby mud puddles and hence these wasps are popularly nominated as the “mud daubers” or even the “dirt daubers”. Sphecidae is a cosmopolitan family of bees with solitary or altruistic demeanors that contains digger wasps, for example, mud bees, Sceliphron madraspatanum (Fabricius), and other familiar species, all of which fall into the category of thread-waisted wasps. Nest construction of wasps is very important to protect their larvae from enemies or predators and store the chow for long life. Specific architectural ability and materials used for nest construction are species-specific in the group of wasps.  Earlier, few studies have been done in various species of wasps in the aspects of nest characteristic features and prey selection [2-5].

The individual forage search profession defines a circumstance in which homogeneous individuals in a general population show dissimilarities in food search behavior, each of which specializes in various kinds of prey. Individual expertise is widespread in animals but has not been studied in invertebrates, despite its potential effects on the food networks and population dynamics [6]. In the genus Sceliphron, females create their mud nests in various isolated and dry places, but some of them are usually related to human residential. A single cellule is first created, prepared with a spider, and sealed by a female before working on another cell. Typically, more than one cellule is created to form a cumulative nest. Cells that are not fully accumulated in a day may be temporarily sealed overnight [7, 8].

Generally, many cells of a nest are occult with a mud layer [9-12]. Halder et al. [2] have been observed to make around 10–13 round trips to construct each cell (2.38±0.19 cm x 0.975±0.083 cm) carrying soft mud collected mainly from frequently irrigated fields or nearby irrigation channels with their mandibles and forelegs in S. madraspatanum.

This study was carried out the nest architectural characteristics features and site selection for the nest construction. Moreover, the present study also deals with the prey availability in the nest cells of active nests of Mud dauber wasps.

MATERIALS AND METHODS

The nests were obtained from A.V.C. College Campus, Mannampandal, Mayiladuthurai, Tamil Nadu. The study area belongs to the vegetable agroecosystem and cultivated several vegetable crops like brinjal, bhendi, banana, etc., A total of 25 nests of S. madraspatanum were collected randomly during the period from January to March 2019 every week (every week two to three nests were collected and analyzed) and taken to the laboratory and put in plastic boxes (10 x 8 x 5 cm). Directly after opening the nests to analyze the cells and their structure. Bait was separated from the cells in terms of species and counted manually. The designation of spiders has been done using the thematic expertise and textbook of Indian spiders [13]. Some direct comments of nests were made at the nest site. The statistical analyses are diversity indices and correlation matrix proved the significance of the study and it was done by using IBM SPSS version 25.

RESULTS AND DISCUSSION

Sceliphron madraspatanum mud nests are well lit on surfaces and covered from water and direct sunlight. Some of them were huge, with a solid base, and were challenging to separate. Mud dauber nests showed that mean height from the ground was 52.44 ± 28.86 cm and the average length and width were 4.78±1.67 and 2.35±0.44 cm respectively. The weight of the nest was also studied, the mean weight was 13.94±11.70 g. The mean number of orifices was showed 6.0±1.58 and recorded the highest 10 orifices and four orifices were least.  The number of chambers in the nest was 6.0±1.58 (n=25) and the range of the chamber or cell length was 2.25 to 1.91cm. Nests' shape was maximum rectangle (96%) and few were irregular (4%) and nest substrate orientation was 40% east direction followed by 32% north and 28% west direction. The nature of nest substrate was nearly 80% were walls followed by all other materials have each 4% namely, bamboo poles, strips, cloth, switch box and tables. The nest status also noted its shows nearly 84% of the nest were inactive, with the rest of them being active and were taken further studies such as feed on the chambers.

Among the 25 nests of Mud daubers, four nests were found as active nests and it was showed the mean height from the ground was 32±14.99 cm. Likewise, the nest length and width average was noted 5.13±1.45 and 2.48±0.21 respectively. The nest varied among the four nests from 10.26 g to 42.49 g and the average was calculated as 21.94±7.50 g.  The number of orifices also varied according to their size and weight, it shows four to six and a mean calculated as 5±0.41.

Active nests showed that the mean number of chambers was 5.0±0.7 and length range between 2.25 to 1.91cm. The chamber diameter range was 0.52 to 0.46cm. Active nests were opened for analyzing the prey and larvae of Mud dauber, a total of 24 larvae were isolated from the four active nests and weighed around 3.15 g. Similarly, the feed was also isolated and tally as 153 individuals which belong to order ‎Araneae and weighed 17.27 g. Among the four active nests of Mud dauber, two nests alone have been noticed that the prey items of family Salticidae (5 genera) were showed the highest frequency as well as diversity followed by Lycosidae (1 genus) and Araneidae (1 genus) (Table 1).

Table 1. Spider recorded inactive nests of S. madraspatanum during the study period (n=2)

The diversity indices showed, there is not much variation among the two nests of Mud daubers.  The species richness, dominance index, Simpson diversity index, Shannan’H index, and Evenness are quite the same and individuals vary among the nests (Table 2). 

The active nest shape of the mud daubers was rectangle shape and the substrate orientation of the nest shows 75% west followed by 25% east orientation. The substrate of the nest was preferred as the wall. Statically proved that the water sources positively influence the other dependent factors like nest height from the ground, nest length, number of orifices, and waste materials.  The nest height from the ground positively influenced nest length alone and nest length positively influenced the nest weight.  The nest length significantly influenced the number of orifices and nest weight (Table 3). The correlation matrix for active nests indicated that nest height from the ground significantly influenced spider weight, number of larva in the nest, and larval weight (Table 4).

Table 2. Diversity indices of spiders inactive nest of Mud dauber (n=2)

Table 3. Correlation matrix of variables irrespective of nests S. madraspadnum collected during the study period

Table 4. Correlation matrix of variables Active nests S. madraspadnum collected during the study period

NHG- Nest height from the ground; WS- Water source; NW- Nest width; NL- Nest length; NO- No. of orifices; NWt- Nest weight; WM- Waste materials; SW- Spider weight; No L- No of larva; LW- Larval weight; No S- No of spider